洱海流域农业面源污染空间分布特征及分类控制策略

作为典型的高原坝区农业型流域,洱海流域农业面源污染严重,威胁洱海水质.以洱海流域为研究对象,综合数理分析及GIS技术,开展流域农业面源污染负荷分析及评价,使用排污系数法估算了2018年洱海流域农村生活、畜禽养殖业和种植业污染中COD（化学耗氧量）、TN（总氮）、TP（总磷）的排放负荷,并通过等标污染负荷法在GIS空间分析反映流域内污染排放分布情况.结果表明:①2018年洱海流域农业面源主要污染物COD、TN、TP的排放量分别为11 188.20、2 752.56和259.33 t.COD排放量主要来自畜禽养殖,TN与TP的排放量均主要来自种植业.②洱海流域农业面源主要污染物COD、TN、TP等标污染负荷分别为559.41、2 752.56和1 296.63 m3/a.种植业等标污染负荷在总等标污染负荷中的占比最高,为36.40%,其次是畜禽养殖业,为34.44%.③各乡镇的等标污染负荷差异较大,等标污染负荷范围为（286.16±150.67）m3/a,等标污染负荷强度范围（0.13±0.067）m3/a.④聚类分析结果表明,洱海流域农业面源污染可分为种植业主导型、种植业高污染型、生活污染主导型和畜禽养殖业主导高污染型等4种类型.研究显示:来源于种植业的面源污染是洱海流域水环境保护需要控制的首要污染源,TN是需要控制的首要污染物;排放量与等标污染负荷的空间分布特征均呈流域北部乡镇污染物排放量较高,但流域西部各乡镇排放强度较大的特征;流域内各乡镇防治面源污染需要针对其污染来源特点分别采取推进种养平衡、推广绿色种植、分区控制农田径流以及推进农村生活污水治理等分类控制策略.      

汉丰湖流域农业面源污染氮磷排放特征分析

为把握汉丰湖流域农业面源污染现状,探明其首要污染源和重点控制区域,应用排污系数法估算了汉丰湖流域2015年种植业源、畜禽养殖业源和农村生活源TN、TP污染物的贡献量,利用GIS空间分析法研究了其排放的空间分布特征.结果表明,2015年汉丰湖流域农业面源污染TN和TP的总负荷量分别为2721.42 t和492.04 t;等标污染负荷量以南河子流域最大,汉丰湖子流域最小;不同类型农业面源等标污染负荷总量差异很大,以肥料源和畜禽养殖源为主要来源,其中肥料源等标污染贡献率为76.92%,是汉丰湖流域首要污染源;各乡镇中,敦好镇、铁桥镇和白桥镇的等标污染负荷量较高,均高于350 m³·a^-1,为重点控制乡镇.等标污染负荷评价及聚类分析结果表明,汉丰湖流域农业面源有种植业源-畜禽养殖源复合主导型、肥料源-畜禽养殖源复合主导型、种植业源严重污染型和肥料源复合主导型这4种污染类型.     

武宜运河小流域平原河网地区氮磷污染来源解析

采用源解析法对工业污染源、生活污染源、农业面源(含种植业、养殖业)进行分析,并统计分析了武宜运河全线水质现状。结果表明,农业面源是武宜运河流域总氮、总磷污染的主要来源,且以养殖业为主,生活污染源是太湖流域氨氮污染的主要来源,且以农村生活污水为主;武宜运河水质以氮磷污染为主,总氮污染最为严重。武宜运河核心区研究范围占总研究范围的比例为35%,总氮、氨氮和总磷入河量分别占研究范围内各类污染物总入河量的42.8%,45.0%,34.1%,污染分布重点区域为武进前黄镇、牛塘镇及宜兴和桥镇所辖行政村。研究范围内农业面源污染分布重点区域为武进前黄镇、牛塘镇、宜兴屺亭街道及和桥镇;生活污染源氮磷污染物排放主要来自高新区及牛塘镇的农村生活污水排放,其次是屺亭街道和前黄镇的农村生活污水。     

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.     

