洱海沉积物中溶解性有机氮季节性变化

选取洱海10个表层沉积物样品,研究不同季节DON（溶解性有机氮）和易分解组分DFAA（游离氨基酸）的含量变化. 结果表明:①洱海沉积物中w(DON)在10.41~59.58 mg/kg之间,平均值为27.43 mg/kg,约占w(TDN)(溶解性总氮质量分数)的40%,w(TN)的6%,其季节性变化呈春季>冬季>夏季>秋季的趋势,各季节洱海不同湖区均呈南部>北部>中部的特点;②洱海沉积物中w(DFAA)在4.11~9.89 mg/kg之间,平均值为5.96 mg/kg,约占w(DON)的22%,占w(TDN)的9%,季节性变化呈秋季相对较高、冬春次之、夏季相对较少的趋势,区域性变化呈南北高、中间低的特点,污染较严重的区域沉积物中w(DFAA)较高;③作为沉积物活性氮重要成分,w(DON)和w(DFAA)的季节性变化明显,对湖泊氮代谢有重要影响,在水生植物旺盛区域尤为明显. 在洱海富营养化治理中,除了TN,更应关注DON在湖泊氮循环及其富营养化中的作用.      

重金属元素在贵州红枫湖水体中的分布特征

以贵州红枫湖为研究对象,分析了该湖13个采样点的上覆水、表层沉积物间隙水和表层沉积物中的Cd、Pb、Cu、Zn、Fe、Mn 6种重金属的浓度.其中,上覆水和间隙水中的金属浓度呈现相同的分布趋势:Fe>Mn>Zn>Pb>Cu>Cd;而沉积物中的金属浓度略有不同,为Fe>Mn>Zn>Cu>Pb>Cd.同种重金属在三者间的分布顺序为:沉积物>间隙水>上覆水,表明该湖中的重金属有从沉积物向上覆水扩散的可能.相关性分析表明,上覆水、表层沉积物间隙水和沉积物中的金属浓度之间没有明显的相关性;通过主成分分析,对该湖水体重金属的来源及迁移趋势进行评估,其中沉积物中重金属提取出一个主成分(贡献率为67.7%),而间隙水和上覆水的分析中分别提取出2个主成分,其中间隙水贡献率为73.6%和16.73%,上覆水为44.2%和25.1%.红枫湖水体重金属元素含量相对国内湖泊偏高,其中北湖水体各金属元素含量普遍高于南湖水体.     

Spatial variation of phosphorus fractionation in the coral reef sediments of Lakshadweep Archipelago,Indian Ocean

Surface sediments were collected from the shore and lagoons of Kavaratti, Kadamat and Agatti islands of Lakshadweep Archipelago during May 2015 and analysed for the spatial distribution of the micronutrient element, phosphorus. Phosphorus was separated by sequential extraction procedure into five fractions – exchangeable (Ex-P), iron bound, (Fe-P), calcium bound (Ca-P), organic and residual fractions (OP) and total phosphorus (TP). The average relative contribution of each P species to TP was: OP?>?Ca –P?>?Ex – P?>?Fe – P. The high concentration of organic and residual phosphorus (87–96%) compared to inorganic phosphorus is particularly evident at stations characterised by higher total phosphorus concentrations. Among the three forms of IP in the sediments, Ca-P was dominant at all stations. The OC/OP ratio ranged from 3 to 163 in the sediments, suggesting that the organic matter in sediments had been subjected to degradation. Hence, the major contribution towards organic and residual phosphorus form is from the residual fraction comprising biologically resistant or non-available phosphorus form composed of refractory materials. The concentration of phosphorus reported in the present study is higher than that of the earlier studies in Lakshadweep, indicating a terrestrial and anthropogenic in?uence on the sediment.     

