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961.
A review of rapid transport of pesticides from sloping farmland to surface waters:Processes and mitigation strategies 总被引:3,自引:0,他引:3
Pesticides applied to sloping farmland may lead to surface water contamination through rapid transport processes as influenced by the complex topography and high spatial variability of soil properties and land use in hilly or mountainous regions. However, the fate of pesticides applied to sloping farmland has not been sufficiently elucidated. This article reviews the current understanding of pesticide transport from sloping farmland to surface water. It examines overland flow and subsurface lateral flow in areas where surface soil is underlain by impervious subsoil or rocks and tile drains. It stresses the importance of quantifying and modeling the contributions of various pathways to rapid pesticide loss at catchment and regional scales. Such models could be used in scenario studies for evaluating the effectiveness of possible mitigation strategies such as constructing vegetated strips, depressions, wetlands and drainage ditches, and implementing good agricultural practices. Field monitoring studies should also be conducted to calibrate and validate the transport models as well as biophysical-economic models, to optimize mitigation measures in areas dominated by sloping farmland. 相似文献
962.
Risky Ayu Kristanti Masahiro Kanbe Tadashi Toyam Yasuhiro Tanak Yueqin Tang Xiaolei Wu Kazuhiro Mori 《环境科学学报(英文版)》2012,24(5):800-807
We investigated the biodegradation of 2-nitrophenol (2-NP), 4-nitrophenol (4-NP), and 2,4-dinitrophenol (2,4-DNP) in the rhizosphere of Spirodela polyrrhiza plants by conducting degradation experiments with three river water samples supplemented with each nitrophenol (NP). We then isolated NP-degrading bacteria both from the S. polyrrhiza roots and from the river water. In the river water samples, removal of the three NP was accelerated in the presence of S. polyrrhiza plants. The three NPs persisted in an autoclaved solution with sterile plants suggests that NP removal was accelerated largely by bacterial NP biodegradation rather than by adsorption and uptake by the plants. We isolated 8 strains of NP-degrading bacteria: 6 strains from the S. polyrrhiza roots and 2 strains from river water without the plants. The 2-NP- and 2,4-DNP-degrading bacteria were isolated only from the S. polyrrhiza roots. The 4-NPdegrading bacteria different from those isolated from the river water samples were also found on S. polyrrhiza roots. The 2-NP- and 4-NP-degrading strains isolated from the roots utilized the corresponding NP (0.5 mmol/L) as the sole carbon and energy source. The 2,4-DNP-degrading strains isolated from the roots showed substantial 2,4-DNP-degrading activity, but the presence of other carbon and energy sources was required for their growth. The isolated NP-degrading bacteria from the roots must have contributed to the accelerated degradation of the three NPs in the rhizosphere of S. polyrrhiza. Our results suggested that rhizoremediation with S. polyrrhiza may be effective for NP-contaminated surface water. 相似文献
963.
Whether plant coexistence can reduce the impacts of lead (Pb) on crops in agroecosystems has not been well understood. We conducted a factorial experiment to investigate the effects of weeds coexisting with maize (Zea mays L.) on Pb accumulation in maize and soil microbes at two Pb levels (ambient and 300 mg/kg). Elevated Pb tended to increase the Pb concentration in maize and decreased soil microbial activity (indicated by the average well color development, AWCD), functional group diversity, as well as arbuscular mycorrhizal (AM) colonization and vesicle number of maize. Compared to the monoculture, weeds coexisting with maize reduced the Pb concentrations in the root, leaf, sheath and stem of maize at both seedling and mature stages. In maize-weed mixtures, soil microbial activity and functional group diversity tended to increase for both Pb treatments relative to the monoculture. Furthermore, principal component analysis revealed that the soil microbial community structure changed with the introduction of weeds. The highest Pb accumulation in weeds occurred for the elevated Pb treatment in a three species mixture. The results suggest that multiple plant species coexistence could reduce lead accumulation in crop plants and alleviate the negative impacts on soil microbes in polluted land, thereby highlighting the significance of plant diversity in agroecosystems. 相似文献
964.
