扬州古运河沉积物污染物释放强度与特征研究

研究了扬州古运河沉积物中氮、磷、铁和锰等污染物释放强度与特征,着重考察了上覆水中DO和污染物负荷对污染物释放强度的影响,分析了氮、磷、铁和锰等污染物释放条件.结果表明:扬州古运河有一定的自净能力,且呈现初期释放NH4+ -N、后期转化为NO3-- N的特征;随着水环境条件改变,沉积物NH4+ -N、PO34-、铁和锰平均释放强度变化范围是123.14～445.68、13.50～32.45、25.20～198.47、19.97～25.02 mg/(m2·d);上覆水DO浓度越低,污染物平均释放强度越大;上覆水污染物浓度越小,污染物(除铁外)平均释放强度越大;在DO＜5 mg/L条件下,沉积物向上覆水释放NH4+ -N;在DO＜1 mg/L条件下,沉积物向上覆水释放PO34-、铁和锰;在DO为2～5 mg/L条件下,上覆水PO34-和铁向沉积物中汇入,但锰则呈现释放和汇入的交替变化.     

活性炭固定沉积物中HCHs和DDTs的研究

在对沉积物的修复技术中,原位覆盖技术能够降低污染物向水体的释放,降低污染物对底栖生物和水生生物的生物可利用性,以及能够减少污染物向下游的迁移.在本研究中,将活性炭添加到受HCHs、DDTs污染的沉积物中,考察了活性炭剂量、粒径以及活性炭与沉积物接触的方式对HCHs、DDTs水相平衡浓度的影响,及对半渗透膜(SPMD)吸...     

水体沉积物重金属生物有效性及评价方法

在研究以重金属为主要污染物的水体中,通常把沉积物视为探索环境重金属污染的工具。由于沉积物中重金属化学行为和生态效应的复杂性,对沉积物中重金属生物有效性的研究是当前学术界的热点研究课题。本文就沉积物中重金属的生物有效性及沉积物质量评价方法作了简要评述。包括沉积物对水生生物的作用机理,孔隙水重金属浓度的估算,沉积物质量评价方法,沉积物质量基准。     

富碳沉积物对多环芳烃的截存及其环境意义

沉积物是多环芳烃(PAHs)等憎水性有机污染物的蓄积库,同时它也是该类污染物的源,沉积物中污染物的吸附/解吸,控制着污染物在水环境中的行为和生态毒性.然而,沉积物并不均一,沉积物中的异质组分表现出对PAHs差异显著的吸附/解吸性能.研究表明,富碳沉积物对PAHs存在截存效应,控制着污染物的吸附/解吸过程,表现为吸附/解吸滞后、缓慢解吸和受限的生物有效性.最后,在综述沉积物中的富碳物质及截存效应机制的基础上,讨论了截存效应所带来的环境意义和启示.     

湖泊沉积物—水界面采样装置的研制

湖泊沉积物中富集的污染物潜育着水体二次污染的危险.为评价上述潜在危害、必须了解污染物自沉积物中产生再迁移的速率和通量,因而必须完好地采集湖泊沉积物—水界面附近的样品.本采样装置包括取样器、起吊架及分样台.取样器采用自重下垂和脱销密闭封顶的原理制成.本取样器可改变三级配重和两种内径的采样管.对75m深水湖泊完整地采集到约30—90cm深的沉积物柱及10—30cm的底层水柱样品.沉积物分样精度可达0.1cm.整个装置重量轻、可拆卸、便于野外运输、操作方便.     

第二松花江(哈达湾-松花江村段)沉积物中有机物污染研究

本文所研究江段的有机污染物主要来自两岸工业排放的废水、生活污水、工业废弃物及生活垃圾。污染源主要位于右岸,上游右岸沉积物中有机污染物的总浓度高于左岸,下游两岸沉积物中有机污染物的总浓度趋于一致。两岸沉积物中污染物总浓度随距离的变化规律如下: 右岸:C=92.044S~(-0.3028) R=-0.962 左岸:C=9.231e~(-0.0058) R=0.946 在该江段沉积物中共检出51种有机污染物。其中致癌、可疑致癌、致突变化合物25种,占检出化合物的49％。淤泥质沉积物中有机污染物的存在量60.67吨,岸边滩及心滩土壤中存在量138.2吨。     

