基于正态分布假设检验的湖泊营养盐浓度分级评价方法研究

目前湖泊营养盐浓度级别评价常采用的平均值法忽视了变量的不确定性.本文据此提出一种基于正态分布总体均值假设检验的级别评价方法,并结合我国地表水环境质量标准(GB3838—2002)对营养盐浓度的分类,提出了简便快捷的图示法.结果发现,该方法能体现营养盐浓度变量的不确定性,融合先验级别假设,将决策风险定量化,可提供较为广阔的决策空间.同时,采用该方法对滇池外海观音山监测断面氨氮浓度的水质级别进行评价,发现先验级别假设、样本容量和决策偏好对评价结果有显著影响;与平均值法的比较发现,假设检验法具有更小的错误概率(例如,样本容量13时,风险0.21),评价结果具有更高的可信度,验证了假设检验法的适用性.     

不确定性流域污染负荷优化分配模型及其应用

流域优化决策模型以最优化建模方法指导流域管理决策过程,然而流域系统的不确定性会导致决策存在一定风险.本研究通过建立区间参数机会约束线性规划(ICILP)模型来处理流域决策过程中的不确定性,并将该模型运用于太滆运河流域优化决策中,探讨在不同违反概率下系统最优解.结果表明,随着允许入湖量约束违反概率增加,系统对污染物削减量和削减成本有所降低.由于受到经济成本和削减量约束,系统优先减小环境代价较大、削减效率较低的工程项目规模.但受到最低处理率约束,违反概率增加到一定水平时各工程项目趋于定值.虽然较高的违反概率使系统成本降低,但也会导致削减效率降低,不利于流域保护.因此,在实际管理中应根据管理需求选择合适的削减方案以达到保护流域水质的目标.     

流域系统优化调控的新模型与应用

流域系统具有复合性和非线性特征,其机理过程的数值描述本身也存在随机和认知不确定性.在此前提下,如何优化调控流域系统,实现水质改善和水生态系统健康成为当前水资源、水环境及水生态领域亟待解决的突出问题.本文提出了贝叶斯递归回归树模型和区间不确定性的风险决策分析方法,与强化区间线性规划结合形成了新的不确定性＂模拟-优化＂间接耦合模型,实现流域系统优化调控及风险决策方案.上述方法将应用于美国佛杰尼亚州Chesterfield县Swift Creek水库营养盐TMDL分配方案,确定8个子流域的最小负荷分配以实现叶绿素a浓度达标.结果表明该耦合模型既能表征流域系统特征,也能兼顾不确定性模拟的准确度、计算效率以及不确定性优化与风险决策的解空间全局最优性、绝对可行性,为流域系统优化调控及其未来非线性系统的预测与最优控制提供了新的计算工具.     

流域水质目标管理的风险识别与对策研究

以水质目标为约束和核心的管理将逐步完善、补充和强化当前的总量控制模式,成为我国中长期流域水环境管理的重要内容.流域水质目标管理是一个"响应→调控"并不断反馈调整的过程,但由于流域系统的非线性和不确定性,流域污染减排并不能完全确保水质目标的实现.本文将这种由不确定性而引致的流域水质目标的不完全可达性界定为风险,并在分析流域水质目标管理框架思路的基础上,识别并实证了水质目标管理中的主要风险来源,主要包括:1在"响应"层面,由于水质响应与负荷削减等措施间的非线性、时滞性、指标不协同等不对应关系带来的风险;2在"调控"层面,由于水环境管理缺乏适应性的调控和反馈机制而产生的水质达标风险.在此基础上,提出了流域水质目标风险管理的转变途径及其定量表征方法,以期为流域水质目标风险管理提供借鉴.     

