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Health Risks Assessment of Heavy Metal Pollution in the Soil-Crop System from an E-Waste Dismantling Area 被引量:1
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作者 Shengting Rao Jia Fang Keli Zhao 《Phyton-International Journal of Experimental Botany》 SCIE 2022年第12期2669-2685,共17页
Soil is an essential resource for agricultural production.In order to investigate the pollution situation of heavy metals in the soil-crop system in the e-waste dismantling area,the crop and soil samples(226 pairs,inc... Soil is an essential resource for agricultural production.In order to investigate the pollution situation of heavy metals in the soil-crop system in the e-waste dismantling area,the crop and soil samples(226 pairs,including leaf vegetables,solanaceous vegetables,root vegetables,and fruits)around the e-waste dismantling area in southeastern Zhejiang Province were collected.The concentrations of Cd,Cu,Pb,and Cr were determined.The average concentrations of Cd,Cu,Pb,and Cr in soils were 0.94,107.79,80.28,and 78.14 mg kg-1,respectively,and their corresponding concentrations in crops were 0.024,0.7,0.041,and 0.06 mg kg-1,respectively.The transfer capacity of leaf vegetables was significantly higher than that of non-leaf vegetables,and the accumulation of four heavy metals in crops tended to be Cd>Cu>Cr/Pb.The pollution index’s results revealed that the soil pollution degree under different land uses ranked as root vegetables soil>leaf vegetables soil>solanaceous vegetables soil>fruit soil.The carcinogenic and non-carcinogenic risks of heavy metal exposure were ranked as food intake>accidental ingestion>dermal contact>inhalation.The comprehensive non-carcinogenic risk was ranked as Cr>Cd>Pb/Cu.Our results could be used to provide useful information for further crop cultivation layout in the study area,which can guarantee the local residents’health and food safety. 展开更多
关键词 e-waste dismantling area soil-crop system heavy metal pollution risk assessment
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Mercury speciation, bioavailability and risk assessment on soil–rice systems from a watershed impacted by abandoned Hg mine-waste tailings
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作者 Jian Pang Jialiang Han +4 位作者 Xuelu Fan Chan Li Xian Dong Longchao Liang Zhuo Chen 《Acta Geochimica》 EI CAS CSCD 2019年第3期391-403,共13页
Mercury(Hg) is a global pollutant and can be accumulated in the food chain, posing exposure risks to humans. In this study, rice plants and corresponding rhizosphere soil samples were collected from a watershed of the... Mercury(Hg) is a global pollutant and can be accumulated in the food chain, posing exposure risks to humans. In this study, rice plants and corresponding rhizosphere soil samples were collected from a watershed of the Wawu River Basin that is heavily impacted by historic Hg mining and retorting activities. Total mercury(THg)and methylmercury(MeHg) in rice grains, as well as other tissues and soil samples, were measured. Five soil Hg fractions, as well as soil parameters, were also determined.The results show that the average concentrations of THg and MeHg in rice grains were 14 ± 7.0 lg kg^(-1) and7.2 ± 4.0 lg kg^(-1). Soil organic-bound(Hg-o) and strong complex-bound(Hg-s) were the main Hg fractions,accounting for 44% of the total. To estimate the Hg–ligand interaction in the soils, soil-N/Hg(R = 0.451, p \ 0.05),-S/Hg(R = 0.372, p \ 0.1), and-OM/Hg ratio(R = 0.320,p \ 0.5) with MeHg_(soil) were observed with significant positive correlations, indicating that the formation of Hg–OM, Hg–N–OM or Hg–S–OM complexes could prevent Hg(II) from methylation in soils. The significant positive correlations of the-N/Hg ratio,-S/Hg ratio and-OM/Hg ratio with MeHg in rice tissues suggested that Hg methylation and MeHg demethylation occurred throughout the rice paddy ecosystem. The estimated MeHg daily intake(EDI) was 0.075 ± 0.041 lg kg^(-1) bw d^(-1) and was lower than the RfD level of 0.1 lg kg^(-1) bw d^(-1) recommended by the US EPA. However, approximately 29% of the hazardous index(HI) of MeHg in grain exceeded 1, posing a potential threat to local populations, particularly pregnant women and children. 展开更多
关键词 MERCURY and METHYLMERCURY RICE MERCURY speciation and BIOAVAILABILITY Paddy soil Risk assessment
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Contamination and Remediation of Heavy Metals in Soils near E-waste Recycling Area
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作者 Chen Haitang He Huayan +2 位作者 Zhou Dandan Lou Linjie Hu Qingnian 《Meteorological and Environmental Research》 CAS 2015年第4期21-24,共4页
In order to assess heavy metals pollution in agricultural soil after renovation in typical e-waste recycling areas, 212 soil samples were col- lected and the mass fractions of 7 kinds of heavy metals (Cd, Cr, Cu, Hg,... In order to assess heavy metals pollution in agricultural soil after renovation in typical e-waste recycling areas, 212 soil samples were col- lected and the mass fractions of 7 kinds of heavy metals (Cd, Cr, Cu, Hg, Ni, Pb and Zn) were analyzed. The results indicated that heavy metals pollution in agricultural soil was commonly existed in the study areas, and the soil was slightly contaminated by Pb but was moderately or critically polluted by Cd and Cu. However, the carcinogenic risk and non-carcinogenic risk status by heavy metals pollution were beyond acceptable levels, and soil remediation was quite necessary. After some investigations of bioremediation, we found that saponin as washing agent could highly strenqthen the behavior of heavy metals desorption from soil ,which had a good prospect of engineering practice. 展开更多
