To understand the factors causing frequent outbreaks of harmful algae blooms in the Taihu Lake, China, we studied water quality and nutrient budget in Chinese mitten crab (Eriocheir sinensis) farm ponds in the eastern...To understand the factors causing frequent outbreaks of harmful algae blooms in the Taihu Lake, China, we studied water quality and nutrient budget in Chinese mitten crab (Eriocheir sinensis) farm ponds in the eastern part of the lake from November 2007 to December 2009. We estimated the nitrogen (N), phosphorus (P), and chemical oxygen demand (COD) loads. Materials input and output ponds, water exchange, and applied management practices of 838.5-hm2 crab ponds were surveyed using questionnaires. Water quality of 12 ponds, which were located no more than 2 km from East Taihu Lake, were monitored. The results show that water quality in the crab ponds was better than reference data. Feeds, including corn seed, commercial feed, trash fish, and gastropod, were the major sources of N and P input in the crab ponds, contributing 88.7% and 94.9%, respectively. In total, 60.5% of N and 37.3% of P were sequestered by macrophytes, and only 15.7% and 8.5% of them were discharged as effluent. The net loads of N and P in effluent were 16.43 kg/hm2/cycle and 2.16 kg/hm2/cycle, respectively, while the COD load was -17.88 kg/hm2/cycle. This indicated that crab farming caused minor negative impact on the trophic status of the lake area, which was attenuated by macrophytes. However, wastewater purification is still necessary in crab faming.展开更多
Reclaimed water has been widely applied in irrigation and industrial production.Revealing the behavior of emerging contaminants in the production process of reclaimed water is the first prerequisite for developing rel...Reclaimed water has been widely applied in irrigation and industrial production.Revealing the behavior of emerging contaminants in the production process of reclaimed water is the first prerequisite for developing relevant water quality standards.This study investigated 43 emerging contaminants,including 22 pharmaceuticals and personal care products(PPCPs),11 organophosphorus flame retardants(OPFRs),and 10 antibiotic resistance genes(ARGs)in 3 reclaimed wastewater treatment plants(RWTPs)in Beijing.The composition profiles and removal efficiencies of these contaminants in RWTPs were determined.The results indicated that the distribution characteristics of the different types of contaminants in the three RWTPs were similar.Caffeine,sul2 and tris(1-chloro-2-propyl)phosphate were the dominant substances in the wastewater,and their highest concentrations were 27104 ng/L,1.4×10^(7) copies/mL and 262 ng/L,respectively.Ofloxacin and sul2 were observed to be the dominant substances in the sludge,and their highest concentrations were 5419 ng/g and 3.7×10^(8) copies/g,respectively.Anaerobic/anoxic/oxic system combined with the membrane bioreactor process achieved a relatively high aqueous removal of PPCPs(87%).ARGs and OPFRs were challenging to remove,with average removal rates of 6.5%and 31%,respectively.Quantitative meta-analysis indicated that tertiary treatment processes performed better in emerging contaminant removal than secondary processes.Diethyltoluamide exhibited the highest mass load discharge,with 33.5 mg/d per 1000 inhabitants.Octocrylene and tris(2-ethylhexyl)phosphate posed high risks(risk quotient>1.0)to aquatic organisms.This study provides essential evidence to screen high priority pollutants and develop corresponding standard in RWTPs.展开更多
