鄱阳湖沉积物可转化态氮分布特征及其对江湖关系变化的响应

选取不同高程鄱阳湖表层沉积物,通过研究其总可转化态氮与各形态可转化态氮含量及分布特征,试图揭示江湖关系变化导致的水位变化对鄱阳湖沉积物氮潜在释放风险的影响.结果表明:1鄱阳湖表层沉积物总氮(TN)含量在389~3 865 mg·kg-1之间,空间分布上呈"五河"入湖尾闾区湖心区北部湖区的趋势;总可交换态氮含量在319.36~904.56 mg·kg-1之间,占TN的52%,空间分布趋势与TN相同;2鄱阳湖3个湖区沉积物各形态可转化态氮的含量大小排列次序均为:SOEF-N(强氧化剂可提取态氮)≈SAEF-N(强碱可提取态氮)WAEF-N(弱酸可提取态氮)IEF-N(离子交换态氮);3江湖关系变化致使鄱阳湖枯水期沉积物出露时间提前并且延长,进而导致不同高程沉积物可转化态氮(TTN)含量差异明显,3个湖区沉积物可转化态氮含量均表现为枯水期丰水期,高程越高,由于其沉积物出露时间较长,可转化态氮含量较高,即可转化态氮含量12 m~13 m高程沉积物11 m~12 m高程沉积物10m~11 m高程沉积物;4随着高程的增加,沉积物各形态可转化态氮含量都呈现增加的趋势,其中SAEF-N和WAEFN含量及其占总可转化态氮的比例变化幅度较小,而IEF-N和SOEF-N含量以及其占总可转化态氮比例的增幅均较为显著.如果江湖关系进一步变化,枯水期水位继续下降,势必会引起沉积物出露面积增大及出露时间延长,从而导致沉积物TN、可转化态氮以及释放风险较高的氮形态IEF-N和SOEF-N含量的增大,来年丰水期可能会增加鄱阳湖沉积物氮释放风险.     

外秦淮河底泥污染及疏浚效果

外秦淮河是南京市一条重要的城市景观行洪河道,多年来受工业及生活污水影响,内源污染严重.为充分了解外秦淮河底泥污染特征,为疏浚提供决策依据,对河道上、中和下游典型断面底泥界面微环境以及营养物含量进行调查,采用有机指数法和污染指数法对底泥污染状况进行评估,同时根据污染物垂向分布特征模拟清淤对底泥内源释放削减的影响.结果表明,上中下游底泥界面以上DO均值分别为4.62、 3.25和3.41mg·L^-1,且分别在4.4、 3.5和5.5 mm处消耗殆尽,是典型的城市河道污染特征体现.调查河段表层底泥的ω(TN)、ω(TP)和ω(OM)均值分别为1 734mg·kg^-1、 1 337 mg·kg^-1和4.82%,底泥TN和OM的有机污染指数均值为0.48,处于尚清洁水平,TP的单项污染指数均值为3.18,处于重度污染水平.模拟30 cm清淤深度结果表明,底泥SRP和Fe²⁺的释放速率较清淤前分别削减42%～82%和88%～96%,而NH⁺₄-N的释放速率却较清淤前有...     

淮河流域安徽段水体和沉积物微塑料赋存特征及风险评估

为探究淮河流域安徽段水体与沉积物微塑料赋存特征及生态风险级别,采用野外采样、体式显微镜、扫描电镜、傅里叶红外光谱（FTIR）以及风险指数（H）和污染负荷指数（PLI）模型等方法,分析了流域水体和沉积物微塑料现状,并进行了微塑料生态风险评估.结果表明,流域各点位微塑料检测率为100%,表层水与沉积物微塑料平均丰度分别为（39800±3367） n ·m^-3和（5078±447） n ·kg^-1,下游微塑料平均丰度要高于上游和中游.水体和沉积物微塑料粒径以20~150 μm为主,占比分别为82.96%和80.77%.微塑料形状主要为纤维（水体76.05%、沉积物84.53%）、薄膜（水体21.83%、沉积物15.43%）和碎片（水体2.12%、沉积物0.04%）.水体和沉积物中微塑料主要以透明颜色为主,占比分别为63.31%和83.69%.水体和沉积物主要以聚乙烯（水体65.74%、沉积物80.62%）和聚丙烯（水体18.43%、沉积物9.71%）为主,微塑料主要来源于农业薄膜、废弃渔具渔网和港口人为废弃的塑料袋.微塑料风险指数（H）模型评估表明部分点位风险指数较高,淮河流域安徽段微塑料风险等级为Ⅱ级,污染负荷指数（PLI）模型评估表明流域地表水体和沉积物总体上生态风险较低.     