关键词 Electrical and electronic waste recycling Heavy metals soil pollution Health risk soil remediation China
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Heavy Metal Profile of Oreochromis niloticus Harvested from E-Waste Polluted Vials and Associated Fungi
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作者 Adeyemi Isaac Sanusi 《Advances in Microbiology》 2016年第8期555-565,共11页
This study was designed to investigate the possible variation in bioaccumulation of heavy metals (lead, cadmium, zinc, cobalt, chromium, nickel, and manganese) in the tissue of harvested Oreochromis niloticus (tilapia... This study was designed to investigate the possible variation in bioaccumulation of heavy metals (lead, cadmium, zinc, cobalt, chromium, nickel, and manganese) in the tissue of harvested Oreochromis niloticus (tilapia) and the associated fungi from vials treated with soil from e-waste dumpsite and soil without e-waste. E-waste is electronic waste which contains valuable metals as well as potential environmental contaminants. The heavy metals in soil and fish samples were determined using flame atomic absorption spectrophotometer (AAS) after homogeneity and digestion of samples. The associated fungi were identified using standard microbiological methods. The genera of the associated fungi were: Penicillium, Candida, Articulospora, Aspergillus, Aspergillus, Aspergillus, Rhizopus, Mucor, Zoopage, Varicosporium and Rhodoturula. The quantity of fungi isolated from each pollution treatments showed that the number of fungi were inversely proportional to the quantity of e-waste soil pollution and directly proportional to the quantity of soil without e-waste pollution. The occurrence of the fungi species revealed that the untreated (control) vial had the highest occurrence (191) while the lowest occurrence (103) occurred in the vial polluted with the highest quantity of soil from e-waste dumpsite. The pH and the biochemical oxygen demand (BOD) of the vials were significantly affected by the pollutions. Variations were also observed in the bioaccumulation of the heavy metals by Oreochromis niloticus. Cadmium (0.01 mg/kg) and nickel (0.02 - 0.08 mg/kg) were the least recorded metal in the tissue of the fish while cobalt was not detected after the five weeks period. The sequence of the heavy metals concentrations in Oreochromis niloticus tissue samples was Zn > Mn > Pb > Cr > Ni > Cd > Co. The accumulation of the metals in the fish tissue were, however, lower than the international maximum guidelines, except for manganese (0.29 - 3.13 mg/kg) that exceeded the 0.01 - 0.05 mg/kg threshold levels for manganese by Federal Environmental Protection Agency (FEPA). Protecting the environments from toxic metals is necessary, hence a need for public awareness on the dangers of these toxic metals and law for proper disposal of e-waste. 展开更多
关键词 BIOACCUMULATION FUNGI Heavy Metals Vial e-waste soil Oreochromis niloticus
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Polychlorinated biphenyls in the atmosphere of Taizhou,a major e-waste dismantling area in China 被引量:19
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作者 Wenliang Han Jialiang Feng +3 位作者 Zeping Gu Minghong Wu Guoying Sheng Jiamo Fu 《Journal of Environmental Sciences》 SCIE EI CAS CSCD 2010年第4期589-597,共9页
PM2.5, total suspended particles (TSP) and gas phase samples were collected at two sites of Talzhou, a major e-waste dismantling area in China. Concentrations, seasonal variations, congener profiles, gas-particle pa... PM2.5, total suspended particles (TSP) and gas phase samples were collected at two sites of Talzhou, a major e-waste dismantling area in China. Concentrations, seasonal variations, congener profiles, gas-particle partitioning and size distribution of the atmospheric polychlorinated biphenyls (PCBs) were studied to assess the current state of atmospheric PCBs after the phase out of massive historical dismantling of PCBs containing e-wastes. The average ∑38PCBs concentration in the ambient air (TSP plus gas phase) near the e-waste dismantling area was (12,407 ± 9592) pg/m^3 in winter, which was substantially lower than that found one decade ago. However, the atmospheric PCBs level near the e-waste dismantling area was 54 times of the reference urban site, indicating that the impact of the historical dismantling of PCBs containing e-wastes was still significant. Tri-Penta-CBs were dominant homologues, consisting with their dominant global production. Size distribution of particle-bound PCBs showed that higher chlorinated CBs tended to partition more to the fine particles, facilitating its long range air transportation. 展开更多
关键词 polychlorinated biphenyls e-waste PM2.5 total suspended particles Talzhou
