湖泊沉积物中元素相态的连续提取分析—以岱海为例

如何利用湖泊/海洋沉积物地球化学代用指标有效地指示环境很大程度取决于元素的来源及其在沉积物中赋存形态的确定.对位于半干旱区的内蒙古岱海14个沉积物样品的连续提取实验及18个元素在水可溶态、可交换态、碳酸盐结合态、铁锰氧化物结合态、有机物结合态及残留态等六种赋存相态中含量变化进行了测试和研究,结合沉积物的矿物组成,结果表明在岱海流域内只经历了较弱的化学风化过程,除了Ca和Sr外,其他元素主要赋存于残留态中,只发生了很小程度的活化溶解.受元素亲合性和湖水物理化学状态的制约,出溶的Sr与Ca的赋存相态基本一致,而出溶的Pb、Be、Co、Cu、K、Mn、Fe等元素则与自生碳酸盐、有机质表现出一定的亲合性.元素在不同赋存相态中分布为地球化学环境代用指标的提取和解释提供了机理性的实验依据.     

太湖近代沉积物中重金属元素的累积

利用210Pb、137Cs定年技术,对来自太湖不同生态和沉积特征的三个湖区的沉积物柱状样品进行了定年,用ICP—AES分析了沉积物中重金属等元素的含量,分析了太湖沉积物中重金属的累积特征及其成因.污染较重、蓝藻水华暴发频繁的梅梁湾沉积物中的重金属含量在近25年来逐年增加;太湖上游风浪较大的夹浦湖区表层10cm沉积速率大、粒度粗,除表层1cm外,1—10cm沉积物中各种重金属含量都较低,且层间变化剧烈;下游湖区正逐渐草型化的胥口湾除表层3cm外,沉积物中重金属的含量自底层向表层大致呈不断下降的趋势.研究表明,不同年代的太湖沉积物中重金属含量差异很大,明显大于不同湖区间沉积物重金属平均含量间的差异.水动力作用引起的沉积物粒度分异很可能是影响沉积物中重金属积累的一个重要因素.总体上太湖沉积物中重金属的污染比较轻微,但已经有一定程度的Cd污染,梅梁湾沉积物中自上世纪70年代开始明显积累Cd,其他重金属元素的积累也逐渐增加,值得关注.     

密云水库沉积物中金属元素形态分析研究

研究了北京密云水库沉积物中As, Hg, Cd, Pb和Zn的化学形态、分布及其来源. 连续提取结果显示, 砷、铅、锌以残留态为主, 汞以硫化物结合态为主, 镉以碳酸盐结合态和残留态为主. 沉积物中元素总量及各形态的含量在垂向剖面上, 大部分都随着深度的减小而增加, 表明水库近年来上游水系带入库区的重金属元素的量呈逐年增加的趋势. 沉积物中代表地球化学背景, 与土壤侵蚀密切相关的元素残留态、硫化物结合态、碳酸盐结合态之和占元素总量的60.03%~85.60%, 经主因子分析得出水库沉积物主要来自上游水土流失和土壤侵蚀. 其次为上游点源污染和生活污染. 此外, 发生于沉积物-水界面的生物活动也是导致元素有机结合态、铁锰氧化物结合态含量增高的主要原因. 水库水环境的改变可使重金属的可迁移性增加, 从而导致沉积物孔隙水中重金属浓度增加, 对水库水质造成威胁.     

太湖梅梁湾沉积岩芯元素地球化学记录的多元统计分析

通过沉积岩芯元素含量垂直分布和富集因子分析,结合多元统计方法如系统聚类和模糊聚类分析,研究了太湖梅梁湾沉积岩芯元素地球化学记录的湖泊环境演化过程.以系统聚类分析和模糊聚类分析为基础,将梅梁湾地球化学记录的环境过程划分为如下几个层段:0-6cm为人类活动强烈干扰的阶段,25-50cm和55-72cm层段都是自然过程的表现,反映了流域物源的影响,而两层段元素记录的差异反映了不同自然作用驱动下的湖泊环境变化;6-25cm和50-55cm层段则是不同环境特征的过渡阶段,因此,综合应用多元统计方法可以更直观更精确地量化影响湖泊环境的因素,有助于恢复湖泊环境历史演化过程.     

