海南东寨港红树林沉积物中重金属的分布及其生物有效性

对东寨港红树林湿地沉积物中7种典型重金属元素(Cr、Ni、Cu、Zn、As、Cd 和Pb)的有效态含量和全量进行测定,并讨论了红树林湿地沉积物中重金属元素的分布特征及其生物有效性.结果表明： 7种重金属在东寨港红树林湿地的含量大于亚龙湾和三亚湾的红树林湿地,但与中国南方和世界各地的典型红树林湿地相比仍处于中等偏低水平.东寨港红树林湿地光滩、林缘、林内表层沉积物的重金属含量存在差异;在柱状沉积物中重金属伴随沉积明显,表现出较强的同源性.经EDTA萃取出的有效态金属在表层沉积物中含量依次为Cu＞Cr＞Zn＞Ni＞As＞Pb＞Cd;垂直梯度重金属有效态含量占总量的比例的最大值(除Ni外)均出现在表层或中上层;目标重金属元素有效态和总量在空间分布上具有明显正相关性,元素总量指标能较好地评估该元素的生物有效性     

生物扰动对沉积物中污染物环境行为的影响研究进展

生物扰动由于显著改变沉积物结构和性质,进而影响沉积物中污染物的环境行为。综述生物扰动对沉积物中氮、磷、重金属和疏水性有机污染物环境行为的影响。生物扰动促进这些污染物从沉积物向水体释放。生物扰动还对不同的污染物产生其它不同的影响。对于氮,生物扰动还影响其硝化与反硝化作用;对于磷,生物扰动不仅改变其化学形态,还提高有机磷降解。对于重金属,生物扰动还能改变其在沉积物中的分布及化学形态。对于疏水性有机污染物,生物扰动主要增强生物富集和代谢,以及提高生物降解。     

光裸方格星虫生物扰动对沉积物氮磷物质释放的影响

通过测定养殖箱内(24 cm×17 cm×16 cm))的沉积物管道数量和水体氮磷指标, 研究方格星虫生物扰动对沉积物氮磷物质释放和表层物质迁移的影响。养殖箱底部铺设粗沙(3200 g, 有机质含量27.6 mg·g–1), 上层为细沙(2200 g, 有机质含量11.0 mg·g–1), 星虫密度分别为0条·箱–1(T0))、1条·箱–1(T1))、2条·箱–1(T2))和4条·箱–1(T4)), 各组均设4个重复, 实验时间为11 d。数据显示: 1)方格星虫组沉积物侧面和底部的管道数量增加, 并且表层细沙向下迁移, 方格星虫密度越大, 管道数量越多。实验期间水体悬浮颗粒物无明显变化(P>0.05)), 且处理组之间亦无显著差异(P>0.05)), 表明方格星虫扰动对表层沉积物的再悬浮作用无明显影响。2)实验前3天水体中的亚硝态氮、硝态氮、氨氮和总无机氮均无明显增加, 而在第4天亚硝态氮、硝态氮、总无机氮表现增加趋势, 并且星虫密度越大含量越高(P<0.05))。实验期间, 各组活性磷含量呈现下降趋势, 并且T0组平均含量低于其他三组。结果表明, 底层有机质含量高于表层时, 方格星虫生物扰动可以促进底层含氮物质的释放, 并且密度越大促氮释放作用越明显; 方格星虫对沉积物含磷物质的释放影响较小, 可能与其含量较低和转化过程有关。     

重金属污染对珠江口红树林表层沉积物碳含量的影响

湿地沉积物是红树林生态系统中重要的组成部分,其总有机碳储量的变化对红树林生态系统的固碳能力有着重要影响。现有对红树林湿地重金属的研究多集中于污染评价,鲜有涉及重金属含量对沉积物总有机碳（TOC）含量影响的研究。于2018-2019年期间4次前往珠江口典型红树林湿地,采集了0-30 cm表层土壤沉积物的样品,并测定其重金属含量和TOC含量,以探讨重金属含量变化对TOC的影响。结果表明,与广东地区的背景值相比,研究区沉积物重金属含量超标较为严重,重金属来源应是人类活动;沉积物的重金属含量能够显著影响TOC含量（P<0.01,R²=0.39）,间接对红树林湿地的固碳能力、甚至全球变暖产生一定影响;Cd、As、Zn含量高的沉积物环境有利于TOC的积累,Cu、Cr、Ni、Hg含量低的沉积物环境则不利于TOC的积累。沉积物的重金属对TOC的影响的机制是非常复杂的,它们可以通过影响土壤结构、土壤化学组分、土壤内微生物、上部植被群落的生长以及凋落物归还等一系列过程,导致沉积物TOC和固碳能力的变化。     

