利用BP神经网络模型对太湖水体叶绿素a含量的估算

利用太湖2001-2006年常规水质监测资料和气象资料进行主成分分析,确定影响太湖水体叶绿素a 含量的主要因子。在此基础上构建BP神经网络模型,利用模型对太湖湖心区水体叶绿素a含量进行估算,并对模型进行敏感度分析;将所建模型运用于太湖梅梁湾、贡湖湾、竺山湾以及东太湖4个湖区叶绿素a含量的估算,以验证其适用性。结果表明：基于主成分分析的BP神经网络模型估算的湖心区叶绿素a含量与实测值的拟合度良好,对已建立的BP神经网络预测模型进行敏感度分析表明,气温和溶解氧与浮游植物叶绿素a含量密切相关;该模型对太湖其它4个湖区水体叶绿素a含量的估算结果与实测值拟合度良好, 表明其适用性也较好,因此,可以运用于对太湖水体叶绿素a含量的估算及预测。     

薄膜扩散梯度技术测定水体中砷及其影响因素研究

薄膜扩散梯度技术（Diffusive Gradientsin Thin Films Technique,DGT）是近年来应用于水体、沉积物和土壤中的铜镉等重金属生物有效性研究的一种新技术。采用标准溶液培养方法研究了以氧化铁作为吸附剂的DGT测定水环境中无机砷含量的可行性,并探讨了待测介质的pH和As价态对DGT测定结果的影响。结果表明,研究所用DGT装置中的吸附凝胶对砷吸附的最大容量≤42μg,其有效容量≤13μg,为确保DGT测定值的准确性,需要对DGT装置的放置时间加以控制;当水体中砷浓度为0.1～11.0mg·L-1时,DGT测定的溶液中无机砷浓度与直接用HG-AFS测定待测水体中无机砷浓度之间有较好的响应关系,DGT测定水体中无机砷的浓度能较好反应水体中无机砷的真实浓度;当溶液的pH值为2.95～8.18时,不同pH下吸附凝胶对砷的吸附量间差异不显著,溶液pH值在一定范围不影响DGT的测定结果;As（V）、As（Ⅲ）在进行DGT试验时不存在竞争吸附关系,砷离子的价态对DGT测定水体中的无机砷的浓度没有显著影响。总之,在各种环境相关的条件下,DGT是一种可以用于测定水体中总无机砷的有效方法。     

藻华暴发期太湖不同湖区水样对斑马鱼胚胎发育及仔鱼生长毒性研究

为了评价太湖蓝藻暴发对生态系统的危害程度,于蓝藻水华暴发的2009年7月在太湖梅梁湾（M1和M2）、湖心区（H）和胥口湾（X）4个点采集水样,将斑马鱼（Danio rerio）胚胎直接暴露于水样中,研究太湖不同湖区水质对斑马鱼胚胎发育和仔鱼生长的影响。结果表明,暴露于梅梁湾M2点的斑马鱼胚胎畸形率为7%,显著高于空白组（K）（P〈0.01）,湖心H和梅梁湾M1点为5%左右,也高于空白组（P〈0.01）,而胥口湾X点和空白组无显著性差别（P〉0.05）。蓝藻暴发水体对斑马鱼胚胎产生致畸作用,表现为脊椎弯曲、尾部弯曲和心包水肿等。同时,不同湖区水样对仔鱼生存活力指数（SAI）的影响表明,梅梁湾M2点仔鱼活力最弱,胥口湾X点仔鱼活力最强。试验期间梅梁湾M2点蓝藻密度最高,胥口湾最低,太湖蓝藻密度的分布与斑马鱼胚胎发育的畸形频率具高度的一致性。因此,藻华暴发水体会对脊椎动物胚胎发育和仔鱼生长产生不利影响,危害水生态系统的安全。     

霍甫水丝蚓（Limnodrilus hoffmeisteri）扰动对表层沉积物细菌群落结构和多样性的影响

为研究大型底栖动物霍甫水丝蚓（Limnodrilus hoffmeisteri）对表层沉积物中细菌群落结构和多样性的影响,设计了沉积物-水微宇宙的实验,模拟太湖梅梁湾霍甫水丝蚓（Limnodrilus hoffmeisteri）的自然分布特征,运用末端限制性片段长度多态性技术（T-RFLP）比较了有无霍甫水丝蚓（Limnodrilus hoffmeisteri）分布的沉积物样品中细菌群落的动态变化。结果表明,水丝蚓组和对照组沉积物细菌群落结构相似性无显著差异（P〉0.05）,可见太湖梅梁湾目前的水丝蚓生物量引起的生物扰动对表层沉积物细菌群落结构影响不明显;实验中后期只在处理组中出现的206 bp以及处理组含量高于对照组的370 bp T-RFs都可能是Nitrosomonas属的氨氧化细菌,提示大型底栖动物霍甫水丝蚓的存在可能为氨氧化细菌提供了适合的生态位。     

