Speciation of heavy metals in sediments from the Scheldt estuary,Belgium

A simple three-step sequential extraction procedure was applied to study the speciation of heavy metals in sediment from Scheldt estuary, and their relationship to sediment grain size and organic matter content. The sedimentary metal content was fractionated into carbonate and exchangeable, metals bound to organic matter and residual fractions. Sedimentary total metal content was also determined using an industrial microwave (ETHOS 900) HF/HNO₃ extraction method. The extracts were analysed for metals using inductively coupled plasma atomic emission spectrometry. The bioavailable fraction (exchangeable and metals bound to organic matter) comprised less than the other forms. Residue metals were the dominant form of metals in almost all studied sites. The average total metal content for the studied sites decreased in the order Fe>Cr>Cu>Co>Zn>Pb>Cd. Based on average values for the studied sites, the highest bioavailable metals in sediments were Cd (38%) from Westkapelle, Zn (17%) from Yerseke, Co (12%) from Domburg, Cr (9%) from Vlissingen, Fe and Pb each (2%) from Yerseke, and Cu (1%) from Domburg. Metal recovery was good, with<10% difference between the total metal recovered through the extractant steps and the total metal determined using HF/HNO₃ extract.     

Spatio-temporal population and reproductive responses in Perinereis gualpensis (Polychaeta: Nereididae) from estuaries under different anthropogenic influences

Reproductive and population-level responses are ecologically relevant diagnostic tools for revealing the cost of long-term tolerance to contaminants. Spatial density distribution, seasonal density, biomass, size frequency histograms and oocytes stages in Perinereis gualpensis (Polychaeta: Nereididae) from a highly anthropogenically impacted estuary (Lenga, south-central Chile) were compared with low-polluted estuaries (Tubul and Raqui). Spatial distribution showed that the highest P. gualpensis abundances occur in the central (middle) estuarine area, establishing them as suitable zones for comparisons of estuaries. Middle areas also showed differences among estuaries in terms of population and reproductive responses. Mature stage oocytes and juvenile recruitment limited to certain seasons and low adult survival led to significant low densities and biomasses in Lenga individuals (p?estuary is a factor to be considered when evaluating these responses.     

长江口浮游植物群落特征及其与环境的响应关系

根据2009年4月、8月、11月对长江口30个站位的调查,分析了浮游植物群落结构的时空变化及其与环境因子的响应特征. 共鉴定出浮游植物8门95属330种,主要优势种是硅藻和甲藻,其中中肋骨条藻占绝对优势. 浮游植物细胞丰度呈单周期季节性变化,夏季为高峰期,长江口近海区为高值区. 浮游植物群落多样性11月最高,主要分布在长江口过渡水域. 浮游植物群落可分为四大类群,各区域不同季节种类组成具有显著差异. CCA(典范对应分析)显示,浮游植物群落与环境因子密切相关,并且其响应机制存在季节性差异.硅藻细胞丰度4月与ρ(NO₃--N)、ρ(COD_Mn),8月与ρ(SiO₄4--Si)、ρ(NO₃--N)、ρ(PO₄3--P),11月与透明度呈显著正相关(P<0.01);11月与ρ(PO₄3--P)、ρ(SiO₄4--Si)呈显著负相关(P<0.01). 甲藻细胞丰度4月与ρ(NH₄+-N),8月与ρ(COD_Mn),11月与透明度、ρ(NO₃--N)呈显著正相关(P<0.05). 长江口环境因子的改变影响浮游植物群落结构的时空变化,各季节引起浮游植物群落结构变异的驱动因素存在差异.      

Positive relationships between phenol oxidase activity and extractable phenolics in estuarine soils

Decomposition of recalcitrant materials such as phenolics is known to play a pivotal role in organic matter decomposition and nutrient cycling in estuaries. The specific goals of this study were to determine temporal and spatial variations of phenol oxidase and phenolics in estuarine soils, and to elucidate controlling factors for phenol oxidase activity. To achieve these goals, phenol oxidase activity and phenolic content were measured in soils developed along the side of an estuary in the Han River, Korea. Soil samples were collected in three locations with different vegetation: mud flats, Zizania-dominated soils, and Salix-dominated soils. Monthly measurements were also made in a Zizania-dominated site over a year period. Phenol oxidase activity varied between 0.00 and 0.28 diqc min^?1 g^?1, whilst phenolic content ranged from 0.0–10.5 μg g^?1. A correlation analysis revealed that phenol oxidase activity exhibited positive correlations with phenolic content in both seasonal and spatial data. The same relationship was found when the data were analysed separately for each site. Unlike peatlands or upland forest soils where negative correlations were often found between phenol oxidase activity and phenolics, substrate induction appears to account for the positive correlation in the present study.     

太湖大浦口河口区沉积物中铁、磷的地球化学特征

对太湖西部大浦口河口区沉积物中的w(Fe2+),w(TP)和w(Fe-P)及间隙水中ρ(Fe2+)和ρ(PO₄3-)的空间及垂向分布特征进行了测定分析. 结果表明,上覆水中,河道的各项指标均大于湖区及河口,而在河道与河口沉积物中w(TP)基本相似,均小于湖区. 在河口沉积物垂向剖面上,存在约5,9及11 cm 的3个明显变化阶段. w(Fe-P)占w(TP)的16.7%～47.8%,与ρ(TP)的相关性较好(R0.526),但与其他指标的相关性并不明显. Fe-P是重要的磷形态,厌氧状态下有向间隙水解析扩散的潜力,并形成Fe3+与Fe2+间的转换. 间隙水中ρ(PO₄3-)与w(Fe-P)/w(TP)和ρ(Fe2+)存在非对应性,但与ρ(Fe)呈显著相关(R0.853).河口区PO₄3-的迁移转化受多种因素的作用,复杂的水动力活动和地球化学作用是主要控制因素.      