基于贝叶斯网络的流域水环境承载力超载风险评价——以北运河流域为例

现有流域水环境承载力评估研究大多从确定性角度进行评价,从流域水环境承载力超载风险角度评价的较少.为弥补以上不足,本文从不确定性分析角度,耦合水环境和水资源两个水环境承载力分量超载风险及其对应的概率,构建了基于贝叶斯网络的流域水环境承载力超载风险评价模型,并依据超载风险的概率分布确定流域各控制单元的超载风险指数.最后以北运河流域为例,对其水环境承载力超载风险进行了评价,并依据评价结果进行超载风险分区.结果表明：中度超载风险区包含清河闸、榆林庄、大红门闸上、东堤头闸上4个控制单元,重度超载风险区包含南沙河入昌平、前侯尚村桥2个控制单元;基于“卸荷”和“强载”的双向调控理念,在产业结构、技术手段和环保意识等方面从全过程控制角度提出降低流域水环境承载力超载风险的调控措施.     

异龙湖及主要入湖河流(含湿地)水质监测与评价

介绍了异龙湖基本情况,对异龙湖主要入湖河流(含湿地)进行现状监测,结果显示,按照Ⅲ类水质标准评价,大水河入湖口、城河入湖口水质均不达标.若按《异龙湖流域水环境保护治理"十三五"规划(2016—2020年)》确定的Ⅴ类水质目标评价,大水河入湖口水质达标,城河入湖口水质不达标.提出了对策建议.     

基于非线性响应函数和蒙特卡洛模拟的滇池流域污染负荷削减情景分析

为定量了解滇池外海水质对流域污染负荷削减率的响应变化程度,并评估相关决策的潜在风险,在长期的水质模拟结果基础之上,本文使用内嵌非线性响应函数的蒙特卡罗模拟方法,在2个不确定性水平下（5%和10%的变异范围）分析滇池外海为达到3个水质目标情景（Ⅲ类、Ⅳ类和Ⅴ类）的污染负荷削减及其不确定性.模型结果表明,在2种不确定性水平...     

抚仙湖流域负荷削减的水质风险分析

以抚仙湖为研究对象,基于三维水动力-水质模型EFDC平台,开发了EFDC-神经网络(NN)耦合模型;并选用30d移动平均值为解译方式核算抚仙湖在不同风险下的流域负荷削减(TMDL).结果表明,对于100%的达标频度,为了达到I类水质,TP允许增加14%~18%,COD允许增加9%~11%,但TN需要削减13%~14%.如果放松对达标频度的要求,污染负荷将允许相应地增加.研究结果可为流域管理依据不同的风险与管理费用偏好实施流域削减提供基础.     

基于随机-模糊耦合的污染场地健康风险评价及案例

采用模糊理论描述风险评价过程的模糊不确定性,采用概率理论描述随机不确定性,同时为解决模糊数计算过程复杂的问题,将模糊变量表示成均匀随机变量的函数,用Monte Carlo算法模拟模糊变量之间的函数运算,从而实现模糊-随机方法的耦合.为验证该模糊-随机耦合模型的有用性,选取青海某汞化工污染场地进行案例研究,通过与RBCA模型比较,验证了该模型的基本精度,且能较好地表征场地参数的不确定性对风险评价结果的影响.案例分析的结果表明:人群主要暴露途径为经口摄入,贡献率为80%左右;正常暴露情形下,该场地的健康风险水平为0.28,风险水平可以接受,最不利情况下的健康风险风险水平为1.28,最不利情况出现的概率小于等于1%;该场地对人群的健康风险随着时间减小,在第6年左右其风险减小至可接受水平,建议无需对场地开展污染治理,只需在污染物高峰段(第1~6年或第6~8年)为居民提供替代水源以截断暴露途径,待场地污染水平自然衰减.     

浅谈地下水污染环境评价

地下水污染风险研究在工程决策中具有重要意义.但地下水系统本身具有各种不确定性,基于这些不确定性,地下水污染风险评价因此也具有不确定性,而且贯穿整个地下水污染风险评价过程.所以,进行不确定性分析是对地下水污染风险进行评价时的必要步骤.通过对地下水地质环境影响要素的分析,研究了评价的基本原理,构建了评价模型.     

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.     

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.     

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.     

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.     

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.     

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.     

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.     

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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