An assessment of heavy-metal contamination in surface sediments of the Suez Gulf using geoaccumulation indexes and statistical analysis

An assessment of marine pollution due to metals was made in the Suez Gulf based on surface costal sediment collected from 18 locations along the Gulf. The samples were dried and acid-digested, and the metal contents (Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb, and Zn) were determined using a flame atomic absorption spectrophotometer (air-acetylene) with deuterium background correction. An evaluation of the heavy-metal pollution status of the Gulf was carried out using enrichment factors (EF) and geo-accumulation Indexes (I_geo). Also, heavy-metal concentrations in Suez Gulf sediments were evaluated using the Effect Range-Low (ERL) and the Effect Range-Median (ERM). The results of a Spearman correlation and factor and cluster analysis of the heavy metals analysed in the collected sediment were discussed. The main source of contamination is offshore oil field and industrial wastes, which arise due to the ineffective and inefficient operation equipments, illegal discharge and lack of supervision, and prosecution of offenders.     

SPATIAL AND TEMPORAL VARIABILITY IN SUSPENDED SEDIMENT YIELDS OF NORTH ISLAND BASINS,NEW ZEALAND1

ABSTRACT: Specific annual suspended sediment yields and their standard deviations are presented for 47 basins of North Island, New Zealand. Most of the variance in yields is explained by catchment mean rainfall. Rivers with similar flow range have similar suspended sediment concentration ratings, independent of differing watershed lithology and regolith, except for six basins having an abundance of soft fine sediments. Prediction equations for yield and its standard deviation are derived for four essentially arbitrary regions. AU feature rainfall as the independent variable. Differences between regions may owe to variations in intensity, frequency, and duration patterns of storms and, in one area, to bed material size as well. The temporal distribution of annual yields from a basin m be modeled by a two-parameter lognormal function: the prediction equations above may be used to evaluate this function at a site for which suspended sediment data are unavailable.     

Heavy metals associated with reduced sulfur in sediments from different deposition environments in the Pearl River estuary, China

Distribution of acid volatile sulfur (AVS) and the simultaneously extracted metals (SEM: Cu, Pb, Zn, Cd, Ni) in sediment profiles has been studied at five sites in Pearl River estuary, China. Of the five sampling locations, Nos.1 and 2 are in the middle shoal, Nos.3 and 4 in the west shoal and No. 5 locates to the south of the estuary. The AVS content in the sediments of the middle shoal varies in a small range (0.25–4.06 μmol g⁻¹), while that of west shoal increases with depth from 0 to ultimately 26.09 μmol g⁻¹. The SEM concentration in the sediment profiles at location Nos. 1, 2 and 5 is generally in the range of 0.95±0.2 μmol g⁻¹ with a slight upward increase, while that in the sediment of west shallows are much higher (1.43–2.42 μmol g⁻¹) with a significant upward increase, especially in the upper layer of ca. 15 cm. The observed upward increase of SEM content at all the sites implies that heavy metal contamination of sediment in the Pearl River estuary is increasing. Calculations of the excess heavy metal content which is defined by SEM-AVS molar difference suggests that the upper sediment in the Pearl River estuary, especially on the west shallows, could be a source of heavy metal contaminants and may cause toxicity to the benthos. The site-specific distribution patterns in the AVS and SEM profiles were interpreted according to the hydrogeochemistry of deposition environments.     

官厅水库底泥对染料的吸附特征研究

采用静态吸附法研究了北京官厅水库底泥对亚甲基蓝、孔雀石绿和刚果红3种染料化合物的吸附行为,探讨了pH值、离子强度、温度等因素对吸附的影响,测定了染料的吸附等温线.结果表明,3种染料的吸附等温线都很好地符合Freundlich方程,底泥对孔雀石绿的吸附量最大.吸附染料过程是在分形表面上发生的反应.不同染料吸附时计算出的分形维数不同,底泥的表面分形维数均处于2～3之间.pH值是影响吸附的主要因素,刚果红和亚甲基蓝受离子强度影响较大.吸附动力学研究表明,吸附分为快速吸附和慢速吸附两个阶段.     