茅尾海红树林表层沉积物重金属含量分布特征及评价

对2012 年11 月采集到的茅尾海红树林自然保护区沉积物的20 个样点进行了重金属含量及分布特征分析, 并利用地累积指数法和Hakanson 潜在生态危害指数法对该区域重金属污染进行评价。研究结果显示: 红树林表层沉积物重金属含量为: Zn>Cr>Cu>Pb>As>Ni>Cd>Hg, 各重金属含量分别为59.85±14.40 mg⋅kg–1(Zn)、30.02±5.79 mg⋅kg–1(Cr)、24.81±19.19 mg⋅kg–1(Cu)、18.31±3.85 mg⋅kg–1(Pb)、11.56±4.28 mg⋅kg–1(As)、9.24±3.77 mg⋅kg–1(Ni)、0.34±0.26 mg⋅kg–1(Cd)、99.85±37.25 μg⋅kg–1(Hg)。Hakanson 潜在生态风险评价表明茅尾海红树林表层沉积物中重金属的潜在生态危害程度为中等, 而且, 地累积指数法评价结果表明截止目前该红树林未受到Zn、Cr、Ni、Pb 金属元素的污染。     

红树林恢复对潮滩表层沉积物氮素的影响

研究了不同树种的红树林恢复对潮滩表层沉积物氮素的影响。结果表明,红树林恢复提高了潮滩表层沉积物中总氮(TN)含量。以光滩为对照,外来树种和乡土树种的恢复使表层沉积物中的可交换态无机态N(IEF-N)分别朝着相反的方向发展:外来树种——无瓣海桑(Sonneratia apetala)和海桑(S. caseolaris)提高了IEF-N的含量,而乡土树种——秋茄(Kandelia candel)和桐花树(Aegiceras corniculatum)使IEF-N的含量下降。当与近岸水体发生物质营养交换作用时,乡土树种和外来树种的恢复可能导致营养盐在潮滩沉积物\水界面间的迁移和交换过程中存在不同的潜在环境效应。     

福建漳江口红树林湿地沉积物中四种重金属的空间分布特征

对漳江口红树林湿地沉积物中4种重金属(Pb、Cd、Ni、Fe)含量空间分布的研究表明,漳江口红树林湿地沉积物中Pb、Fe含量较高,Cd、Ni含量相对较低;林内沉积物的Pb、Cd含量显著高于林外沉积物;在垂岸方向上,表层沉积物中除Ni外其它三种元素含量均表现出从林外到林内增加的趋势;在垂直梯度上,四种元素含量均随着沉积物深度增加而逐渐降低。     

淇澳岛潮间带沉积物及红树植物中重金属分布

采集珠海市淇澳岛大围湾的红树林区潮间带沉积物和植物组织样品若干,处理后用电感耦合等离子体发射光谱仪(ICP-OES )测定各样品中Cu 、Zn 、Cd 和Pb 的含量.分析发现,淇澳岛红树林潮滩的Cu 、Zn 和Cd 平均含量均超过第一类海洋沉积物质量标准,中潮带的重金属污染最严重.红树植物对Cu 、Zn 、Cd 和Pb 四种重金属的平均富集系数分别为0.10～0.81 ,0.07～0.58 ,0.19～1.19 ,0.02～0.14 ;平均迁移系数分别为0.44～1.66 ,0.5～0.82 ,0.49～0.73 和0.01～0.28 .富集能力与林龄正相关,但富集和迁移能力的种间差距均不明显.四种重金属中,无论在植物体内向地上的迁移能力还是落叶后从植物组织向外界环境的归还能力Zn 和Cu 均强于Cd 和Pb .结果显示目前淇澳岛的红树林在修复被重金属污染的河口水体及潮滩沉积物方面有较高的利用价值,红树林在此地区的扩种将有积极的意义.     