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Ecotoxicological effects of mixed pollutants resulted from e-wastes recycling and bioaccumulation of polybrominated diphenyl ethers in Chinese loach(Misgurnus anguillicaudatus) 被引量:6
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作者 QIN Xiaofei XIA Xijuan +8 位作者 LI Yan ZHAO Yaxian YANG Zhongzhi FU Shan TI-AN Mi ZHAO Xingru QIN Zhanfen XU Xiaobai YANG Yongjian 《Journal of Environmental Sciences》 SCIE EI CAS CSCD 2009年第12期1695-1701,共7页
To understand potential ecotoxicological effects of electrical and electronic equipment waste (e-waste) recycling and polybrominated diphenyl ethers (PBDEs) bioaccumulation in loaches, a semi-field experiment usin... To understand potential ecotoxicological effects of electrical and electronic equipment waste (e-waste) recycling and polybrominated diphenyl ethers (PBDEs) bioaccumulation in loaches, a semi-field experiment using Chinese loach (Misgurnus anguiUicaudatus) as experimental fish was performed. Larval loaches were kept in net-cage for three months in an e-wastes recycling site and a reference site in Southeastern China. There was significant difference of the survival rate between the loaches from the e-wastes recycling site (27%, 19/70) and from reference site (70%, 49/70). Histopathological responses were also found in all the livers examined in loaches from the e-wastes recycling site. These results showed that mixed pollutants resulted from e-wastes recycling led to ecotoxicological effects on loaches. The bioaccumulation of polybrominated diphenyl ethers (PBDEs), the main pollutants in e-waste, in loaches was also studied, the mean concentration of total PBDEs in sediment was 6726.17 ng/g wet weight and in water samples was 4.08 ng/L (dissolved phase). BDE 209 was the dominant congener in sediment and with relatively high concentration in water. Relatively low concentration of BDE 209 (less than 0.01% of total PBDEs) and high concentration of BDE47 (up to 39.34% of total PBDEs) were detected in loaches. 展开更多
关键词 e-wastes LOACH ecotoxicological effects polybrominated diphenyl ethers semi-field experiment
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Effects of Environmental Lead Pollution on Blood Lead and Sex Hormone Levels among Occupationally Exposed Group in An E-waste Dismantling Area 被引量:5
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作者 YANG Yan LU Xiao Song +1 位作者 LI Ding Long YU Yun Jiang 《Biomedical and Environmental Sciences》 SCIE CAS CSCD 2013年第6期474-484,共11页
Objective To study the effects of environmental multi-media lead pollution on blood lead and sex hormone levels among lead exposed males engaged in E-waste dismantling, and the correlation between confounding factors ... Objective To study the effects of environmental multi-media lead pollution on blood lead and sex hormone levels among lead exposed males engaged in E-waste dismantling, and the correlation between confounding factors and sex hormone levels. Methods An E-waste dismantling area in Taizhou of Zhejiang Province was selected as the research site. One hundred and fifty two samples were collected from the groundwater, soil, rice, corn, chicken, and pork in the dismantling area. The effects of the multi-media lead pollution on the male blood lead and sex hormone levels of FSH, LH, and T, as well as the correlation with confounding factors, were studied. Results The blood lead concentrations in the males aged under 31, from 31 to 45 and from 46 to 60 were 98.55, 100.23, and 101.45 I~/L, respectively. Of all the environmental media lead exposures, the groundwater, rice and soil were main contributing factors to the lead accumulation in humans. FSH and LH levels increased with the age while the T levels decreased with the age instead. There was a significant correlation between the FSH and LH levels and wearing masks. Conclusion There was correlation between the FSH, LH, and T levels, and the mean values of lead concentrations in environmental media, and the sex hormone levels were correlated with the confounding factor of wearing masks. 展开更多
关键词 Lead e-waste dismantling Follicle stimulating hormone (FSH) Luteinizing hormone (LH) Testosterone (T) Blood lead
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Evaluating the treatment of E-waste──a case study of discarded refrigerators 被引量:1
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作者 DENG Jian-jun WEN Xue-feng ZHAO Yue-min 《Journal of China University of Mining and Technology》 EI 2008年第3期454-458,共5页
