An arsenic hyperaccumulator Pteris vittata L. (Chinese brake) was first discovered in China by means of field survey and greenhouse cultivation. Field survey showed that Chinese brake had large accumulating capacity t...An arsenic hyperaccumulator Pteris vittata L. (Chinese brake) was first discovered in China by means of field survey and greenhouse cultivation. Field survey showed that Chinese brake had large accumulating capacity to arsenic; the orders of arsenic content in different parts of the fern were as follows: leaves】leafstalks】roots, which is totally different from that of ordinary plants; bioaccumulation coefficients of the above ground parts of the fern decreased as a power function of soil arsenic contents. In the control of pot trials with normal unpolluted soil containing 9mg/kg of arsenic, the bioaccumulation coefficients of the above ground parts and rhizoids of Chinese brake were as high as 71 and 80 respectively. Greenhouse cultivation in the contaminated soil from mining areas has shown that more than 1 times greater arsenic can be accumulated in the leaves of the fern than that of field samples with the largest content of 5070 mg/kg As on a dry matter basis. During greenhouse cultivation, arsenic展开更多
A total of 219 agricultural soil and 48 vegetable samples were collected from the midstream and downstream of the Xiangjiang River（the Hengyang-Changsha section）in Hunan Province.The accumulation characteristics,spa...A total of 219 agricultural soil and 48 vegetable samples were collected from the midstream and downstream of the Xiangjiang River（the Hengyang-Changsha section）in Hunan Province.The accumulation characteristics,spatial distribution and potential risk of heavy metals in the agricultural soils and vegetables were depicted.There are higher accumulations of heavy metals such as As,Cd,Cu,Ni,Pb and Zn in agricultural soils,and the contents of Cd（2.44 mg kg^-1 ）,Pb（65.00 mg kg^-1 ）and Zn（144.13 mg kg^-1 ）are 7.97,3.69 and 1.63 times the corresponding background contents in soils of Hunan Province,respectively. 13.2%of As,68.5%of Cd,2.7%of Cu,2.7%of Ni,8.7%of Pb and 15.1%of Zn in soil samples from the investigated sites exceeded the maximum allowable heavy metal contents in the China Environmental Quality Standard for Soils（GB15618-1995,Grade Ⅱ）.The pollution characteristics of multi-metals in soils are mainly due to Cd.The contents of As,Cd,Cu,Pb and Zn in vegetable soils are significantly higher than the contents in paddy soils.95.8%, 68.8%,10.4%and 95.8%of vegetable samples exceeded the Maximum Levels of Contaminants in Foods（GB2762-2005）for As,Cd,Ni and Pb concentrations,respectively.There are significantly positive correlations between the concentrations of Cd,Pb and Zn in vegetables and the concentrations in the corresponding vegetable soils（p〈0.01）.It is very necessary to focus on the potential risk of heavy metals for food safety and human health in agricultural soils and vegetables in the midstream and downstream of the Xiangjiang River,Hunan Province of China.展开更多
A systematic survey of As, Cd, Cr, Cu, Ni, Pb and Zn concentrations in vegetables from 416 samples （involving 100 varieties） in Beijing was carried out for assessing the potential health risk to local inhabitants. T...A systematic survey of As, Cd, Cr, Cu, Ni, Pb and Zn concentrations in vegetables from 416 samples （involving 100 varieties） in Beijing was carried out for assessing the potential health risk to local inhabitants. The results indicated that the metal concentrations in vegetables ranged from 〈 0.001 to 0.479 μg/g fresh weight （fw） （As）, 〈 0.001 to 0.101 μg/g fw （Cd）, 〈 0.001 to 1.04 μg/g fw （Cr）, 0.024 to 8.25μg/g fw （Cu）, 0.001 to 1.689 μg/g fw （Ni）, 〈 0.001 to 0.655 μg/g fw （Pb） and 0.01 to 25.6 μg/g fw （Zn）, with average concentrations of 0.013, 0.010, 0.023, 0.51, 0.053, 0.046 and 2.55 μg/g fw, respectively. The results showed that the concentrations of As, Cr, Cu, Cd, Pb and Ni in vegetables from open-fields were all significantly higher than those grown in greenhouses. In addition, in local-produced vegetables, all HMs except Zn were significantly higher than those in provincial vegetables. The estimated daily intake （EDI） of As, Cd, Cr, Cu, Ni, Pb and Zn from vegetables was 0.080, 0.062, 0.142, 3.14, 0.327, 0.283 and 15.7 μg/（kg body weight （bw）.d） for adults, respectively. Arsenic was the major risk contributor for inhabitants since the target hazard quotient based on the weighted average concentration （THQw） of arsenic amounted to 44.3% of the total THQ （TTHQ） value according to average vegetable consumption. The TTHQ was lower than 1 for all age groups, indicating that it was still safe for the general population of Beijing to consume vegetables.展开更多
Pot experiment was conducted to understand the effect of phosphorus on arsenic accumulation in As-hyperaccumulator Chinese brake (Pteris vittata L.). It is shown that arsenic concentrations in the fronds and rhizoids,...Pot experiment was conducted to understand the effect of phosphorus on arsenic accumulation in As-hyperaccumulator Chinese brake (Pteris vittata L.). It is shown that arsenic concentrations in the fronds and rhizoids, the arsenic bioaccumulation factor, and the total arsenic in the fronds were not influenced significantly under low levels of phosphorus (≤400 mg/kg) and increased sharply under high levels of phosphorus (】400 mg/ kg). The discovery implies that the efficiency of arsenic removal in phytoremedia-tion using the hyperaccumulating plant can be greatly elevated by the phosphorus addition at high rates. The interaction between the accumulation of phosphorus and that of arsenic in plant was stimulated mutually. The result represents that Chinese brake is a good material for plant physiologist to conduct comparative and mechanism studies on the uptake behaviors of phosphorus and arsenic, and phosphorus is also a potential accelerator for phytoremediation of arsenic-contaminated soils.展开更多
The purpose of this study was to assess the extent of cadmium （Cd） contamination in agricultural soil and its potential risk for people. Soils, rice, and vegetables from Chenzhou City, Southern China were sampled an...The purpose of this study was to assess the extent of cadmium （Cd） contamination in agricultural soil and its potential risk for people. Soils, rice, and vegetables from Chenzhou City, Southern China were sampled and analyzed. In the surface soils, the 95% confidence interval for the mean concentration of Cd varied between 2.72 and 4.83 mg/kg （P 〈 0.05） in the survey, with a geometric mean concentration of 1.45 mg/kg. Based on the GIS map, two hot spot areas of Cd in agricultural soils with high Cd concentrations were identified to be located around the Shizhuyuan, Jinshiling, and Yaogangxian mines, and the Baoshan and Huangshaping mines, in the center of the city. About 60% of the total investigated area, where the agricultural soil Cd concentration is above 1 mg/kg, is distributed in a central belt across the region. The critical distances, at which the soil Cd concentration were increased by the mining activities, from the mines of the soils were 23 km for the Baoshan mine, 46 km for the Huangshaping mine, and 63 km for the Shizhuyuan mine, respectively. These are distances calculated from models. The Cd concentrations in rice samples ranged from 0.01 to 4.43 mg/kg and the mean dietary Cd intake from rice for an adult was 191 μg/d. Results of risk indexes showed that soil Cd concentrations possessed risks to local residents whose intake of Cd from rice and vegetables grown in soils in the vicinity of the mine was 596 μg/d.展开更多
