The Experts below are selected from a list of 15234 Experts worldwide ranked by ideXlab platform
Sardar Khan - One of the best experts on this subject based on the ideXlab platform.
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human health risk due to consumption of vegetables contaminated with carcinogenic polycyclic aromatic hydrocarbons
Journal of Soils and Sediments, 2012Co-Authors: Sardar Khan, Qing CaoAbstract:Purpose Polycyclic aromatic hydrocarbons (PAH) are persistent, toxic, and carcinogenic contaminants present in soil ecosystem globally. These pollutants are gradually accumulating in wastewater-Irrigated Soils and lead to the contamination of vegetables. Food chain contamination with PAH is considered as one of the major pathways for human exposure. This study was aimed to investigate the concentrations of PAH in Soils and vegetables collected from wastewater-Irrigated fields from metropolitan areas of Beijing, China. Origin of PAH, daily intake, and health risks of PAH through consumption of contaminated vegetables were studied.
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A comparative study of human health risks via consumption of food crops grown on wastewater Irrigated soil (Peshawar) and relatively clean water Irrigated soil (lower Dir)
Journal of Hazardous Materials, 2010Co-Authors: Mohammad Ishaq, Sardar Khan, I. Ihsanullah, Imtiaz Ahmad, M. ShakirullahAbstract:Abstract Food crops Irrigated with wastewater are mostly contaminated with heavy metals and considered as a main pathway for human exposure. In this study, soil and food crops samples were collected from wastewater Irrigated Soils, background and relatively less polluted areas. Results of the sequential extraction and total metals concentrations in Soils indicated that wastewater irrigation has significantly increased (p ≥ 0.001) the bioavailable and total metal contents in wastewater Irrigated soil as compared to background and control Soils. Heavy metal concentrations in the food crops grown on wastewater Irrigated soil were higher than those grown on background and control Soils but were found within WHO/FAO permissible limits except for Zn. Health risk index values were less than 1 for both control and wastewater Irrigated Soils (except Mn). However, the food crops such as Brassica rapa, Spinacia oleracae L., Lycopersicum esculantum, Mentha viridis, Coriandum sativum and Lactuca sativa grown on wastewater Irrigated soil can pose health risks because of the high concentration of Mn.
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health risks of heavy metals in contaminated Soils and food crops Irrigated with wastewater in beijing china
Environmental Pollution, 2008Co-Authors: Sardar Khan, Yingjuan Zheng, Youda HuangAbstract:Abstract Consumption of food crops contaminated with heavy metals is a major food chain route for human exposure. We studied the health risks of heavy metals in contaminated food crops Irrigated with wastewater. Results indicate that there is a substantial buildup of heavy metals in wastewater-Irrigated Soils, collected from Beijing, China. Heavy metal concentrations in plants grown in wastewater-Irrigated Soils were significantly higher (P ≤ 0.001) than in plants grown in the reference soil, and exceeded the permissible limits set by the State Environmental Protection Administration (SEPA) in China and the World Health Organization (WHO). Furthermore, this study highlights that both adults and children consuming food crops grown in wastewater-Irrigated Soils ingest significant amount of the metals studied. However, health risk index values of less than 1 indicate a relative absence of health risks associated with the ingestion of contaminated vegetables.
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health risks of heavy metals in contaminated Soils and food crops Irrigated with wastewater in beijing china
Environmental Pollution, 2008Co-Authors: Sardar Khan, Yingjuan Zheng, Youda Huang, Qing Cao, Yongguan ZhuAbstract:Consumption of food crops contaminated with heavy metals is a major food chain route for human exposure. We studied the health risks of heavy metals in contaminated food crops Irrigated with wastewater. Results indicate that there is a substantial buildup of heavy metals in wastewater-Irrigated Soils, collected from Beijing, China. Heavy metal concentrations in plants grown in wastewater-Irrigated Soils were significantly higher (P
Changhui Peng - One of the best experts on this subject based on the ideXlab platform.
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distribution of soil inorganic carbon storage and its changes due to agricultural land use activity in china
Agriculture Ecosystems & Environment, 2009Co-Authors: Zhengtang Guo, Changhui Peng, Qiong GaoAbstract:The accurate estimation of soil carbon (C) stocks is a necessary component for understanding the global C budget. Although the importance of soil organic C (SOC) within the C cycle is well established, the quantity of soil inorganic C (SIC, including lithogenic and pedogenic inorganic C) pool, another important soil C pool component, has been poorly studied to date. In this study, soil profile data compiled by China’s second national soil survey conducted in the 1980s was used to investigate the spatial distribution of SIC for the entire country under present day conditions as well as changes in SIC under historical land use. Results showed that the total SIC storage in China was approximately 55.3 � 10.7 Pg C with a current average content of 6.3 � 1.2 kg C m � 2 , representing 5.8% of the global SIC pool. Land use has significantly affected SIC levels in cultivated Soils. Approximately 51% of total cultivated soil surfaces in China have experienced C loss where the most significant loss has been observed in the eastern part of northern China in dry farmlands as well as Irrigated Soils and paddy Soils. On the contrary, SIC has increased (� 10%) in Irrigated Soils in northwestern China. No significant change (� 39%) has been observed in Soils in southern and the eastern part of northeast China. The total loss of SIC in China was approximately 1.6 Pg C due to extensive human activity. Results of this study indicate that human activity may have had a great impact on SIC as well as SOC pools.