Disassembly and recycling of E-waste creates a series of environmental problems. The selection of a technologically reliable, environmentally friendly, economically affordable and socially acceptable recycling technol... Disassembly and recycling of E-waste creates a series of environmental problems. The selection of a technologically reliable, environmentally friendly, economically affordable and socially acceptable recycling technology for E-waste is a significant question. This study establishes a Monte-Carlo mathematical model of cost minimization, given the constraints of environmentally sound handling of the e-waste, in the context of Crystal Ball risk assessment and evaluation software. By following the streams of the different treatment processes, which consist of various technologies including disassembly, recycling and disposal, the econom-ics of various possibilities were identified and the optimal recycling technology proposed. The key factors of the proposed scenarios were determined by using sensitivity analysis. The results of this study show that, for discarded refrigerators, the operating life span plays the key role. The model supports maintenance and resale of the short lived refrigerators. For the longer lived refrigerators material recycling is recommended by the model. Sensitivity analysis shows that purchase cost, plastic sale price, condenser sale price and disassembly costs are the main effects. This study provides a significant technical support for policy making in E-waste management. 展开更多
关键词 e-waste end-of-life refrigerator RECYCLING Monte-carlo method sensitivity analysis
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Comparative Study on the E-waste Recycling Systems in Japan and China 被引量:1
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作者 Kayoko Y amamloto Bi Bo 《Journal of Environmental Science and Engineering(A)》 2013年第7期427-439,共13页
This study aims to identify processes, current situations and issues of recycling systems for four home appliances, namely, air conditioners, television receivers, refrigerators, and washing machines, among e-wastes i... This study aims to identify processes, current situations and issues of recycling systems for four home appliances, namely, air conditioners, television receivers, refrigerators, and washing machines, among e-wastes in China and Japan for understanding and comparison of their characteristics. In accordance with results of a literature search, review of information disclosed online, and questionnaire survey conducted, the findings of this study are summarized in the following two points: (1) The results show that in Japan most of the home appliances mentioned above have been collected through home appliance recycling tickets, resulting in an issue of "requiring some effort" in treatment and recycling stages, and most plants have contracted out their e-waste recycling; (2) It is found out that advantages of the recycling system in Japan include easiness to monitor concrete data and thorough environmental friendliness ensured while its disadvantages include illegal dumping and export. It becomes apparent that advantages of the recycling system in China include a high reuse rate, low treatment cost, and fewer illegal dumping while its disadvantages include less safe reused products, environmental pollution caused by e-waste treatment, illegal import and difficulty in obtaining data. 展开更多
关键词 e-waste recycling systems home appliances Japan and China.
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Developing an Extended Theory of Planned Behavior Model for Small E-Waste Recycling:An Analysis of Consumer Behavior Determinants 被引量:1
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作者 Joshua E.Lou 《Journal of Environmental Science and Engineering(A)》 2022年第3期71-86,共16页
WEEE(Waste Electrical and Electronic Equipment),also called e-waste,has become the world’s fastest-growing waste stream but only has a 17.4%recycling rate according to the Global E-waste Monitor 2020.The collection r... WEEE(Waste Electrical and Electronic Equipment),also called e-waste,has become the world’s fastest-growing waste stream but only has a 17.4%recycling rate according to the Global E-waste Monitor 2020.The collection rate for sWEEE(Small WEEE),e.g.,used mobile phones,is even lower than 10%due to stockpiling at home and improper disposal via the general waste or private informal channels.The purpose of this paper was to(a)review how the TPB(Theory of Planned Behavior)was applied in the literature related to consumer behavioral intention for WEEE recycling and determine the most significant TPB predictors by comparing their standardized influence coefficients across various studies,and(b)identify additional behavior determinants specific to sWEEE recycling and thus develop a new TPB-sWEEE theoretical framework by integrating the TPB model with these new determinants in order to improve the predictability of consumers’sWEEE recycling behavioral intention.This paper reviewed over 30 peer-reviewed studies from Scopus and high impact factor journals and led to the following three key findings:(a)More variables of recycling behavioral intention determinants such as the size of WEEE need to be considered;(b)Eight sWEEE-specific behavioral determinants have been identified and included in the newly developed TPB-sWEEE model,including consumers’Sentimental Attachment,Data Security Concern,Economic Incentives,and How-to Knowledge;(c)For some sWEEE-specific determinants,their extent of influence differs across various regions and countries.This paper contributes to the sWEEE-specific consumer recycling behavior theoretical framework to fill the existing gap in the literature and provides recommendations through the new model for research-based behavioral intervention strategies and policy designs globally. 展开更多
关键词 WEEE sWEEE e-waste consumer recycling behavioral intention TPB determinants TPB-sWEEE theoretical framework.