苦草生长对沉积物中磷迁移转化的影响

构建了不同营养盐负荷的沉积物环境"水-苦草-沉积物"生态系统,监测分析了沉积物中总磷(TP)、生物可获得磷及其环境因子的垂直分布及变化,以苦草为例,研究了沉水植物生长对沉积物中磷迁移转化的影响,结果表明:生长期的苦草通过改变沉积物环境因子或自身的生理活动,直接或间接地对沉积物中不同形态磷的迁移转化产生了影响,并随着深度的增加而出现不同的变化。具体表现在,低(L)、中(M)、高(H)营养负荷的沉积物总磷(TP),相对于初始值均有不同程度的下降,但苦草组下降的幅度大,分别比对照组多下降了11.63、18.50和46.25 mg/kg;在垂直方向上均表现出随深度的增加TP呈减少趋势,苦草对沉积物影响的深度随根系的活动范围变化而变化,根系增长最长(比试验初始增加了9.2 cm)的低营养负荷苦草组(LV),可影响到6 cm以下的沉积物;中营养负荷苦草组(MV)、高营养负荷苦草组(HV)根系增加不明显(分别为2.60和2.10 cm),影响深度主要在6 cm以内;检验发现,苦草组与对照组差异显著(P0.05)。交换态磷(Ex-P)、铝磷(Al-P)随深度增加而升高,苦草组小于对照组;铁磷(Fe-P),随深度的增加而降低,苦草组大于对照组,其中,在L、M、H中,苦草组的Ex-P分别比对照组下降了0.065、0.215和1.483 mg/kg,Al-P分别为1.198、2.040和2.390 mg/kg;LV中苦草的影响深度可达到10 cm的深,而MV、HV中主要集中在6 cm以内;苦草组中的Fe-P分别比对照组高8.135、16.689和8.598 mg/kg,在垂直方向上的变化幅度亦大于对照组。检验发现,L中苦草组Ex-P与对照组有极显著差异(P0.01),M、H苦草组与对照组无显著差异(P0.05);L、M、H中Al-P、FeP苦草组与对照组均无显著差异(P0.05)。     

福建漳江口红树林沉积物重金属汞(Hg)的分布特征

对福建漳江口红树林沉积物中重金属汞(Hg)含量的时空分布进行了研究。结果表明漳江口红树林湿地汞含量为0.0815 mg•kg–1—0.3431 mg•kg–1。在潮间带水平分布上, 从光滩到高潮位汞含量显著上升(P<0.05), 相对光滩, 红树林沉积物更易富集汞, 其中高潮位红树林底泥中汞含量最高。在垂直方向上, 大多数的汞富集在表层及亚表层, 随着深度的加深, 汞含量呈现下降趋势。汞在红树林湿地沉积物中的积累主要与有机碳(TOC), 含水率, 盐度相关。从计算的单一污染指数(Pi)来看, 漳江口地区汞污染等级为Ⅲ级以下, 大多数采样点属于自由污染或轻度污染。就该地区汞污染的时空变化趋势以及和其他红树林区汞污染状况的对比来看, 漳江口地区存在一定程度的汞污染威胁加剧的现象, 值得引起注意。     

Incidence of heavy metals in the mangrove flora and sediments in Kerala, India

The mangroves of Kerala on the south-west coast of India are fast disappearing due to land reclamation and other anthropogenic disturbances. There are very few ecosystem level studies made in these much threatened biotopes in Kerala. The present study involves the measurement of heavy metals in the mangrove flora and sediments of three mangrove habitats along the Kerala coast. Sampling was carried out for a period of one year at bi-monthly intervals, with concentrations of Fe, Mn, Cu,Zn,Pb and Co analysed using atomic absorption spectrophotometry. An appreciable variation was observed in metal concentrations indifferent mangrove species. Cu, Zn and Pb were found to be in higher concentrations in Avicennia officinalis whereas higher levels of Fe, Mn and Co were observed in the species Barringtonia racemosa. The analysis of heavy metals indicated a high level of metal pollutants such as Fe, Cu, Zn and Pb in the mangrove habitats of Quilon and Veli compared to the relatively uncontaminated areas of Kumarakom. This revised version was published online in August 2006 with corrections to the Cover Date.     