流域农业面源污染生态工程调控措施

农业面源污染是导致目前流域水环境质量恶化的重要原因。文章从流域水环境状况、农业面源污染现状出发,结合面源污染的特点和研究发展历程,重点探讨了流域农业面源污染生态工程调控的可行性。     

农业面源污染视角下的三峡库区重庆段水资源的安全性评价——基于DPSIR框架的分析

农业面源污染已成为我国流域污染的主要来源,并已威胁到城乡居民的饮水安全,影响社会经济的可持续发展.三峡库区是生态脆弱区,水资源安全对促进库区生态环境保护与区域经济社会和谐发展尤为重要.为探明三峡库区重庆段农业面源污染与流域水资源安全演进变化的过程与内在机制,根据DPSIR框架原理,运用结构方程模型进行分析,并评价了2000-2011年流域水资源安全程度.结果表明:流域水资源安全程度分为两个阶段,2000-2005年水资源安全等级从一般安全下降到很不安全,2005-2011年水资源安全等级从很不安全上升到安全,出现阶段变化的主要原因在于从2006年开始,政府认识到流域生态环境的重要性并加大了对农业面源污染的控制力度,加强了对水土流失的治理.因此,为有效地减缓农业面源污染、改善流域水体质量,需要调整农业经济发展方式和农业产业结构,依靠科学技术提高农业生产效率,降低农用化学药品的投入,推广有机农业、改善耕地质量;加强水资源监督管理,实施农业生产节水措施;进一步加强面源污染控制投入,有效控制水土流失程度以减缓面源污染,实现流域水资源安全可持续利用.     

农业流域营养盐流失的关键因素及其防治途径

全面分析农业流域氮、磷等污染物质流失的关键过程,识别主要影响因素,研究探讨农业面源污染影响因素的作用方式和治理途径,对于农业面源污染控制具有重要意义。以国内外大量相关研究成果为基础,全面分析了农业面源污染的主要产生机理,以及影响农业面源污染时空分布的主要因素及相互作用关系,详细探讨了土壤性质、植被类型、土地利用格局、径流驱动因素、农业生产模式等关键因素对农业面源污染流失特征的影响作用,并从农田管理、景观结构调整、农业生产格局优化等方面有针对性的提出了适合中国农业流域特点的面源污染防控措施。     

海河流域农业面源污染潜在风险识别方法

在综合分析农业面源污染风险源汇因子的基础上,筛选出影响海河流域农业面源污染的8个主要因子（年降水量、溶解态面源污染物入河系数、吸附态面源污染物入河系数、年植被覆盖度、坡度、土壤可侵蚀性因子、农田氮表观平衡量和农田磷表观平衡量）,建立了农业面源污染潜在风险识别指标体系,采用多因子综合分析法对海河流域农业面源污染潜在风险等级进行评价,并与DPeRS模型风险识别结果进行偏差分析.结果表明,海河流域有61.91%的区域存在农业面源污染潜在风险,集中分布在流域的中部和南部地区,高风险区主要分布在北京市东南部、天津市中部、流域山东段东北部和河南段南部等区域;与DPeRS模型识别结果对比验证,显示同一风险等级面积相差不超过12%,且高风险级别面积相差仅为0.12%,97.17%以上的区域均为偏差小或无偏差,表明该识别方法具有与DPeRS模型法同等水平的农业面源污染潜在风险识别精准度,可实现区域农业面源污染潜在风险的快速、高效识别.     

南四湖流域种植业面源污染氮磷源解析研究

利用田间径流池采集南四湖流域种植业农田地表径流样品,分析其不同形态的氮磷数据,汇总数据得到南四湖流域种植业的氮磷源成分谱;并在南四湖区11条主要入湖河流入湖口处采集水样,测定氮磷含量,利用主成分分析法对南四湖流域种植业面源污染氮磷来源进行了源解析.结果表明,南四湖流域氮磷种植业面源污染来源有3种,3个主成分累积方差贡献率为95.275%.第一类污染途径为降雨淋溶小麦-玉米轮作农田产生的地表径流对河流产生的污染,这种污染的范围广且贡献率较大为50.220%;第二类污染途径为降雨淋溶大蒜-玉米轮作农田产生的地表径流流入南四湖入湖河流引起的,影响面也较广,贡献率为25.119%;第三类污染途径为自然降雨时,小麦-水稻轮作农田产生的地表径流对河流的污染,贡献率为19.937%.     