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Sustainable Guideline for Developing the E-Waste Sector in Egypt
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作者 Ahmed Tarek Salah El-Haggar 《Journal of Environmental Protection》 2019年第8期1043-1071,共29页
The amount of electronic waste generated globally is alarming especially that it is on the rise. The impact of the generated amounts is not only Environmental. The electronic waste sector is unregulated in most develo... The amount of electronic waste generated globally is alarming especially that it is on the rise. The impact of the generated amounts is not only Environmental. The electronic waste sector is unregulated in most developing countries;this results in the informal sector being heavily involved in managing and handling it. Due to the lack of regulations, informal handlers are exposed to hazardous materials that affect both their health and health of the communities living in their proximity. Moreover, the informal sector involves illegal child and women labor under harsh conditions. In addition to the social impact, the lack of regulations leads to missing major economic opportunities associated with developing a recycling industry for the safe handling and material recovery from the generated e-waste volumes. Electronic waste may contain up to 60 different materials including precious and rare-earth metals with estimated equivalent economic value of 48 billion Euros. Egypt is one the countries which lack policies and regulations dedicated to e-waste, hence the Egyptian economy is missing the economic potential and job creation opportunities associated with developing the e-waste sector as well as facing major Environmental and health challenges due to the improper handling of the generated amounts. This paper briefly reviews the current situation of e-waste in Egypt. The paper then proposes an adapted guideline for the sustainable management of e-waste in Egypt. The guideline is based on the international regulations and guidelines especially those of countries similar to the Egyptian socioeconomic context. The produced guideline focuses on establishing a collection and recycling framework for e-waste in Egypt with EPR at its center. The guideline also establishes a financing system to help foster the recycling industry in Egypt while fulfilling the three main pillars of sustainability. 展开更多
关键词 e-waste e-waste Management SUSTAINABLE GUIDELINES e-waste in EGYPT
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The competition between Bidens pilosa and Setaria viridis alters soil microbial composition and soil ecological function 被引量:1
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作者 Qiao Li Jianying Guo +1 位作者 Han Zhang Mengxin Zhao 《Journal of Integrative Agriculture》 SCIE CSCD 2024年第1期267-282,共16页
Bidens pilosa is recognized as one of the major invasive plants in China.Its invasion has been associated with significant losses in agriculture,forestry,husbandry,and biodiversity.Soil ecosystems play an important ro... Bidens pilosa is recognized as one of the major invasive plants in China.Its invasion has been associated with significant losses in agriculture,forestry,husbandry,and biodiversity.Soil ecosystems play an important role in alien plant invasion.Microorganisms within the soil act as intermediaries between plants and soil ecological functions,playing a role in regulating soil enzyme activities and nutrient dynamics.Understanding the interactions between invasive plants,soil microorganisms,and soil ecological processes is vital for managing and mitigating the impacts of invasive species on the environment.In this study,we conducted a systematic analysis focusing on B.pilosa and Setaria viridis,a common native companion plant in the invaded area.To simulate the invasion process of B.pilosa,we constructed homogeneous plots consisting of B.pilosa and S.viridis grown separately as monocultures,as well as in mixtures.The rhizosphere and bulk soils were collected from the alien plant B.pilosa and the native plant S.viridis.In order to focus on the soil ecological functional mechanisms that contribute to the successful invasion of B.pilosa,we analyzed the effects of B.pilosa on the composition of soil microbial communities and soil ecological functions.The results showed that the biomass of B.pilosa increased by 27.51% and that of S.viridis was significantly reduced by 66.56%.The organic matter contents in the bulk and rhizosphere soils of B.pilosa were approximately 1.30 times those in the native plant soils.The TN and NO_(3)^(-)contents in the rhizosphere soil of B.pilosa were 1.30 to 2.71 times those in the native plant soils.The activities of acid phosphatase,alkaline phosphatase,and urease in the rhizosphere soil of B.pilosa were 1.98-2.25 times higher than in the native plant soils.Using high-throughput sequencing of the16S rRNA gene,we found that B.pilosa altered the composition of the soil microbial community.Specifically,many genera in Actinobacteria and Proteobacteria were enriched in B.pilosa soils.Further correlation analyses verified that these genera had significantly positive relationships with soil nutrients and enzyme activities.Plant biomass,soil p H,and the contents of organic matter,TN,NO_(3)^(-),TP,AP,TK,and AK were the main factors affecting soil microbial communities.This study showed that the invasion of B.pilosa led to significant alterations in the composition of the soil microbial communities.These changes were closely linked to modifications in plant traits as well as soil physical and chemical properties.Some microbial species related to C,N and P cycling were enriched in the soil invaded by B.pilosa.These findings provide additional support for the hypothesis of soil-microbe feedback in the successful invasion of alien plants.They also offer insights into the ecological mechanism by which soil microbes contribute to the successful invasion of B.pilosa.Overall,our research contributes to a better understanding of the complex interactions between invasive plants,soil microbial communities,and ecosystem dynamics. 展开更多
