A 45-d laboratory experiment was conducted to compare the effect of four crop straws on the transformations of organic matter （OM） during composting of sewage sludge. The four crop straws included rape straw, wheat ...A 45-d laboratory experiment was conducted to compare the effect of four crop straws on the transformations of organic matter （OM） during composting of sewage sludge. The four crop straws included rape straw, wheat straw, maize straw and rice straw. The following parameters such as temperature, OM, humic-like substances （HS）, fulvic-like acids （FA） and humic-like acids （HA） were determined. The degradation of OM and the formation of HS and HA could be described well by the first-order kinetic model, while the FA content fluctuated during composting. The maximal degradation rates of OM in the compost piles added with rape straw, wheat straw, maize straw and rice straw were 34.7, 46.9, 54.7 and 52.8%, respectively, and the final contents of HS were 118, 128, 141 and 134 g kg-1, respectively, while the humification indices were higher in the compost piles added with maize straw and wheat straw than in those with rice straw and rape straw. The results indicate that a higher hemicellulose content and a lower C/N ratio in crop straw can result in a higher rate of OM degradation and higher contents of HS, while a higher content of lignin can lead to a higher polymerization degree of humic substances in compost piles. The final compost piles added with maize straw has the highest contents of OM, total nitrogen and humus substance as well as the highest values of polymerization degree, while compost piles with rape straw have the highest potassium content and those with rice straw have the highest pH values.展开更多
Biochar has received increasing attention due to its applications as a soil amendment. Here, the chemical properties of solid and water-extractable fractions of four biochar samples were investigated. The results show...Biochar has received increasing attention due to its applications as a soil amendment. Here, the chemical properties of solid and water-extractable fractions of four biochar samples were investigated. The results showed that wood biochar and bamboo biochar samples were 60%-80% more hydrophobic than those of rice husk biochar and rice husk ash. In addition, the acidity was 3.88 mmol/g from the total functional groups and 1.03 mmol/g from the carboxyl groups/lactones/phenols found in the wood biochar sample, which were about 1.5 times greater than those of the bamboo biochar sample. These functional groups could be used to determine the sorptive capacity of biochar for ionic solutes and water content and to increase the degradation of compost organics. The wood biochar sample was found to have the most humification materials （fulvic acid-like material ＋ humic acid-like material） in the water-extractable fraction, which was 3-10 times higher than that in the rice husk biochar and rice husk ash; humified materials were not detected in the bamboo biochar sample. Humification materials in biochar may be involved in increasing the proportion of humic acid-like materials in humic-like substances within the compost product. Wood biochar had better hydrophobic, sorptive, aromatic, and humification properties compared to other biochars, suggesting that it may be used in composting in order to exert its effect as both a bulking agent and a composting amendment during the solid waste composting process.展开更多
Humic substances(HS),which are defined as a series of highly acidic,relatively high-molecular-weight,and yellow to black colored substances formed during the decay and transformation of plant and microbial remains,ubi...Humic substances(HS),which are defined as a series of highly acidic,relatively high-molecular-weight,and yellow to black colored substances formed during the decay and transformation of plant and microbial remains,ubiquitously occur in nature.Humic substances represent the largest stable organic carbon pool in terrestrial environments and are the central characteristic of the soil.However,the validity of the HS concept and the justification of their extraction procedure have been recently debated.Here,we argue that the traditional humic paradigm is still relevant.Humic substances are distinctive and complex because the extracted HS formed during the humification are chemically distinct from their precursors and are heterogeneous among soils.By reviewing the concept,formation pathways,and stabilization of HS,we propose that the key question facing soil scientists is whether HS are soil microbial residues or unique synthesized compounds.Without revealing the distinctiveness of HS,it is impossible to address this question,as the structure,composition,and reactivity of HS are still poorly known owing to the heterogeneity and geographical variability of HS and the limits of the currently available analytical techniques.In our view,the distinctiveness of HS is fundamental to the soil,and thus further studies should be focused on revealing the distinctiveness of HS and explaining why HS hold this distinctiveness.展开更多
以水稻田田间定位试验为研究对象，利用三维荧光光谱技术（3D EEMs）和454测序技术，采集4个施磷水平（0、30、60、90 kg hm-2a-1）土壤，测定其有机碳矿化、溶解有机碳（DOC）组成和结构特征及细菌群落结构和丰度的变化。结果显示：水...以水稻田田间定位试验为研究对象，利用三维荧光光谱技术（3D EEMs）和454测序技术，采集4个施磷水平（0、30、60、90 kg hm-2a-1）土壤，测定其有机碳矿化、溶解有机碳（DOC）组成和结构特征及细菌群落结构和丰度的变化。结果显示：水田施磷增加了土壤速效磷（Olsen-P），从而提高了土壤DOC含量，加速了有机碳的矿化速率和累积矿化量。3D EEMs 结果表明，施磷分别显著增加了荧光指数和鲜度指数值1%～10%和3%～21%，而降低了腐殖化指数，且与土壤生化性质（Olsen-P、DOC和β-葡萄糖苷酶）具有显著相关性。说明施磷通过提高Olsen-P，促进了微生物源DOC的生成，同时降低了DOC的芳香化程度、分子量及腐殖化程度，从而提高了DOC生物可降解性。同时，施磷提高了细菌群落的丰度和多样性，特别是磷诱导了多种具有碳降解功能细菌的增加，从而加速了复杂有机碳的降解和甲烷氧化。此外，主成分分析表明稻田磷素施用量在30～60 kg hm-2a-1时对土壤有机碳矿化及细菌群落多样性的提高作用最为明显。因此，适度施磷能显著提高涉碳降解微生物的活性，从而提高DOC的生物可降解性，加速有机碳的矿化速率，促进稻田土壤有机碳循环。展开更多