A large number of pharmaceuticals and personal care products(PPCPs)persist in wastewater,and the consumption of PPCPs for COVID-19 control and prevention has sharply increased during the pandemic.This study investigat...A large number of pharmaceuticals and personal care products(PPCPs)persist in wastewater,and the consumption of PPCPs for COVID-19 control and prevention has sharply increased during the pandemic.This study investigated the occurrence,removal efficiency,and risk assessment of six typical PPCPs commonly used in China in two wastewater treatment plants(WWTPs).Ribavirin(RBV)is an effective pharmaceutical for severely ill patients with COVID-19,and the possible biodegradation pathway of RBV by activated sludge was discovered.The experimental results showed that PPCPs were detected in two WWTPs with a detection rate of 100%and concentrations ranging between 612 and 2323 ng L^(-1).The detection frequency and concentrations of RBV were substantially higher,with a maximum concentration of 314 ng L^(-1).Relatively high pollution loads were found for the following PPCPs from influent:ibuprofen>ranitidine hydrochloride>RBV>ampicillin sodium>clozapine>sulfamethoxazole.The removal efficiency of PPCPs was closely related to adsorption and biodegradation in activated sludge,and the moving bed biofilm reactor(MBBR)had a higher removal capacity than the anoxic-anaerobic-anoxicoxic(AAAO)process.The removal efficiencies of sulfamethoxazole,ampicillin sodium,ibuprofen,and clozapine ranged from 92.21%to 97.86%in MBBR process and were relatively low,from 61.82%to 97.62%in AAAO process,and the removal of RBV and ranitidine hydrochloride were lower than 42.96%in both MBBR and AAAO processes.The discrepancy in removal efficiency is caused by temperature,hydrophilicity,and hydrophobicity of the compound,and acidity and alkalinity.The transformation products of RBV in activated sludge were detected and identified,and the biodegradation process of RBV could be speculated as follows:first breaks into TCONH_(2) and an oxygen-containing five-membered heterocyclic ring under the nucleosidase reaction,and then TCONH_(2) is finally formed into TCOOH through amide hydrolysis.Aquatic ecological risks based on risk quotient(RQ)assessment showed that展开更多
Experiments on grouting-reinforced rock mass specimens with different particle sizes and features were carried out in this study to examine the effects of grouting reinforcement on the load-bearing characteristics of ...Experiments on grouting-reinforced rock mass specimens with different particle sizes and features were carried out in this study to examine the effects of grouting reinforcement on the load-bearing characteristics of fractured rock mass.The strength and deformation features of grouting-reinforced rock mass were analyzed under different loading manners;the energy evolution mechanism of grouting-reinforced rock mass specimens with different particle sizes and features was investigated;the energy dissipation ratio and post-peak stress decreasing rate were employed to evaluate the bearing stability of grouting-reinforced rock mass.The results show that the strength and ductility of granite-reinforced rock mass(GRM)under biaxial loading are higher than that of sandstone-reinforced rock mass(SRM)under uniaxial loading.Besides,the energy evolution characteristics of grouting-reinforced rock mass under uniaxial and biaxial loading mainly could be divided into early,middle,and late stages.In the early stage,total,elastic,and dissipation energies were quite small with flatter curves;in the middle stage,elastic energy increased rapidly,whereas dissipation energy increased slowly;in the late stage,dissipation energy increased sharply.The energy dissipation ratio was used to represent the pre-peak plastic deformation.Under uniaxial loading,this ratio increased as the particle size increased and the pre-peak plastic deformation of grouting-reinforced rock mass became larger;under biaxial loading,it dropped as the particle size increased,and the pre-peak plastic deformation of grouting-reinforced rock mass became smaller.The post-peak stress decline rate A_(v) was used to assess the post-peak bearing performance of grouting-reinforced rock mass.Under uniaxial loading,parameter A_(v) exhibited reduction as the particle size kept increasing,and the ability of post-peak of grouting-reinforced rock mass to allow deformation development was greater,and the bearing capacity was greater;under biaxial loading,A_(v) increased with the p展开更多
