海河流域水体沉积物中多氯联苯污染特征及风险评价

截至目前,尚没有研究从流域尺度系统分析海河流域水体沉积物中多氯联苯(PCBs)的污染特征及风险水平。以海河流域7大河系及典型湖库为研究对象,基于文献中PCBs的数据统计,从流域尺度探讨了不同水体沉积物中PCBs的组成和其空间分布特征,并利用潜在生态危害指数法和毒性当量法评价其生态风险。结果表明,海河流域水体沉积物总PCBs污染呈"北高南低"趋势。二氯联苯至十氯联苯在海河流域中都有不同程度的检出,主要以低氯原子数的二氯联苯至五氯联苯为主。海河流域沉积物中PCBs毒性主要取决于PCB-126和PCB-169。两种生态风险评价方法评价结果存在一定的不确定性,需将两种方法结合,进行综合判断。     

第二松花江沉积物中汞的形态分布

河流水体中的汞,大部分积累在沉积物中。而汞含量高的沉积物,也向水和大气中释放汞。沉积物是汞迁移转化过程的一个重要环节。沉积物中汞的形态分布,决定着沉积汞的稳定性,同时对汞的迁移转化、河流对汞的自净能力,也有着十分重要的影响。化学浸提法,历来是汞形态研究的主要方法之一。近年来,国内一些单位对各种浸提法进行了研究和评价。在前人工作的基础     

黄河内蒙古段沉积物中硅的赋存形态及分布特征研究

应用连续浸提技术研究了黄河内蒙古段表层沉积物中硅的赋存形态及沿程分布特征。结果表明,沉积物中残渣态硅(Residual-Si)含量最高,占5种硅形态总量(∑Si)的91.78%(质量分数,下同)～98.08%,但Residual-Si对上覆水影响不大,其余4种硅形态均为生物有效硅(Valid-Si),Valid-Si仅占∑Si的1.92%～8.22%,但对黄河水体硅循环具有重要影响。人工筑坝会导致水体总颗粒物(TMP)浓度减少,使大坝下游沉积物中可交换态硅(IEF-Si)、碳酸盐结合态硅(CF-Si)和上覆水溶解硅(DSi)含量明显降低;旅游景点和电厂产生的人为污染会通过大气沉降和地表径流等进入到水体,使水体营养程度进一步升高,浮游植物在沉积物中汇集,导致下游沉积物IEF-Si、CF-Si含量升高,增加沉积物中硅的释放风险。     

我国环境介质中多环芳烃的分布及其生态风险

持久性有机污染物多环芳烃(PAHs)在我国环境介质中广泛分布,美国EPA规定的16种.优先控制多环芳烃大多在我国大气、水体、沉积物、土壤和生物体内检出.总结了我国环境介质中PAHs污染水平及特点,分析了其存在的环境风险.我国大气中PAHs污染较重,尤其是北方.水体已普遍受PAHs污染,其中部分水体污染严重;沉积物多环芳烃污染大多处于低生态风险水平,但沉积记录研究表明有越来越严重的趋势.我国土壤和生物体PAHs含量较低,污染生态风险较小.部分区域蔬菜中PAHs含量较高,存在不可忽视的生态风险.     

我国部分磷肥厂周围地区土壤的氟污染

磷肥生产的主要原料磷灰石通常都含有3％左右的氟。在矿石粉碎,酸化等生产过程中,有大量的含氟废气、废水和废渣产生,虽然经过除氟设备的回收处理,但仍有相当数量的氟化物以各种途径从工厂逸散出来,污染工厂附近的空气和水源,并在土壤中富集,造成周围地区土壤的氟污染。共结果,一方面土氟被植物吸收,造成植物体内累积;另一方面上氟还可以向水中迁移,向空气中扩散,造成水体和大气的二次污染。长期以来,人们对大气和水体的氟污染较为重视,但对土壤氟污染的严重后果还认识不     

上海大气氮湿沉降的污染特征

为探讨上海大气氮湿沉降的污染特征,采集了2007年11月至2008年10月上海雨水样品,分析了大气氮湿沉降浓度,探讨了上海大气湿沉降氮通量及上海市区,市郊和远郊大气氮湿沉降的时空污染特征.结果表明:(1)上海市区、市郊和远郊大气氮湿沉降质量浓度平均值分别为2.96、2.31、2.21 mg/L.从上海大气湿沉降总体来看,大气氮湿沉降劣V类、V类的超标率分别达到51.09%和13.87%.推断大气氮湿沉降的主要来源是机动车辆所排放的大量氮氧化物.(2)除冬季外,其余季节上海市区大气氮湿沉降浓度均大于市郊和远郊;市区和远郊大气氮湿沉降浓度均在秋季最大,市郊大气氮湿沉降浓度在春季最大.(3)上海大气年氮湿沉降通量为78.42 kg/hm~2,同其他区域相比较,属于世界上高氮沉降区域.(4)上海大气月氮沉降通量与月平均降雨量呈显著的线性正相关(p<0.05),说明上海大气氮湿沉降通量主要受降雨量的影响.     