The migration of soil dissolved organic carbon(DOC) from terrestrial to aquatic environments has important impacts on the adjacent water quality and the transport of organic and inorganic contaminants.However,few stud...The migration of soil dissolved organic carbon(DOC) from terrestrial to aquatic environments has important impacts on the adjacent water quality and the transport of organic and inorganic contaminants.However,few studies have investigated the sources and properties of DOC in riparian zones.A total of 34 soil samples were collected across four riparian buffer zones(Zones A-D) on Chongming Island,China.The vertical distributions of soil organic carbon(SOC) and DOC,fluorescence excitation-emission matrix(EEM) spectra of DOC and the optical indices,including fluorescence index(FI),index of recent autochthonous contribution(BIX),and humification index(HIX),were measured across the riparian environment to investigate the sources and fluorescence properties of DOC.The results showed that SOC stored in the surface soil(0-30 cm) accounted for 40%of the total soil profile SOC.The DOC accumulated in Zones A-C,which accounted for 5%of the SOC.The fluorescence EEM spectra of DOC showed that DOC contained humic-like and protein-like substances,which were mainly derived from recent plant debris by microbes.A large amount of humic-like substances were sorbed to minerals in the surface soil(0-30 cm).In addition,the riparian topography and soil physico-chemical properties(pH,EC and moisture) dictated the transformation and transport of DOC.The results suggested that EEMs could reveal the source of DOC in riparian soil systems,and that optical indices were complementary tools that revealed the characteristics of soil DOC and provided supplemental evidence about DOC sources.展开更多
基金funded by the the Key Technologied R&D Program of China during the 12th Five-Year Plan period (2013BAJ11B03)the Science & Technology Commission of Chongqing, China (CSTC, 2008AC7013)
文摘A 45-d laboratory experiment was conducted to compare the effect of four crop straws on the transformations of organic matter （OM） during composting of sewage sludge. The four crop straws included rape straw, wheat straw, maize straw and rice straw. The following parameters such as temperature, OM, humic-like substances （HS）, fulvic-like acids （FA） and humic-like acids （HA） were determined. The degradation of OM and the formation of HS and HA could be described well by the first-order kinetic model, while the FA content fluctuated during composting. The maximal degradation rates of OM in the compost piles added with rape straw, wheat straw, maize straw and rice straw were 34.7, 46.9, 54.7 and 52.8%, respectively, and the final contents of HS were 118, 128, 141 and 134 g kg-1, respectively, while the humification indices were higher in the compost piles added with maize straw and wheat straw than in those with rice straw and rape straw. The results indicate that a higher hemicellulose content and a lower C/N ratio in crop straw can result in a higher rate of OM degradation and higher contents of HS, while a higher content of lignin can lead to a higher polymerization degree of humic substances in compost piles. The final compost piles added with maize straw has the highest contents of OM, total nitrogen and humus substance as well as the highest values of polymerization degree, while compost piles with rape straw have the highest potassium content and those with rice straw have the highest pH values.
基金supported by the National Basic Research Program (973) of China (No. 2012CB719801)the National High Technology Research and Development Program (863) of China (No. 2012AA063504)+1 种基金the Key Special Program on the Science and Technology for the Pollution Control and Treatment of Water Bodies (No. 2011ZX07303-004-03)the Fok Ying-Tong Education Foundation (No. 132012), and the Program of Shanghai Subject Chief Scientist (No. 10XD1404200)
文摘Biochar has received increasing attention due to its applications as a soil amendment. Here, the chemical properties of solid and water-extractable fractions of four biochar samples were investigated. The results showed that wood biochar and bamboo biochar samples were 60%-80% more hydrophobic than those of rice husk biochar and rice husk ash. In addition, the acidity was 3.88 mmol/g from the total functional groups and 1.03 mmol/g from the carboxyl groups/lactones/phenols found in the wood biochar sample, which were about 1.5 times greater than those of the bamboo biochar sample. These functional groups could be used to determine the sorptive capacity of biochar for ionic solutes and water content and to increase the degradation of compost organics. The wood biochar sample was found to have the most humification materials （fulvic acid-like material ＋ humic acid-like material） in the water-extractable fraction, which was 3-10 times higher than that in the rice husk biochar and rice husk ash; humified materials were not detected in the bamboo biochar sample. Humification materials in biochar may be involved in increasing the proportion of humic acid-like materials in humic-like substances within the compost product. Wood biochar had better hydrophobic, sorptive, aromatic, and humification properties compared to other biochars, suggesting that it may be used in composting in order to exert its effect as both a bulking agent and a composting amendment during the solid waste composting process.