Anthropogenic architectures have a significant impact to the environment. The Three Gorges Dam(TGD),as the largest dam in the world, is a typical example, and has influenced the mass anomalies transported by the flow ...Anthropogenic architectures have a significant impact to the environment. The Three Gorges Dam(TGD),as the largest dam in the world, is a typical example, and has influenced the mass anomalies transported by the flow downstream in the Yangtze River since June 2003. However, the evidence of TGD influence on downstream mass transportation is not documented. In this study, we analyze the monthly gravity solutions from GRACE to investigate the downstream mass variations of Yangtze River. From our results,the considerable mass loss is detected in the downstream of TGD. By comparing our estimations with the in situ water level data of TGD, we find that the mass variations derived from GRACE at Datong station decreases shortly after the impoundment of TGD. This confirms a strong connection between them.Furthermore, by comparing with the in situ sediment load and river discharge at Yichang and Datong gauging stations, we find that the sediment load data shows a similar mass loss signature while the river discharge of both stations has stay at a relative stable level. This indicates that further study is still needed to understand the mechanism better.展开更多
Deformation modulus of a rock mass(E_m) is one of the most important design parameters in construction of rock engineering projects such as underground excavations.However,difficulties are frequently encountered durin...Deformation modulus of a rock mass(E_m) is one of the most important design parameters in construction of rock engineering projects such as underground excavations.However,difficulties are frequently encountered during in-situ tests which are also time-consuming and expensive for determining this parameter.Although E_m is often estimated indirectly from proposed equations by different researchers,many of these equations cannot be used in case of problematic rock conditions(thinly bedded,highly jointed rock masses,etc.) as high quality core samples are required.This study aims to explore more practical and useful equation for E_m estimation using Rock Quality Designation(RQD) and point load index values.Comparisons were made between available empirical equations and the proposed E_m equation in terms of the estimation capacity.Multiple comparison tests(ANOVA) showed that E_m can be reliably estimated using proposed equation especially at the preliminary stages of projects.展开更多
冲击荷载作用下的岩体层裂是围岩屈曲失稳及岩爆的重要诱发因素。为研究围岩内部浅层节理对层裂行为的影响,采用相关键元胞力学模型(Correlated Lattice Bond CellCLBC)对此问题进行数值模拟研究。为了便于分析,以冲击荷载作用下不含节...冲击荷载作用下的岩体层裂是围岩屈曲失稳及岩爆的重要诱发因素。为研究围岩内部浅层节理对层裂行为的影响,采用相关键元胞力学模型(Correlated Lattice Bond CellCLBC)对此问题进行数值模拟研究。为了便于分析,以冲击荷载作用下不含节理的石梁层裂作为参考,将其层裂裂纹作为参考裂纹,层裂位置作为参考位置。相对于参考位置,分别在石梁中预设平行裂纹和斜裂纹组(相对于参考层裂裂纹),然后模拟相同荷载作用下的层裂行为。研究结果表明:浅层节理是否对岩体层裂产生影响取决于其相对参考层裂的位置和夹角。当平行节理位于参考层裂以内(远离自由面)时,平行节理对层裂没有影响;而当其处于参考层裂以外(近于自由面)时,应力波将其拉开、扩展,形成阶梯状层裂。对于斜节理组情形则更为复杂,但对于不同斜节理组其共同点都会在参考位置处产生层裂,并且表层岩石(层裂以外)都会被切割成块体沿斜节理方向弹出。当斜节理组位于参考位置以内时,斜节理发生扩展至自由面;当其位于参考位置以外时,只是在参考位置发生层裂;而当其跨越参考位置延伸至自由面时,在参考位置以内会产生平行于斜节理的衍生裂纹。该研究揭示了含浅层节理的岩体层裂规律,为分析围岩层裂行为提供了有意义参考,进而为进一步分析围岩屈曲失稳和岩爆提供必要的前提。展开更多
基金Supported by the Major Projects on Control and Rectification of Water Body Pollution (No. 2008ZX07101-012)the Knowledge Innovation Program of the Chinese Academy of Sciences (No. KZCX1-YW14)+1 种基金the Aquaculture "three projects" of Jiangsu (No. J2009-12)the Agricultural Basic Research Fund of Suzhou (No. YJG0912)
