农业面源污染治理的技术与政策研究进展

随着固定源污染治理的成效日益显现,农业生产活动所导致的农业面源污染已成为水环境质量改善的主要影响因素。国内外经过近40年的研究,在农业面源污染治理方面积累了大量的经验做法。本文通过从农业面源污染负荷核算与关键源区识别、农业面源污染治理措施评估以及监督指导农业面源污染治理政策三个方面对国内外相关研究进展进行综述,以期为该领域未来学科发展提供一定的思路和借鉴。主要建议如下:(1)编制我国监督指导农业面源污染治理技术路线图;(2)开展农业面源污染监测网络优化研究;(3)开展农业面源污染评估技术体系研究;(4)开展构建"萝卜+大棒"的治理政策体系研究。     

流域农业面源污染防治科学问题与技术研发需求

农业面源污染是当前我国面临的重要环境问题之一,也是影响我国水体环境质量持续改善的瓶颈.近年来,我国面源污染治理日益受到重视,相关治理管理体系逐步建立,但我国农业面源污染治理起步相对较晚、研究基础较薄弱.本文针对农业面源污染的现状及研究进展,总结提出了流域农业面源污染的三大科学问题及技术难题：流域面源污染发生规律及水体水质响应机制、农业面源污染削减和资源化原理、监管机制,并从农业面源污染通量监测、负荷核算、适用性技术研发、考核评估机制建立等方面提出了技术研发的需求,以期为我国流域农业面源污染防治及管理提供科学参考.     

农业面源污染立体遥感监测体系构建设想

农业面源污染已成为河流湖库污染的重要来源。然而,农业面源污染成因复杂,从监测、评估到管理、治理都存在很多不确定性问题。本文对目前我国农业面源污染监测现状和问题进行了系统梳理,提出了"以遥感监测为主、地面校验为辅"的农业面源污染立体遥感监测评估新思路,以期为"十四五"及更长时间我国农业面源污染监督治理提供技术支撑。     

农业面源污染形势和“十四五”政策取向——基于两次全国污染源普查公报的比较分析

治理农业面源污染是发展绿色农业的首要任务,从两次污染源普查公报数据来看,10年间农业面源污染治理成效显著。在种植业播种面积上升、养殖当量大幅增加的情况下,农业面源污染排放总量和强度均实现大幅下降,政策驱动、结构调整、经营方式转变是面源污染减排的主要动力。"十四五"期间,面对世情、国情、农情的变化,本文提出农业面源污染治理需做到三个转变:工作策略从攻坚战转向持久战;工作抓手从要素减量转向系统绿化;工作方式从单兵突进转向协同治理。进一步提出建立和完善农业面源监测体系、构建种养结合的绿色发展格局、综合考虑工业和农业污染排放协调治理和继续积极推进农业支持政策向绿色生态转型等具体建议。     

剑湖流域农业面源污染防治技术

农业面源污染正在成为水体污染的主要原因之一。剑湖流域内分布着大量农田,农业面源污染严重,通过"源头控制,过程减污,末端截污"来实现剑湖流域农业面源污染防治,源头控制是核心,配合沿程及末端污染治理,才能做好农业面源污染治理工作。     

农业面源对水环境污染及防治对策

农业面源污染已成为我国水环境的主要贡献源之一。就农业面源的产生、分布、特征、形成进行了分析,并通过三峡库区农业面源污染对河流水环境影响为例,论证农业面源对水环境污染的形成机理,指出污染发展趋势,主要污染负荷,已发生和潜在的污染问题,并提出治理面源的对策与建议。     

三台县农业面源污染的生态补偿机制与措施研究

三台县是一个农业大县,随着农业经济的迅速发展,农业面源污染日趋严重。种植业污染、畜禽养殖、农村生活污染成为三台县农业面源污染的主要因素。面源污染具有分散性、随机性和监测成本高的特点。对三台县农业面源污染产生进行了经济学分析,农业面源污染属于外部不经济性,通过建立生态补偿机制,控制农业面源污染。以三台县建立生态县和新农村建设为基础,通过转变农业生产方式,调整产业结构,发展生态农业,推进生态村的建设等生态补偿治理措施,改善三台县的农业生态环境。     

发达国家控制农业面源污染经验借鉴

随着工业污染减排成效的日益显著,农业面源污染逐步成为影响水质的重要因素.虽然中国对农业面源污染十分重视,但农业面源污染的治理却没达到预期效果.欧美国家在农业面源污染控制方面的探索,可为中国在农业面源污染控制方面提供丰富的经验和教训.     