The subcellular distribution of arsenic (As) in Pteris vittata L., an As-hyperaccumulator, was studied to de- termine As compartmentalization and to explore the mecha- nisms that confer As tolerance. When the plant wa...The subcellular distribution of arsenic (As) in Pteris vittata L., an As-hyperaccumulator, was studied to de- termine As compartmentalization and to explore the mecha- nisms that confer As tolerance. When the plant was grown in a nutrient solution without additional As, most of the accu- mulated As was isolated to the cell wall. However, in plants growing in a nutrient solution containing 0.1 or 0.2 mmol/L As, approximately 78% of the total As accumulated within the pinna. The proportions of As accumulation in the cyto- plasmic supernatant fraction were 78% of that in the pinna and 61% of that in the plant. In either treatment group (0.1 or 0.2 mmol/L As), the fraction containing the lowest level of As was the organelle fraction. These results suggest that As accumulates in the pinna where it is primarily distributed in the cytoplasmic supernatant fraction. The role of As com- partmentalization may be intricately linked with As detoxi- fication in P. vittata L.展开更多
To investigate the effects of Cd on tolerance and antioxidant activities of castor, two different castor（Ricinus communis L.） cultivars（Zibo No. 5 and Zibo No. 8） were used for a hydroponic experiment（0, 1 and 2 ...To investigate the effects of Cd on tolerance and antioxidant activities of castor, two different castor（Ricinus communis L.） cultivars（Zibo No. 5 and Zibo No. 8） were used for a hydroponic experiment（0, 1 and 2 mg/L Cd） and a pot experiment using Cd-contaminated soil（34 mg/kg） with the addition of ethylenedinitrilotetraacetic acid（EDTA）. The results indicated that there were significant differences between the two cultivars with respect to Cd uptake in shoots（113–248 mg/kg for Zibo No. 5 and 130–288 mg/kg Zibo No. 8）, biomass tolerance indexes（64.9%–74.6% for Zibo No. 5 and 80.1%–90.9% for Zibo No. 8） in the hydroponic experiment and survival rates（0% for Zibo No. 5 and 100% for Zibo No. 8）determined by the addition of EDTA in the pot experiment, suggesting that Zibo No. 8 has higher tolerance than Zibo No. 5. Moreover, the castor cultivars have low bioconcentration factors（4.80% for Zibo No. 5 and 5.43% for Zibo No. 8） and low translocation factors（〈1%）.Consequently, Zibo No. 8 can participate in Cd phytostabilization in highly Cd-polluted areas. The results indicated that glutathione（GSH） as a non-enzymatic antioxidant, and antioxidant enzymes including superoxide dismutase（SOD）, catalase（CAT） and guaiacol peroxidase（GPX）, were cultivar- and dose-dependent. The higher tolerance of Zibo No. 8compared with Zibo No. 5 can be attributed to the higher GSH levels in the root and higher GPX activity in the leaf.展开更多
Biological soil disinfestation is an effective method to control soil-borne disease by flooding and incorporating with organic amendments, but field conditions and resources sometimes limited its practical application...Biological soil disinfestation is an effective method to control soil-borne disease by flooding and incorporating with organic amendments, but field conditions and resources sometimes limited its practical application. A laboratory experiment was conducted to develop practice guidelines on controlling Fusarium wilt, a widespread banana disease caused by Fusarium oxysporum f. sp. cubense（FOC）. FOC infested soil incorporated with rice or maize straw at rates of 1.5 tons/ha and 3.0 tons/ha was incubated under flooded or water-saturated（100% water holding capacity） conditions at 30℃ for 30 days. Results showed that FOC populations in the soils incorporated with either rice or maize straw rapidly reduced more than 90% in the first 15 days and then fluctuated till the end of incubation, while flooding alone without organic amendment reduced FOC populations slightly. The rapid and dramatic decrease of redox potential（down to- 350 m V） in straw-amended treatments implied that both anaerobic condition and strongly reductive soil condition would contribute to pathogen inactivation. Water-saturation combined with straw amendments had the comparable effects on reduction of FOC, indicating that flooding was not indispensable for inactivating FOC. There was no significant difference in the reduction of FOC observed in the straw amendments at between 1.5 and 3 tons/ha. Therefore,incorporating soil with straw（rice or maize straw） at a rate of 3.0 tons/ha under 100%water holding capacity or 1.5 tons/ha under flooding, would effectively alleviate banana Fusarium wilt caused by FOC after 15-day treating under 30℃.展开更多
Field investigation and greenhouse experiments were conducted to study the tolerance of Pteris vittata L. （Chinese brake） to cadmium （Cd） and its feasibility for remediating sites co-contaminated with Cd and arsen...Field investigation and greenhouse experiments were conducted to study the tolerance of Pteris vittata L. （Chinese brake） to cadmium （Cd） and its feasibility for remediating sites co-contaminated with Cd and arsenic （As）. The results showed that P. vittata could survive in pot soils spiked with 80 mg/kg of Cd and tolerated as great as 301 mg/kg of total Cd and 26.8 mg/kg of diethyltriaminepenta acetic acid （DTPA）-extractable Cd under field conditions. The highest concentration of Cd in fronds was 186 mg/kg under a total soil concentration of 920 mg As/kg and 98.6 mg Cd/kg in the field, whereas just 2.6 mg/kg under greenhouse conditions. Ecotypes of P. vittata were differentiated in tolerance and accumulation of Cd, and some of them could not only tolerate high concentrations of soil Cd, but also accumulated high concentrations of Cd in their fronds. Arsenic uptake and transportation by P. vittata was not inhibited at lower levels （〈20 mg/kg） of Cd addition. Compared to the treatment without addition of Cd, the frond As concentration was increased by 103.8% at 20 mg Cd/kg, with the highest level of 6434 mg/kg. The results suggested that the Cd-tolerant ecotype of P. vittata extracted effectively As and Cd from the site co-contaminated with Cd and As, and might be used to remediate and revegetate this type of site.展开更多
Environmental scanning electron microscope(ESEM)fitted with an energy disper-sive X-ray microanalyzer(EDX)was used to investigate the surface micromorphology and arse-nic(As)micro-distribution in Chinese brake(Pteris ...Environmental scanning electron microscope(ESEM)fitted with an energy disper-sive X-ray microanalyzer(EDX)was used to investigate the surface micromorphology and arse-nic(As)micro-distribution in Chinese brake(Pteris vittata L.).It was found that amounts of trichome,which possessed multicellular structure with the average length of 160μm and with an average diameter of 28μm,existed in the frond of P.vittata,and the density of trichome on the pinnate axial surface was higher than that on the petiole.Visible X-ray peak of As was recorded in the epidermal cell and trichome.The relative weight of As in the pinnate trichome,which con-tained the highest concentration of As among all tissues of the plant,was 2.4 and 3.9 times as much as that in the epidermal and mesophyllous cells,respectively.The As concentrations in the basal and stalk cells of the same trichome were higher than that in its cap cell.This is the first time to report that the trichome of P.vittata plays an important role in arsenic hyperaccumulation.The finding from the present study implies that much attention should be paid to the role of the trichome in understanding the hyperaccumulation and detoxicity of As in the hyperaccumulator and improving the ability of As accumulation.展开更多
