PT-GC-CVAFS法测定沉积物中甲基汞的影响因素及应用

研究了碱提取吹扫捕集气相色谱冷原子荧光光谱法测定沉积物中甲基汞的影响因素,包括载气流速、柱温、衍生化试剂、样品称取量、前处理时碱性提取液加入量和反应瓶中提取液加入量的影响,分析了提取液加入量对Tenax管的影响、提取液保存的影响因素、沉积物样品保存的影响因素以及样品中Hg²⁺的干扰影响。根据影响情况确定最佳测定条件,应用于广西龙江河流域上9个代表性监测断面的底泥样品中甲基汞的测定,采用污染指数法对该流域甲基汞的污染现状进行评价。结果表明,最佳载气流速范围为22～27 mL/min,最佳柱温为46℃。衍生化试剂选择四乙基硼化钠和四丙基硼化钠均能达到较好的回收率。样品称取量选择0.50 g时回收率好。前处理时碱性提取液的加入量对甲基汞的提取效率没有显著影响。为保证水相衍生反应体系最终pH在5左右,乙酸-乙酸钠缓冲溶液的加入量随提取液加入量的增加而增加。当缓冲溶液为300μL时,提取液小于150μL不会影响Tenax管性能。避光与否对提取液的保存和样品的保存影响都不大,提取液保存3 d后、样品保存15 d后,甲基汞回收率将低于80%。衍生化前定量体积提取液中Hg     

胶州湾沉积物中的磷及其环境指示意义

研究了胶州湾沉积物中磷形态的地球化学分布特征、控制因素及环境意义,将胶州湾沉积物中的磷分为可交换态磷、铝结合态磷、铁结合态磷、闭蓄态磷、自生钙磷、碎屑态磷和有机磷7种不同的形态,并结合210Pb测年法计算了不同年代各形态磷的埋藏通量,在此基础上,分析了胶州湾沉积物中磷所给出的环境信息.结果表明,无机磷是胶州湾沉积物中磷的主要形态,有机磷只占较小的比例,无机磷中钙磷占的比例相对较大,其中碎屑态磷是含量最高.磷的含量及埋藏通量的垂向分布受到pH、盐度、温度、生物扰动、沉积速率等环境因子的影响.相关分析及元素的OC/OP比值分析证明,近20a,陆源输入是胶州湾沉积物主要来源,并且沉积速率不断增大.由于近年来采取的较为得力的治污与排放措施,胶州湾的环境状况已有明显改观.研究还表明,Fe-P,Al-P和Oc-P的含量与海域污染程度有较密切的关系,可作为表征海洋沉积环境污染状况的指示因子之一.     

湟水河流域西宁段河流表层沉积物重金属空间分布及生态风险评估

采集湟水河流域西宁段16个表层沉积物样品,运用电感耦合等离子体质谱和测汞仪测定了沉积物中重金属含量,结合污染负荷指数法、潜在生态风险指数法、沉积物质量基准法查明了流域表层沉积物重金属(H g、Cr、Zn、Cu、Cd)污染现状、空间分布特征、潜在生态风险,使用聚类分析和Pearson相关分析方法分析了五种重金属可能来源....     

巢湖近代沉积物及其间隙水中营养物的分布特征

湖泊沉积物及其间隙水中的营养盐对于研究湖泊营养盐的生物地球化学和湖泊营养状态的历史变化具有重要的作用.系统研究了巢湖东、西湖区沉积物和间隙水中营养盐的剖面分布特征及其营养盐之间的相互关系.结果表明,巢湖近代沉积物中营养盐含量总体上随着深度的增加而降低,上层沉积物(1～15cm)中TOC(总有机碳)、TN(总氮)、TP(总磷)和Pi(无机磷)的含量都表现出明显的区域差异性,从西到东逐渐减小,含量的大小顺序为C1C3C16;东、西湖区下层沉积物(15～30cm)中TOC、TN和TP的含量差异不明显,分别在5mg.g-1、0.5mg.g-1和0.45mg.g-1左右变化;Po(总有机磷)在整个剖面上的分布则相反,总体上从西向东逐渐增大,含量大小顺序为C16C3C1.沉积物间隙水中的营养盐在空间上的分布规律与沉积物相似,西湖区两个点(C1、C3)沉积物间隙水中的营养物浓度总体上高于东湖区的C16点,大小顺序为C1C3C16,间隙水中的氮、磷酸盐、硅酸盐处于协同变化.间隙水中的氮与沉积物总氮含量密切相关;西湖区间隙水中的磷与沉积物磷含量密切相关,但在东湖区相关性不显著.表层沉积物间隙水中营养盐浓度都明显高于上覆水体,表明沉积物中的营养盐是水体营养盐的主要来源之一.     