当前农业面源污染现状、特征及对策研究

我国是农业生产大国,大量化肥、农药、地膜的过量施用,以及规模化养殖的增加,加剧了农业面源污染。农业面源污染的分散性、隐蔽性、随机性和难监测性等特点,导致对农业面源污染的治理提出了更高要求,需要牢固树立"创新、协调、绿色、开放、共享"的发展理念,积极推广农业清洁生产和标准化生产,大力发展现代生态循环农业,建立农业面源污染监测预警和管理体系,切实解决农业面源污染难题。     

农业面源污染及防治对策

农村面源污染源分布广泛,没有确切位置,其治理一直是个难题.由于化肥和农药的大量使用,农业面源污染已成为我国农村生态环境恶化的重要原因之一.本文对农业面源污染的特点、危害和现状进行了论述,并提出防治农业面源污染的具体防治对策和建议.     

Effects of two sludge application on fractionation and phytotoxicity of zinc and copper in the soil

The potential harm of heavy metals is a primary concern in application of sludge to the agricultural land. A pot experiment was conducted to evaluate the effect of two sludges on fractionation of Zn and Cu in soil and their phytotoxicity to pakchoi. The loamy soil was mixed with 0%, 20%, 40%, 60% and 80% (by weight) of digested sewage sludge (SS) and composted sludge (SC). The additions of both sludges caused a significant raise in all fractions, resulting in that exchangeable (EXCH) and organic bound (OM) became predominance of Zn and organic bound Cu occupied the largest portion. There was more available amount of Zn and Cu in SS treatments than SC treatments. During the pot experiment, the concentration of Zn in EXCH, carbonate (CAR) and OM and Cu in EXCH and OM fractions decreased in all treatments, so their bioavailability reduced. Germination rate and plant biomass decreased when the addition rate was high and the best yield appeared in 20% mixtures at the harvest of pakchoi. The two sludges increased tissue contents of Zn and Cu especially in the SS treatments. Zn in pakchoi was not only in relationship to ΔEXCH and ΔCAR forms but also in ΔOM forms in the sludge-soil mixtures. Tissue content of Cu in pakchoi grown on SC-soils could not be predicted by ΔEXCH. These correlation rates between Zn and Cu accumulation in pakchoi and variation of different fractions increased with time, which might indicate that sludges represented stronger impacts on the plant in long-term land application.     

Intraspecific differences in effects of co-contamination of cadmium and

A hydroponic experiment was carried out to study intraspecific differences in the effects of different concentrations of cadmium (Cd)(0-10 mg/L) and arsenate (As(V)) (0-8 mg/L) on the growth parameters and accumulation of Cd and As in six wheat varieties Jing-9428, Duokang-1, Jingdong-11, Jing-411, Jingdong-8 and Zhongmai-8. The endpoints of wheat seedlings, including seed germination,biomass, root length and shoot height, decreased with increasing the Cd and As concentrations. Significant differences in seed germination, biomass, root length, shoot height and the accumulation of Cd and As were observed between the treatments and among the varieties (p ＜ 0.05). The lethal dosage 50% were about 20, 80, 60, 60, 80 and 20 mg As/L for Jing-9428, Duokang-1, Jingdong-11,Jing-411, Jingdong-8 and Zhongmai-8, respectively, and the corresponding values for Cd were about 30, 80, 20, 40, 60 and 10 mg Cd/L, respectively. Among the six varieties, Duokang-1 was found to be the most resistant to Cd and As toxicity, and Zhongmai-8 was the most sensitive to Cd and As co-contamination. The resistance of the six varieties was found dependant on the seedling uptake of Cd and As. Duokang-1 was the most suitable for cultivation in Cd and As co-contaminated soils.     