基于梯度薄膜扩散技术的广西环江流域桑田土壤中铅的生物有效性研究

梯度薄膜扩散技术（Diffusive gradients in thin-films,DGT）是一种原位连续环境采样和测量方法,自20世纪90年代中期被报道以来,一直以固态结合相采集和测量水体、沉积物和土壤中有效态重金属,目前液态结合相的DGT多应用于水体中金属离子的检测。分别采用固态结合相（chelex100）和改进的液态结合相（sodium polyacrylate,PAAS）的DGT装置,对广西桑田土壤中有效态Pb进行了累积和测定。简单分析结果表明,两种装置提取的土壤有效态Pb含量与桑树老叶和嫩叶中的Pb含量都呈极显著相关关系,改进的PAAS-DGT装置对土壤中有效态Pb的提取能力更强。融合土壤pH、阳离子交换量（CEC）、有机质（OM）和土壤颗粒组成等理化指标影响,运用多元统计分析,建立了逐步回归模型。多元统计分析表明,两种结合相的DGT技术所构建的回归模型是可靠的,其调整判定系数R2adj分别为0.87、0.89、0.96和0.95,且预测结果融合了影响土壤有效态Pb含量的pH、CEC、有机质和土壤质地等主要因素。研究结果表明两种结合相的DGT装置均能较好预测桑田土壤中Pb的生物有效性,拓展了DGT技术的应用范围。关键词：梯度扩散薄膜技术（DGT）;聚丙烯酸钠（PAAS）;铅（Pb）;生物有效性;桑田;广西     

赫章土法炼锌区水-沉积物重金属污染的时空变化特征

对赫章土法炼锌区河流水体和沉积物重金属污染状况及时空变化特征进行了研究。结果表明,水体和沉积物受到多种重金属污染：地表水体中Pb、Zn、Cd的均值分别为137.19×10-3、1 919.38×10-3、14.21×10-3 mg.L-1,分别是地表水环境质量标准Ⅲ类水质标准的2.74、1.91、2.84倍;沉积物中Cu、Pb、Zn和Cd的均值分别为702.79、3 242.8、5 427.6、32.19 mg.kg-1,分别是土壤环境质量标准三级标准的1.76、6.49、10.86、32倍。水体和沉积物中Cu、Pb、Zn和Cd沿河流总体呈无规律性的变化,受炼锌废渣堆和铅锌选矿厂影响的地点,水体和沉积物重金属含量均较高,污染严重。近10年来,炼锌区河流水体和沉积物重金属污染仍然很严重,水体重金属污染呈加重特征,沉积物中Pb、Zn污染呈减轻趋势,Cd和Cu污染则加重。     

化学提取法与梯度扩散薄膜技术提取太湖沉积物中有效砷的比较

以底栖生物河蚬（Corbicula fluminea）为实验生物,外源三价砷污染太湖沉积物为研究对象,利用生物富集实验分别比较了DGT（Diffusive gradients in thin films）梯度扩散薄膜技术和化学连续提取法所测浓度与河蚬中砷的生物有效性的相关性,并分析了这两种方法的差异。实验结果显示随着沉积物中染毒的总砷浓度（9.48,14.12,19.88,26.86,35.66,46.42,54.25mg·kg^-1）增加,DGT测得砷浓度和化学提取法所测砷含量也随之增加,Pearson相关系数均在0.98以上（P〈0.01）,表明这两种技术均能很好地预测沉积物中有效砷含量。通过河蚬对三价砷的暴露实验,发现当沉积物总砷含量在35.66mg·kg^-1以下时,暴露14d和28d后河蚬体内富集的总砷含量与暴露浓度增加趋势一致。Pearson分析结果显示DGT法和化学提取法测得结果均与河蚬体内砷的富集量显著相关,因此这两种方法都可用于预测河蚬体内肉质部的总砷富集量。     