The distributions of arsenic and 6 essential elements in the pinna of As hyperaccumulator, Pteris vittata L., were studied using synchrotron radiation X-ray fluorescence (SRXRF). Significant correlation between the di...The distributions of arsenic and 6 essential elements in the pinna of As hyperaccumulator, Pteris vittata L., were studied using synchrotron radiation X-ray fluorescence (SRXRF). Significant correlation between the distribution and mobility of the elements revealed that SRXRF study on the elemental distribution was feasible to inspect the transportations of elements in plants. The distribution of As in the pinna showed that As had great abilities to be transported in xylem vessels and from xylem to mesophyll. The distribution of K, one of the most mobile elements in plants, was similar to that of As, whereas the distributions of Fe and Ca with less mobility in plants were almost opposite to that of As in the pinna.展开更多
Arsenic(As)is a top human carcinogen widely distributed in the environment.As-contaminated soil exists worldwide and poses a threat on human health through water/food consumption,inhalation,or skin contact.More than 2...Arsenic(As)is a top human carcinogen widely distributed in the environment.As-contaminated soil exists worldwide and poses a threat on human health through water/food consumption,inhalation,or skin contact.More than 200 million people are exposed to excessive As concentration through direct or indirect exposure to contaminated soil.Therefore,affordable and efficient technologies that control risks caused by excess As in soil must be developed.The presently available methods can be classified as chemical,physical,and biological.Combined utilization of multiple technologies is also common to improve remediation efficiency.This review presents the research progress on different remediation technologies for As-contaminated soil.For chemical methods,common soil washing or immobilization agents were summarized.Physical technologies were mainly discussed from the field scale.Phytoextraction,the most widely used technology for As-contaminated soil in China,was the main focus for bioremediation.Method development for evaluating soil remediation efficiency was also summarized.Further research directions were proposed based on literature analysis.展开更多
Reductive soil disinfestation（RSD）, namely amending organic materials and mulching or flooding to create strong reductive status, has been widely applied to improve degraded soils.However, there is little informatio...Reductive soil disinfestation（RSD）, namely amending organic materials and mulching or flooding to create strong reductive status, has been widely applied to improve degraded soils.However, there is little information available about sulfate（SO4^2-） transformation and sulfur（S）gas emissions during RSD treatment to degraded vegetable soils, in which S is generally accumulated. To investigate the effects of liming on SO4^2-transformation and S gas emissions,two SO4^2--accumulated vegetable soils（denoted as S1 and S2） were treated by RSD, and RSD plus lime, denoted as RSD0 and RSD1, respectively. The results showed that RSD0 treatment reduced soil SO4^2-by 51% and 61% in S1 and S2, respectively. The disappeared SO4^2-was mainly transformed into the undissolved form. During RSD treatment, hydrogen sulfide（H2S）,carbonyl sulfide（COS）, and dimethyl sulfide（DMS） were detected, but the total S gas emission accounted for 〈 0.006% of total S in both soils. Compared to RSD0, lime addition stimulated the conversion of SO42-into undissolved form, reduced soil SO4^2-by 81% in S1 and 84% in S2 and reduced total S gas emissions by 32% in S1 and 57% in S2, respectively. In addition to H2S, COS and DMS, the emissions of carbon disulfide, methyl mercaptan, and dimethyl disulfide were also detected in RSD1 treatment. The results indicated that RSD was an effective method to remove SO4^2-, liming stimulates the conversion of dissolved SO4^2-into undissolved form,probably due to the precipitation with calcium.展开更多
Investigation of temperature effect on mechanical parameters of coal is very important for understanding the mechanical response of coal bed at high temperature.It is especially benefcial for mitigating the thermal-in...Investigation of temperature effect on mechanical parameters of coal is very important for understanding the mechanical response of coal bed at high temperature.It is especially benefcial for mitigating the thermal-induced disasters occurred in those coal mines suffering from heat hazard.In this work,coal samples,obtained from the No.2442 working face of Baijiao Coal Mine,were subjected to uniaxial compression ranging from 20 to 40℃ with an interval of 5℃.The apparatus used was designed to obtain deformation of a stressed sample,as well as the emission of gases desorbing from coal matrix.The adsorbed gas desorption caused by heating is measured during the entire testing.It is evident that the concentrations of releasing gas(containing methane,carbon dioxide and ethane)slightly rise with increasing temperature.Gas movement observed is closely related to the deformation of coal sample.Both uniaxial compressive strength and elastic modulus of coal samples tend to reduce with temperature.It reveals that increasing temperature can not only result in thermal expansion of coal,but also lead to desorption of preexisting gas in coal which can in turns harden coal due to shrinks of the coal matrix.Even though desorption of adsorbed gas can contribute to the hardening effect for the heated coal,by comparison to the results,it could be inferred that the softening of coal resulted from thermal expansion still predominates changes in mechanical characters of coal sample with temperature at the range from20 to 40℃.展开更多
Identifying the factors that influence the heavy metal contents of soil could reveal the sources of soil heavy metal pollution.In this study,a categorical regression was used to identify the factors that influence soi...Identifying the factors that influence the heavy metal contents of soil could reveal the sources of soil heavy metal pollution.In this study,a categorical regression was used to identify the factors that influence soil heavy metals.First,environmental factors were associated with soil heavy metal data,and then,the degree of influence of different factors on the soil heavy metal contents in Beijing was analyzed using a categorical regression.The results showed that the soil parent material,soil type,land use type,and industrial activity were the main influencing factors,which suggested that these four factors were important sources of soil heavy metals in Beijing.In addition,population density had a certain influence on the soil Pb and Zn contents.The distribution of soil As,Cd,Pb,and Zn was markedly influenced by interactions,such as traffic activity and land use type,industrial activity and population density.The spatial distribution of soil heavy metal hotspots corresponded well with the influencing factors,such as industrial activity,population density,and soil parent material.In this study,the main factors affecting soil heavy metals were identified,and the degree of their influence was ranked.A categorical regression represents a suitable method for identifying the factors that influence soil heavy metal contents and could be used to study the genetic process of regional soil heavy metal pollution.展开更多