The effects of heavy metals on microbial biomass in sediments of Palestine Lake

Effects of metal contamination on microbial biomass in sediment samples from three areas in Palestine Lake (one area highly polluted with chromium, cadmium and zinc) were determined. Adenosine triphosphate (ATP) concentrations, determined by the luciferin-luciferase bioluminescent technique, and microbial colony numbers on pour plates were used as biomass indicators. Plate counts showed a significant (P < 0.01) site effect with the highly contaminated area having an order of magnitude lower microbial population than the control area. ATP concentrations also indicated lower microbial biomass in contaminated sediments. The metal concentrations of the most contaminated area averaged 17,840 µg Zn/g, 4380 µg Cr/g and 585 µg Cd/g based on dry weight of sediments. A suppression of organic decomposition was evident in the impacted area; high metal levels and resultant low microbial biomass may have been causative.     

Scandinavian limnochronology of sediments and heavy metals

Sediment and peat accumulation rates as well as heavy metal fluxes are examined in Scandinavian lakes, marine coasts and peatlands. Modern accumulation rates are determined using Pb-210 and other chronological tools. Mean deposition rates in the past 150 ± 20 yrs are 3–95, 40–190 and 1–5 mg·cm^–2·yr^–1 for lakes, marine coasts and peatlands respectively. The Pb-210 fluxes at the investigated sites are quite variable. The lowest values are found for peatlands 0.04–0.20 pCi·cm^–2·yr^–1 while coastal marine environments showed 0.35–0.70 pCi·cm^–2·yr^–1. A wide range of variation of Pb-210 fluxes is obtained for the studied lake sediments 0.01–0.51 pCi·cm^–2·yr^–1.The chronological records of Pb, Zn, Cu, Cd and Hg show that heavy metal fluxes are much higher in coastal marine areas. Inland lakes and ombrotrophic peat-bogs indicate that Pb is introduced exclusively through the atmosphere and decrease exponentially from South to North Scandinavia. However, the other heavy metals are transported to freshwater systems by different hydrologic and atmospheric processes. Zn and Fe exhibit some correlation with lake-drainage area.     

Interactive effects of porewater nutrient enrichment, bioturbation and sediment characteristics on benthic assemblages in sandy sediments

Effective management of eutrophic ecosystems requires an understanding of how nutrient input affects the structure and function of benthic communities. The effects of nutrients in soft sediment habitats can be influenced by a variety of factors including sediment characteristics, hydrodynamic exposure, and the presence of bioturbating macroinvertebrates. We used a large scale exclusion experiment (400 m² areas, n = 6) to test if bioturbating lugworms, Arenicola marina mediate the effects of nutrient enrichment. We incorporated small plots (30 × 30 cm) dosed with household garden fertilizer within the lugworm exclusion and corresponding control areas and predicted that the effects of nutrient enrichment would be greater in the absence of lugworms. We found that the increases in nutrient concentrations were higher in the absence of lugworms, but only in the less permeable sediment in the low intertidal zone compared to the more permeable sediment in the high intertidal. Contrary to expectations, the accumulation of nutrients in the plots did not affect the organic matter and chlorophyll levels in the sediment. Interestingly, there were overall negative effects of nutrient additions on some of the most abundant molluscs, Hydrobia ulvae, Retusa obtusa and juvenile Cerastoderma edule. Possible explanations for these adverse effects such as the changes in the sediment chemistry or the physical presence of the fertilizer in the sediment caused by the nutrient additions are discussed. We conclude that the effects of nutrient enrichment in soft sediment habitats on benthic assemblages are determined by the interplay between the presence of bioturbating macroinvertebrates, tidal height and sediment characteristics.     