Hua Fang Wei Zhou Zhengya Cao Feifan Tang Dandan Wang Kailin Liu Xiangwei Wu Xiao''e Yang Yongge Sun Yunlong Yu 《环境科学学报(英文版)》2012,24(6):1036-1046
Combined pollution of 1,1,1-trichloro-2,2-bis (4-chlorophenyl) ethane (DDT) and cadmium (Cd) in agricultural soils is of great concern because they present serious risk to food security and human health.In order to develop a cost-effective and safe method for the removal of DDTs and Cd in soil,combined remediation of DDTs and Cd in soil by Sphingobacterium sp.D-6 and the hyperaccumulator,Sedum alfredii Hance was investigated.After treatment for 210 days,the degradation half-lives of DDTs in soils treated by strain D-6 decreased by 8.1% to 68.0% compared with those in the controls.The inoculation of strain D-6 into soil decreased the uptake of DDTs by pak choi and S.alfredii.The shoots/roots ratios of S.alfredii for the Cd accumulation ranged from 12.32 to 21.75.The Cd concentration in soil decreased to 65.8%-71.8% for S.alfredii treatment and 14.1%-58.2% for S.alfredii and strain D-6 combined treatment,respectively,compared with that in the control.The population size of the DDTs-degrading strain,Simpson index (1/D) and soil respiratory rate decreased in the early stage of treatment and then gradually increased,ultimately recovering to or exceeding the initial level.The results indicated that synchronous incorporation of strain D-6 and S.alfredii into soil was found to significantly (p 0.05) enhance the degradation of DDTs in soil and the hyperaccumulation of Cd in S.alfredii.It was concluded that strain D-6 and S.alfredii could be used successfully to control DDTs and Cd in contaminated soil. 相似文献
965.
Yu Hu Yanli Li Lei Wang Yushu Tang Jinhai Chen Xiaohua Fu Yiquan Le Jihua Wu 《环境科学学报(英文版)》2012,24(6):1053-1063
Two representative zones in Chongming Dongtan which faced the Yangtze River and East China Sea respectively were selected to study the variability of soil organic carbon (SOC) reservation capability between coastal wetland and riverside wetland in the Chongming Dongtan wetland as well as its mechanism by analyzing soil characteristics and plant biomass. The results showed the SOC content of riverside wetland was only 48.61% (P = 0.000 < 0.05) that of coastal wetland. As the organic matter inputs from plant litter of the coastal wetland and riverside wetland were approximately the same, the higher soil microbial respiration (SMR) of riverside wetland led to its lower SOC reservation capability. In the riverside wetland, the high soil microbial biomass, higher proportion of β-Proteobacteria, which have strong carbon metabolism activity and the existence of some specific aerobic heterotrophic bacteria such as Bacilli and uncultured Lactococcus, were the important reasons for the higher SMR compared to the coastal wetland. There were additional differences in soil physical and chemical characteristics between the coastal wetland and riverside wetlands. Path analysis of predominant bacteria and microbial biomass showed that soil salinity influenced β-Proteobacteria and microbial biomass most negatively among these physical and chemical factors. Therefore the low salinity of the riverside area was suitable for the growth of microorganisms, especially β-Proteobacteria and some specific bacteria, which led to the high SMR and low SOC reservation capability when compared to the coastal area. 相似文献
966.
With the development of transgenic crops, there is an increasing concern about the possible adverse effects of their vegetation and residues on soil environmental quality. This study was carried out to evaluate the possible effects of the vegetation of transgenic Bt rice lines Huachi B6 (HC) and TT51 (TT) followed by the return of their straw to the soil on soil enzymes (catalase, urease, neutral phosphatase and invertase), anaerobic respiration activity, microbial utilization of carbon substrates and community structure, under field conditions. The results indicated that the vegetation of the two transgenic rice lines (HC and TT) and return of their straw had few adverse effects on soil enzymes and anaerobic respiration activity compared to their parent and distant parent, although some transient differences were observed. The vegetation and subsequent straw amendment of Bt rice HC and TT did not appear to have a harmful effect on the richness, evenness and community structure of soil microorganisms. No different pattern of impact due to plant species was found between HC and TT. It could be concluded that the vegetation of transgenic Bt rice lines and the return of their straw as organic fertilizer may not alter soil microbe-mediated functions. 相似文献
967.
968.
969.
恶臭污染源环境影响评价要点问题探讨 总被引:1,自引:0,他引:1
针对城市恶臭发生源的无组织与无组织排放方式及臭气成分复杂且大多属复合臭气成分的特点,重点对恶臭源的监测、组分分析方法以及源强综合评价等关键问题进行了研究和总结。 相似文献
970.