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。     

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.     

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.     

Impact of atrazine and nitrogen fertilizers on the sorption of chlorotoluron in soil and model sorbents

Sorption of chlorotoluron in ammonium sulfate, urea and atrazine multi-solutes system was investigated by batch experiments. The results showed application of nitrogen fertilizers to the soil could affect the behavior of chlorotoluron. At the same concentration of N, sorption of chlorotoluron decreased as the concentration of atrazine increased on the day 0 and 6 in soil, respectively. The sorption of chlorotoluron increased from 0 to 6 d when soils were preincubated with deionized water, ammonium sulfate and urea solution for 6 d. That indicated incubation time was one of the most important factors for the sorption of chlorotoluron in nitrogen fertilizers treatments. The individual sorption isotherms of chlorotoluron in rubbery polymer and silica were strictly linear in single solute system, but there were competition sorption between pesticides or between pesticides and nitrogen fertilizers. That indicated the sorption taken place by concurrent solid-phase dissolution mechanism and sorption on the interface of water-organic matter or water-mineral matter.     

Degradation of metabolites accumulated of benzo[a]pyrene by coupling Penicillium Chrysogenum with KMnO4

Several main metabolites of benzo[a]pyrene （BaP） formed by Penicillium chrysogenum, Benzo[a]pyrene-1,6-quinone （BP 1,6- quinone）, trans-7,8-dihydroxy-7,8-dihydrobenzo[a]pyrene （BP 7,8-diol）, 3-hydroxybenzo[a]pyrene （3-OHBP）, were identified by high-performance liquid chromatography （HPLC）. The three metabolites were liable to be accumulated and were hardly further metabolized because of their toxicity to microorganisms. However, their further degradation was essential for the complete degradation of BaP. To enhance their degradation, two methods, degradation by coupling Penicillium chrysogenum with KMnO4 and degradation only by Penicillium chrysogenum, were compared; Meanwhile, the parameters of degradation in the superior method were optimized. The results showed that （1） the method of coupling Penicillium chrysogenum with KMnO4 was better and was the first method to be used in the degradation of BaP and its metabolites; （2） the metabolite, BP 1,6-quinone was the most liable to be accumulated in pure cultures; （3） the effect of degradation was the best when the concentration of KMnO4 in the cultures was 0.01% （w/v）, concentration of the three compounds was 5 mg/L and pH was 6.2. Based on the experimental results, a novel concept with regard to the bioremediation of BaP-contaminated environment was discussed, considering the influence on environmental toxicity of the accumulated metabolites.     

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.     

Removal of heavy metals from sewage sludge by low costing chemical method and recycling in agriculture

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Isolation and preliminary characterization of a 3-chlorobenzoate degrading bacteria

A study was conducted to compare the diversity of 2-, 3-, and 4-chlorobenzoate degraders in two pristine soils and one contaminated sewage sludge. These samples contained strikingly different populations of mono-chlorobenzoate degraders. Although fewer cultures were isolated in the uncontaminated soils than contaminated one, the ability of microbial populations to mineralize chlorobenzoate was widespread. The 3- and 4-chlorobenzoate degraders were more diverse than the 2-chlorobenzoate degraders. One of the strains isolated from the sewage sludge was obtained. Based on its phenotype, chemotaxonomic properties and 16S rRNA gene, the organism S-7 was classified as Rhodococcus erythropolis. The strain can grow at temperature from 4 to 37℃. It can utilize several （halo）aromatic compounds. Moreover, strain S-7 can grow and use 3-chlorobenzoate as sole carbon source in a temperatures range of 10-30℃ with stoichiometric release of chloride ions. The psychrotolerant ability was significant for bioremediation in low temperature regions. Catechol and chlorocatechol 1,2-dioxygenase activities were present in cell free extracts of the strain, but no （chloro）catechol 2,3- dioxygenase activities was detected. Spectral conversion assays with extracts from R. erythropolis S-7 showed accumulation of a compound with a similar UV spectrum as chloro-cis,cis-muconate from 3-chlorobenzoate. On the basis of these results, we proposed that S-7 degraded 3-chlorobenzoate through the modified ortho-cleave pathway.     