Adding organic amendments to stimulate the biodegradation of pesticides is a subject of ongoing interest. The effect of sewage sludge on the bioremediation of dichlorodiphenyltrichloroethane（DDT） and hexachlorocyclo...Adding organic amendments to stimulate the biodegradation of pesticides is a subject of ongoing interest. The effect of sewage sludge on the bioremediation of dichlorodiphenyltrichloroethane（DDT） and hexachlorocyclohexane（HCH） contaminated soil was investigated in bench scale experiments,and intermittent aeration strategy was also used in this study to form an anaerobic–aerobic cycle. Bioremediation of DDT and HCH was enhanced with the addition of sewage sludge and the intermittent aeration. The removal rates of HCH and DDT were raised by 16.8%–80.8% in 10 days. Sewage sludge increased the organic carbon content from 6.2 to218 g/kg,and it could also introduce efficient degradation microbes to soil,including Pseudomonas sp.,Bacillus sp. and Sphingomonas sp. The unaerated phase enhanced the anaerobic dechlorination of DDT and HCH,and anaerobic removal rates of β-HCH,o,p′-DDT and p,p′-DDT accounted for more than 50% of the total removal rates,but the content of α-HCH declined more in the aerobic phase.展开更多
Water-soluble chitosan(WSC)has been studied for its ability to mobilize soil Pb and promote the phytoremediation by Hylotelephium spectabile in Pb-contaminated fields.We aimed to clarify the internal mechanism by whic...Water-soluble chitosan(WSC)has been studied for its ability to mobilize soil Pb and promote the phytoremediation by Hylotelephium spectabile in Pb-contaminated fields.We aimed to clarify the internal mechanism by which wSC impacts phytoremediation by examining plant growth and Pb accumulation performance of H.spectabile as well as the Pb form,functional groups,and mineral phases of Pb-contaminated soil.WSC effectively decreased soil pH and activated Pb migration in rhizosphere soils,with a considerable increase in water-soluble and acid-extractable Pb by 29%-102%and 9%-65%,respectively,and a clear decreasing trend in reducible and oxidizable Pb.Fourier-transform infrared spectroscopy revealed a significant increase in amino and hydroxyl groups in the soil generated by WSC.The coordination of Pb with amino and hydroxyl groups may play an important role in the formation of Pb complexes and activation of Pb in soil.In field trials,the application of WSC significantly increased Pb accumulation in H.spectabile by 125.44%,reaching 92 g/hm^(2).Moreover,the organic matter and nitrogen in the soils were increased by WSc,which improved the growth conditions of H.spectabile.No obvious growth inhibition was observed in either the pot or field trials.Therefore,WSC is a promising chelating agent for mobilizing Pb in soil.Additionally,WSC can be potentially used to boost H.spectabil-mediated phytoremediation of Pb-contaminatedfarmland.展开更多
Stockaded villages of the Qiang nationality that are made up of watchtowers and watch-houses are an important part of its cultural heritage. The earliest documentary records of its blockhouse-styled construction can b...Stockaded villages of the Qiang nationality that are made up of watchtowers and watch-houses are an important part of its cultural heritage. The earliest documentary records of its blockhouse-styled construction can be found in Biography of the Ethnic Minority Groups in Southwest China of History of Eastern Hart. In 2006, watchtowers and stockaded villages of the Qiang nationality was placed in the preparatory declaration list of world cultural heritage .in China and became a minority architectural heritage that is of potential value for world cultural heritage. The Wenchuan earthquake, which happened on May 12th, 2008, caused severe damage to settlements of the Qiangs in the upper reaches of Min River, including the ＂Tangping Qiang village,＂ which plays a prominent role in Qiang stockaded villages. In conserving this important architectural heritage, we observe the idea ＂everything for heritage value＂. We discuss and draw up a series of salvage conservation countermeasures and research for antiseimatic key technology during post-earthquake reconstruction period of Tibetan and Qiang settlement engineering projects, including six engineering principles on priority of structure rescue, heritage vatue, former address maintenance, traditional way of use, protection against and mitigation of earthquake disasters, and spot cleaning and separating. We draw up three rules in engineering strategy, namely： （1） we should follow ultimate orientation of heritage value protection in rescue, maintenance, and protection engineering; （2） degrees of priority of engineering measures should be differentiated according to the situation of the disaster and residential situations of stockaded villages and; （3） we should keeplocal smiths and conventional art as the base, and modern technology as a supplement in rescue, maintenance, and protection engineering.展开更多
Follow-up investigation on hair arsenic concentration was conducted in an arsenic heavily polluted area of southern China in 2002 and 2006. The results showed that the geometric mean of hair arsenic concentration decr...Follow-up investigation on hair arsenic concentration was conducted in an arsenic heavily polluted area of southern China in 2002 and 2006. The results showed that the geometric mean of hair arsenic concentration decreased from 2.95 mg/kg in 2002 to 1.78 mg/kg in 2006, when the percentage of the population with levels over 1 mg/kg only decreased from 93.4% in 2002 to 80.5% in 2006. Over this four-year period, the population with high arsenic concentrations decreased significantly while there was no obvious change in hair arsenic concentration for people who had relatively low concentrations. In terms of age distribution, young and old people had higher hair arsenic concentrations than the middle-aged. All of these results showed that it is difficult to reverse the negative impact of arsenic pollution on human health. Arsenic pollution has a long-term continuous influence on the health of local residents.展开更多
A better understanding of nitrogen transformation in soils could reveal the capacity for biological inorganic N supply and improve the efficiency of N fertilizers. In this study, a15 N tracing study was carried out to...A better understanding of nitrogen transformation in soils could reveal the capacity for biological inorganic N supply and improve the efficiency of N fertilizers. In this study, a15 N tracing study was carried out to investigate the effects of converting woodland to orchard, and orchard age on the gross rates of N transformation occurring simultaneously in subtropical soils in Eastern China. The results showed that inorganic N supply rate was remained constant with soil organic C and N contents increased after converting woodland into citrus orchard and with increasing orchard age. This phenomenon was most probably due to the increase in the turnover time of recalcitrant organic-N, which increased with decreasing soil p H along with increasing orchard age significantly. The amo A gene copy numbers of both archaeal and bacterial were stimulated by orchard planting and increased with increasing orchard age. The nitrification capacity（defined as the ratio of gross rate of nitrification to total gross rate of mineralization） increased following the Michaelis–Menten equation, sharply in the first 10 years after woodland conversion to orchard, and increased continuously but much more slowly till 30 years. Due to the increase in nitrification capacity and unchanged NO3-consumption, the dominance of ammonium in inorganic N in woodland soil was shifted to nitrate dominance in orchard soils. These results indicated that the risk of NO3-loss was expected to increase and the amount of N needed from fertilizers for fruit growth did not change although soil organic N accumulated with orchard age.展开更多
基金This work was cosponsored by the National Natural Science Foundation of China (Grant Nos. 49941003 and 40071075)the Chinese Academy of Sciences (Innovation Project KZCX-401-2)the State Key Basic Research Plan of China (Grant No. 1999011808).