关键词 plant invasion Bidens pilosa soil microbial composition soil properties soil enzyme activities
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Biochar Decreases Soil Cadmium(Cd) Availability and Regulates Expression Levels of Cd Uptake/Transport-Related Genes to Reduce Cd Translocation in Rice 被引量:1
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作者 WANG Han HUANG Qina +3 位作者 ZHANG Yan SHAO Guosheng HU Yijun XU Youxiang 《Rice science》 SCIE CSCD 2024年第5期494-498,I0006-I0013,共13页
Biochar has been used as a soil amendment for heavy metal-contaminated soils, and it has the potential to mitigate Cd accumulation in plants. In this study, we used rice straw biochar(RSB) and kitchen waste biochar(KW... Biochar has been used as a soil amendment for heavy metal-contaminated soils, and it has the potential to mitigate Cd accumulation in plants. In this study, we used rice straw biochar(RSB) and kitchen waste biochar(KWB) to clarify the effect of biochar on Cd-contaminated neutral soil, the physiological responses to biochar application, and the gene regulatory networks in a rice genotype. 展开更多
关键词 soil STRAW soils
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Subsoil tillage enhances wheat productivity,soil organic carbon and available nutrient status in dryland fields 被引量:1
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作者 Qiuyan Yan Linjia Wu +6 位作者 Fei Dong Shuangdui Yan Feng Li Yaqin Jia Jiancheng Zhang Ruifu Zhang Xiao Huang 《Journal of Integrative Agriculture》 SCIE CSCD 2024年第1期251-266,共16页
Tillage practices during the fallow period benefit water storage and yield in dryland wheat crops.However,there is currently no clarity on the responses of soil organic carbon(SOC),total nitrogen(TN),and available nut... Tillage practices during the fallow period benefit water storage and yield in dryland wheat crops.However,there is currently no clarity on the responses of soil organic carbon(SOC),total nitrogen(TN),and available nutrients to tillage practices within the growing season.This study evaluated the effects of three tillage practices(NT,no tillage;SS,subsoil tillage;DT,deep tillage)over five years on soil physicochemical properties.Soil samples at harvest stage from the fifth year were analyzed to determine the soil aggregate and aggregate-associated C and N fractions.The results indicated that SS and DT improved grain yield,straw biomass and straw carbon return of wheat compared with NT.In contrast to DT and NT,SS favored SOC and TN concentrations and stocks by increasing the soil organic carbon sequestration rate(SOCSR)and soil nitrogen sequestration rate(TNSR)in the 0-40 cm layer.Higher SOC levels under SS and NT were associated with greater aggregate-associated C fractions,while TN was positively associated with soluble organic nitrogen(SON).Compared with DT,the NT and SS treatments improved soil available nutrients in the 0-20 cm layer.These findings suggest that SS is an excellent practice for increasing soil carbon,nitrogen and nutrient availability in dryland wheat fields in North China. 展开更多
关键词 TILLAGE dryland wheat fields soil aggregate size soil nutrients soil carbon and nitrogen fractions
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A dynamic soil freezing characteristic curve model for frozen soil 被引量:1
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作者 Xiaokang Li Xu Li Jiankun Liu 《Journal of Rock Mechanics and Geotechnical Engineering》 SCIE CSCD 2024年第8期3339-3352,共14页
The soil freezing characteristic curve(SFCC)plays a fundamental role in comprehending thermohydraulic behavior and numerical simulation of frozen soil.This study proposes a dynamic model to uniformly express SFCCs ami... The soil freezing characteristic curve(SFCC)plays a fundamental role in comprehending thermohydraulic behavior and numerical simulation of frozen soil.This study proposes a dynamic model to uniformly express SFCCs amidst varying total water contents throughout the freezing-thawing process.Firstly,a general model is proposed,wherein the unfrozen water content at arbitrary temperature is determined as the lesser of the current total water content and the reference value derived from saturated SFCC.The dynamic performance of this model is verified through test data.Subsequently,in accordance with electric double layer(EDL)theory,the theoretical residual and minimum temperatures in SFCC are calculated to be-14.5℃to-20℃for clay particles and-260℃,respectively.To ensure that the SFCC curve ends at minimum temperature,a correction function is introduced into the general model.Furthermore,a simplified dynamic model is proposed and investigated,necessitating only three parameters inherited from the general model.Additionally,both general and simplified models are evaluated based on a test database and proven to fit the test data exactly across the entire temperature range.Typical recommended parameter values for various types of soils are summarized.Overall,this study provides not only a theoretical basis for most empirical equations but also proposes a new and more general equation to describe the SFCC. 展开更多