文摘To understand the factors causing frequent outbreaks of harmful algae blooms in the Taihu Lake, China, we studied water quality and nutrient budget in Chinese mitten crab (Eriocheir sinensis) farm ponds in the eastern part of the lake from November 2007 to December 2009. We estimated the nitrogen (N), phosphorus (P), and chemical oxygen demand (COD) loads. Materials input and output ponds, water exchange, and applied management practices of 838.5-hm2 crab ponds were surveyed using questionnaires. Water quality of 12 ponds, which were located no more than 2 km from East Taihu Lake, were monitored. The results show that water quality in the crab ponds was better than reference data. Feeds, including corn seed, commercial feed, trash fish, and gastropod, were the major sources of N and P input in the crab ponds, contributing 88.7% and 94.9%, respectively. In total, 60.5% of N and 37.3% of P were sequestered by macrophytes, and only 15.7% and 8.5% of them were discharged as effluent. The net loads of N and P in effluent were 16.43 kg/hm2/cycle and 2.16 kg/hm2/cycle, respectively, while the COD load was -17.88 kg/hm2/cycle. This indicated that crab farming caused minor negative impact on the trophic status of the lake area, which was attenuated by macrophytes. However, wastewater purification is still necessary in crab faming.
基金the Major Science and Technology Program for Water Pollution Control and Treatment(No.2018ZX07111003)the National Natural Science Foundation of China(Grant No.41977142)+1 种基金the Key Technologies Research and Development Program(No.2019YFC1806104)the Fundamental Research Funds for the Central Universities(No.JD2006).
文摘Reclaimed water has been widely applied in irrigation and industrial production.Revealing the behavior of emerging contaminants in the production process of reclaimed water is the first prerequisite for developing relevant water quality standards.This study investigated 43 emerging contaminants,including 22 pharmaceuticals and personal care products(PPCPs),11 organophosphorus flame retardants(OPFRs),and 10 antibiotic resistance genes(ARGs)in 3 reclaimed wastewater treatment plants(RWTPs)in Beijing.The composition profiles and removal efficiencies of these contaminants in RWTPs were determined.The results indicated that the distribution characteristics of the different types of contaminants in the three RWTPs were similar.Caffeine,sul2 and tris(1-chloro-2-propyl)phosphate were the dominant substances in the wastewater,and their highest concentrations were 27104 ng/L,1.4×10^(7) copies/mL and 262 ng/L,respectively.Ofloxacin and sul2 were observed to be the dominant substances in the sludge,and their highest concentrations were 5419 ng/g and 3.7×10^(8) copies/g,respectively.Anaerobic/anoxic/oxic system combined with the membrane bioreactor process achieved a relatively high aqueous removal of PPCPs(87%).ARGs and OPFRs were challenging to remove,with average removal rates of 6.5%and 31%,respectively.Quantitative meta-analysis indicated that tertiary treatment processes performed better in emerging contaminant removal than secondary processes.Diethyltoluamide exhibited the highest mass load discharge,with 33.5 mg/d per 1000 inhabitants.Octocrylene and tris(2-ethylhexyl)phosphate posed high risks(risk quotient>1.0)to aquatic organisms.This study provides essential evidence to screen high priority pollutants and develop corresponding standard in RWTPs.
基金The authors gratefully acknowledge the financial support provided by Jiangsu Policy Guidance Program(International Science and Technology Collaboration)(BZ2021030)Wuxi Innovation and Entrepreneurship Program for Science and Technology(M20211003)+1 种基金the Pre-research Fund of Jiangsu Collaborative Innovation Center of Technology and Material of Water Treatment(XTCXSZ2020-2)Jiangsu Special Funding of Science and Technology Innovation for Carbon Emission Peaking and Carbon Neutrality(BE2021409).