文摘An arsenic hyperaccumulator Pteris vittata L. (Chinese brake) was first discovered in China by means of field survey and greenhouse cultivation. Field survey showed that Chinese brake had large accumulating capacity to arsenic; the orders of arsenic content in different parts of the fern were as follows: leaves】leafstalks】roots, which is totally different from that of ordinary plants; bioaccumulation coefficients of the above ground parts of the fern decreased as a power function of soil arsenic contents. In the control of pot trials with normal unpolluted soil containing 9mg/kg of arsenic, the bioaccumulation coefficients of the above ground parts and rhizoids of Chinese brake were as high as 71 and 80 respectively. Greenhouse cultivation in the contaminated soil from mining areas has shown that more than 1 times greater arsenic can be accumulated in the leaves of the fern than that of field samples with the largest content of 5070 mg/kg As on a dry matter basis. During greenhouse cultivation, arsenic
基金National Natural Science Foundation of China, No.20507022
文摘A total of 219 agricultural soil and 48 vegetable samples were collected from the midstream and downstream of the Xiangjiang River（the Hengyang-Changsha section）in Hunan Province.The accumulation characteristics,spatial distribution and potential risk of heavy metals in the agricultural soils and vegetables were depicted.There are higher accumulations of heavy metals such as As,Cd,Cu,Ni,Pb and Zn in agricultural soils,and the contents of Cd（2.44 mg kg^-1 ）,Pb（65.00 mg kg^-1 ）and Zn（144.13 mg kg^-1 ）are 7.97,3.69 and 1.63 times the corresponding background contents in soils of Hunan Province,respectively. 13.2%of As,68.5%of Cd,2.7%of Cu,2.7%of Ni,8.7%of Pb and 15.1%of Zn in soil samples from the investigated sites exceeded the maximum allowable heavy metal contents in the China Environmental Quality Standard for Soils（GB15618-1995,Grade Ⅱ）.The pollution characteristics of multi-metals in soils are mainly due to Cd.The contents of As,Cd,Cu,Pb and Zn in vegetable soils are significantly higher than the contents in paddy soils.95.8%, 68.8%,10.4%and 95.8%of vegetable samples exceeded the Maximum Levels of Contaminants in Foods（GB2762-2005）for As,Cd,Ni and Pb concentrations,respectively.There are significantly positive correlations between the concentrations of Cd,Pb and Zn in vegetables and the concentrations in the corresponding vegetable soils（p〈0.01）.It is very necessary to focus on the potential risk of heavy metals for food safety and human health in agricultural soils and vegetables in the midstream and downstream of the Xiangjiang River,Hunan Province of China.
基金supported by the Foundation of State Key Laboratory of Resources and Environmental Information System (LREIS) (No. 08R8B000SA)the Beijing Commission of Science and Technology (No.D0706007040291-02)the Key Innovation Project of Chinese Academy of Sciences (No. KZCX1-YW-06-03)
文摘A systematic survey of As, Cd, Cr, Cu, Ni, Pb and Zn concentrations in vegetables from 416 samples （involving 100 varieties） in Beijing was carried out for assessing the potential health risk to local inhabitants. The results indicated that the metal concentrations in vegetables ranged from 〈 0.001 to 0.479 μg/g fresh weight （fw） （As）, 〈 0.001 to 0.101 μg/g fw （Cd）, 〈 0.001 to 1.04 μg/g fw （Cr）, 0.024 to 8.25μg/g fw （Cu）, 0.001 to 1.689 μg/g fw （Ni）, 〈 0.001 to 0.655 μg/g fw （Pb） and 0.01 to 25.6 μg/g fw （Zn）, with average concentrations of 0.013, 0.010, 0.023, 0.51, 0.053, 0.046 and 2.55 μg/g fw, respectively. The results showed that the concentrations of As, Cr, Cu, Cd, Pb and Ni in vegetables from open-fields were all significantly higher than those grown in greenhouses. In addition, in local-produced vegetables, all HMs except Zn were significantly higher than those in provincial vegetables. The estimated daily intake （EDI） of As, Cd, Cr, Cu, Ni, Pb and Zn from vegetables was 0.080, 0.062, 0.142, 3.14, 0.327, 0.283 and 15.7 μg/（kg body weight （bw）.d） for adults, respectively. Arsenic was the major risk contributor for inhabitants since the target hazard quotient based on the weighted average concentration （THQw） of arsenic amounted to 44.3% of the total THQ （TTHQ） value according to average vegetable consumption. The TTHQ was lower than 1 for all age groups, indicating that it was still safe for the general population of Beijing to consume vegetables.
基金The work was jointly supported by the National High-tech R & D Program (Grant No. 2001AA640501)Chinese Academy of Sciences Innovation Program (Grant No. KZCX-401-01)the National Natural Science Foundation of China (Grant No. 40071075) and the Nat
文摘Pot experiment was conducted to understand the effect of phosphorus on arsenic accumulation in As-hyperaccumulator Chinese brake (Pteris vittata L.). It is shown that arsenic concentrations in the fronds and rhizoids, the arsenic bioaccumulation factor, and the total arsenic in the fronds were not influenced significantly under low levels of phosphorus (≤400 mg/kg) and increased sharply under high levels of phosphorus (】400 mg/ kg). The discovery implies that the efficiency of arsenic removal in phytoremedia-tion using the hyperaccumulating plant can be greatly elevated by the phosphorus addition at high rates. The interaction between the accumulation of phosphorus and that of arsenic in plant was stimulated mutually. The result represents that Chinese brake is a good material for plant physiologist to conduct comparative and mechanism studies on the uptake behaviors of phosphorus and arsenic, and phosphorus is also a potential accelerator for phytoremediation of arsenic-contaminated soils.
文摘The purpose of this study was to assess the extent of cadmium （Cd） contamination in agricultural soil and its potential risk for people. Soils, rice, and vegetables from Chenzhou City, Southern China were sampled and analyzed. In the surface soils, the 95% confidence interval for the mean concentration of Cd varied between 2.72 and 4.83 mg/kg （P 〈 0.05） in the survey, with a geometric mean concentration of 1.45 mg/kg. Based on the GIS map, two hot spot areas of Cd in agricultural soils with high Cd concentrations were identified to be located around the Shizhuyuan, Jinshiling, and Yaogangxian mines, and the Baoshan and Huangshaping mines, in the center of the city. About 60% of the total investigated area, where the agricultural soil Cd concentration is above 1 mg/kg, is distributed in a central belt across the region. The critical distances, at which the soil Cd concentration were increased by the mining activities, from the mines of the soils were 23 km for the Baoshan mine, 46 km for the Huangshaping mine, and 63 km for the Shizhuyuan mine, respectively. These are distances calculated from models. The Cd concentrations in rice samples ranged from 0.01 to 4.43 mg/kg and the mean dietary Cd intake from rice for an adult was 191 μg/d. Results of risk indexes showed that soil Cd concentrations possessed risks to local residents whose intake of Cd from rice and vegetables grown in soils in the vicinity of the mine was 596 μg/d.