Toxic effects of acetochlor, methamidophos and their combination on nifH gene in soil

Toxic effects of two agrochemicals on nifH gene in agricultural black soil were investigated using denaturing gradient gel electrophoresis （DGGE） and sequencing approaches in a microcosm experiment. Changes of soil nifH gene diversity and composition were examined following the application of acetochlor, methamidophos and their combination. Acetochlor reduced the nifH gene diversity （both in gene richness and diversity index values） and caused changes in the nifH gene composition. The effects of acetochlor on nifH gene were strengthened as the concentration of acetochlor increased. Cluster analysis of DGGE banding patterns showed that nifH gene composition which had been affected by low concentration of acetochlor （50 mg/kg） recovered firstly. Methamidophos reduced nifH gene richness that except at 4 weeks. The medium concentration of methamidophos （150 mg/kg） caused the most apparent changes in nifH gene diversity at the first week while the high concentration of methamidophos （250 mg/kg） produced prominent effects on nifH gene diversity in the following weeks. Cluster analysis showed that minimal changes of nifH gene composition were found at 1 week and maximal changes at 4 weeks. Toxic effects of acetochlor and methamidophos combination on nifH gene were also apparent. Different nifH genes （bands） responded differently to the impact of agrochemicals： four individual bands were eliminated by the application of the agrochemicals, five bands became predominant by the stimulation of the agrochemicals, and four bands showed strong resistance to the influence of the agrochemicals. Fifteen prominent bands were partially sequenced, yielding 15 different nifH sequences, which were used for phylogenetic reconstructions. All sequences were affiliated with the alpha- and beta-proteobacteria, showing higher similarity to eight different diazotrophic genera.     

EDTA-enhanced phytoremediation of lead contaminated soil by Bidens maximowicziana

Phytoremediation is a potential cleanup technology for the removal of heavy metals from contaminated soils.Bidens maximowicziana is a new Pb hyperaccumulator,which not only has remarkable tolerance to Pb but also extraordinary accumulation capacity for Pb.The maximum Pb concentration was 1509.3 mg/kg in roots and 2164.7 mg/kg in overground tissues.The Pb distribution order in the B. maximowicziana was:leaf>stem>root.The effect of amendments on phytoremediation was also studied.The mobility of soil Pb and the Pb concentrations in plants were both increased by EDTA application.Compared with CK(control check),EDTA application promoted translocation of Pb to overground parts of the plant.The Pb concentrations in overground parts of plants was increased from 24.23-680.56 mg/kg to 29.07-1905.57 mg/kg.This research demonstrated that B.maximowicziana appeared to be suitable for phytoremediation of Pb contaminated soil,especially,combination with EDTA.     

Distribution and ecological effect of mercury in Laogang landfill, Shanghai, China

Laogang landfill near Shanghai is the largest landfill in China, and receives about 10000 t of daily garbage per day, Samples of topsoil and plants were analyzed to evaluate mercury pollution from the landfill. For topsoil samples, there were significant correlations among total mercury （HgT）, combinative mercury （Hgc） and gaseous mercury （HgG）, and content of total organic carbon （TOC）, but, no significantly relationship was found between Hg content and filling time. Hg content changes in vertical profiles with time showed that the average Hgv of profiles 1992, 1996, and 2000 was similar, but their average HgG was quite different. HgT was significantly correlated with Hgc in profile 1992 and 2000, and Hgv was significantly correlated with Hg6 in profile 1996. HgG/Hgv ratio in profile samples decreased in the order of （HgG,/HgT）1992〉（HgG/HgT）1996〉〉（HgG/HgT）2000. A simple outline of Hg release in landfill could be drawn： with increasing of filling time, degradation undergoes different biodegradation, accordingly, gaseous mercury goes through small, more, and small proportion to total mercury. Distribution of Hg in plants was inhomogeneous, following the order of leaf〉root〉stem. The highest value of leaf may be associated with higher atmospheric Hg from landfill. Ligneous plants （e.g. Phyllostachys glanca, Prunus salicina and Ligustrum lucidum） are capable of enriching more Hg than herbaceous plants.     