饮用水源水、出厂水有机污染物GC/MS分析

于1998年对成都市饮用水源水、出厂水的有机污染物进行了GC／MS分析,该市饮用水和出厂水均存在有机物污染,且含有优先控制污染物;污染来源主要为生活污水。枯水期有机物检出率高于丰水期。     

农药在土壤上吸着／解吸及其对生物利用率影响的研究进展

正确预测有机污染物在环境中的归缩，在很大程度上依赖对它们的吸着－解吸动力学行为的认识。自20世纪80年代起，吸着－解吸动力逐渐受到重视。本文介绍了国内外有关农药在土壤／沉积物上的吸着－解吸动力学和吸着－解吸对土壤有污染物的生物利用率的影响等方面的近期研究成果，着重从实验方法，模型，机理等方面进行了详细的综述。     

水体重金属稳定性的问题

在天然水体中,重金属污染物大多以沉积物为其最终归宿.相对水相而言,底沉积物固相浓缩重金属的倍数可高达数千至数万倍. 已知存在于底沉积物或悬浮沉积物中的重金属污染物具有不同的结合形式,其生物可给性也具有明显的差别,如沉积物间隙水中溶解态重金属被认为是最迅速生物可给     

三垟湿地沉积物-间隙水-上覆水界面磷形态研究

沉积物与上覆水间营养物质交换,成为导致水体发生富营养化的首要化学变迁过程.分别在三垟湿地的柑橘林(S1)、景观用地(S2)和生活用地(S3)取样,研究了沉积物-间隙水-上覆水界面磷形态以及相互关系.结果表明:(1)沉积物TP增加时,间隙水PO3-4和可溶性总磷(TDP)也增加.要削减磷在上覆水中的含量,控制间隙水PO3-4或TDP是一良策.(2)随着沉积物铁磷、铝磷的增加,间隙水PO3-4也增加.在三垟湿地沉积物中,铁磷和铝磷含量都可作为间隙水PO34-含量的指示.(3)S1、S2和S3的沉积物活性磷、间隙水TDP和上覆水TDP存在明显的浓度梯度,沉积物活性磷＞间隙水TDP＞上覆水TDP.说明在三垟湿地中,沉积物活性磷是磷释放的关键因子,而沉积物-间隙水界面则是磷释放的关键界面.     

Evaluating the exchange of DDTs between sediment and water in a major lake in North China

A large-scale sampling program was conducted to simultaneously collect surface water, overlying water, pore water, and sediment samples at monthly intervals between March and December 2010 from Baiyangdian Lake, North China to assess the distribution of DDTs and determine the net direction of sediment–water exchange. Total DDT concentrations ranged 2.36–22.4 ng/L, 0.72–21.9 ng/L, 2.25–33.7 ng/L, and 4.42–7.29 ng/g in surface water, overlying water, pore water, and sediments, respectively, which were at the intermediate levels compared to those of other area around the world. Seasonal variations of DDTs were featured by higher concentration in summer. This was likely associated with (a) the increase of land runoff in the summer and (b) application of dicofol and DDT-containing antifouling paints for ships in summer. Sediment–water fugacity ratios of the DDT isomers were used to predict the direction of the sediment–water exchange of these isomers. The sediment–surface water, sediment–overlying water, and sediment–pore water fugacity ratios of DDT isomers averaged 0.34, 0.44, and 0.1, which are significantly lower than the equilibrium status (1.0), suggesting that the net flux direction were from the water to sediment and the sediment acted as a sink for the DDTs. The difference of DDT concentrations between sediment and water samples was found to be an important factor affecting the diffusion of DDT from the water to sediment.     

Repartition du virus poliomyelitique a l'interface eau de mer-sediment d'un systeme experimental

The distribution between sea water and sediment of a polio virus has been studied under an experimental system. Throughout 7 days of incubation, a significant statistical difference exist between the viral concentration of sea water in times T₀ and T₇ (P～0,99) and the viral concentration of sea water samples and sediments in times T₇ (P～0,95). this for any type of sediment.     