小麦生长周期中土壤Cu的迁移转化实验研究

通过盆栽试验,研究了不同土壤Cu添加浓度下,在小麦生长不同时期,小麦根区土壤与非根区土壤中总量Cu和有效态Cu的浓度,以此揭示其迁移转化特征。研究发现:小麦生长可以对土壤中的Cu进行吸收,拔节期小麦吸收能力最强;Cu添加有利于小麦对土壤中Cu的吸收,在试验水平下,添加浓度越高促进作用越明显,在200 mg/kg Cu添加浓度下,成熟期土壤中Cu含量较幼苗期减少了79%;小麦生长使土壤中有效态Cu占总量Cu的比重增加,并且使非根区土壤中Cu向根区土壤迁移。     

难降解氯代有机物污染环境的生物修复技术研究进展

氯代有机物是一类在生产和生活中广泛应用并被大量排放到环境中的难降解有机污染物质,一旦进入生态环境,就会在水体、土壤和底质中长期残留,并在食物链中不断积累、富集,从而对生物体产生危害。因此,对受这类难降解有机物污染的环境修复是目前所迫切需要解决的环境问题之一。基于物理和化学修复方法成本较高易造成二次污染,文中探讨了国内外生物修复技术的研究进展,并对难降解氯代有机物污染环境修复的研究方向进行了展望,由于环境中的污染物质复杂多变,联合生物修复技术将成为未来的研究热点。     

金矿污染河流的水体和沉积物中重金属分布特征及生态风险评价

金矿开采导致严重的水体和沉积物重金属污染。采用电感耦合等离子体质谱仪(ICP/MS)分析了金矿开采区河道32个采样点的水体和表层沉积物样品,研究了水样的溶解态及颗粒态重金属(As、Pb、Cd、Cr、Cu、Zn)组成;通过分步化学提取法研究了各重金属在沉积物中的地球化学形态组成,利用地累积指数法和潜在生态风险指数法评价了河流沉积物中重金属污染状况。结果表明:水体中Cu、Zn、As主要以溶解态存在,Pb、Cr、Cd以颗粒态为主。水体中重金属元素形态分布主要受点源污染排放影响。沉积物中,Cd浓度较低;As、Zn主要以氧化物结合态、有机物结合态和残渣态存在;Pb、Cr、Cu以有机物结合态和残渣态为主。结合地累积指数和潜在生态风险指数分析表明,Cd和Cu为主要的风险元素。     

可变电荷土壤介入应急混凝处置镉污染的可行性研究

以南方可变电荷土壤作为突发高浓度镉污染水体应急混凝处置的强化混凝药剂,考察了可变电荷土壤介入应急处置对混凝效果的影响。并模拟构建了镉污染应急处置产生沉积物,通过静态释放实验方式,开展了可变电荷土壤介入应急混凝处置对含镉沉积物中Cd释放的影响的研究。结果表明混凝时,在偏碱性条件下,投加可变电荷土壤有利于提高镉的去除率,可以将水体镉浓度由1.892 mg·L-1降到30μg·L-1。在静态释放实验中,不同的溶解氧条件下镉释放量存在差异,但可变电荷土壤介入应急混凝处置都不同程度地促进了沉积物中Cd的释放。在镉污染水体的应急处置中投加可变电荷土壤来强化混凝可以有效降低水体的残余镉浓度,但可变电荷土壤的介入使得沉积物组分发生了变化,使得混合沉积物在应急处置后具有二次污染的风险。     

Environmental fate of amitrole: influence of dissolved organic matter

In this study the environmental fate of amitrole in terrestrial and aquatic model ecosystems was investigated. Under aerobic conditions mineralization of amitrole is the main degradation pathway. The experiments revealed that the leaching behaviour is low in the presence or the absence of dissolved organic matter (DOM) despite the high water solubility due to a strong binding of amitrole to soil constituents. Under anaerobic conditions the addition of DOM increases the transport of amitrole in soil columns. The tests with water/sediment model ecosystems showed that the mineralization of amitrole is lower in comparison to aerobic soil experiments. Up to 80.6% of the applied 14C-labelled amitrole transfer into the sediment and about 1/3 of this amount formed bound residues, which are not extractable.     