Arsenic uptake by arbuscular mycorrhizal maize （Zea mays L.） grown in an arsenic-contaminated soil with added phosphorus

The effects of arbuscular mycorrhizal (AM) fungus (Glomus mosseae) and phosphorus (P) addition (100 mg/kg soil) on arsenic (As) uptake by maize plants (Zea mays L.) from an As-contaminated soil were examined in a glasshouse experiment.Non-mycorrhizal and zero-P addition controls were included.Plant biomass and concentrations and uptake of As,P,and other nutrients,AM colonization,root lengths,and hyphal length densities were determined.The results indicated that addition of P significantly inhibited root colonization and development of extraradical mycelium.Root length and dry weight both increased markedly with mycorrhizal colonization under the zero-P treatments,but shoot and root biomass of AM plants was depressed by P application.AM fungal inoculation decreased shoot As concentrations when no P was added,and shoot and root As concentrations of AM plants increased 2.6 and 1.4 times with P addition,respectively.Shoot and root uptake of P,Mn,Cu,and Zn increased,but shoot Fe uptake decreased by 44.6%,with inoculation, when P was added.P addition reduced shoot P,Fe,Mn,Cu,and Zn uptake of AM plants,but increased root Fe and Mn uptake of the nonmycorrhizal ones.AM colonization therefore appeared to enhance plant tolerance to As in low P soil,and have some potential for the phytostabilization of As-contaminated soil,however,P application may introduce additional environmental risk by increasing soil As mobility.     

Enzymatic oxidation of aqueous pentachlorophenol

The influence of the nonionic surfactant Tween 80 on pentachlorophenol （PCP） oxidation catalyzed by horseradish peroxidase was studied. The surfactant was tested at concentrations below and above its critical micelle concentration （CMC）. Enhancement of PCP removal was observed at sub-CMCs. The presence of Tween 80 in the reaction mixture reduced enzyme inactivation which occurred through a combination of free radical attack and sorption by precipitated products. A simple first-order model was able to simulate time profiles for enzyme inactivation in the presence or absence of Tween 80. At supra-CMCs, the surfactant caused noticeable reductions in PCP removal, presumably through micelle partitioning of PCP which precluded the hydrophobic PCP molecule from interacting with the enzyme.     

Decomposition of alachlor by ozonation and its mechanism

Decomposition and corresponding mechanism of alachlor, an endocrine disruptor in water by ozonation were investigated. Results showed that alachlor could not be completely mineralized by ozone alone. Many intermediates and final products were formed during the process, including aromatic compounds, aliphatic carboxylic acids, and inorganic ions. In evoluting these products, some of them with weak polarity were qualitatively identified by GC-MS. The information of inorganic ions suggested that the dechlorination was the first and the fastest step in the ozonation of alachlor.     

基于综合水质标识指数和对应分析法的校园河道水质评价

以三峡大学的校园河道求索溪为研究对象,利用综合水质标识指数法确定求索溪水质类别,分析其水质时空变化规律,并利用对应分析法得出求索溪中不同监测点的主要污染因子.研究结果表明:求索溪整体的综合水质标识指数为7.423,整体水质为劣V类(地表水环境质量标准GB 3838-2002)且黑臭.从时间变化来看,求索溪4月份的水质最差,5月份次之,4、5月份所有监测点的水质都劣于V类且黑臭;8月份水质最好,水质为Ⅳ类;从空间分布来看,8个监测点综合水质标识指数均超过6.0,水质为劣V类,其中6号监测点的水质相对最好,监测点3号的水质相对最差;对应分析法得出求索溪的整体水体污染程度受总氮因子的影响最大,其次为总磷.该研究拟为求索溪及类似校园河道的水环境治理研究提供基础依据和参考.     

Potential of plant polyphenol oxidases in the decolorization and removal of textile and non-textile dyes

In this study an effort has been made to use plant polyphenol oxidases; potato （Solanum tuberosum） and brinjal （Solanum melongena）, for the treatment of various important dyes used in textile and other industries. The ammonium sulphate fractionated enzyme preparations were used to treat a number of dyes under various experimental conditions. Majority of the treated dyes were maximally decolorized at pH 3.0. Some of the dyes were quickly decolorized whereas others were marginally decolorized. The initial first hour was sufficient for the maximum decolorization of dyes. The rate of decolorization was quite slow on long treatment of dyes. Enhancement in the dye decolorization was noticed on increasing the concentration of enzymes. The complex mixtures of dyes were treated with both preparations of polyphenol oxidases in the buffers of varying pH values. Potato polyphenol oxidase was significantly more effective in decolorizing the dyes to higher extent as compared to the enzyme obtained from brinjal polyphenol oxidase. Decolorization of dyes and their mixtures, followed by the formation of an insoluble precipitate, which could be easily removed simply by centrifugation.