长潭水库水体沉积物营养盐分布特征及其污染评价

探究长潭水库库区沉积物中碳(C)、氮(N)、磷(P)含量特征及其污染状况,可为区域水环境质量提升提供理论依据。研究于2021年9月在水库中心区及8条入库支流断面设置28个采样点,对表层沉积物中的总有机碳(TOC)、总氮(TN)、总磷(TP)含量进行测定,并采用单因子指数法、综合污染指数法和有机污染指数法对库区污染状况进行了评价。结果表明：库区表层沉积物中TOC,TN和TP含量分别为(13.67±3.81) g/kg,(1.46±0.37) g/kg,(0.43±0.17) g/kg;其中,以柔极溪(RJR)含量较高,其TOC含量显著高于库中心区与其余入库支流(p<0.05)。表层沉积物中C/N,C/P,N/P比值范围分别为7.72～15.07,15.28～63.20,1.66～6.26。由单因子指数法和综合污染指数法分析可知,整个库区水体沉积物TN污染严重,基本属于重度污染;有机氮评价结果进一步表明库区整体处于Ⅲ级污染水平(尚清洁),其中以库中心区和RJR污染较重,存在有机氮污染(等级为Ⅳ级)。长潭水库存在一定的内源污染,且以有机污染为主。未来应加强库区水体沉积物营养盐含量动态的...     

乐清湾养殖区表层沉积物重金属含量分布及污染评价

以乐清湾养殖区表层沉积物中Cu等7种重金属为研究对象,在野外实地调查取样及重金属含量测定基础上,以中国海洋沉积物质量(GB18668-2002)一类标准值为评价标准,利用单因子指数评价法、内梅罗综合污染指数评价法和沉积物质量基准(sediment quality guideline,SQG),对单项重金属污染程度、多种重金属综合污染效应及重金属潜在生物毒性风险进行了评价。结果表明,乐清湾养殖区表层沉积物重金属含量分布差别明显,所有采样点表层沉积物均受到Cu污染,局部受到严重Hg污染;大部分养殖区表层沉积物重金属污染达到轻度等级;所有养殖区均可发生由Cu偶尔引起的不利生物毒性效应,个别养殖区可发生由Hg频繁引发的不利生物毒性效应。乐清湾养殖区表层沉积物重金属主要来源于沿岸电镀企业废水排放及农药化肥造成的农业面源污染。开展Cu、Hg污染治理修复是实现乐清湾养殖环境安全的迫切需求。     

松花江沉积物重金属形态赋存特征研究

采用Tessier连续提取法分析了松花江表层沉积物中Cu、Pb、Zn、Mn4种重金属的赋存形态,并结合次生相富集系数法,探讨了沉积物中重金属的潜在生态风险及来源。结果表明,沉积物中Cu以残渣态为主（高于50%）,其次为有机质结合态,从上游至下游,沉积物中Cu形态的稳定程度逐渐增加;沿程所有沉积物样品中可交换态Pb的含量均高于当地沉积物背景值,存在较高的可迁移性和二次释放风险;在二松大部分江段和松花江干流,Zn主要以比较稳定的残渣态存在,不存在二次释放污染水体的风险;Mn的有效态含量均在流域沉积物背景值范围之内。对重金属次生相富集系数的研究表明,沿程沉积物中Cu、Pb均有一定程度的富集,主要来源于人为输入;Zn在二松中下游的哈达湾至松原江段有一定的富集,其余江段人为输入的Zn较少;沉积物中的Mn主要为自然来源。     

中国太湖环境土壤磷测试与磷释放

A microtiter plate assay (MPA) for soluble reactive phosphorus (SRP) was applied to samples in overlying water and pore water as well as in three forms of environmental soil test phosphorus (P) types: water soluble phosphorus (WSP), diluted calcium chloride extractable phosphorus (PCaCl2), and Olsen-P in the sediments of Taihu Lake, China, where potential P release in response to pH was analyzed. MPA for rapid P analysis was shown to be promising when applied on samples of natural water and sediment extracts. Concentrations of WSP and PCaCl2 in the sediments were much lower than those of Olsen-P. Olsen-P levels in the littoral sediments along the north coast of Meiliang Bay in Taihu Lake (80 to 140 mg kg^-1) were much higher than those in the mouth of the bay (less than 50 mg kg^-1). The risk of P release in the mouth area of Meiliang Bay was lower than that in the north littoral zone with a risk of sediment P release induced by pH increases.     