基金supported by the National Natural Science Foundation of China(Nos.41571231 and 41201221)the National Key Research and Development Program of China(No.2016YFD0200304)+3 种基金the Scientific Instrument and Equipment Development Project of Chinese Academy Sciences(CAS)(No.YJKYYQ20170058)the Natural Science Foundation of Jiangsu Province,China(No.BK2012496)the Youth Innovation Promotion Association,CAS(No.2017362)the Natural Science Foundation of the Jiangsu Higher Education Institutions of China(No.19KJB180010)。
文摘Humic substances(HS),which are defined as a series of highly acidic,relatively high-molecular-weight,and yellow to black colored substances formed during the decay and transformation of plant and microbial remains,ubiquitously occur in nature.Humic substances represent the largest stable organic carbon pool in terrestrial environments and are the central characteristic of the soil.However,the validity of the HS concept and the justification of their extraction procedure have been recently debated.Here,we argue that the traditional humic paradigm is still relevant.Humic substances are distinctive and complex because the extracted HS formed during the humification are chemically distinct from their precursors and are heterogeneous among soils.By reviewing the concept,formation pathways,and stabilization of HS,we propose that the key question facing soil scientists is whether HS are soil microbial residues or unique synthesized compounds.Without revealing the distinctiveness of HS,it is impossible to address this question,as the structure,composition,and reactivity of HS are still poorly known owing to the heterogeneity and geographical variability of HS and the limits of the currently available analytical techniques.In our view,the distinctiveness of HS is fundamental to the soil,and thus further studies should be focused on revealing the distinctiveness of HS and explaining why HS hold this distinctiveness.
文摘以水稻田田间定位试验为研究对象，利用三维荧光光谱技术（3D EEMs）和454测序技术，采集4个施磷水平（0、30、60、90 kg hm-2a-1）土壤，测定其有机碳矿化、溶解有机碳（DOC）组成和结构特征及细菌群落结构和丰度的变化。结果显示：水田施磷增加了土壤速效磷（Olsen-P），从而提高了土壤DOC含量，加速了有机碳的矿化速率和累积矿化量。3D EEMs 结果表明，施磷分别显著增加了荧光指数和鲜度指数值1%～10%和3%～21%，而降低了腐殖化指数，且与土壤生化性质（Olsen-P、DOC和β-葡萄糖苷酶）具有显著相关性。说明施磷通过提高Olsen-P，促进了微生物源DOC的生成，同时降低了DOC的芳香化程度、分子量及腐殖化程度，从而提高了DOC生物可降解性。同时，施磷提高了细菌群落的丰度和多样性，特别是磷诱导了多种具有碳降解功能细菌的增加，从而加速了复杂有机碳的降解和甲烷氧化。此外，主成分分析表明稻田磷素施用量在30～60 kg hm-2a-1时对土壤有机碳矿化及细菌群落多样性的提高作用最为明显。因此，适度施磷能显著提高涉碳降解微生物的活性，从而提高DOC的生物可降解性，加速有机碳的矿化速率，促进稻田土壤有机碳循环。
基金supported by the Major Science and Technology Program for Water Pollution Control and Treatment of China(Nos.2011ZX07303-001 and 2014ZX07303-003)the State Key Laboratory of Soil and Sustainable Agriculture,Institute of Soil Science,Chinese Academy of Sciences(No.Y412201426)
文摘The migration of soil dissolved organic carbon(DOC) from terrestrial to aquatic environments has important impacts on the adjacent water quality and the transport of organic and inorganic contaminants.However,few studies have investigated the sources and properties of DOC in riparian zones.A total of 34 soil samples were collected across four riparian buffer zones(Zones A-D) on Chongming Island,China.The vertical distributions of soil organic carbon(SOC) and DOC,fluorescence excitation-emission matrix(EEM) spectra of DOC and the optical indices,including fluorescence index(FI),index of recent autochthonous contribution(BIX),and humification index(HIX),were measured across the riparian environment to investigate the sources and fluorescence properties of DOC.The results showed that SOC stored in the surface soil(0-30 cm) accounted for 40%of the total soil profile SOC.The DOC accumulated in Zones A-C,which accounted for 5%of the SOC.The fluorescence EEM spectra of DOC showed that DOC contained humic-like and protein-like substances,which were mainly derived from recent plant debris by microbes.A large amount of humic-like substances were sorbed to minerals in the surface soil(0-30 cm).In addition,the riparian topography and soil physico-chemical properties(pH,EC and moisture) dictated the transformation and transport of DOC.The results suggested that EEMs could reveal the source of DOC in riparian soil systems,and that optical indices were complementary tools that revealed the characteristics of soil DOC and provided supplemental evidence about DOC sources.