太湖沉积物重金属和营养盐变化特征及污染历史

通过对太湖北部开阔湖区沉积岩芯粒度、营养盐、重金属元素等指标的分析,结合硅藻分析结果,讨论了该湖区近100年来沉积环境变化特征、营养演化规律及重金属元素污染历史.结果表明,20世纪20年代前后,流域人为活动方式的改变及强度加大使沉积物特征开始发生变化,沉积物粒度变粗,重金属元素及TP含量减少.20世纪50年代～20世纪70年代末期,受人为污染影响,沉积物及水体TP含量逐渐增加,湖泊处于中等营养水平.20世纪70年代末期以来,沉积物中TOC,TN含量升高,C/N比值增大,沉积物中人为排放的外源有机成分所占比例增加,沉积物及水体中TP含量明显升高,硅藻组合以富营养型种属为主,湖泊水体发生显著富营养化;同期,随着重金属元素人为污染程度的加重,Cu,Mn,Ni,Pb和Zn等元素总量及有效结合态含量升高,并具有一定程度的潜在生物毒性.     

首钢工业区土壤剖面重金属含量及其结合态的磁指示作用的研究

对取自首都钢铁厂附近的土壤样芯进行了重金属含量、形态分析和的磁学测量.探讨了利用磁参数追踪和指示重金属污染和有机结合态和铁锰氧化结合态重金属的可行性.结果表明:土壤样芯中Cu、Pb、Zn、Fe和Mn的含量与χ、SIRM和ARM存在着十分相似的垂向变化特征,且相关关系显著(0.98>R>0.86).进一步对磁化率和Cu、Pb、Zn、Fe和Mn各结合态进行相关分析表明:五种元素的有机结合态与铁锰结合态和磁化率呈显著相关关系(0.98>R>0.56),而交换态和残渣态重金属与磁化率基本不存在相关关系.反映了磁性矿物和和重金属在赋存状态的本质联系.表明了磁性测量可作为工业区土壤重金属污染及有机结合态与铁锰结合态重金属记录信息提取的辅助手段.     

太湖富营养化湖区秋季水体和沉积物中硝化微生物分布特征及控制因素

微生物参与下的氮循环是富营养化湖泊十分重要的生物地球化学循环过程.采用基于amoA功能基因和16S rRNA基因的荧光定量PCR、PCR-DGGE与高通量测序等分子生物学技术,调查秋季太湖不同水体和表层沉积物中氨氧化古菌(AOA)、氨氧化细菌(AOB)和亚硝酸盐氧化菌(NOB)群落丰度和组成,探讨影响硝化微生物分布的关键环境因子.结果表明,中度富营养化的梅梁湾湖区水体表层、中层和底层水样和表层底泥中AOA amoA基因的丰度分别低于轻度富营养化的湖心区,而不同层水样中AOB amoA基因的丰度分别高于湖心区.梅梁湾湖区和湖心区水样中AOA群落组成基本相似,2个湖区表层沉积物样品中AOA群落组成亦基本相似,水体中AOA群落组成与表层沉积物中AOA群落组成有差异,AOA群落丰度显著受硝态氮、pH和DO影响;表层沉积物中AOB群落丰度有明显差异且显著受总氮含量影响,表层沉积物中NOB群落丰度也有明显差异且显著受亚硝态氮含量影响.太湖梅梁湾湖区和湖心区水体与表层沉积物AOA群落包括Nitrosopumilium和Nitrosotalea两大属;表层沉积物AOB群落主要包括亚硝化单胞菌(Nitrosomonas)和亚硝化螺菌(Nitrosospira)两大属,NOB群落主要包括硝化刺菌(Nitrospina)和硝化螺菌(Nitrospira)两大属,其中硝化螺菌属是淡水湖泊中比较少见的亚硝酸盐氧化菌.影响太湖水体和沉积物中AOA和AOB丰度的最主要环境因子为总氮、总磷与铵态氮.研究表明典型富营养指标(总氮、总磷、铵态氮、硝态氮和硝态氮等)是影响太湖梅梁湾和湖心区水体和沉积物中AOA或AOB丰度以及硝化微生物群落丰度的重要因素.     