基金supported by the National Science Foundation for Distinguished Young Scholar(Grant No.40325003)the.National Natural Science Foundation of China(Grant No.40232022)the National High-Tech R&D Program(No.2003AA645010).
文摘The subcellular distribution of arsenic (As) in Pteris vittata L., an As-hyperaccumulator, was studied to de- termine As compartmentalization and to explore the mecha- nisms that confer As tolerance. When the plant was grown in a nutrient solution without additional As, most of the accu- mulated As was isolated to the cell wall. However, in plants growing in a nutrient solution containing 0.1 or 0.2 mmol/L As, approximately 78% of the total As accumulated within the pinna. The proportions of As accumulation in the cyto- plasmic supernatant fraction were 78% of that in the pinna and 61% of that in the plant. In either treatment group (0.1 or 0.2 mmol/L As), the fraction containing the lowest level of As was the organelle fraction. These results suggest that As accumulates in the pinna where it is primarily distributed in the cytoplasmic supernatant fraction. The role of As com- partmentalization may be intricately linked with As detoxi- fication in P. vittata L.
基金supported by the One Hundred Talents Program of the Chinese Academy of Sciences (Guo Q.J. 2010)973 Program (No. 2014CB238906)+1 种基金863 Program (No. 2013AA06A211-2)National Natural Science Foundation of China (No. 41201312)
文摘To investigate the effects of Cd on tolerance and antioxidant activities of castor, two different castor（Ricinus communis L.） cultivars（Zibo No. 5 and Zibo No. 8） were used for a hydroponic experiment（0, 1 and 2 mg/L Cd） and a pot experiment using Cd-contaminated soil（34 mg/kg） with the addition of ethylenedinitrilotetraacetic acid（EDTA）. The results indicated that there were significant differences between the two cultivars with respect to Cd uptake in shoots（113–248 mg/kg for Zibo No. 5 and 130–288 mg/kg Zibo No. 8）, biomass tolerance indexes（64.9%–74.6% for Zibo No. 5 and 80.1%–90.9% for Zibo No. 8） in the hydroponic experiment and survival rates（0% for Zibo No. 5 and 100% for Zibo No. 8）determined by the addition of EDTA in the pot experiment, suggesting that Zibo No. 8 has higher tolerance than Zibo No. 5. Moreover, the castor cultivars have low bioconcentration factors（4.80% for Zibo No. 5 and 5.43% for Zibo No. 8） and low translocation factors（〈1%）.Consequently, Zibo No. 8 can participate in Cd phytostabilization in highly Cd-polluted areas. The results indicated that glutathione（GSH） as a non-enzymatic antioxidant, and antioxidant enzymes including superoxide dismutase（SOD）, catalase（CAT） and guaiacol peroxidase（GPX）, were cultivar- and dose-dependent. The higher tolerance of Zibo No. 8compared with Zibo No. 5 can be attributed to the higher GSH levels in the root and higher GPX activity in the leaf.
基金supported by the National Natural Science Foundation of China (Nos. 41222005, 41330744, 413301335)the Natural Science Foundation of Jiangsu Province (Nos. BK2010611, SBK201220477)+1 种基金Research Fund of State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences (Y412201404)the Priority Academic Program Development of Jiangsu Higher Education Institutions
文摘Biological soil disinfestation is an effective method to control soil-borne disease by flooding and incorporating with organic amendments, but field conditions and resources sometimes limited its practical application. A laboratory experiment was conducted to develop practice guidelines on controlling Fusarium wilt, a widespread banana disease caused by Fusarium oxysporum f. sp. cubense（FOC）. FOC infested soil incorporated with rice or maize straw at rates of 1.5 tons/ha and 3.0 tons/ha was incubated under flooded or water-saturated（100% water holding capacity） conditions at 30℃ for 30 days. Results showed that FOC populations in the soils incorporated with either rice or maize straw rapidly reduced more than 90% in the first 15 days and then fluctuated till the end of incubation, while flooding alone without organic amendment reduced FOC populations slightly. The rapid and dramatic decrease of redox potential（down to- 350 m V） in straw-amended treatments implied that both anaerobic condition and strongly reductive soil condition would contribute to pathogen inactivation. Water-saturation combined with straw amendments had the comparable effects on reduction of FOC, indicating that flooding was not indispensable for inactivating FOC. There was no significant difference in the reduction of FOC observed in the straw amendments at between 1.5 and 3 tons/ha. Therefore,incorporating soil with straw（rice or maize straw） at a rate of 3.0 tons/ha under 100%water holding capacity or 1.5 tons/ha under flooding, would effectively alleviate banana Fusarium wilt caused by FOC after 15-day treating under 30℃.
基金This work was supported by the National Science Foundation for the Distinguished Young Scholar of China(No.40325003).
文摘Field investigation and greenhouse experiments were conducted to study the tolerance of Pteris vittata L. （Chinese brake） to cadmium （Cd） and its feasibility for remediating sites co-contaminated with Cd and arsenic （As）. The results showed that P. vittata could survive in pot soils spiked with 80 mg/kg of Cd and tolerated as great as 301 mg/kg of total Cd and 26.8 mg/kg of diethyltriaminepenta acetic acid （DTPA）-extractable Cd under field conditions. The highest concentration of Cd in fronds was 186 mg/kg under a total soil concentration of 920 mg As/kg and 98.6 mg Cd/kg in the field, whereas just 2.6 mg/kg under greenhouse conditions. Ecotypes of P. vittata were differentiated in tolerance and accumulation of Cd, and some of them could not only tolerate high concentrations of soil Cd, but also accumulated high concentrations of Cd in their fronds. Arsenic uptake and transportation by P. vittata was not inhibited at lower levels （〈20 mg/kg） of Cd addition. Compared to the treatment without addition of Cd, the frond As concentration was increased by 103.8% at 20 mg Cd/kg, with the highest level of 6434 mg/kg. The results suggested that the Cd-tolerant ecotype of P. vittata extracted effectively As and Cd from the site co-contaminated with Cd and As, and might be used to remediate and revegetate this type of site.
基金This work was supported by the National Science Fund for Distinguished Young Scholar(Grant No.40325003)the China State Program for Basic Research(No.2002CCA03800)+1 种基金the National Natural Science Foundation of China(Grant No.40232022)the National High-Tech R&D Program(No.2001AA6450).
