Species distribution of arsenic in sediments after an unexpected emergent discharge of high-arsenic wastewater into a river

The unexpected emergent discharge of high-arsenic wastewater into water environments results in significantly increased levels of arsenic in water; however, the species distribution of arsenic in sediments has never been reported before for such cases. This study focuses on an As pollution accident in the Dasha River, and uses sequential extraction procedures with deionized water, 1?mol·L^-1 MgCl₂ at pH= 8, 1?mol·L^-1 NaH₂PO₄ at pH= 5, and 1?mol·L^-1 HCl to investigate four binding phases of arsenic (i.e., water soluble, ion-exchangeable, strongly-bound, and precipitates) in sediments at different layers in different cross-sections along the river. The average ratio of arsenite (As(III)) to arsenate (As(V)) was found to decrease from 0.74:1 in river water to 0.48:1 in sediment, owing to its higher affinity toward As(V) than As(III). The content of arsenic in the sediments was relatively low and the maximum content was observed to be 36.3?mg·kg^-1 for As(III) and 97.5?mg·kg^-1 for As(V). As(III) and As(V) showed different binding phases in sediments, and the average fractions of these four species were determined to be 0.09, 0.11, 0.17, and 0.63 for As(III) and 0.03, 0.14, 0.63, and 0.20 for As(V), respectively. For all the sediment samples, the content of arsenic showed no relationship with the characteristics of the sediments such as the particle diameter, the content of organic carbon, Fe, and Mn, although a negative correlation with particle diameter was observed for the sediments in the uppermost 2-cm layer. The unexpected emergent As incident results in the high content of total arsenic in the surface sediment, which may be potential secondary source to the elevated As levels in surface water.     

海南岛东部陆架表层沉积物重金属污染评价

对海南岛东部陆架29个站位的表层沉积物重金属元素(Cu、Cr、As、Pb、Zn和Cd)进行了含量测试及分布特征分析,采用地累积指数(I_geo)、富集因子(EF)和潜在生态危害指数对其进行了评价.研究结果表明:重金属含量空间分布趋势较为相似,呈现出由陆向海略微减小的趋势.6种重金属元素可能有相同或相似的来源,但Pb和As受到了人类活动影响.以上地壳和海南岛近岸未受污染沉积物为背景值的I_geo和EF值排序有所不同.研究区单项潜在生态危害系数平均值排序为Cd> As> Cu> Pb> Cr> Zn,Cu、Cr、Pb和Zn等4种重金属为轻微潜在生态危害,As和Cd在个别站位达到了中等潜在生态危害水平.综合潜在生态危害指数评价结果显示,研究区绝大多数站位处于轻微潜在生态危害水平.潜在生态危害水平相对较高的区域邻近万泉河、陵水河和三亚河河口.     

Organochlorines in the surface sediments of the Bahiret el Bibane lagoon (Tunisia,Southwestern Mediterranean Sea)

Organochlorines (including organochlorine pesticides (OCPs) and polychlorinated biphenyls (PCBs)) were analysed in 10 surface sediment samples collected from the Bahiret el Bibane lagoon, which is one of the most productive lagoons and one of the most important active commercial fish traps in the southern Tunisia. The aim was to obtain information concerning the recent deposition of these compounds in this area, together with the levels, the distribution and any potential biological risk. Total concentrations of OCPs and PCBs in the sediments ranged from below the limit of detection (?1 and from 29.5 to 88.2?ng?g^?1?dw, respectively. The spatial distribution of PCBs suggested that the sources of these contaminants are probably located outside the lagoon and are transported by water currents and atmospheric deposition. Compared with some other regions of the world, the Bahiret el Bibane lagoon exhibited low to moderate levels of PCBs and OCPs. According to established sediment quality guidelines, PCBs and Lindane at most of the study sites would be more concerned for the ecotoxicological risk in the Bahiret el Bibane lagoon. The results of this study could provide a useful aid for the sustainable marine management of the region.     

曼谷湾沉积物重金属元素的富集效应与生物有效性

2010年在曼谷湾(泰国湾北部)及其北部主要河口(湄干河、拉塞河、湄南河和邦巴功河)采集了46个表层沉积物样品,分析了样品中重金属元素(Cd、Co、Cu、Pb、Zn)的含量水平,并用Al均一化数据,获得消除了粒度效应的重金属地球化学特征.利用1mol/L的HCl对该区沉积物进行了处理,通过分析沉积物重金属在酸溶相和残渣相的分布,揭示其生物有效性.结果表明,曼谷湾周边河流沉积物中重金属元素含量明显高于曼谷湾;曼谷湾沉积物中重金属(Co、Cu、Pb、Zn)从北向南随着离岸距离的增加而增加,Cd没有明显分布规律;地累积指数显示Cd和Pb存在显著的地球化学富集特征.Cd和Pb在酸溶相中的比例相对较高,表明其生物有效性较高,易引发二次污染.     