太湖梅梁湾摇蚊亚化石沉积记录及营养演化研究

对太湖梅梁湾T0905岩芯摇蚊幼虫亚化石组合进行了分析,探讨了自1940年以来梅梁湾湖区摇蚊幼虫对营养盐演化的响应.结果表明,梅梁湾湖区摇蚊组合变化以1970年为分界点,经历了由Tanytarsus为优势属种向富营养属种Chironomus plumosus-type和Microchironomus为优势组合转变的过程...     

太湖梅梁湾上空颗粒态磷浓度2003年春季的变化

太湖水体氮磷营养盐的研究比较多,但对大气营养物质的输入研究方面仍鲜有报道.通过定期采集太湖梅梁湾地区上空颗粒物,测定颗粒中各种形态磷(可溶性无机磷、有机磷、难溶性磷)浓度,探讨大气磷输入对梅梁湾水质的磷的贡献.结果表明2003年春季梅梁湾上空平均颗粒态磷浓度分别为0.157μg/m3,其中水溶性无机磷的含量在15.6%-51.0%.最后估算了春季大气总磷输入量,春季两次采样周期中大气磷沉降通量相差不大.进一步估算了大气总磷的沉降通量最大为0.57kg(hm2·a)(6.84t/a),显示大气沉降对太湖水体的影响.     

太湖五里湖区表层沉积物中酸挥发性硫化物和同步提取金属

湖泊底泥中的酸溶硫化物易与二价金属生成难溶金属硫化物,从而制约沉积物中二价有毒金属的化学活性以及生物有效性,进而影响沉积物的环境质量.对沉积物中的酸溶硫化物(AVS)和同步提取金属(SEM)进行测定,依据SEM/AVS的比值可以判定重金属生物有效性.通过对太湖五里湖、梅梁湾表层沉积物夏季和秋季AVS与SEM的采样分析,结果表明:研究区域内AVS的含量夏季高于秋季,SEM受季节影响很小,SEM/AVS大于1,且秋季高于夏季,初步判断该湖区沉积物中重金属具有潜在的生物毒性.     

Variation characteristics of heavy metals and nutrients in the core sediments of Taihu Lake and their pollution history

The sedimentary environment change, trophic evolution and heavy metals pollution history of the northern Taihu Lake in the last 100 years are studied according to the sedimentary geo-chemical proxies of the core sediments, such as grain size, nutrients, heavy metals, diatom, etc. The nutrients in the sediments depended mainly on the lake internal circulation and the heavy metals were from natural geogenic sources before the 1920s, which were not influenced by human activities generally, and grain size was one of the key factors influencing heavy metals content in the sediments. The alternation of manner and strength of human activities in Taihu Lake catchment before and after the 1920s made the lake sediments coarser, and hence heavy metals and TP content decreased contrasted with that before the 1920s. TP content in sediments and water increased from the 1950s to late 1970s due to anthropogenic pollutants discharge, and the lake belonging to mesotrophic state. TN and TOC content and C/N ratio increased due to the increasing external pollutants into Taihu Lake by human activities, TP content also increased obviously in water and sediments, and the diatom association was dominated by eutrophic species since the late 1970s, indicating the eutrophication state of Taihu Lake in this period. Meanwhile the increasing in heavy metals content, such as Cu, Mn, Ni, Pb and Zn, and their proportion of valid fractions in the sediments indicates that they all result from human pollutants since the late 1970s. The heavy metals in the surface sediments have certain potential biological toxicity due to the higher SEM/AVS ratio.     