关键词 Frozen soils Unsaturated soils soil freezing characteristic curve(SFCC) Mathematic models
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Straw return increases crop production by improving soil organic carbon sequestration and soil aggregation in a long-term wheat-cotton cropping system 被引量:2
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作者 Changqin Yang Xiaojing Wang +6 位作者 Jianan Li Guowei Zhang Hongmei Shu Wei Hu Huanyong Han Ruixian Liu Zichun Guo 《Journal of Integrative Agriculture》 SCIE CAS CSCD 2024年第2期669-679,共11页
Straw return is a promising strategy for managing soil organic carbon(SOC)and improving yield stability.However,the optimal straw return strategy for sustainable crop production in the wheat(Triticum aestivum L.)-cott... Straw return is a promising strategy for managing soil organic carbon(SOC)and improving yield stability.However,the optimal straw return strategy for sustainable crop production in the wheat(Triticum aestivum L.)-cotton(Gossypium hirsutum L.)cropping system remains uncertain.The objective of this study was to quantify the long-term(10 years)impact of carbon(C)input on SOC sequestration,soil aggregation and crop yields in a wheat-cotton cropping system in the Yangtze River Valley,China.Five treatments were arranged with a single-factor randomized design as follows:no straw return(Control),return of wheat straw only(Wt),return of cotton straw only(Ct),return of 50%wheat and 50%cotton straw(Wh-Ch)and return of 100%wheat and 100%cotton straw(Wt-Ct).In comparison to the Control,the SOC content increased by 8.4 to 20.2%under straw return.A significant linear positive correlation between SOC sequestration and C input(1.42-7.19 Mg ha^(−1)yr^(−1))(P<0.05)was detected.The percentages of aggregates of sizes>2 and 1-2 mm at the 0-20 cm soil depth were also significantly elevated under straw return,with the greatest increase of the aggregate stability in the Wt-Ct treatment(28.1%).The average wheat yields increased by 12.4-36.0%and cotton yields increased by 29.4-73.7%,and significantly linear positive correlations were also detected between C input and the yields of wheat and cotton.The average sustainable yield index(SYI)reached a maximum value of 0.69 when the C input was 7.08 Mg ha^(−1)yr^(−1),which was close to the maximum value(SYI of 0.69,C input of 7.19 Mg ha^(−1)yr^(-1))in the Wt-Ct treatment.Overall,the return of both wheat and cotton straw was the best strategy for improving SOC sequestration,soil aggregation,yields and their sustainability in the wheat-cotton rotation system. 展开更多
关键词 straw return crop yields SOC soil aggregates wheat-cotton cropping system
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Material Flow Analysis of Electronic Wastes (e-Wastes) in Lagos, Nigeria
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作者 Fatima Badiru Ibrahim Donatus Begianpuye Adie +2 位作者 Abdul-Raheem Giwa Sule Argungu Abdullahi Charles Amen Okuofu 《Journal of Environmental Protection》 2013年第9期1011-1017,共7页
The fate of end-of-life electronics (e-wastes) is of increasing concern because of their toxicity and ever increasing volumes. Addressing these concerns requires proper management plans and strategy which in turn requ... The fate of end-of-life electronics (e-wastes) is of increasing concern because of their toxicity and ever increasing volumes. Addressing these concerns requires proper management plans and strategy which in turn requires reliable estimates of e-waste generation in the present as well as future times. In this study, a material flow model for the analysis of e-waste generation from computer equipments inNigeriahas been developed. Data used to develop the model are the sales data from major distributors of electronics, usage time of computer equipments and transfer coefficients of the electronics from one stage to another. The analysis of individual flows of computer from the material flow model showed that the fate of obsolete computer equipments were storage (41%), reuse (35%) and direct disposal (24%). The projections of the flows for a period of 15 years also indicated that storage and reuse of computer equipments would be preferred over direct disposal;and computer equipments would continue to remain in either storage, re-use or gradually disposed off for about 11 years after its inflow. This delay or staggering disposal is of advantage as it would reduce the amount of e-waste disposed yearly and also afford the country some time to make plans to accommodate and manage the e-wastes generated more efficiently. 展开更多
关键词 e-waste MATERIAL FLOW Model COMPUTER Equipment NIGERIA
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Assessment of the Level of Awareness of E-Waste Management and Concern for the Environment amongst the Populace in Onitsha, Southeastern Nigeria
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作者 Anthony Okoye Chijioke Odoh 《Journal of Environmental Protection》 2014年第2期120-134,共15页