山美水库表层沉积物黑碳分布特征及其对磷形态的影响

对亚热带水库福建山美水库表层沉积物黑碳的时空分布特征及其对不同形态磷的影响进行了研究.结果表明,山美水库表层沉积物黑碳(BC)含量为2.44~5.28g/kg,与国外研究水库水平相当,显著高于国内外海岸带沉积物黑碳水平.黑碳整体分布特征为:丰水期>枯水期, 入库区>库尾>近坝区>库中.沉积物中黑碳与总有机碳呈现显著的正相关性,与沉积物粒径分布无明显相关关系.黑碳与有机碳比值平均为24.95%,表明黑碳来源复杂,是陆源生物质燃烧和化石燃料燃烧的共同结果.黑碳与有机磷和铁铝结合态磷这两种易释放磷之间显著相关,其对有机磷和铁铝结合态磷具有一定的吸附固定作用,这种吸附作用可能对沉积物内源磷释放具有一定的抑制效应.     

九龙江河口表层沉积物中重金属污染评价及来源

采用电感耦合等离子体质谱(ICP-MS)法测定了九龙江河口表层沉积物中24种重金属的质量分数,并采用地累积指数法和潜在生态风险指数法对该水域表层沉积物重金属的污染程度和潜在生态风险进行评价和分析. 结果表明,沉积物中重金属质量分数为w(Fe)>w(Ti)>w(Mn)>w(Ba)>w(Zn)>w(Sc)>w(Co)>w(Rb)>w(Y)>w(Ni)>w(Cr)>w(Pb)>w(Cu)>w(Th)>w(Sr)>w(V)>w(Li)>w(U)>w(Cs)>w(Bi)>w(Cd)>w(Sb)>w(Mo)>w(Hg),其中w(Cd)、w(Sc)、w(Bi)、w(Co)、w(Ni)、w(Zn)、w(Hg)和w(Cu)远高于背景值,说明九龙江河口表层沉积物中上述元素已存在一定程度的富集. 九龙江河口表层沉积物中Cd的I_geo(地累积指数)最高,属于偏重度污染;重金属的潜在生态危害顺序为Cd>Hg>Co>Ni>Cu>Zn>Pb>Cr>Mn>V,其中Cd的潜在生态危害属极强水平,Hg属较强水平. 多元统计分析(因子分析和聚类分析)结果表明,该河口沉积物中重金属污染来源主要有农业生产活动与自然源的复合污染、燃煤污染和采矿污染,其贡献率分别为48.81%、21.51%和13.72%.      

腐殖酸作用下沉积物中纳米氧化铜对铜锈环棱螺生态毒性的影响

为了探讨不同水平腐殖酸作用下沉积物中纳米氧化铜(CuO-NPs)对底栖生物生态毒理学效应的影响,以铜锈环棱螺(Bellamya aeruginosa)为受试生物,通过腐殖酸和CuO-NPs加标沉积物的慢性(28 d)生物测试,研究了肝胰脏中Cu的生物积累、Na+K+-ATP酶(ATPase)、超氧化物歧化酶(SOD)以及过氧化氢酶(CAT)活性的变化规律.结果表明,在低浓度CuO-NPs处理组(60 μg·g1),沉积物中腐殖酸水平对Cu的生物积累以及ATPase、SOD和CAT活性均没有显著影响.在中、高浓度CuO-NPs处理组(≥180 μg·g-1),Cu的生物积累均随腐殖酸水平的增加而显著升高;肝胰脏ATPase活性随腐殖酸水平的增加而显著下降;当腐殖酸水平为0.05 g·g-1时,SOD活性显著高于未添加腐殖酸组,表现为显著诱导,当腐殖酸水平≥0.1g·g-1时,SOD活性开始下降,并具有浓度依赖性;随腐殖酸水平的增加,肝胰脏CAT活性总体上表现为浓度依赖性显著下降.由于沉积物中腐殖酸的存在,显著增加CuO-NPs在沉积物中的分散稳定性,更容易被铜锈环棱螺摄取,从而通过增加CuO-NPs的生物积累而增强对铜锈环棱螺的生态毒性.     