Variation characteristics of heavy metals and nutrients in the core sediments of Taihu Lake and their pollution history

The sedimentary environment change, trophic evolution and heavy metals pollution history of the northern Taihu Lake in the last 100 years are studied according to the sedimentary geochemical proxies of the core sediments, such as grain size, nutrients, heavy metals, diatom, etc. The nutrients in the sediments depended mainly on the lake internal circulation and the heavy metals were from natural geogenic sources before the 1920s, which were not influenced by human activities generally, and grain size was one of the key factors influencing heavy metals content in the sediments. The alternation of manner and strength of human activities in Taihu Lake catchment before and after the 1920s made the lake sediments coarser, and hence heavy metals and TP content decreased contrasted with that before the 1920s. TP content in sediments and water increased from the 1950s to late 1970s due to anthropogenic pollutants discharge, and the lake belonging to mesotrophic state. TN and TOC content and C/N ratio increased due to the increasing external pollutants into Taihu Lake by human activities, TP content also increased obviously in water and sediments, and the diatom association was dominated by eutrophic species since the late 1970s, indicating the eutrophication state of Taihu Lake in this period. Meanwhile the increasing in heavy metals content, such as Cu, Mn, Ni, Pb and Zn, and their proportion of valid fractions in the sediments indicates that they all result from human pollutants since the late 1970s. The heavy metals in the surface sediments have certain potential biological toxicity due to the higher SEM/AVS ratio.     

太湖表层沉积物重金属元素的来源分析

根据太湖MS岩芯重金属元素与Al的线性回归分析及元素/Al、V/Al比率散点图变化规律,讨论了太湖沉积物中重金属元素的来源特征。结果表明:20世纪20年代中期以前,重金属元素主要为自然来源;20年代中期—70年代中期,尽管沉积物中Al、Fe、Zn、Mn、V、Cr等重金属元素含量随沉积物粒度变粗而明显下降,但除Hg受到一定程度的人为污染之外,其它重金属元素仍以自然来源为主,物源有所变化;70年代末期以来,沉积物中重金属元素人为污染逐渐加重,Pb、Cu、Zn、Hg、As等元素既有流域母质来源,又受到一定程度的人为污染。     

Chemical forms of Pb, Zn and Cu in the sediment profiles of the Pearl River Estuary

The chemical forms of heavy metals (Pb, Zn and Cu) in sediment cores of the Pearl River Estuary were studied using a sequential chemical extraction method. The isotope ratios of 206Pb/207Pb in various chemical fractions were also measured to assess the potential Pb sources. Zinc and Cu were mainly associated with the residual fraction. The Fe-Mn oxide and organic/sulphide fractions were the next important phases for Zn and Cu, respectively. For Pb, different chemical partitioning patterns were found among different sediment cores. Most Pb was associated with the residual fraction in the sediments. In some sediment profiles, the major phase of Pb in the top layers was the Fe-Mn oxide fraction. The proportion of Pb in the Fe-Mn oxide fraction decreased significantly with increasing depth. Among the different depths, the 206Pb/207Pb isotope ratios in the residual fraction remained fairly stable, with a mean value of 1.202, which may represent the natural background value. The 206Pb/207Pb ratios in the exchangeable fraction were the lowest among the five fractions, particularly in top sediments, showing the anthropogenic inputs of heavy metals from recent rapid industrial development in the surrounding region. For the other three non-residual fractions, there was a similar trend of increasing 206Pb/207Pb ratios down the profile. Results from this study are useful in assessing both the chemical changes for heavy metals in marine sediments and the potential of heavy metal release into the water environment of an estuary area.     

In-channel surficial fine-grained sediment laminae. Part II: Chemical characteristics and implications for contaminant transport in fluvial systems

Samples of surficial fine-grained laminae (SFGL) were collected in three south-western Ontario rivers. Each sediment sample was subjected to a sequential extraction procedure designed to partition particulate metals (Cd, Pb, Cu, Zn) into five operationally defined fractions: (1) exchangeable; (2) bound to carbonates; (3) bound to Fe-Mn oxides; (4) bound to organic matter; and (5) residual. Particulate phosphus was sequentially extracted from the sediment samples into three fractions: (1) non-apatite inorganic P; (2) apatite P; and (3) organic P. The major accumulate phases of trace metals in SFGL are carbonates, Fe-Mn oxides and organic matter. The content of NAIP in SFGL ranged from 17 to 38% of total particulate P. Compared with suspended and bed sediments, levels of P and trace metals in SFGL were lower at the study sites. A conceptual overview of physical, chemical and biological processes influencing formation of SFGL and the potential role of this fine-grained sediment for contaminant transport in fluvial systems is presented.     