文摘Environmental scanning electron microscope(ESEM)fitted with an energy disper-sive X-ray microanalyzer(EDX)was used to investigate the surface micromorphology and arse-nic(As)micro-distribution in Chinese brake(Pteris vittata L.).It was found that amounts of trichome,which possessed multicellular structure with the average length of 160μm and with an average diameter of 28μm,existed in the frond of P.vittata,and the density of trichome on the pinnate axial surface was higher than that on the petiole.Visible X-ray peak of As was recorded in the epidermal cell and trichome.The relative weight of As in the pinnate trichome,which con-tained the highest concentration of As among all tissues of the plant,was 2.4 and 3.9 times as much as that in the epidermal and mesophyllous cells,respectively.The As concentrations in the basal and stalk cells of the same trichome were higher than that in its cap cell.This is the first time to report that the trichome of P.vittata plays an important role in arsenic hyperaccumulation.The finding from the present study implies that much attention should be paid to the role of the trichome in understanding the hyperaccumulation and detoxicity of As in the hyperaccumulator and improving the ability of As accumulation.
文摘The distributions of arsenic and 6 essential elements in the pinna of As hyperaccumulator, Pteris vittata L., were studied using synchrotron radiation X-ray fluorescence (SRXRF). Significant correlation between the distribution and mobility of the elements revealed that SRXRF study on the elemental distribution was feasible to inspect the transportations of elements in plants. The distribution of As in the pinna showed that As had great abilities to be transported in xylem vessels and from xylem to mesophyll. The distribution of K, one of the most mobile elements in plants, was similar to that of As, whereas the distributions of Fe and Ca with less mobility in plants were almost opposite to that of As in the pinna.
基金the Innovation Academy for Green Manufacture,Chinese Academy of Sciences(Grant No.IAGM-2019-A16-5)the National Key Research and Development Program of China(Grant No.2018YFC1800302)the Youth Innovation Promotion Association of the Chinese Academy of Sciences.
文摘Arsenic(As)is a top human carcinogen widely distributed in the environment.As-contaminated soil exists worldwide and poses a threat on human health through water/food consumption,inhalation,or skin contact.More than 200 million people are exposed to excessive As concentration through direct or indirect exposure to contaminated soil.Therefore,affordable and efficient technologies that control risks caused by excess As in soil must be developed.The presently available methods can be classified as chemical,physical,and biological.Combined utilization of multiple technologies is also common to improve remediation efficiency.This review presents the research progress on different remediation technologies for As-contaminated soil.For chemical methods,common soil washing or immobilization agents were summarized.Physical technologies were mainly discussed from the field scale.Phytoextraction,the most widely used technology for As-contaminated soil in China,was the main focus for bioremediation.Method development for evaluating soil remediation efficiency was also summarized.Further research directions were proposed based on literature analysis.
基金supported by grants from the National Natural Science Foundation of China(Nos:41301313,41330744)the Natural Science Foundation of Jiangsu Province(No.BK20140062)+1 种基金the Natural Science Foundation of the Jiangsu Higher Education Institutions of China(No.13KJA210002)the Outstanding Innovation Team in Colleges and Universities in Jiangsu Province and the Priority Academic Program Development of Jiangsu Higher Education Institutions(164320H116)
文摘Reductive soil disinfestation（RSD）, namely amending organic materials and mulching or flooding to create strong reductive status, has been widely applied to improve degraded soils.However, there is little information available about sulfate（SO4^2-） transformation and sulfur（S）gas emissions during RSD treatment to degraded vegetable soils, in which S is generally accumulated. To investigate the effects of liming on SO4^2-transformation and S gas emissions,two SO4^2--accumulated vegetable soils（denoted as S1 and S2） were treated by RSD, and RSD plus lime, denoted as RSD0 and RSD1, respectively. The results showed that RSD0 treatment reduced soil SO4^2-by 51% and 61% in S1 and S2, respectively. The disappeared SO4^2-was mainly transformed into the undissolved form. During RSD treatment, hydrogen sulfide（H2S）,carbonyl sulfide（COS）, and dimethyl sulfide（DMS） were detected, but the total S gas emission accounted for 〈 0.006% of total S in both soils. Compared to RSD0, lime addition stimulated the conversion of SO42-into undissolved form, reduced soil SO4^2-by 81% in S1 and 84% in S2 and reduced total S gas emissions by 32% in S1 and 57% in S2, respectively. In addition to H2S, COS and DMS, the emissions of carbon disulfide, methyl mercaptan, and dimethyl disulfide were also detected in RSD1 treatment. The results indicated that RSD was an effective method to remove SO4^2-, liming stimulates the conversion of dissolved SO4^2-into undissolved form,probably due to the precipitation with calcium.
基金Financial support for this work,provided by the National Natural Science Foundation of China(Nos.41202194,41172116 and 51074099)the Natural Science Foundation of Shandong Province(No.ZR2012EEQ021)are gratefully acknowledged
文摘Investigation of temperature effect on mechanical parameters of coal is very important for understanding the mechanical response of coal bed at high temperature.It is especially benefcial for mitigating the thermal-induced disasters occurred in those coal mines suffering from heat hazard.In this work,coal samples,obtained from the No.2442 working face of Baijiao Coal Mine,were subjected to uniaxial compression ranging from 20 to 40℃ with an interval of 5℃.The apparatus used was designed to obtain deformation of a stressed sample,as well as the emission of gases desorbing from coal matrix.The adsorbed gas desorption caused by heating is measured during the entire testing.It is evident that the concentrations of releasing gas(containing methane,carbon dioxide and ethane)slightly rise with increasing temperature.Gas movement observed is closely related to the deformation of coal sample.Both uniaxial compressive strength and elastic modulus of coal samples tend to reduce with temperature.It reveals that increasing temperature can not only result in thermal expansion of coal,but also lead to desorption of preexisting gas in coal which can in turns harden coal due to shrinks of the coal matrix.Even though desorption of adsorbed gas can contribute to the hardening effect for the heated coal,by comparison to the results,it could be inferred that the softening of coal resulted from thermal expansion still predominates changes in mechanical characters of coal sample with temperature at the range from20 to 40℃.
基金This research was supported by the National Natural Science Foundation of China(Grant Nos.41771510 and 41271478)the Science and Technology Service Network Initiative(STS)from the Chinese Academy of Sciences(No.KFJ-STS-ZDTP-007)In addition,the authors would like to thank professor Yucheng Chen of South-west University for helping us to analyze the data.
文摘Identifying the factors that influence the heavy metal contents of soil could reveal the sources of soil heavy metal pollution.In this study,a categorical regression was used to identify the factors that influence soil heavy metals.First,environmental factors were associated with soil heavy metal data,and then,the degree of influence of different factors on the soil heavy metal contents in Beijing was analyzed using a categorical regression.The results showed that the soil parent material,soil type,land use type,and industrial activity were the main influencing factors,which suggested that these four factors were important sources of soil heavy metals in Beijing.In addition,population density had a certain influence on the soil Pb and Zn contents.The distribution of soil As,Cd,Pb,and Zn was markedly influenced by interactions,such as traffic activity and land use type,industrial activity and population density.The spatial distribution of soil heavy metal hotspots corresponded well with the influencing factors,such as industrial activity,population density,and soil parent material.In this study,the main factors affecting soil heavy metals were identified,and the degree of their influence was ranked.A categorical regression represents a suitable method for identifying the factors that influence soil heavy metal contents and could be used to study the genetic process of regional soil heavy metal pollution.