Decadal and Episodic Changes in Morphology and Migration of the Confluence Bar of Two Alluvial Rivers in Louisiana,USA

Past research on fluvial dynamics at the confluence of two alluvial rivers has mainly focused on downstream flow structure and bed scoring, often using laboratory experiments and numerical modeling. Little is investigated about yearly and episodic dynamics of confluence mouth bars that can affect downstream morphology using field measurements. In this study, we analyzed the migration of a confluence mouth bar of two free meandering alluvial rivers, the Amite and Comite Rivers in coastal Louisiana, USA from 2002 to 2017. Remote sensing images were utilized to investigate the decade‐long morphologic changes. To assess episodic dynamics, we employed terrestrial laser scanning measurements to acquire high‐accuracy digital elevation models at the confluence before and after three floods in 2017. Our study found that the Amite‐Comite confluence mouth bar migrated downstream 55 m in the past 15 years, and its angle reduced by 55° from 100° to 45°. The fast migration was a result of sediment deposition and channel deformation around the confluence mainly during the years when the tributary‐to‐main channel discharge was lower (<0.25). The study further reveals that a single moderate flood could strongly affect the mouth bar, as shown by an increase of the projected surface area by 114% and an increase of volume of the confluence mouth bar by 68%.     

How are macroinvertebrates of slow flowing lotic systems directly affected by suspended and deposited sediments?

The effects of suspended and deposited sediments on the macroinvertebrates are well documented in upland streams but not in slower flowing lowland rivers. Using species found in lowland lotic environments, we experimentally evaluate mechanisms for sediments to affect macroinvertebrates, and in one experiment whether salinity alters the effect of suspended sediments. Suspended kaolin clay reduced feeding of Ischnura heterosticta (Odonata: Coenagrionidae) at high turbidity (1000-1500 NTU) but had no effects on feeding of Hemianax papuensis (Odonata: Aeshnidae) and Micronecta australiensis (Hemiptera: Corixidae). In freshwater (0.1 mS/cm), survival of Ischnura aurora was poor in clear water, but improved with suspended kaolin. Growth and feeding of I. aurora were unaffected by suspended sediments and salinity. Burial (1-5 mm) of eggs with kaolin or sand reduced hatching in Physa acuta (Gastropoda: Physidae), Gyraulus tasmanica (Gastropoda: Planorbidae) and Chironomus cloacalis (Diptera: Chironomidae). Settling sediments may pose greater risk to lowland lotic invertebrates than suspended sediments.     

北京西城区雨水管道沉积物中重金属污染风险评价

采用地累积指数法、次生相与原生相分布比值法以及Hakanson潜在生态风险指数法从不同角度对雨水管道沉积物中重金属的污染风险进行了评价。地累积指数法的评价结果表明,不同重金属的污染级别为ZnCuCdCrPbNi。而次生相与原生相分布比值法以及Hakanson潜在生态风险指数法的评价结果表明,不同重金属的潜在污染效应关系和潜在生态危害系数大致排序均为CdCuZnPbNiCr。     