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land use induced changes of organic carbon storage in Soils of china
Global Change Biology, 2003Co-Authors: Zhengtang Guo, Changhui PengAbstract:Using the data compiled from China's second national soil survey and an improved method of soil carbon bulk density, we have estimated the changes of soil organic carbon due to land use, and compared the spatial distribution and storage of soil organic carbon (SOC) in cultivated Soils and noncultivated Soils in China. The results reveal that ∼ 57% of the cultivated soil subgroups (∼ 31% of the total soil surface) have experienced a significant carbon loss, ranging from 40% to 10% relative to their noncultivated counterparts. The most significant carbon loss is observed for the non-Irrigated Soils (dry farmland) within a semiarid/semihumid belt from northeastern to southwestern China, with the maximum loss occurring in northeast China. On the contrary, SOC has increased in the paddy and Irrigated Soils in northwest China. No significant change is observed for forest Soils in southern China, grassland and desert Soils in northwest China, as well as Irrigated Soils in eastern China. The SOC storage and density under noncultivated conditions in China are estimated to ∼ 77.4 Pg (1015 g) and ∼ 8.8 kg C m−2, respectively, compared to a SOC storage of ∼ 70.3 Pg and an average SOC density of ∼ 8.0 kg C m−2 under the present-day conditions. This suggests a loss of ∼ 7.1 Pg SOC and a decrease of ∼ 0.8 kg C m−2 SOC density due to increasing human activities, in which the loss in organic horizons has contributed to ∼ 77%. This total loss of SOC in China induced by land use represents ∼ 9.5% of the world's SOC decrease. This amount is equivalent to ∼ 3.5 ppmv of the atmospheric CO2 increase. Since ∼ 78% of the currently cultivated Soils in China have been degraded to a low/medium productivities and are responsible for most of the SOC loss, an improved land management, such as the development of Irrigated and paddy land uses, would have a considerable potential in restoring the SOC storage. Assuming a restoration of ∼ 50% of the lost SOC during the next 20–50 years, the Soils in China would absorb ∼ 3.5 Pg of carbon from the atmosphere.
Xiqing Li - One of the best experts on this subject based on the ideXlab platform.
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occurrence of antibiotics and antibiotic resistances in Soils from wastewater irrigation areas in beijing and tianjin china
Environmental Pollution, 2014Co-Authors: Chaoqi Chen, Peipei Chen, Rui Ding, Pengfei Zhang, Jing Li, Xiqing LiAbstract:Abstract Non-Irrigated and wastewater-Irrigated Soils were collected from five wastewater irrigation areas in Beijing and Tianjin, China. The concentrations of sulfadiazine, sulfamethoxazole, oxytetracycline and chlortetracycline in the Soils were determined. Abundances of antibiotic resistant bacteria and corresponding resistance genes were also measured to examine the impact of wastewater irrigation. No significant difference in antibiotic resistance bacteria was observed between Irrigated and non-Irrigated Soils. However, the concentrations of antibiotics and abundances of resistance genes were significantly greater in Irrigated Soils, indicating that agricultural activities enhanced the occurrence of antibiotics and resistance genes in the Soils. In addition, no significant difference was observed between previously and currently wastewater-Irrigated Soils. Therefore, cessation of wastewater irrigation did not significantly reduce the levels of antibiotic concentrations and resistance gene abundances. Other factors, e.g., manure application, may explain the lack of significant difference in the occurrence of antibiotics and resistance genes between previously and currently wastewater-Irrigated Soils.
Lijuan Chen - One of the best experts on this subject based on the ideXlab platform.