秋茄(Kandelia candel (L))根系分泌低分子量有机酸及其对重金属生物有效性的影响

应用电感耦合等离子体质谱(ICP-Ms)与高效液相色谱(HPLC)分别对福建漳江口红树林湿地不同土壤结构(砂质与泥质)根际与非根际沉积物中重金属(Cu,Pb,Cd,Zn)含量,以及生长于砂质与泥质滩涂上的红树植物秋茄(Kandelia candel(L)Druce))幼苗根系分泌物中的低分子量有机酸进行测定。在室内模拟秋茄根系分泌的低分子量有机酸,作为重金属提取剂提取沉积物中可溶解态与碳酸盐结合态重金属,并与欧盟标准物质局(BCR)连续提取法相比较,探讨红树根系分泌的低分子量有机酸对红树林沉积物重金属生物有效性的影响。研究结果表明:漳江口红树林泥质沉积物中重金属含量大于砂质沉积物,根际沉积物大于非根际沉积物。两样地沉积物中重金属的赋存形态主要以铁锰氧化物结合态为主,根际沉积物中可交换态与碳酸盐结合态重金属含量均大于非根际沉积物。秋茄根系分泌低分子量有机酸为甲酸,丁酸,苹果酸,柠檬酸,乳酸。不同土壤结构对秋茄根系分泌的苹果酸,柠檬酸,乳酸有显著影响(P<0.05)。以低分子量有机酸作为提取剂对沉积物中可溶解态与碳酸盐结合态重金属的提取率表现为:柠檬酸>混合酸>苹果酸>乳酸>乙酸,低分子量有机酸对红树林沉积物重金属的生物有效性有促进作用。     

Accumulative phases for heavy metals in limnic sediments

Data from mechanical concentrates of recent sediments indicate that clay minerals, clay-rich aggregates and heavy minerals are the major carriers of heavy metals in detrital sediment fractions. Hydrous Fe/Mn oxides and carbonates and sulfides, in their specific environments, are the predominant accumulative phases for heavy metals in autochthonous fractions. Sequential chemical extraction techniques permit the estimation of characteristic heavy metal bonding forms: exchangeable metal cations, easily reducible, moderately reducible, organic and residual metal fractions, whereby both diagenetic processes and the potential availability of toxic compounds can be studied. The data from lakes affected by acid precipitation indicate that zinc, cobalt and nickel are mainly released from the easily reducible sediment fractions and cadmium from organic phases. In contrast at pH 4.4, neither lead nor copper seem to be remobilized to any significant extent. Immobilization by carbonate precipitation seems to provide an effective mechanism for the reduction of dissolved inputs 9f metals such as zinc and cadmium in pH-buffered, hard water systems.     

The determination of heavy metals in water,suspended materials and sediments from Langat River,Malaysia

The distributions of heavy metals in the Langat River were studied for a period of six months between September 1984 and February 1985. Heavy metals such as arsenic, cadmium, cerium, cobalt, chromium, caesium, lanthanum, rubidium, antimony, scandium, thorium and zinc were determined in water, suspended materials and sediment samples from the Langat River by neutron activation and atomic absorption spectrometry. The concentrations of arsenic, cadmium, cerium, cobalt, scandium, antimony, and zinc were generally highest in the suspended materials, whereas the concentrations of chromium, rubidium and thorium were always highest in the sediments: Arsenic concentrations in the river were slightly higher than the natural concentration, while other elements were generally at their natural concentration levels. The use of arsenical herbicides in plantations along the river could be a source of arsenic pollution.     

Nutrients and heavy metal contamination of plants and sediments in Futian mangrove forest

An ecological survey was carried out to determine the levels of nutrients and heavy metals in the sediments and leaf tissues of two dominant mangrove plant species, Kandelia candel and Aegiceras corniculatum, in Futian mangrove forest, Shenzhen, the People's Republic of China. The spatial and seasonal variations of these elements were also investigated. The results show that there was no major difference between two sampling sites 150 m apart. In both sites, the sediment concentrations of total and NH₄ ⁺-N, total and extractable P, total and extractable K, total organic carbon were consistently higher in the landward locations and decreased gradually towards the sea. The sediment sample collected at the seaward edge of the mangrove plant community had the lowest levels of nutrient and organic matter. The vertical variations (from the land to the sea) of sediment heavy metals were less obvious and no particular trend could be identified. Extremely high contents of Cu, Cd, Pb, Cr and Zn were found at certain locations, suggesting the occurrence of some local contamination. The mean total metal concentrations in sediments decreased in the order Mn > Zn > Cu > Cr = Pb > Cd for the sample locations. Most of the heavy metals were not in a bioavailable form as the concentrations of extractable metals were relatively low (< 1% of total metals). Pb, Cr and Cd were not detected in leaf samples. Leaf C, N, P and K contents were similar between the two species and no significant difference was found among locations, although A. corniculatum seemed to have lower Mn concentrations than K. candel. With reference to temporal variations, no significant difference in sediment concentrations of some nutrients and metals was found between the spring and autumn seasons.