Sources and major biogeochemical pathways of organic matter in the mangrove system of Rufiji estuary

Fatty acids were extracted from the surface sediments (10 cm) of three sampling sites of Rufiji estuary to infer their sources and biogeochemical pathways. The fatty acids ranging from C₈ to C₂₄ were distinguished from this study, and were broadly classified into saturated (SFAs), monounsaturated (MUFAs) and polyunsaturated fatty acids (PUFAs). SFAs were found to be the major fraction at station 1 and 3 where as at station 2, MUFAs dominated. A total of 19 fatty acids with a total concentration of 64.91 μg/g dry weight were characterised at station 1. C_16:0 was the most abundant fatty acid contributing 21.94% of total fatty acids (TFAs). C_22:2 was the second most abundant, which accounted for 9.46% of TFAs. Fatty acids ranging from C₁₂ to C₂₄ were identified at station 2. C₂₀ fatty acid was the most abundant fatty acid contributing 21.94%, followed by C_16:0. At station 3, fatty acids ranging from C₈ to C₂₄ were obtained. The PUFA C_20:5n-3 was the most abundant fatty acid contributing 21.65%, followed by C_24:0 (15.00% of TFAs). The ratio of lower molecular weight (LMW) to higher molecular weight (HMW) biomarkers was used as an indicators to distinguish higher plants organic matter from algae-derived fatty acids.     

黄河口滨海湿地水质污染物现状研究

于2009年5月(枯水期)、8月(丰水期)和11月(平水期)在黄河入海口滨海湿地典型水域选取14个调查站点采集水样,测定水体营养盐、重金属、石油类等22项污染指标,采用内梅罗指数和综合营养状态指数评价法对水质污染现状进行研究和评价.结果表明,滨海湿地整体水质属于轻度富营养化水平,并呈现逐年加剧趋势.湿地湖泊、黄河故道、国家自然保护区、养殖池塘等静态水域污染较轻,以广利河、挑河、神仙沟、小岛河、孤东油田排涝沟为代表的支流水体污染较重,明显超过黄河主干河道.调查发现滨海湿地水体主要污染物为TN、TP、石油烃、Hg、NH4+-N、UIA和Chl-a等.与历史数据对比,湿地水体氮磷污染明显加剧,石油烃和Hg污染未见显著增长,其他重金属含量均未超标,整体水质污染形势不容乐观.     

河口与近海营养状况评价方法及其应用验证

基于压力-状态-响应(PSR)模型,建立了我国河口与近海营养状况评价法. 通过分析当前富营养化概念模型研究结果,引入A(人为影响指数)和表征过滤与调节作用的ΔSA/SA(层化系数)作为压力指标,从富营养化负面效应筛选出高效的表层ρ(Chla)、d(浮游植物细胞密度)、底层ρ(DO)、a(底栖生物个体丰度)和RT(赤潮指数)作为状态指标,并以v(未来营养盐通量年均变化)作为响应指标. 综合考虑国内外相关标准来界定评价指标分类标准,采用统计处理、矩阵法集成得到G(营养状况等级),并成功应用于九龙江河口区. 应用验证结果表明:2010年九龙江河口区G为“差”,北部采样点优于南部,与人为环境压力空间分布一致;Kolmogorov-Smirnov非参数检验显示,G为“中”和“差”的两类采样点之间的ρ(COD)、ρ(DIN)、ρ(TN)、ρ(DSi)、ρ(SPM)(其中DSi和SPM分别为溶解态硅酸盐、悬浮颗粒物)差异显著(p<0.05),ρ(TP)、ρ(DIP)因“磷缓冲”机制而趋于均匀分布(p>0.05),评价结果可识别出评价体系并未包含的主要环境因子状况;与第一阶段评价法相比,河口与近海营养状况评价法注重富营养化症状的评价,因此具有更易识别营养状况恶化与否的优势.      

三八河河口潮滩有机碳、油类、硫化物及微生物分布特征

为了评价烟台市牟平区三八河河口潮滩中主要污染物的分布及土著微生物的修复潜力,研究了潮滩沉积物中w(TOC),w(油类),w(硫化物)和微生物的水平及垂直分布规律. 利用单因子污染指数法对污染状况进行了分析. 结果表明:各因子污染指数由大到小为有机碳(TOC)>硫化物>油类,河口区域w(TOC),w(油类)和w(硫化物)明显高于对照点,越靠近河口表层(0～≤20 cm)沉积物污染越重,说明潮滩污染主要由河流排污引起. 垂直深度上污染物主要集中在亚表层(5～≤20 cm),0～≤50 cm深度范围内w(TOC),w(油类)和w(硫化物)随深度的增加呈先增大后减小的趋势. 微生物分布规律显示,外源有机物的输入可提高沉积物中异养菌总数和呼吸强度,潮滩微生物可通过呼吸过程实现有机碳的矿化和输出,具有一定的修复潜力.