Preliminary Caesium Data From A Cooperative Us/Ussr Monitoring Survey for Chernobyl Radioactivity in the Black Sea

In June 1990, scientists from the US Environmental Protection Agency's (EPA) Office of Radiation Programs (ORP), and the Woods Hole Oceanographic Institution (WHOI), travelled to Sevastopol in the Soviet Union to work with radioecologists and marine scientists from the USSR Institute of Biology of the Southern Seas (IBSS). the purpose of this cooperative programme was to conduct a monitoring survey for radioactivity in the northwestern Black Sea. Samples of sediment, surface and in-situ water, and biota were collected from fourteen stations for post-survey radionuclide analyses to determine levels of radioactivity in the Black Sea environment resulting from the Chernobyl nuclear power plant explosion and subsequent transport of radioactivity via the Dnepr and Danube rivers. This paper presents the preliminary data for caesium-137 and caesium-134 in sediment samples analyzed by the EPA/ORP. Caesium-137 was measured at four shallow (20-114 m) stations on the shelf near the mouth of the Dnepr and Danube Rivers, but was not detected in sediments from comparable depths at stations further off shore or in slope sediments at depths of 510-1288 meters. Caesium-134 was detected only in sediments from the shallow-water station nearest to the Danube River.     

ESTIMATED BACKGROUND CONCENTRATIONS OF SULFATE IN DILUTE LAKES1

ABSTRACT: Lake water sulfate values were examined for two areas in western Norway and the western United States presently receiving low levels of sulfate in atmospheric deposition. Data from these areas were used to estimate background concentrations of sulfate in lakes found in areas currently receiving acidic deposition. The two areas contain dilute lakes with concentrations of sea-salt corrected Ca+ Mg less than 50 μeq/l or conductivity < 10μS cm^-1and receive precipitation with volume-weighted mean pH > 4.8. Based on observations from these areas, we conclude that background sulfate concentrations were probably no more than 10 to 15 μeq L^-1for areas of Norway and the U.S. containing lakes with low concentrations of base cations. For southern Norway and the northeastern U.S., present lakewater sulfate concentrations represent an increase of 7 to 10 fold above these estimated background values.     

REVERSIBLE ADSORPTION OF AQUEOUS DIVALENT COPPER ION BY ESTUARINE SEDIMENTS1

Sediments were equilibrated with solutions containing divalent copper ion. A colorimetric method using the triethylenete-tramine complex of the metal ion was employed to measure changes in uptake of copper by the sediments. Studies were made with sediments from rivers in the British Isles which were in the proximity of areas which had been mined for metals for several hundred years. For comparison, similar studies were performed with a sample of sand and a soil with a high organic content. It was possible to follow the uptake of copper ion by the materials and estimate their abilities to adsorb copper ion. In particular, a strong correlation was observed between the organic content of the sediment and the total amount of copper adsorbed by the sample. Under the employed circumstances it was possible to demonstrate that the adsorption of the metal ion was reversible.     

长江口及浙江近岸海域表层沉积物中多环芳烃分布、来源与风险评价

2013年对长江口及浙江近岸海域62个站位表层沉积物中多环芳烃(PAHs)进行了测定.结果表明,16种美国EPA优先控制的PAHs均有检出,PAHs总量水平(干重)为31.8~384μg·kg-1,平均含量为131.1μg·kg-1.其分布受到陆源输入和点源污染的影响,高值区域出现在长江口2号站位和宁波21号站位附近.与国内外其它海区相比,调查海域PAHs总体处于较低污染水平.调查海域沉积物中PAHs以4环、3环为主,来源分析显示PAHs主要来源于木柴、煤炭燃烧.利用沉积物质量基准法(SQGs)评价结果显示,调查海域表层沉积物中PAHs处于较低的生态风险水平;按照沉积物质量标准法(SQSs)评价结果表明,调查海域表层沉积物的PAHs污染已经具有一定程度的"显见生态负效应",需要采取相应的措施进行污染控制和削减.     