Partitioning and bioaccumulation of cadmium in artificial sediment systems: application of a stable isotope tracer technique

The utility of stable isotope tracers for investigating the relationship between cadmium (Cd) partitioning in artificial sediment-water systems and Cd accumulation in a benthic detritivore (Asellus racovitzai, Isopoda) was explored. In the laboratory, Cd isotopes were applied to synthetic sediment and isotope concentrations were measured in sediment, overlying water and exposed asellids over a 10-day period. Isotope ratios measured in sediment and water were compared to ratios measured in asellids to determine whether Cd partitioning could predict metal bioaccumulation. Two different parameters which might affect Cd partitioning between the sediment and overlying water compartments were investigated: the chemical form in which Cd was added to systems, and the organic matter content of the sediment. To test the effect of chemical form on Cd partitioning, three isotopes of cadmium were individually applied to formulated sediment in varying combinations of 113Cd(NO3)2, 112Cd-humic acid (HA) 114CdSO4. The results demonstrated that chemical form did not influence partitioning, as the Cd isotope that was applied to sediment in the nitrate form exhibited similar partitioning between sediment and overlying water as the isotope that was applied in the sulfate or HA form. However, Cd isotope concentrations in overlying water were strongly related to the pattern of isotope accumulation in asellids suggesting that overlying water concentrations determined Cd bioaccumulation. In contrast, when the organic matter content of sediment was increased through the addition of Sphagnum peat moss, total Cd concentrations in overlying water and tissue were low, and there was no relationship between Cd-isotope concentrations in tissue and water. These results indicate that Cd accumulation occurred primarily from water, and factors that increase metal partitioning to sediment, such as increased sediment organic matter content, decrease Cd accumulation in asellids. The stable isotope tracer method described herein appears to be a useful technique for investigating the relationship between metal partitioning and bioaccumulation in simple sediment systems, but could also be extended to more complex systems, and used with different metals that have multiple stable isotopes.     

Modification of chemical oxygen demand monitoring in the Yellow River, China, with a high content of sediments.

This paper presents a modification of chemical oxygen demand (COD) monitoring giving a better indication of the pollution level compared with the conventional COD method for rivers with a high content of sediments. The correlation between the sediment organic carbon and COD was investigated using sediments sampled in the middle Yellow River, China. Partitioning of the sediment organic carbon between the water and sediment phases was also investigated using batch experiments, with the sediment concentration varying from 20 to 400 g/L. As a result, the COD modification equations are proposed for both turbid water (mixture of water and sediment) and supematant water (filtrate using a 0.45-microm membrane). The modified COD in turbid water and supernatant water could be 40 and 10% less than the monitored COD values, respectively. These results may have a significant influence on the assessment of water quality class in the Yellow River.     

Heavy metals in water, sediment and tissues of Leuciscus cephalus from a stream in southwestern Turkey

Concentrations of heavy metals (Cd, Cr, Cu, Pb and Zn) were measured in water, bottom sediment and tissues (muscle and gills) of Leuciscus cephalus from the Dipsiz stream in the Yatagan basin (southwestern Turkey), the site of a thermal power plant. Results for levels in water were compared with national and international water quality guidelines, as well as literature values were reported for streams and rivers. Comparisons were made of metal concentrations in water and sediment with those in the muscle and gills of L. cephalus caught from the Dipsiz stream. We found that there was metal accumulation in the gills compared to the muscle. Concentrations of Cd, Pb, Zn and Cr in the gills were higher than that in the muscle; however, Cu levels were higher in muscle than that in gills. Concentrations of heavy metals in L. cephalus muscle were below the legal limits for human consumption, although Cr, Pb and Zn levels in the gills were above the limits in the fish taken from the Dipsiz stream. On the other hand, no correlation was found between metal concentrations in water and sediment or between metal concentrations in water and muscle and gills of L. cephalus. A positive correlation was found between concentrations of Cu and Zn in the sediment and in fish tissue, whereas there was no relationship between other metal concentrations in the sediment and water, and muscle and gills of L. cephalus. As with water, Pb and Cd concentrations in particular were higher in sediment than that in background levels. The results show that the pollutants from the thermal power plant may be a source of these elements.     