纳米Al_2O_3和Cd联合暴露对铜锈环棱螺体内Cd的生物积累和抗氧化酶活性的影响

金属氧化物纳米颗粒的广泛应用导致它们大量地释放到水环境中,其独特的理化性质有可能改变水环境中其他共存污染物(如重金属)的生态毒性。为评价沉积物中纳米氧化铝(Al2O3-NPs)对重金属Cd生态毒性的影响,采用底栖生物慢性暴露研究了Al2O3-NPs存在条件下Cd在底栖动物铜锈环棱螺体内生物积累的变化和Cd对肝胰脏抗氧化防御系统关键成分超氧化物歧化酶(SOD)与脂质过氧化指标丙二醛(MDA)以及Ⅱ相反应的关键酶谷胱甘肽-S-转移酶(GST)的影响。结果表明,低Cd浓度(5μg·g-1)时,Al2O3-NPs对Cd生物积累没有影响;中、高Cd浓度(25、100μg·g-1)时,Al2O3-NPs显著促进Cd的生物积累,Al2O3-NPs对Cd的生物转运具有明显的携带效应。低Cd浓度时,无Al2O3-NPs处理组和Al2O3-NPs处理组的SOD活性与对照组相比均没有显著差异;中Cd浓度时,SOD活性显著升高,而高Cd浓度时,SOD活性显著下降,而且Al2O3-NPs处理组的SOD活性显著低于无Al2O3-NPs处理组,Al2O3-NPs的存在加重了Cd对肝胰脏细胞的氧化胁迫或损伤。高Cd浓度时,无Al2O3-NPs处理组和Al2O3-NPs处理组的MDA水平均显著升高,但Al2O3-NPs处理组的MDA水平显著低于无Al2O3-NPs处理组,进一步证明Al2O3-NPs对Cd氧化损伤的增强作用。中、高Cd浓度时,无Al2O3-NPs处理组和Al2O3-NPs处理组的GST活性均显著下降,但Al2O3-NPs处理组的GST活性均显著低于无Al2O3-NPs处理组,同样说明了Al2O3-NPs对Cd毒性的增强作用。本研究提供了在沉积物-底栖动物体系中Al2O3-NPs促进重金属生物积累的证据,而且Cd毒性的变化与肝胰脏中Cd的生物积累水平的变化基本一致,在中、高Cd浓度下,由于Al2O3-NPs的存在显著促进了Cd的生物积累,因而增强了Cd对铜锈环棱螺的生态毒性。     

多泥沙河流水质模型研究

针对黄河泥沙含量大、泥沙对河流CODMn浓度影响大的突出特点,运用模拟实验方法,探讨了泥沙对CODMn浓度的影响,揭示了浑水、清水中CODMn浓度与含沙量间的关系.研究表明,黄河浑水中CODMn浓度随含沙量增大呈显著上升趋势,而去除泥沙后清水CODMn浓度测定值随其原含沙量增大呈微上升趋势.依据质量平衡原理,建立了充分考虑泥沙影响的CODMn衰减经验模型.清水中CODMn浓度的变化采用完全混合反应器概念来模拟,浑水中CODMn浓度通过清水中CODMn浓度与泥沙中CODMn浓度之和来量化.模型基本方程的求解采用稳态解析解.模型中的参数通过利用实际监测数据及室内实验结果与优化结合的方法确定.同时,利用实际监测数据对参数和模型进行检验.结果表明,模型结构合理,参数取值可靠,模型精度较好.模型既能揭示汇流区间人为污染对河段水质的影响,又可以反映作为面污染源的黄河泥沙对污染的影响,可作为水质预测的实用工具及规划管理的依据.     

Polycyclic Aromatic Hydrocarbon (PAH) Contamination of Surface Sediments from Port Dickson,Malaysia: Distribution,Sources and Ecological Risk Assessment

Distribution and sources of 16 parent polycyclic aromatic hydrocarbons (PAHs) were investigated in surface sediments from Port Dickson, Malaysia. Total PAHs varied from 481.3 to 976.6 with a mean value of 679.3 ng g^?1 dry weight, which can be classified as moderate level of pollution. The toxic assessment suggested that the PAHs in sediments will not cause immediately adverse biological effects. Both petrogenic and pyrogenic PAHs were recorded in the study area with dominance of pyrogenic. The authors believe that effective monitoring and implementation of environmental regulations have resulted in a tremendous improvement of sediment quality in the Malaysian aquatic ecosystem.