Chemical forms of heavy metal contaminants in sediments of Miyun reservoir

The chemical forms, spatial distribution and sources of As, Hg, Cd, Pb and Zn in sediments of the Miyun reservoir were studied. The results of sequential extraction demonstrate that most of As, Pb and Zn were bound to the residual fraction, Hg was associated with the sulfide fraction while Cd was associated with the carbonate fraction and the residual fraction. On the vertical profiles the concentrations of the heavy metals in total and each fractions mostly decreased with increasing depths in sediments, suggesting that the heavy metals input from the upstream watershed increases yearly. Summation of the residual fraction, the sulfide fraction and the carbonate fraction accounts for 60.03%―85.60% of the total heavy metal contents in the sediments, which represent the geochemical background values of the elements and relate closely to soil erosion. Results of the main factor analysis show that most sediments of the reservoir come from the upstream soil erosion, the point source pollution and domestic waste. Moreover, the microbial activities taking place on the sediment-water interface are also one of the major factors to cause the increasing content of the organic matter fraction and the iron-manganese oxide fraction. Environmental change of the reservoir water could make the removability of the heavy metals increase, leading to the increase of their concentrations in pore water in sediments, and imperiling water quality of the reservoir.     

湖泊疏浚堆场淤泥污染及潜在生态风险评价

疏浚淤泥内通常含有不同类型的有毒有害物质,在堆场直接堆放过程中可能会对周围环境产生有害影响.本文针对太湖及巢湖相应疏浚堆场内淤泥进行研究,探讨淤泥中重金属、多环芳烃以及多氯联苯等污染物含量及潜在生态风险;根据重金属的风险指数法和持久性有机污染物的风险商法,对各污染物的潜在生态风险进行定量分析.研究结果表明,太湖白旄堆场以及孔湾堆场淤泥内重金属及多环芳烃含量较小,潜在生态风险较低;巢湖南庄堆场淤泥内各类有害物质含量较大,种类较多,对于周围环境具有较高的潜在生态威胁.多氯联苯则在各个疏浚堆场淤泥中具有很高的积累量,潜在生态风险较高,应引起管理者的重视.     

太湖不同营养水平湖区沉积物磷形态与生物可利用磷的分布及相互关系

采用EDTA螯合剂法和不同的化学提取法,研究了太湖3个不同营养水平湖区中8个位点表层沉积物总磷、各组分磷及生物可利用磷的含量分布,探讨了太湖不同营养水平湖区表层沉积物的释磷潜力和生物可利用磷的来源．结果表明,太湖不同营养水平湖区表层沉积物总磷、无机磷和生物可利用磷含量分布差异较大,且与各湖的营养水平相一致．有机磷含量与有机质和含水率显著相关;沉积物中Fe-P和Ca-P对生物可利用磷的贡献较大,这部分磷具有较大的潜在释放风险．     

The rare earth element compositions of the Changjiang (Yangtze) and Huanghe (Yellow) river sediments

Thirty-four samples from the Changjiang and Huanghe were analyzed to characterize their rare earth element (REE) compositions. Although REE concentrations in the Changjiang sediments are higher than those of the Huanghe sediments, the former are less variable. Bulk samples and acid-leachable fractions have convex REE patterns and middle REE enrichments relative to upper continental crust, whereas flat patterns are present in the residual fractions. Source rock composition is the primary control on REE composition, and weathering processes play a minor role. Grain size exerts some influence on REE composition, as demonstrated by the higher REE contents of clay minerals in sediments from both rivers. Heavy minerals contribute about 10-20% of the total REE in the sediments. Apatite is rare in the river sediments, and contributes less than 2% of the REE content, but other heavy minerals such as sphene, allanite and zircon are important reservoirs of residual REE fractions. The Fe-Mn oxides phase accounts for about 14% of bulk REE content in the Changjiang sediments, which could be one of the more important factors controlling REE fractionation in the leachable fraction.