Spatial distribution of organotins in sediments of lowland river catchments

A method is described for the measurement of nanogram quantities of a range of methyl and butyltin compounds. The method utilises a modified purge and trap/boiling point separation technique for the determination of organotin compounds in sediment samples. A spatial survey of sediment samples within 5 river systems in the East Anglia region of the United Kingdom was undertaken and identified a range of organotin compounds with concentrations of tributyltin (TBT) ranging from <3.9 ng g(-1) up to 1291 ng g(-1). The highest values were found in areas connected with boating activities. Wherever TBT was present, dibutyltin and monobutyltin were most commonly found along with small concentrations of certain methyltins.     

深圳市河流沉积物重金属污染特征及评价

分析了深圳市的深圳河、布吉河、龙岗河和茅洲河等4条河流沉积物中重金属的含量和富集状况,并对重金属污染的潜在生态危害进行了评价。结果表明：（1）1996-2003年,深圳河、布吉河、龙岗河和茅洲河沉积物中重金属的含量都有上升的趋势;布吉河和龙岗河沉积物中的重金属含量较高,特别是Cu、Zn和Cr的含量比其他两条河流高出较多,深圳河居中,茅洲河较小;这4条河流都以Cd、Cu、Cr和Zn的富集为主。（2）在研究时段内,这4条河流沉积物重金属污染的潜在生态危害指数（RI）都有上升的趋势;其中深圳河,布吉河和龙岗河的RI在多数年份都达到强或很强的程度,Cd、Hg、Cu为主要贡献元素;4条河流中,茅洲河受重金属污染最小,其RI为轻微或中等,只有Cd和Hg的生态危害系数为中等或强。针对深圳市河流沉积物中重金属的累积机理,建议通过改善区域水文条件、控制污染物的排放等措施加以控制和治理。     

珠江三角洲某河流型饮用水源地的土壤重金属污染源解析和风险评价

采集分析了珠江三角洲某河流型饮用水源地的土壤重金属Cd、As、Zn、Pb、Cu、Hg、Ni、Cr,对其来源进行解析,并结合地质累积指数和潜在生态危害指数进行风险评价。结果表明,8种重金属的浓度均值均超过了广东省土壤背景值,表明该水源地土壤存在一定的人为源重金属干扰。Cd、Hg、Ni、As来源归因于工业源,Cu、Cr归因于农业源,Zn、Pb归因于交通源。风险评价结果表明,该水源地土壤存在一定的重金属污染风险,污染频率最高、强度最大的重金属是Cd。     

Indirect effect of nutrient accumulation intensified toxicity risk of metals in sediments from urban river network

The levels of metals in sediments of urban river ecosystems are crucial for aquatic environmental health and pollution assessment. Yet little is known about the interaction of nutrients with metals for environmental risks under contamination accumulation. Here, we combined hierarchical cluster, correlation, and principal component analysis with structural equation model (SEM) to investigate the pollution level, source, toxicity risk, and interaction associated with metals and nutrients in the sediments of a river network in a city area of East China. The results showed that the pollution associated with metals in sediments was rated as moderate degree of contamination load and medium-high toxicity risk in the middle and downstream of urban rivers based on contamination factor, pollution load index, and environmental toxicity quotient. The concentration of mercury (Hg) and zinc (Zn) showed a significant correlation with toxic risks, which had more contribution to toxicity than other metals in the study area. Organic nitrogen and organic pollution index showed heavily polluted sediments in south of the study area. Though correlation analysis indicated that nutrients and metals had different input zones from anthropogenic sources in the urban river network, SEM suggested that nutrient accumulation indirectly intensified toxicity risk of metals by 13.6% in sediments. Therefore, we suggested the combined consideration of metal toxicity risk with nutrient accumulation, which may provide a comprehensive understanding to identify sediment pollution.