外源硫酸盐介入下沉积物磷释放、解磷微生物及磷酸酶活性的变化

人类生产活动导致湖泊水体硫酸盐浓度日益增加,硫酸盐与沉积物中磷之间的关系引起关注.该研究以武汉东湖水和沉积物为研究对象进行实验室模拟,研究为期近一年且温度变化的条件下外源硫酸盐对沉积物释磷及微生物的作用.结果表明,硫酸盐输入使沉积物pH和氧化还原电位(E h)总体呈降低趋势.外源硫酸盐促进了沉积物磷的释放,输入硫酸盐(S500)与对照(CK)之间的上覆水存在显著差异(p0.01),S500的上覆水中总磷浓度最高值达0.33 mg·L-1,为对照的2倍.湖泊沉积物中有机磷解磷菌的数量高于无机磷解磷菌,上层沉积物解磷菌的数量和沉积物总磷的含量之间呈负相关.S500的沉积物中磷酸二酯酶活性高于磷酸单酯酶活性,且不同分层沉积物磷酸单酯酶活性和磷酸二酯酶活性之间的正相关性达到显著水平.温度升高,磷酸酶的活性逐渐增强,促使沉积物内源磷释放量增加.     

坦噶尼喀湖东北部入湖河流沉积物重金属分布特征与生态风险评价

坦噶尼喀湖是非洲第二深的湖泊,拥有独特的生态系统,为沿湖居民提供丰富的鱼类蛋白,随着沿湖社会经济的发展和人口的快速增长,坦噶尼喀湖面临着环境污染威胁.为了揭示坦噶尼喀湖的重金属外源输入,本研究采集了湖泊东北部入湖河流的表层沉积物(16个样点),对沉积物重金属含量进行分析,并应用潜在风险指数法对沉积物重金属的生态风险进行了评价,同时分析了重金属分布与土地利用的关系.结果表明Cu、Zn、Cd、Pb和Hg的平均含量分别为18.4、21.2、0.05、6.6mg·kg-1以及8.4 ng·g-1;Zn、Pb、Cd的含量最高值均位于布琼布拉城市入湖河流.潜在生态风险指数(RI)表明,各重金属在各点位的生态风险系数均较低,其中CdHgCuPbZn,Cd是最主要的生态风险贡献因子,所有点位均属于低潜在生态风险区.重金属含量与土地利用的关系表明,城镇附近采样点重金属含量最高,其次是河口湿地,远离城镇的林草地重金属含量最低,表明人类活动会增加河流表层沉积物重金属含量.在以后的研究中,对城镇附近及河口湿地应给予重点关注.     

不同水源补给情形的溪流沟渠沉积物磷形态及释放风险分析

2015年5~12月,在合肥地区3条分别以城市污水厂尾水、食品加工废水和农业排水-地下水渗流为主要补给水源的溪流沟渠上,按季节采集表层沉积物样,分析沉积物磷赋存形态;通过磷吸附指数(PSI)、磷吸附饱和度(DPS)和磷释放风险指数(ERI)计算,评估溪流沟渠沉积物的磷潜在释放风险,并以非参数检验方法,对3条溪流沟渠开展差异性分析.结果表明:1关镇河支渠和陶冲小溪流水体磷素污染严重,3条溪流沟渠磷污染程度排序为:关镇河支渠陶冲小溪流磨店小溪流,其中关镇河支渠沉积物TP平均含量为1 376.95 mg·kg-1,分别是磨店小溪流和陶冲小溪流的2.94和1.91倍;2 3条溪流沟渠沉积物中各形态磷含量差异显著,且在含量高低排序方面存在一定差异性;3 3条溪流沉积物的PSI值季节性变化特征明显,而且每条溪流沟渠所有采样点变化规律基本一致,即总体上都表现出秋季最高,冬季次之,春、夏季基本相当且相对最低的变化特征;4由PSI、DPS及ERI评估得到的磷释放风险特征基本一致,相应的磷释放风险高低排序为:关镇河支渠陶冲小溪流磨店小溪流;5差异性分析表明,3条溪流沟渠几乎在所有指标上存在显著的差异性.     