黄浦江表层沉积物中重金属污染的潜在生态风险评价

采用潜在生态风险指数法对黄浦江表层沉积物中重金属污染的潜在生态风险进行了评价。评价结果表明,黄浦江表层沉积物中重金属的潜在生态风险水平较低,其中杨浦大桥和南市水厂断面达到中等生态风险,其它断面均为轻微生态风险;重金属的潜在生态风险依次为Cd>Hg>Cu>As>Pb>Cr>Zn,除Cd达到中等生态风险外,其余元素均为轻微生态风险。沉积物中重金属的污染水平从上游到下游呈上升趋势,工业排放是水环境中重金属的主要来源,苏州河对黄浦江下游重金属存在一定的输入贡献。相关性分析表明,黄浦江表层沉积物中大多数重金属元素呈现相近的来源特征,有机质是影响沉积物中重金属分布的重要因素。     

洱海表层沉积物溶解性有机氮生物有效性

选取9个洱海表层沉积物样品,提取了DON(溶解性有机氮)进行生物矿化培养,测定了培养过程中各形态氮含量,并运用三维荧光技术研究了DON结构变化. 结果表明:①洱海沉积物中w(DON)范围为43.52~214.71mg/kg,平均值为115.19mg/kg,DON主要由类蛋白和类腐殖质类物质构成,并且以类蛋白为主;②洱海沉积物中DON生物有效性为1.21%~72.77%,平均值为33.23%,生物可利用量平均值为50.22mg/kg;DON生物有效性空间差异明显,北部和南部较高,而中部较低;③洱海生物自身产生及形成的DON主要由类酪氨酸组成,其中有小部分类腐殖质可被生物利用,这是由于类色氨酸和类酪氨酸共存可提高DON类腐殖质生物有效性. 此外,w(DON)占w(TDN)(TDN为可溶性总氮)的比例是影响DON生物有效性的重要因素,w(DON)/w(TDN)越高,类腐殖质及类酪氨酸含量越低,沉积物中DON生物有效性越高. 可见,DON对湖泊富营养化有重要影响,控制洱海富营养化,不仅需要关注沉积物中的w(TN),也应关注w(DON)及DON组成特征.      

Correlation between levels of some heavy metals in plants and sediments from a segment of Calabar River and associated creeks in Cross River state of Nigeria

Plants and sediments were collected at three sites along Calabar River (CR), Upper Town Creek (UCC) and Lower Town Creek (LCC). The CR is a major tributary of Cross River, Nigeria. The concentrations of 10 heavy metals were determined and results for Fe, Mn and Zn at almost all the sites showed that the levels of these metals exceeded the amounts present in non-polluted areas. Fe was found in the highest concentration at all three sites in both plants and sediments. Correlation analysis between levels of heavy metals in plants and sediments were also determined. The occurrence of higher concentrations of heavy metals in plants and coastal sediments at CR, UCC and LCC is an indication of anthropogenically induced pollution rather than contributions from natural sources.     

Metal distribution in sediments from the Adriatic Sea

Total metal concentrations (Cu, Ni, Pb, Zn, Fe, and Mn) and their distribution in different chemical forms (speciation) were determined in sediments from the Adriatic Sea in order to evaluate contamination and mobility of metals. The study was carried out on marine sediments collected in two areas of the Adriatic Sea differently influenced by Po river waters. Metal distribution in the study area depends prevalently on water circulation and on organic matter distribution. Among metal levels, significant correlations between copper and zinc and between lead and nickel were found, suggesting common and specific sources. As regards metal speciation, the distribution of different chemical forms changes with the metal. The prevailing zinc phases, for example mobile forms, and sulphide together are greater than 50% of total metal. Nickel is mainly present in sediments as sulphide, and the preferential association of copper with organic matter is evident. Lead and manganese are preferentially found as mobile forms (more of 30% for lead, 40% or more for manganese).