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shifts in soil microbial metabolic activities and community structures along a salinity gradient of irrigation water in a typical arid region of china
Science of The Total Environment, 2017Co-Authors: Yongjiu Feng, Hang Zheng, Qi Feng, Changsheng Li, Yan Zhao, Lijuan Chen, H LiAbstract:Saline water irrigation can change soil environment, which thereby influence soil microbial process. Based on a field experiment, the shifts in soil microbial metabolic activities and community structures under five irrigation salinities were studied using Biolog and metagenomic methods in this study. The results demonstrated that microbial metabolic activities were greatly restrained in saline water Irrigated Soils, as average well color development (AWCD) reduced under all saline water irrigation treatments. Although no significant difference in carbon substrate utilization of all six categories was observed among Mild, Medium, High and Severe treatments, the consumption of sole carbon source was significantly varied. Especially, asparagine, galacturonic, putrescine and 4-benzoic acid played a decisive role in dominating the differences. Soil bacterial richness and diversity increased with irrigation salinity while the number of bacterial phyla decreased. Three significantly increased (Proteobacteria, Actinobacteria and Chloroflexi), two decreased (Planctomycetes, Bacteroidetes) and two irresponsive (Gemmatimonadetes and Acidobacteria) phyla were observed as the dominant groups in saline water Irrigated Soils. The results presented here could improve the understanding of the soil biological process under saline circumstance.
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impacts of aquaculture wastewater irrigation on soil microbial functional diversity and community structure in arid regions
Scientific Reports, 2017Co-Authors: Yongjiu Feng, Fengrui Li, Hang Zheng, Qi Feng, Changsheng Li, Yan Zhao, Lijuan Chen, Huiya LiAbstract:Aquaculture wastewater is one of the most important alternative water resources in arid regions where scarcity of fresh water is common. Irrigation with this kind of water may affect soil microbial functional diversity and community structure as changes of soil environment would be significant. Here, we conducted a field sampling to investigate these effects using Biolog and metagenomic methods. The results demonstrated that irrigation with aquaculture wastewater could dramatically reduce soil microbial functional diversity. The values of diversity indices and sole carbon source utilization were all significantly decreased. Increased soil salinity, especially Cl concentration, appeared primarily associated with the decreases. Differently, higher bacterial community diversity was obtained in aquaculture wastewater Irrigated Soils. More abundant phyla Actinobacteria, Chloroflexi, Acidobacteria, Gemmatimonadetes and fewer members of Proteobacteria, Bacteroidetes and Planctomycetes were found in this kind of Soils. Changes in the concentration of soil Cl mainly accounted for the shifts of bacterial community composition. This research can improve our understanding of how aquaculture wastewater irrigation changes soil microbial process and as a result, be useful to manage soil and wastewater resources in arid regions.
Pascal Boivin - One of the best experts on this subject based on the ideXlab platform.
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impacts of irrigation with industrial treated wastewater on soil properties
Geoderma, 2013Co-Authors: Andre Mermoud, Hamma Yacouba, Pascal BoivinAbstract:Wastewater reuse in agriculture is a widespread practice in developing countries, especially in urban areas where water shortage and poverty encourage people to use that marginal resource. Raw or treated wastewaters are used by farmers, but even treated wastewaters frequently do not meet WHO and FAO standards for irrigation water. Such practices may lead to health hazards, relatively well documented in the literature and to environmental damages. Adverse environmental impacts such as soil degradation and groundwater contamination are frequently associated with the use of wastewater from industrial sources. Previous studies have demonstrated that wastewater irrigation may decrease soil hydraulic conductivity and infiltration rate. Nevertheless, the effects on soil structural and chemical behaviors have been little studied so far and need further investigations. The impacts of irrigation with alkaline and sodic industrial wastewater previously treated in microphyte ponds on soil physical and chemical properties were studied downstream the sewage treatment plant of Kossodo in Ouagadougou, on plots cropped with eggplants. Plots Irrigated with fresh water and non cropped, non Irrigated plots were used as controls. Different soil properties were characterized: pore volumes determined by using shrinkage analysis, pH and electrical conductivity of water extracts, and major soluble and exchangeable cations (Ca, Mg, K, and Na). Organic matter characterization was performed by means of three dimensional fluorescence spectra analysis to determine its origin and evolution on Irrigated Soils. Plots Irrigated with wastewater showed important structural damages, especially in the subsurface horizon where the soil pore network collapsed dramatically, resulting in a compact impermeable layer. Fluorescence spectra revealed that the organic matter contained in the wastewater was largely dissolved due to a sharp soil pH increase, resulting in black alkali formation at the surface: the soil became sodic, with an exchange complex dominated by sodium, whereas plots Irrigated with fresh water kept properties comparable to that of non Irrigated plots. Such a rapid soil sodication was seldom reported so far. The study emphasizes the need to carefully examine irrigation water quality and particularly calcite residual alkalinity and suggests that shrinkage analysis could be used to monitor the physical changes of soil properties upon sodication. Inadequate wastewater quality is likely to cause deep and irreversible damages to Irrigated Soils. (C) 2013 Elsevier B.V. All rights reserved.