宿鸭湖沉积物重金属空间分布及潜在生态风险评价

为了研究宿鸭湖沉积物中重金属的污染状况,采集了宿鸭湖湖心、中围和外围这3个位置的沉积物,对沉积物中重金属Cu、Cd、Cr、Zn、Pb、Ni的含量进行测定,运用地积累指数法和潜在生态风险指数法对研究区的重金属含量特征和污染状况进行分析,并采用克里格法和相关性分析对重金属的分布规律和相互关系进行评价.结果表明:(1)就平均值而言,最大的是Zn达112.87 mg·kg~(-1),其次是Cr,平均值最小的Cd仅为0.41 mg·kg~(-1).除Cd和Cr之外,Cu、Zn、Pb和Ni的变异系数相对较小,在24%~31%之间,属于中度变异程度.Cd和Cr的变异系数分别为50.41%和41.92%,空间分异明显,说明其可能受到外界的影响更为显著;(2)重金属Cu、Cd、Cr、Zn、Pb和Ni之间具有很强的线性关系,存在显著的正相关性,且6种重金属具有一定的同源特征,有着共同的外源输入;(3)研究区主要的污染元素为Cd、Cr和Zn,污染程度相对比较严重,且范围广泛,其中,Cd的污染程度最为严重,整体的污染水平为中度等级,且在部分样点区的污染程度达至重度污染,Cr、Zn、Pb的污染状况相对比较轻缓,属于轻度污染等级,且Cu、Pb和Ni的整体状况较好,不存在生态风险;(4)就整体而言,宿鸭湖东北部污染程度较轻,西南的污染程度相对比较严重,呈现出明显的西南向东北递减的空间分布特征,位于库区外围的西南方向,各样点的各重金属含量均较高,而外围的东北部,是低含量重金属的聚集区,Cu、Cr、Zn、Ni为无污染状态.     

低分子有机酸对三峡库区沉积物吸附Pb2+影响研究

以长江三峡库区万州段消落带区的沉积物为研究对象,通过等温吸附平衡实验研究不同浓度的柠檬酸、草酸对沉积物吸附Pb2+的影响.实验结果表明:消落带沉积物对Pb2+的吸附量随着Pb2+离子平衡浓度的增加而增大,Pb2+平衡浓度在0.08～80 mg/L时,其最大吸附量为8 762.00 mg/Kg.不同浓度的柠檬酸、草酸会在不同程度上抑制沉积物对Pb2+吸附,2 mmol/L柠檬酸对沉积物吸附Pb2+的能力是浓度为4 mmol/L时的1.12倍,草酸条件下为1.02倍.即高浓度的低分子有机酸抑制消落带沉积物对Pb2+的吸附.     

1株嗜酸硫杆菌的分离鉴定及其对污染底泥中重金属的去除效果

采用常规细菌分离方法,从河流底泥中筛选到1株细菌FD97,通过序批式摇瓶培养考察了不同温度下(22~40℃)该菌株对污染底泥中Zn、Cu和Cr的去除效果.结果表明,形态学和16S rDNA序列同源性分析鉴定菌株FD97为嗜酸硫杆菌属(Acidithiobacillussp.).在22~40℃条件下,以Acidithiobacillussp.FD97为主要菌株的生物沥浸作用可有效去除污染底泥中Zn、Cu和Cr.沥浸处理16 d,Zn、Cu和Cr的去除率可分别达70%、90%和25%.从底泥pH值变化、SO42-产生以及重金属去除率角度衡量不同温度的底泥沥浸处理效果依次为:34℃28℃≈40℃22℃.控温28℃较适宜今后的实际应用.底泥重金属生物沥浸去除率的大小与底泥pH值变化密切相关,与温度无直接关系.当底泥pH值降至5.0、3.5和2.5时,底泥中Zn、Cu和Cr分别开始溶出,pH值降为2.0,重金属去除率达最大.