文摘A large number of pharmaceuticals and personal care products(PPCPs)persist in wastewater,and the consumption of PPCPs for COVID-19 control and prevention has sharply increased during the pandemic.This study investigated the occurrence,removal efficiency,and risk assessment of six typical PPCPs commonly used in China in two wastewater treatment plants(WWTPs).Ribavirin(RBV)is an effective pharmaceutical for severely ill patients with COVID-19,and the possible biodegradation pathway of RBV by activated sludge was discovered.The experimental results showed that PPCPs were detected in two WWTPs with a detection rate of 100%and concentrations ranging between 612 and 2323 ng L^(-1).The detection frequency and concentrations of RBV were substantially higher,with a maximum concentration of 314 ng L^(-1).Relatively high pollution loads were found for the following PPCPs from influent:ibuprofen>ranitidine hydrochloride>RBV>ampicillin sodium>clozapine>sulfamethoxazole.The removal efficiency of PPCPs was closely related to adsorption and biodegradation in activated sludge,and the moving bed biofilm reactor(MBBR)had a higher removal capacity than the anoxic-anaerobic-anoxicoxic(AAAO)process.The removal efficiencies of sulfamethoxazole,ampicillin sodium,ibuprofen,and clozapine ranged from 92.21%to 97.86%in MBBR process and were relatively low,from 61.82%to 97.62%in AAAO process,and the removal of RBV and ranitidine hydrochloride were lower than 42.96%in both MBBR and AAAO processes.The discrepancy in removal efficiency is caused by temperature,hydrophilicity,and hydrophobicity of the compound,and acidity and alkalinity.The transformation products of RBV in activated sludge were detected and identified,and the biodegradation process of RBV could be speculated as follows:first breaks into TCONH_(2) and an oxygen-containing five-membered heterocyclic ring under the nucleosidase reaction,and then TCONH_(2) is finally formed into TCOOH through amide hydrolysis.Aquatic ecological risks based on risk quotient(RQ)assessment showed that
基金Project(2023YFC2907600)supported by the National Key Research and Development Program of ChinaProject(202203a07020011)supported by the Major Science and Technology Projects of Anhui Province,China+4 种基金Project(T2021137)supported by the National Talent Project,ChinaProject(T000508)supported by the Leading Talent Project of the Special Support Plan of Anhui Province,ChinaProject(GXXT-2021-075)supported by the University Synergy Innovation Program of Anhui Province,ChinaProject(2022AH010053)supported by the Excellent Scientific Research and Innovation Team of Universities in Anhui Province,ChinaProject(2022CX1004)supported by the Anhui University of Science and Technology Postgraduate Innovation Fund Project,China。
文摘Experiments on grouting-reinforced rock mass specimens with different particle sizes and features were carried out in this study to examine the effects of grouting reinforcement on the load-bearing characteristics of fractured rock mass.The strength and deformation features of grouting-reinforced rock mass were analyzed under different loading manners;the energy evolution mechanism of grouting-reinforced rock mass specimens with different particle sizes and features was investigated;the energy dissipation ratio and post-peak stress decreasing rate were employed to evaluate the bearing stability of grouting-reinforced rock mass.The results show that the strength and ductility of granite-reinforced rock mass(GRM)under biaxial loading are higher than that of sandstone-reinforced rock mass(SRM)under uniaxial loading.Besides,the energy evolution characteristics of grouting-reinforced rock mass under uniaxial and biaxial loading mainly could be divided into early,middle,and late stages.In the early stage,total,elastic,and dissipation energies were quite small with flatter curves;in the middle stage,elastic energy