Toxicity rate of metals in sediments from urban river network indirectly intensified by nutrients accumulation

     

Nematode communities in contaminated river sediments

Nematode communities of eight sites from three river catchments were investigated in terms of the genera composition, feeding types, and life-history strategists. The sampling sites showed a gradient of anthropogenic contamination with heavy metals and organic pollutants being important factors in differentiating the sites. Nematode community structure was related to sediment pollution and the hydro-morphological structure of the sampling sites. Heavily contaminated sites were characterized by communities with high relative abundances of omnivorous and predacious nematodes (Tobrilus, c-p 3; Mononchus, c-p 4), while sites with low to medium contamination were dominated by bacterivorous nematodes (Monhystera, Daptonema; c-p 2) or suction feeders (Dorylaimus, c-p 4). The relatively high Maturity Index values in the heavily polluted sites were surprising. Nematodes turned out to be a suitable organism group for monitoring sediment quality, with generic composition being the most accurate indicator for assessing differences in nematode community structure.     

Toxicity of combined sewer overflows on river phytoplankton: the role of heavy metals

The toxic effect of a combined sewer overflow (CSO) on the phytoplankton community of the river Seine has been studied by means of short-term primary production measurements. As the discharged solids usually do not remain in the water column, only filtered or centrifugated fractions were tested. The collected phytoplankton were grown in the laboratory for 2 days, after addition of N, P and EDTA. Stock cultures in exponential growth were directly tested with heavy metals, but resuspended algal cells were used for effluent testing. The results show an increase of EC50 value for the single metal species in the order Cu相似文献   

南宁市城市近郊型地下河表层沉积物多环芳烃污染特征及来源解析

为研究西南岩溶地区城市近郊型地下河沉积物中多环芳烃(PAHs)的污染特征及来源,选择南宁市清水泉地下河进行分析,沿地下河流动方向共采集8个表层沉积物样品,并检测16种PAHs的含量。结果表明,地下河表层沉积物中总PAHs为257.7～609.5ng/g(基于表层沉积物干质量计算),整体浓度处于中等污染水平;从PAHs组成来看,16种PAHs均被检出,且含量表现为4环PAHs5～6环PAHs2～3环PAHs;空间分布规律呈下游中游上游的趋势,且2～3环PAHs占比先增大后降低,而4～6环PAHs占比变化则相反;不同区域的PAHs来源各不相同,上游地区PAHs为燃烧来源,中游地区PAHs为石油来源,下游地区为混合来源,燃烧来源、石油来源与混合来源对PAHs的贡献率分别为28.4%、16.5%和55.1%。     

Sequential extraction of heavy metals in river sediments of an abandoned pyrite mining area: pollution detection and affinity series

In this paper heavy metal pollution at an abandoned Italian pyrite mine has been investigated by comparing total concentrations and speciation of heavy metals (Fe, Cu, Mn, Zn, Pb and As) in a red mud sample and a river sediment. Acid digestions show that all the investigated heavy metals present larger concentrations in the sediment than in the tailing. A modified Tessier's procedure has been used to discriminate heavy metal bound to organic fraction from those originally present in the mineral sulphide matrix and to detect a possible trend of metal mobilisation from red mud to river sediment. Sequential extractions on bulk and size fractionated samples denote that sediment samples present larger percent concentrations of the investigated heavy metals in the first extractive steps (I-IV) especially in lower dimension size fractionated samples suggesting that heavy metals in the sediment are significantly bound by superficial adsorption mechanisms.     

河流重金属污染底泥的稳定化实验研究

以实现河道疏浚底泥中富含的重金属Cu、Zn、Ni的稳定化为目标,选用EDTA、DTCR、Na2S、Na2S2O3、膨润土、水泥及自主研发的特殊胶凝材料作为稳定剂,对底泥中的重金属进行固化稳定,通过分析稳定后重金属浸出液浓度及赋存形态变化,探讨各药剂稳定效果,并寻求稳定剂的最佳投加量.研究表明,7种稳定剂对3种重金属的综合稳定化效果由好到差依次为:水泥> 胶凝材料> 膨润土> DTCR> 硫化钠> 硫代硫酸钠> EDTA;对Cu、Zn、Ni单种重金属而言,稳定效果最好的药剂分别为膨润土、胶凝材料及DTCR,而EDTA则使重金属浸出液浓度升高.除EDTA外,其他药剂对重金属Cu和Zn的稳定效果要明显优于Ni.根据稳定后重金属赋存形态变化结果,EDTA可使重金属可交换态比例升高,而膨润土对重金属4种形态分布基本无影响,其他药剂使重金属可交换态比例降低.     