三峡库区典型次级支流表层沉积物中PAHs的分布特征及来源分析

本文表征了三峡库区典型次级支流(梁滩河)表层沉积物中18种多环芳烃(PAHs)的浓度,并对其分布特征和污染来源进行了探讨。18种PAHs的总浓度(∑18 PAHs)范围为198.5～4349 ng/g-dw(干重),平均浓度为1441ng/g,中值为1160 ng/g。与其他地区沉积物污染情况相比,梁滩河沉积物中PAHs浓度处于中等偏低的污染程度,支流污染程显著高于干流,流经城镇的右支污染程度显著高于流经农村或人口较少的左支和主干流。大部分采样点以高环(4～6环)PAHs污染为主。PAHs源解析结果表明,梁滩河表层沉积物中PAHs污染以燃烧源为主,主要源于化石燃料和生物质的不完全燃烧。沉积物中苯并[a]芘的毒性当量因子(TEF)值为39.38～384.37 ngTEQ/g,平均值110.94 ngTEQ/g。生态风险评价的结果表明,右支流的两个采样点R3和R4点沉积物中PAHs可能存在生物负效应影响,R4点的高风险可能与附近白市驿机场污染有关。     

The toxicity of composted sediments from Mediterranean ports evaluated by several bioassays

This work investigates the ecotoxicological evaluation of contaminated dredged sediments from French Mediterranean navy harbour (A), commercial port (B) and two composite specimens (C) and (D) coming from the mixture of A and B with other port sediments. The toxicity of elutriates from these sediments is estimated using embryo-toxicity test, Microtox® solid phase test, LuminoTox, phytotoxicity tests and genotoxicity test. Bioassay responses are not clearly correlated with chemical contamination in the whole sediment and vary as a function of tested organisms. The highest contaminated samples (A and C) are almost always more toxic than the less contaminated samples (B and D). Among composite sediments, the mixture effect with other sediments is not efficient to decrease toxicity in sample C, suggesting that other parameters influence toxicity level such as particle size or organic matter content. These parameters should be taken into consideration in order to improve the efficiency of the mixture process and produce composite sediments with low toxicity.     

Presence of DDT metabolites in water,sediment and fish muscle tissue from Lake Prespa,Republic of Macedonia

Organochlorine pesticides were determined in water and sediment samples collected from the littoral zone of Lake Prespa, as well as from its three main tributaries (the rivers Golema, Brajcinska and Kranska), during the period 2004 to 2006. In addition, muscle tissue samples of barbus fish (Barbus prespensis Karaman, 1928) collected from the littoral zone of Lake Prespa were also analysed. The obtained results give an overview of the contamination levels of these problematic compounds at their potential sources in the river mouths, in the potentially affected, species-rich littoral section of the lake and in the muscle tissue of one selected fish species, collected near the rivers’ deltas. Special attention was paid to the presence of some DDT metabolites (1,1-dichloro-2,2-bis(p-chlorophenyl)ethylene (p,p′–DDE); (1,1-dichloro-2,2-bis(p-chlorophenyl)ethane (p,p′–DDD) and 1,1,1-trichloro-2,2-bis(p-chlorophenyl)ethane (p,p′–DDT). The extraction of pesticides from water samples was done by liquid-liquid partition in dichloromethane. For the sediment and fish tissue we used solid-liquid extraction. The extracted residues were analyzed on a gas chromatograph equipped with an electron capture detector (GC-ECD). The results of the respective studies indicated the presence of DDT metabolic forms in the samples of the three analysed matrixes. The highest levels of presence for these pollutants were found in the muscle tissue of the fish samples. The total DDTs content in the analysed muscle tissue samples range from 11.67 to 13.58 μg kg^?1of fresh tissue. The average total DDTs content for the sediment samples were within the range of 2.32 to 4.17 μg kg^?1 of dry sediment. Higher DDT metabolites content were found in the sediments collected from the rivers than in the samples from the littoral zone. The lowest average total concentrations of DDTs, on the other hand, were recorded in the water samples and ranged between 0.036 and 0.057 μg L^?1. The obtained results indicated that the dominant metabolic form in the samples of the three investigated matrixes (water, sediment and fish tissue) from Lake Prespa was p,p′-DDE. There was a very good linear correlation in this study between the content of DDT's (total DDT metabolites) detected and the percentage of total organic material in the sediment. The detected concentrations are clearly below the toxicity thresholds; consequently, severe effects on the endemic species of Lake Prespa are not very likely.