Single and joint effects of pesticides and mercury on soil urease

The influence of two pesticides including chlorimuron-ethyl and furadan and mercury （Hg） on urease activity in 4 soils （meadow burozem and phaeozem） was investigated. The soils were exposed to various concentrations of the two pesticides and Hg individually and simultaneously. Results showed that there was a close relationship between urease activity and organic matter content in soil. Chlorimuron-ethyl and furadan could both activate urease in the 4 soils. The maximum increment of urease activity by chlorimuronethyl was up to 14%-18%. There was almost an equal increase （up to 13%-21%） in the urease activity by furadan. On the contrary, Hg markedly inhibited soil urease activity. A logarithmic equation was used to describe the relationship （P〈0.05） between the concentration of Hg and the activity of soil urease in the 4 tested soils. Semi-effect dose （ED50） values by the stress of Hg based on the inhibition of soil urease in the 4 soils were 88, 5.5, 24 and 20 mg/kg, respectively, according to the calculation of the corresponding equations. The interactive effect of chlorimuron-ethyl or furadan with metal Hg on soil urease was mainly synergic at the highest tested concentrations.     

Organochlorine pesticides in soils under different land usage in the Taihu Lake region, China

A field study was conducted in the Taihu Lake region, China in 2004 to reveal the organochlorine pesticide concentrations in soils after the ban of these substances in the year 1983. Thirteen organochlorine pesticides (OCPs) were analyzed in soils from paddy field, tree land and fallow land. Total organochlorine pesticide residues were higher in agricultural soils than in uncultivated fallow land soils. Among all the pesticides, ΣDDX (DDD, DDE and DDT) had the highest concentration for all the soil samples, ranging from 3.10 ng/g to 166.55 ng/g with a mean value of 57.04 ng/g and followed by ΣHCH, ranging from 0.73 ng/g to 60.97 ng/g with a mean value of 24.06 ng/g. Dieldrin, endrin, HCB and α-endosulfan were also found in soils with less than 15 ng/g. Ratios of p,p'-(DDD DDE)/DDT in soils under three land usages were: paddy field ＞ tree land ＞ fallow land, indicating that land usage inlfuenced the degradation of DDT in soils. Ratios of p,p'-(DDD DDE)/DDT ＞1, showing aged residues of DDTs in soils of the Taihu Lake region. The results were discussed with data from a former study that showed very low actual concentrations of HCH and DDT in soils in the Taihu Lake region, but according to the chemical half-lives and their concentrations in soils in 1980s, the concentration of DDT in soils seemed to be underestimated. In any case our data show that the ban on the use of HCH and DDT resulted in a tremendous reduction of these pesticide residues in soils, but there are still high amounts of pesticide residues in soils, which need more remediation processes.     

Alterations of organ histopathology and metallolhionein mRNA expression in silver barb, Puntius gonionotus during subchronic cadmium exposure

Common silver barb,Puntius gonionotus,exposed to the nominal concentration of 0.06 mg/L Cd for 60 d,were assessed for histopathological alterations(gills,liver and kidney),metal accumulation,and metallothionein(MT)mRNA expression.Fish exhibited pathological symptoms such as hypertrophy and hyperplasia of primary and secondary gill lamellae,vacuolization in hepatocytes,and prominent tubular and glomerular damage in the kidney.In addition,kidney accumulated the highest content of cadmium,more than gills and liver.Expression of MT mRNA was increased in both liver and kidney of treated fish.Hepatic MT levels remained high after fish were removed to Cd-free water.In contrast,MT expression in kidney was peaked after 28 d of treatment and drastically dropped when fish were removed to Cd-free water.The high concentrations of Cd in hepatic tissues indicated an accumulation site or permanent damage on this tissue.