水葫芦对滇池底泥氮磷营养盐释放的影响

为了探讨水葫芦对富营养湖泊底泥氮磷营养盐释放的影响,通过原位采集滇池柱状底泥,以蒸馏水为上覆水,进行了25d的室内静态模拟实验。实验比较了水葫芦处理组和空白对照组底泥氨氮（NH4-N）、硝态氮（NO3^-N）、溶解性总氮（DTN）、正磷酸盐（PO4^3--P）等的释放特征。结果表明,与对照组相比,水葫芦处理组上覆水溶解氧、pH显著性降低,而PO4^3-P浓度显著性升高;在实验前2d,水葫芦处理组上覆水NH4^＋N和DTN浓度显著性高于对照组,而在5～25d时,其显著性低于对照组。根据上覆水营养盐浓度、水葫芦植株吸收营养盐总量,推算底泥氮磷营养盐释放的平均速率,表明水葫芦加速了滇池底泥氮、磷营养盐的释放速率,处理组氮、磷释放速率分别为对照组的5．3～170．2和1．5～21．6倍。     

Bottom sediment as a source of organic contaminants in Lake Mead, Nevada, USA

Treated wastewater effluent from Las Vegas, Nevada and surrounding communities’ flow through Las Vegas Wash (LVW) into the Lake Mead National Recreational Area at Las Vegas Bay (LVB). Lake sediment is a likely sink for many hydrophobic synthetic organic compounds (SOCs); however, partitioning between the sediment and the overlying water could result in the sediment acting as a secondary contaminant source. Locating the chemical plumes may be important to understanding possible chemical stressors to aquatic organisms. Passive sampling devices (SPMDs and POCIS) were suspended in LVB at depths of 3.0, 4.7, and 6.7 (lake bottom) meters in June of 2008 to determine the vertical distribution of SOCs in the water column. A custom sediment probe was used to also bury the samplers in the sediment at depths of 0-10, 10-20, and 20-30 cm. The greatest number of detections in samplers buried in the sediment was at the 0-10 cm depth. Concentrations of many hydrophobic SOCs were twice as high at the sediment-water interface than in the mid and upper water column. Many SOCs related to wastewater effluents, including fragrances, insect repellants, sun block agents, and phosphate flame retardants, were found at highest concentrations in the middle and upper water column. There was evidence to suggest that the water infiltrated into the sediment had a different chemical composition than the rest of the water column and could be a potential risk exposure to bottom-dwelling aquatic organisms.     

Response of sediment calcium and magnesium species to the regional acid deposition in eutrophic Taihu Lake,China

Acid deposition causes carbonate dissolution in watersheds and leads to profound impacts on water chemistry of lakes. Here, we presented a detailed study on the seasonal, spatial, and vertical variations of calcium and magnesium species in the overlying water, interstitial water, and sediment profiles in eutrophic Taihu Lake under the circumstance of regional acid deposition. The result showed that both the acid deposition and biomineralization in Taihu Lake had effects on Ca and Mg species. In the lake water, calcium carbonate was saturated or over-saturated based on long-term statistical calculation of the saturation index (SI). On the sediment profiles, significant difference in Ca and Mg species existed between the surface sediment (0–10 cm) and deeper sediments (>10 cm). The interstitial water Ca²⁺ and Mg²⁺, ion-exchangeable Ca and Mg in the surface sediment were higher than those in the deeper sediment. In the spring, when the acid deposition is more intensive, the acid-extracted Ca and Mg in the surface sediment were lower than that in the deeper sediment in the northwest lake, due to carbonate dissolution caused by the regional acid deposition. Spatially, the higher concentration of acid-extracted Ca and Mg in the northwest surface sediment than that in the east lake was observed, indicating the pronounced carbonate biomineralization by algae bloom in the northwest lake. Statistical analysis showed that acid deposition exerted a stronger impact on the variation of acid-extracted Ca and Mg in the surface sediment than the biomineralization in Taihu Lake. For the total Ca and Mg concentration in the spring, however, no significant change between the surface and deeper sediment in the northwest lake was observed, indicating that the carbonate precipitation via biomineralization and the carbonate dissolution due to acidic deposition were in a dynamic balance. These features are of major importance for the understanding of combined effects of acid deposition and eutrophication on freshwater lakes.

     

Sediment-water distribution of perfluorooctane sulfonate (PFOS) in Yangtze River Estuary

Analysis of Perfluorooctane sulfonate (PFOS) distribution in water and sediment in Yangtze River Estuary showed that the estuary was a sink for PFOS. Salinity was an important parameter in controlling the sediment-water interactions and the fate or transport of PFOS in the aquatic environment. As the salinity (S‰) increased from 0.18 to 3.31, the distribution coefficient (K_d) between sediment and water linearly increased from 0.76 to 4.70 L g⁻¹. The study suggests that PFOS may be carried with the river water and transported for long distances before it reaches to the sea and largely scavenged to the sediment in the estuaries due to the dramatic change in salinity.