Arrested municipal solid waste incinerator fly ash as a source of heavy metals to the UK environment

Arrested fly ash samples from most currently operating municipal solid waste (MSW) incinerators in the UK have been analysed for a range of elements. Some of the more important heavy metals ranged in concentration as follows: Cd, 21-4646 (median = 271) mg kg(-1); Cu, 296-1307 (642) mg kg(-1); Cr, 44-1328 (574) mg kg(-1); Ni, 45-2204 (74) mg kg(-1); Pb, 447-9704 (4337) mg kg(-1); and Zn, 2285-13,500 (9232) mg kg(-1). These concentrations represent considerable enrichments relative to median UK soil concentrations. Enrichment ratios (defined as median fly ash: median UK soil) were as follows: Mn 1.6; Co 2.6; Ni 3.3; Ba 11; Sr 11; Cr 15; Cu 35; Pb 108; Zn 113; Cd 387. It is estimated that MSW incinerator ash contributes c. 15 t Cd and 241 t Pb to UK landfill sites per annum. These figures compare with previous studies by Hutton & Symon (Hutton, M. & Symon, C. (1986). The quantities of cadmium, lead, mercury and arsenic entering the UK environment from human activities. Sci. Total Environ., 57, 129-50.) which estimated that annual inputs to UK landfills from coal fly ash are c. 60 t Cd and 1270 t Pb. However, it is argued that metals associated with MSW ashes are potentially of greater environmental significance than in coal ashes, because they are much more available and present at much higher concentrations.     

Risk assessment of heavy metals in suspended particulate matter in a typical urban river

Environmental Science and Pollution Research - Suspended particulate matter (SPM) is a major source of contamination in urban rivers as it serves as a carrier for pollutants, such as heavy metals....     

The wall as a source of hydroxyl radicals in smog chambers

The role of the wall of a smog chamber as a radical source has been investigated in several ways. From data in the literature evidence is obtained that HNO₃, present on the reactor wall, may react with NO in the gas phase according to the reaction HNO₃(wall) + 2NO + H₂O → 3HNO₂ to give nitrous acid. Nitrous acid may subsequently photolyze to give hydroxyl radicals.Experimental evidence about the occurrence of this reaction was obtained by u.v.-irradiation of propane-NO_x mixtures with and without NH₃. The presence of NH₃ resulted in a drastically reduced photochemical reactivity, suggesting that neutralization of nitric acid prevented the reaction of HNO₃ with NO. Inclusion of the reaction mentioned above into a computer-model gave a good agreement between experimental and calculated concentration profiles of NO, NO₂ and O₃ in experiments with CO-NO_x and propane-NO_x, mixtures. The results of our findings and those from others are discussed.     

Heavy metals detection in river water with cantilever nanobiosensor

Abstract

Heavy metals can be highly toxic depending on the dose and the chemical form. In this context, sensing devices such as nanobiosensors have been presented as a promising tool to monitor contaminants at micro and nanoscale. In this work, cantilever nanobiosensors with phosphatase alkaline were developed and applied to detect heavy metals (Pb, Ni, Cd, Zn, Co, and Al) in river water. The nanobiosensor surface was functionalized by the self-assembled monolayers (SAM) technique using 16-mercaptohexadecanoic acid, N-(3-dimethylaminopropyl)-N′-ethylcarbodiimide (EDC) and N- hydroxysuccinimide (NHS), and phosphatase alkaline enzyme. The sensing layer deposited on the cantilever surface presented a uniform morphology, at nanoscale, with 80?nm of thickness. The nanobiosensor showed a detection limit in the ppb range and high sensitivity, with a stability of fifteen days. The developed cantilever nanobiosensor is a simple tool, suitable for the direct detection of contaminants in river water.     