increased rapidly,whereas dissipation energy increased slowly;in the late stage,dissipation energy increased sharply.The energy dissipation ratio was used to represent the pre-peak plastic deformation.Under uniaxial loading,this ratio increased as the particle size increased and the pre-peak plastic deformation of grouting-reinforced rock mass became larger;under biaxial loading,it dropped as the particle size increased,and the pre-peak plastic deformation of grouting-reinforced rock mass became smaller.The post-peak stress decline rate A_(v) was used to assess the post-peak bearing performance of grouting-reinforced rock mass.Under uniaxial loading,parameter A_(v) exhibited reduction as the particle size kept increasing,and the ability of post-peak of grouting-reinforced rock mass to allow deformation development was greater,and the bearing capacity was greater;under biaxial loading,A_(v) increased with the p
基金support from the National Natural Science Foundation of China (41774094, 41704013 and 51809250)the Strategic Priority Research Program of the Chinese Academy of Sciences (XDB23030100)
文摘Anthropogenic architectures have a significant impact to the environment. The Three Gorges Dam(TGD),as the largest dam in the world, is a typical example, and has influenced the mass anomalies transported by the flow downstream in the Yangtze River since June 2003. However, the evidence of TGD influence on downstream mass transportation is not documented. In this study, we analyze the monthly gravity solutions from GRACE to investigate the downstream mass variations of Yangtze River. From our results,the considerable mass loss is detected in the downstream of TGD. By comparing our estimations with the in situ water level data of TGD, we find that the mass variations derived from GRACE at Datong station decreases shortly after the impoundment of TGD. This confirms a strong connection between them.Furthermore, by comparing with the in situ sediment load and river discharge at Yichang and Datong gauging stations, we find that the sediment load data shows a similar mass loss signature while the river discharge of both stations has stay at a relative stable level. This indicates that further study is still needed to understand the mechanism better.
基金the Karadeniz Technical University (KTU)for funding this work through the research(No.9706)
文摘Deformation modulus of a rock mass(E_m) is one of the most important design parameters in construction of rock engineering projects such as underground excavations.However,difficulties are frequently encountered during in-situ tests which are also time-consuming and expensive for determining this parameter.Although E_m is often estimated indirectly from proposed equations by different researchers,many of these equations cannot be used in case of problematic rock conditions(thinly bedded,highly jointed rock masses,etc.) as high quality core samples are required.This study aims to explore more practical and useful equation for E_m estimation using Rock Quality Designation(RQD) and point load index values.Comparisons were made between available empirical equations and the proposed E_m equation in terms of the estimation capacity.Multiple comparison tests(ANOVA) showed that E_m can be reliably estimated using proposed equation especially at the preliminary stages of projects.
文摘冲击荷载作用下的岩体层裂是围岩屈曲失稳及岩爆的重要诱发因素。为研究围岩内部浅层节理对层裂行为的影响,采用相关键元胞力学模型(Correlated Lattice Bond CellCLBC)对此问题进行数值模拟研究。为了便于分析,以冲击荷载作用下不含节理的石梁层裂作为参考,将其层裂裂纹作为参考裂纹,层裂位置作为参考位置。相对于参考位置,分别在石梁中预设平行裂纹和斜裂纹组(相对于参考层裂裂纹),然后模拟相同荷载作用下的层裂行为。研究结果表明:浅层节理是否对岩体层裂产生影响取决于其相对参考层裂的位置和夹角。当平行节理位于参考层裂以内(远离自由面)时,平行节理对层裂没有影响;而当其处于参考层裂以外(近于自由面)时,应力波将其拉开、扩展,形成阶梯状层裂。对于斜节理组情形则更为复杂,但对于不同斜节理组其共同点都会在参考位置处产生层裂,并且表层岩石(层裂以外)都会被切割成块体沿斜节理方向弹出。当斜节理组位于参考位置以内时,斜节理发生扩展至自由面;当其位于参考位置以外时,只是在参考位置发生层裂;而当其跨越参考位置延伸至自由面时,在参考位置以内会产生平行于斜节理的衍生裂纹。该研究揭示了含浅层节理的岩体层裂规律,为分析围岩层裂行为提供了有意义参考,进而为进一步分析围岩屈曲失稳和岩爆提供必要的前提。