基金supported by the National Natural Science Foundation of China (No.41271478,41101463,and 41271479)the Special Fund for Scientific Research of China's Ministry of Land and Resources in the Public Interest (No.201111020)
文摘Adding organic amendments to stimulate the biodegradation of pesticides is a subject of ongoing interest. The effect of sewage sludge on the bioremediation of dichlorodiphenyltrichloroethane（DDT） and hexachlorocyclohexane（HCH） contaminated soil was investigated in bench scale experiments,and intermittent aeration strategy was also used in this study to form an anaerobic–aerobic cycle. Bioremediation of DDT and HCH was enhanced with the addition of sewage sludge and the intermittent aeration. The removal rates of HCH and DDT were raised by 16.8%–80.8% in 10 days. Sewage sludge increased the organic carbon content from 6.2 to218 g/kg,and it could also introduce efficient degradation microbes to soil,including Pseudomonas sp.,Bacillus sp. and Sphingomonas sp. The unaerated phase enhanced the anaerobic dechlorination of DDT and HCH,and anaerobic removal rates of β-HCH,o,p′-DDT and p,p′-DDT accounted for more than 50% of the total removal rates,but the content of α-HCH declined more in the aerobic phase.
基金The research was financially supported by the National Natural Science Foundation of China(Nos.42277237,22206149,and 41907125)the Applied Basic Research Project of Shanxi Province(China)(No.20210302124220)the Horizontal Scientific Research Funds of Taiyuan University of Technology(Nos.RH2200002532 and RH2300002821).
文摘Water-soluble chitosan(WSC)has been studied for its ability to mobilize soil Pb and promote the phytoremediation by Hylotelephium spectabile in Pb-contaminated fields.We aimed to clarify the internal mechanism by which wSC impacts phytoremediation by examining plant growth and Pb accumulation performance of H.spectabile as well as the Pb form,functional groups,and mineral phases of Pb-contaminated soil.WSC effectively decreased soil pH and activated Pb migration in rhizosphere soils,with a considerable increase in water-soluble and acid-extractable Pb by 29%-102%and 9%-65%,respectively,and a clear decreasing trend in reducible and oxidizable Pb.Fourier-transform infrared spectroscopy revealed a significant increase in amino and hydroxyl groups in the soil generated by WSC.The coordination of Pb with amino and hydroxyl groups may play an important role in the formation of Pb complexes and activation of Pb in soil.In field trials,the application of WSC significantly increased Pb accumulation in H.spectabile by 125.44%,reaching 92 g/hm^(2).Moreover,the organic matter and nitrogen in the soils were increased by WSc,which improved the growth conditions of H.spectabile.No obvious growth inhibition was observed in either the pot or field trials.Therefore,WSC is a promising chelating agent for mobilizing Pb in soil.Additionally,WSC can be potentially used to boost H.spectabil-mediated phytoremediation of Pb-contaminatedfarmland.
文摘Stockaded villages of the Qiang nationality that are made up of watchtowers and watch-houses are an important part of its cultural heritage. The earliest documentary records of its blockhouse-styled construction can be found in Biography of the Ethnic Minority Groups in Southwest China of History of Eastern Hart. In 2006, watchtowers and stockaded villages of the Qiang nationality was placed in the preparatory declaration list of world cultural heritage .in China and became a minority architectural heritage that is of potential value for world cultural heritage. The Wenchuan earthquake, which happened on May 12th, 2008, caused severe damage to settlements of the Qiangs in the upper reaches of Min River, including the ＂Tangping Qiang village,＂ which plays a prominent role in Qiang stockaded villages. In conserving this important architectural heritage, we observe the idea ＂everything for heritage value＂. We discuss and draw up a series of salvage conservation countermeasures and research for antiseimatic key technology during post-earthquake reconstruction period of Tibetan and Qiang settlement engineering projects, including six engineering principles on priority of structure rescue, heritage vatue, former address maintenance, traditional way of use, protection against and mitigation of earthquake disasters, and spot cleaning and separating. We draw up three rules in engineering strategy, namely： （1） we should follow ultimate orientation of heritage value protection in rescue, maintenance, and protection engineering; （2） degrees of priority of engineering measures should be differentiated according to the situation of the disaster and residential situations of stockaded villages and; （3） we should keeplocal smiths and conventional art as the base, and modern technology as a supplement in rescue, maintenance, and protection engineering.
基金supported by the Knowledge Innovation Program of Chinese Academy of Sciences (No.KZCX2-YW-Q02-02)
文摘Follow-up investigation on hair arsenic concentration was conducted in an arsenic heavily polluted area of southern China in 2002 and 2006. The results showed that the geometric mean of hair arsenic concentration decreased from 2.95 mg/kg in 2002 to 1.78 mg/kg in 2006, when the percentage of the population with levels over 1 mg/kg only decreased from 93.4% in 2002 to 80.5% in 2006. Over this four-year period, the population with high arsenic concentrations decreased significantly while there was no obvious change in hair arsenic concentration for people who had relatively low concentrations. In terms of age distribution, young and old people had higher hair arsenic concentrations than the middle-aged. All of these results showed that it is difficult to reverse the negative impact of arsenic pollution on human health. Arsenic pollution has a long-term continuous influence on the health of local residents.
基金supported by the National Natural Science Foundation of China (Nos.41401339, 41330744)the Natural Science Foundation of Jiangsu Province (No.BK20140062)and Fujian Province (No.2014J01145)
文摘A better understanding of nitrogen transformation in soils could reveal the capacity for biological inorganic N supply and improve the efficiency of N fertilizers. In this study, a15 N tracing study was carried out to investigate the effects of converting woodland to orchard, and orchard age on the gross rates of N transformation occurring simultaneously in subtropical soils in Eastern China. The results showed that inorganic N supply rate was remained constant with soil organic C and N contents increased after converting woodland into citrus orchard and with increasing orchard age. This phenomenon was most probably due to the increase in the turnover time of recalcitrant organic-N, which increased with decreasing soil p H along with increasing orchard age significantly. The amo A gene copy numbers of both archaeal and bacterial were stimulated by orchard planting and increased with increasing orchard age. The nitrification capacity（defined as the ratio of gross rate of nitrification to total gross rate of mineralization） increased following the Michaelis–Menten equation, sharply in the first 10 years after woodland conversion to orchard, and increased continuously but much more slowly till 30 years. Due to the increase in nitrification capacity and unchanged NO3-consumption, the dominance of ammonium in inorganic N in woodland soil was shifted to nitrate dominance in orchard soils. These results indicated that the risk of NO3-loss was expected to increase and the amount of N needed from fertilizers for fruit growth did not change although soil organic N accumulated with orchard age.