Fate and effects of heavy metals in salt marsh sediments

The fate and effects of selected heavy metals were examined in sediment from a restored salt marsh. Sediment cores densely covered with Spartina patens were collected and kept either un-amended or artificially amended with nickel (Ni) under standardized greenhouse conditions. Ni-amendment had no significant effect on the fate of other metals in sediments, however, it increased root uptake of the metals. Metal translocation into the shoots was small for all metals. Higher Ni concentrations in plants from amended cores were accompanied by seasonal reductions in plant biomass, photosynthetic capacity and transfer efficiency of open photosystem II reaction centers; these effects, however, were no longer significant at the end of the growing season. Root colonization by arbuscular mycorrhizal fungi (AMF) resembled that of natural salt marshes with up to 20% root length colonized. Although Ni-amendment increased AMF colonization, especially during vegetative growth, in general AMF were largely unaffected.     

The flame retardant tetrabromobisphenol-A and its metabolite found in river and marine sediments in Japan

Tetrabromobisphenol-A (TBBP), used as a flame retardant, was detected in river sediments collected in Osaka, Japan, at a concentration range from 22 to 140 μg/kg (ppb), as determined on a dry weight basis. TBBP was also found in marine sediments collected at Osaka Bay, though the TBBP levels of these samples were much lower than those from river sediments. Dimethyl ether derivative of TBBP (TBBP-DM), thought to be a decomposition product from microbial methylation, was found in the river sediments but in none of the marine sediments. TBBP-DM residues were about one-hundredth of the TBBP levels.     

Occurrence and microbial degradation of phthalate esters in Taiwan river sediments

Concentrations and microbial degradation rates were measured for eight phthalate esters (PAEs) found in 14 surface water and six sediment samples taken from rivers in Taiwan. The tested PAEs were diethyl phthalate (DEP), dipropyl phthalate (DPP), di-n-butyl phthalate (DBP), diphenyl phthalate (DPhP), benzylbutyl phthalate (BBP), dihexyl phthalate (DHP), dicyclohexyl phthalate (DCP), and di-(2-ethylhexyl) phthalate (DEHP). In all samples, concentrations of DEHP and DBP were found to be higher than the other six PAEs. DEHP concentrations in the water and sediment samples ranged from ND to 18.5 μg/l and 0.5 to 23.9 μg/g, respectively; for DBP the concentration ranges were 1.0–13.5 μg/l and 0.3–30.3 μg/g, respectively. Concentrations of DHP, BBP, DCP and DPhP were below detection limits. Under aerobic conditions, average degradation half-lives for DEP, DPP, DBP, DPhP, BBP, DHP, DCP and DEHP were measured as 2.5, 2.8, 2.9, 2.6, 3.1, 9.7, 11.1 and 14.8 days, respectively; under anaerobic conditions, respective average half-lives were measured as 33.6, 25.7, 14.4, 14.6, 19.3, 24.1, 26.4 and 34.7 days. In other words, under aerobic conditions we found that DEP, DPP, DBP, DPhP and BBP were easily degraded, but DEHP was difficult to degrade; under anaerobic conditions, DBP, DPhP and BBP were easily degraded, but DEP and DEHP were difficult to degrade. Aerobic degradation rates were up to 10 times faster than anaerobic degradation rates.     

阳宗海沉积物中重金属生物有效性评估

通过测定和分析阳宗海表层沉积物中酸可挥发性硫化物(AVS)和同步提取重金属(SEM)的含量和分布特征,采用SEM/AVS方法对阳宗海表层沉积物中重金属的生物有效性进行评估;同时,采用生物有效阈值法评估了单一重金属的生物有效性。研究得出以下结论:阳宗海表层沉积物中AVS含量为15.09~149.74 μmol/g,平均值为49.42 μmol/g,从南向北呈递减趋势;AVS在南部和中部均与湖泊水深呈现正相关关系;∑SEM(包括Cu、Cr、Pb、Zn、Mn、As、Cd)含量分布波动较小,其范围为4.84~16.10 μmol/g,平均值为10.28 μmol/g,其分布规律为北部大于南部;阳宗海各采样点SEM/AVS<1,说明阳宗海表层沉积物中重金属不会对生物产生不良影响;从单一重金属来看,Pb可能经常产生生物毒性,Cu有可能产生生物毒性,其他金属除部分点可能产生生物毒性外,整体上几乎不会产生生物毒性。