This study was carried out to ascertain the peoples’ level of awareness of the regulation, their mode of disposal of the e-wastes and their awareness of the dangers inherent in improper handling and disposal of waste... This study was carried out to ascertain the peoples’ level of awareness of the regulation, their mode of disposal of the e-wastes and their awareness of the dangers inherent in improper handling and disposal of wastes. Data for this study were collected through the distribution of 247 well-structured questionnaires. Likert Scale was adopted for the analysis of the respondents. The results revealed that awareness is critically low. Though the respondents have concern for their environment in various degrees, majority dispose their e-waste alongside municipal wastes without knowing the implications. Awareness strategy was designed for sensitization campaign. 展开更多
关键词 AWARENESS DISPOSAL e-waste Strategy CAMPAIGN
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Estimation of Future Generated Amount of E-Waste in the United States
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作者 Shoou-Yuh Chang Godwin Appiah Assumaning Yassir Abdelwahab 《Journal of Environmental Protection》 2015年第8期902-928,共27页
Electrical and electronic equipment waste, or e-waste, is one of the fastest growing waste streams in the United States. The main objective of this study is to estimate the future quantities of e-waste of thirteen sel... Electrical and electronic equipment waste, or e-waste, is one of the fastest growing waste streams in the United States. The main objective of this study is to estimate the future quantities of e-waste of thirteen selected electric and electronic products in the United States in 2025. To estimate the future amount of e-waste, the authors performed a material flow analysis. The model inputs are historical and future product sales data and the product’s average life span. Sensitivity analysis was constructed to evaluate the effect of the model inputs (average life span and future sales data) in the generation of e-waste. The results show that about 1.0835 billion units will reach their end of life (EOL) in 2025;cell phone devices are the highest occurring product among the thirteen selected products and weighted for about 66.0% of units of the total amount, followed by computer products at 18.0%, TV products at 11.6%, computer monitors at 1.7%, hard copy peripherals (HCP) at 1.6%, and computer accessories at 1.0%. The sensitivity analysis shows that the product life span has an effect on the e-waste generation amounts from the products under study, while the sensitivity analysis of forecasted future sales indicates that the generated waste will increase or decrease according to the sales trend. 展开更多
关键词 e-waste Material Flow Analysis UNITED STATES ESTIMATION
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Assessment of soil erosion in the Irga watershed on the eastern edge of the Chota Nagpur Plateau,India 被引量:1
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作者 Ratan PAL Buddhadev HEMBRAM Narayan Chandra JANA 《Regional Sustainability》 2024年第1期54-68,共15页
Human activities to improve the quality of life have accelerated the natural rate of soil erosion.In turn,these natural disasters have taken a great impact on humans.Human activities,particularly the conversion of veg... Human activities to improve the quality of life have accelerated the natural rate of soil erosion.In turn,these natural disasters have taken a great impact on humans.Human activities,particularly the conversion of vegetated land into agricultural land and built-up area,stand out as primary contributors to soil erosion.The present study investigated the risk of soil erosion in the Irga watershed located on the eastern fringe of the Chota Nagpur Plateau in Jharkhand,India,which is dominated by sandy loam and sandy clay loam soil with low soil organic carbon(SOC)content.The study used the Revised Universal Soil Loss Equation(RUSLE)and Geographical Information System(GIS)technique to determine the rate of soil erosion.The five parameters(rainfall-runoff erosivity(R)factor,soil erodibility(K)factor,slope length and steepness(LS)factor,cover-management(C)factor,and support practice(P)factor)of the RUSLE were applied to present a more accurate distribution characteristic of soil erosion in the Irga watershed.The result shows that the R factor is positively correlated with rainfall and follows the same distribution pattern as the rainfall.The K factor values in the northern part of the study area are relatively low,while they are relatively high in the southern part.The mean value of the LS factor is 2.74,which is low due to the flat terrain of the Irga watershed.There is a negative linear correlation between Normalized Difference Vegetation Index(NDVI)and the C factor,and the high values of the C factor are observed in places with low NDVI.The mean value of the P factor is 0.210,with a range from 0.000 to 1.000.After calculating all parameters,we obtained the average soil erosion rate of 1.43 t/(hm^(2)•a),with the highest rate reaching as high as 32.71 t/(hm^(2)•a).Therefore,the study area faces a low risk of soil erosion.However,preventative measures are essential to avoid future damage to productive and constructive activities caused by soil erosion.This study also identifies the spatial distribution of soil erosion rate,which will help policy-makers to implement targeted soil erosion control measures. 展开更多
关键词 soil erosion soil organic carbon Rainfall-runoff erosivity factor soil erodibility factor Slope length and steepness factor Cover-management factor Support practice factor Irga watershed
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