渤海湾河口沉积物重金属污染及潜在生态风险评价

对渤海湾大神堂、高沙岭、海河、子牙河和南排河入海口表层沉积物和野生矛尾鰕虎鱼(除海河口)肌肉的As、Cd、Cr、Cu、Pb和Zn重金属进行了分析,发现各入海口表层沉积物重金属以Zn的浓度水平最高,平均达81.55mg/kg,而Cd最低(平均值为0.28 ± 0.08 mg/kg).在鱼体内, Zn浓度仍是最高(平均为96.75 ± 30.98 mg/kg),而Cd未检出.以生态危害指数法(RI)评价河口沉积物重金属的潜在生态风险表明,海河河口沉积物重金属的潜在生态风险最高,其他依次为子牙河口、南排河口、大神堂和高沙岭.另外,通过对各地鰕虎鱼肝脏金属硫蛋白的分析,发现子牙河的野生复鰕虎鱼金属硫蛋白较其他河口稍高(除海河),与沉积物重金属的RI分布一致.     

福建龙岩市龙潭湖甲藻水华成因的研究

2009年12月初,在福建龙岩市龙硿洞风景名胜区龙潭湖首次发现拟多甲藻水华,最高细胞密度达到1.11×107cells.经过应急处置,甲藻和其他藻类被杀灭.监测发现,上游小溪和溶洞地下水营养物质均优于国家Ⅱ类标准,但入湖后,TN和TP浓度明显上升.结果表明,龙潭湖蓄水改变了小溪的自然流态,形成了营养盐的累积和甲藻的快速增殖;环境和水温度的明显升高,也起到了一定的促进作用;沉积物营养盐蓄积和内释放对甲藻水华具有重要的贡献,而TP可能是本次水华的主要限制因子.     

城市内河强还原性沉积物耗氧及相关因素研究

2009年7—8月间选择浙江省宁波市4条污染程度不同的内河,采集沉积物和水质样品. 采用自制的多管、多电极沉积物耗氧研究装置测得沉积物耗氧(SOD)值高达13.8～9.4×104 mg/(m2·h),其中张桂河路林市场段(ST2站)SOD为87.0 mg/(kg·h);同时测定了各站水质、沉积物理化指标. 结果表明:水体水温和沉积物w(氨氮)与SOD有较高的相关性,而有机质、底层ρ(DO)和ρ(COD_Cr)与SOD的相关性较差.表观污染严重的站位其沉积物表现出强烈的“瞬时耗氧”现象,这很可能是造成水体缺氧的主要原因之一.      

基于人工神经网络方法的河北省近海沉积物重金属污染综合评价

利用误差反相传播神经（BP）网络对河北省近海沉积物中的铅、镉、锌、汞、砷5种重金属元素的污染水平进行分析,利用自组织特征映射（SOFM）网络对上述重金属元素分布特征进行分类,通过分类与污染水平量化值的结合,进行综合评价。SOFM把52个沉积物样品分别划分为3、4、6类和9类。对比各种分类,分为3类的物理意义较明确。每个类别分别对应高中低不同的污染物浓度水平,差异显著、分类方式比较合理。通过此种分类可以判断河北省近海的沉积物重金属污染在不同海域存在一定的差别,整体上是离海岸越远,沉积物的重金属污染水平越高,距海岸较近的海域内,沉积物的重金属污染水平较低,但渤海湾内的重金属污染水平高于其他海域。     

两种底质对狐尾藻生长和生理指标的影响

在温室条件下,分别以土壤和沉积物作为底质,模拟研究狐尾藻(Myriophyllum spicatum)生长和生理指标的变化。结果表明:与营养水平相当的沉积物相比,以土壤作为底质的处理,其狐尾藻茎叶生物量降低了87.15%,根系生物量增加了226.54%,根系活力降低了46.46%,超氧化物歧化酶(SOD)和过氧化物酶(POD)活性分别增加了134.20%和119.91%,上覆水和间隙水中活性磷浓度分别增加了146.67%和1382.61%。以土壤为底质,增加该处理水体中磷浓度,抑制狐尾藻生长。