太湖北部湾沉积物有机氯农药残留特征及评价

采用GC-ECD联用检测技术分析了太湖北部贡湖大贡山（1号点）、小贡山（2号点）与梅梁湖马山（3号点）、拖山（4号点）不同季节有机氯农药中4种HCHs同系物及4种DDTs同系物含量。结果表明,含量最高的为γ-HCH与DDT,分别占总量的45%以上,其次是β-HCH与DDD,而o,p-DDE基本未检出。不同监测点表现出了季节变化,受＂引江济太＂调长江水入太湖的影响,贡湖中1号与2号监测点夏季OCP总量高于其他季节,而梅梁湖受周围生产及竺山湖大桥入污影响,3号监测点不同季节OCPs总量变化不显著,4号监测点冬季高于春季,夏季受高温影响,OCPs总量出现最小值。采用生态风险值对沉积物中OCPs进行风险评价,太湖北部湾沉积物中OCPs总量较低,尚未对生态构成严重威胁,但由于这类物质的生态累积效应,其潜在危害仍不容忽视。     

Occurrence of polycyclic aromatic hydrocarbons in the estuarine sediments of the Taihu Lake and their associated toxic effects on aquatic organisms

Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous toxic organic pollutants in the natural environment that are strongly associated with socioeconomic activities. Exploring the distribution, sources, and ecological toxicity of PAHs is essential to abate their pollution and biological risks. The 16 priority PAHs in different lakeside city estuarine sediments in the northern Taihu Lake in China were determined using gas chromatography-mass spectrometry. Results showed that total concentrations...     

Measuring bioavailable trace metals by diffusive gradients in thin films (DGT): soil moisture effects on its performance in soils

Conventional methods of measuring labile chemical species of trace metals in soil solutions, such as chemical competition following centrifuging, are inadequate if the speciation changes during sampling and extraction. A new technique, diffusive gradients in thin films (DGT), measures labile species of trace metals in natural waters and sediments in situ. A well-defined diffusive gel layer distinguishes it from other resin-based techniques. It perturbs the soil in a controlled way by introducing an in situ local sink for metal ions. Resulting fluxes to the device are quantitatively measured, allowing assessment of re-supply kinetics and in some cases measurement of in situ soil solution concentrations. We used DGT to measure fluxes of Cd, Co, Cu, Ni, Pb and Zn in a sludge-treated soil at various moisture contents (27–106%). Replicate measurements showed that the precision of DGT-measured fluxes was within 10%. For moisture contents exceeding the field capacity (42%), the DGT response reflected soil water concentrations. At smaller moisture contents, changes related to tortuosity and dilution were reflected in the measurements. This technique has the potential for in situ measurements in the field where it should provide quantitative flux data on individual soils and provide a good surrogate for bioavailable metal.     

Occurrence and distribution of chemical pollutants in Lake Mariut,Egypt. II. Heavy metals

The occurrence and distribution of heavy metals in the water of Lake Mariut, a heavily polluted brackish water lake in Egypt, and their accumulation in the different parts ofTilapia fish in this lake were studied. The variations in concentrations of the metals (Zn, Cu, Fe, Mn, and Cd) in the lake water are mostly due to variations in the discharge rate of dumped wastes. The mean concentrations of these metals in different fish parts were much higher than those in the lake water.     

抚仙湖重金属污染强度、历史及来源的沉积记录

This study focused on the concentration change of heavy metals of sediment cores in heavily polluted north area and less polluted middle area of Fuxian Lake in Southwest China.On the basis of the analysis of Cu,Ni,Ti,V,Pb,Cd,and Zn concentration-depth profiles,the pollution history of heavy metals was studied using ¹³⁷cesium (¹³⁷Cs) dating.The sources of heavy metals were distinguished by normalization of their profiles to aluminum and analysis of heavy metal concentrations of potential source materials.Geoaccumulation index (I_geo) was used to quantify their contamination intensity.The results showed that all the heavy metals found in the Fuxian Lake sediments originated naturally before 1980s.Cu,Ni,Ti,and V were still mainly natural in the north lake after 1980s,Cu,Ni,Ti,V,and Pb were mainly natural in the middle lake at all time,but the concentrations of Pb and Zn in the north lake were influenced by industrial wastes from the phosphorus fertilizer factory and cement plants.In all the lake,the contaminations of Cd and Zn were the results of agricultural cultivation using a large amount of fertilizers and the atmospheric fallouts of dusts from cement plants.At present,the geoaccumulation indices showed that the Fuxian Lake sediments were moderately to strongly polluted by Cd in the middle lake,and unpolluted to moderately polluted by Pb and Zn and strongly polluted by Cd in the north lake.Moreover,the pollution intensities of Cd,Zn,and Pb have been increased since 1980s.