Simulating the temporal changes of OCP pollution in Hangzhou, China

A dynamic fugacity model was applied to simulate the changes of contents and transfer fluxes of hexachlorocyclohexane (HCHs) and dichloro-diphenyl-trichloroethane (DDTs) from 1950s in the environment of Hangzhou, China. The receptors are composed of air, surface water, soils, sediment and biota compartments. The model provides a method to combine loadings of HCHs and DDTs from various sources with a series of physical-chemical processes to estimate concentrations and transport fluxes of HCHs and DDTs. Model results suggested that the calculated concentrations were in line with the observed ones. The highest contents of HCH and DDT in the environment of study area were 523 t and 471 t before 1983, among which about 80.7% HCHs and 93.2% DDTs remained in the soil compartment. From 1984 to now, contents of HCHs and DDTs had decreased to about 0.07% and 0.40% of their highest amount (before 1983), and only about 0.001% and 0.014% will expect to be left in 2020 in the study area according to the model prediction. Before 1983, the main transfer fluxes of HCHs were deposition from air to soil, runoff from soil to water and diffusion from soil to air, but for DDTs the main transfer fluxes were deposition from air to soil and water, and transfer from water to sediment. From 1984 to now, runoff from soil to water and transfer from water to sediment became the dominant processes. Although a large amount of HCHs and DDTs had been applied to the study area, their residue levels in the soils were much lower than those in North China (had lesser HCHs and DDTs application than in South China) at present time, and close to other locations of South China (had similar HCHs and DDTs application level). It can be attributed to the high precipitation and temperature that enhances the processes of wet deposition, evaporation and degradation of OCPs. Sensitivities of the input parameters to the calculated concentrations were evaluated using coefficient-of-variation normalized sensitivity coefficients. The model was also subjected to uncertainty analyses using a Monte Carlo simulation.     

Fate of the herbicide 14C-terbuthylazine in Brazilian soils under various climatic conditions

14C-terbuthylazine was applied to three Brazilian soils in closed aerated laboratory microcosms, both under standardized and under natural Brazilian climate conditions. Volatilization from soil to air, leaching from soil to percolate water, and transport from upper to deeper soil layers were higher in sandy soil than in clay soil and in organic soil. Mineralization of 14C-terbuthylazine to 14CO2 was higher in sandy soil than in clay and organic soils under standardized climatic conditions, whereas it was higher in organic soil than in sandy soil under Brazilian summer conditions. Under natural Brazilian summer conditions, leaching as well as vertical transport within the soil were enhanced as compared to standardized climate conditions comprising lower precipitation rates; volatilization was strongly reduced under high irrigation conditions.     

Evaluation of the ecotoxicological impact of the organochlorine chlordecone on soil microbial community structure,abundance, and function

The insecticide chlordecone applied for decades in banana plantations currently contaminates 20,000 ha of arable land in the French West Indies. Although the impact of various pesticides on soil microorganisms has been studied, chlordecone toxicity to the soil microbial community has never been assessed. We investigated in two different soils (sandy loam and silty loam) exposed to different concentrations of CLD (D0, control; D1 and D10, 1 and 10 times the agronomical dose) over different periods of time (3, 7, and 32 days): (i) the fate of chlordecone by measuring ¹⁴C-chlordecone mass balance and (ii) the impact of chlordecone on microbial community structure, abundance, and function, using standardized methods (-A-RISA, taxon-specific quantitative PCR (qPCR), and ¹⁴C-compounds mineralizing activity). Mineralization of ¹⁴C-chlordecone was inferior below 1 % of initial ¹⁴C-activity. Less than 2 % of ¹⁴C-activity was retrieved from the water-soluble fraction, while most of it remained in the organic-solvent-extractable fraction (75 % of initial ¹⁴C-activity). Only 23 % of the remaining ¹⁴C-activity was measured in nonextractable fraction. The fate of chlordecone significantly differed between the two soils. The soluble and nonextractable fractions were significantly higher in sandy loam soil than in silty loam soil. All the measured microbiological parameters allowed discriminating statistically the two soils and showed a variation over time. The genetic structure of the bacterial community remained insensitive to chlordecone exposure in silty loam soil. In response to chlordecone exposure, the abundance of Gram-negative bacterial groups (β-, γ-Proteobacteria, Planctomycetes, and Bacteroidetes) was significantly modified only in sandy loam soil. The mineralization of ¹⁴C-sodium acetate and ¹⁴C-2,4-d was insensitive to chlordecone exposure in silty loam soil. However, mineralization of ¹⁴C-sodium acetate was significantly reduced in soil microcosms of sandy loam soil exposed to chlordecone as compared to the control (D0). These data show that chlordecone exposure induced changes in microbial community taxonomic composition and function in one of the two soils, suggesting microbial toxicity of this organochlorine.     

Fate, effects and potential environmental risks of ethylene glycol: a review

The fate, effects, and potential environmental risks of ethylene glycol (EG) in the environment were examined. EG undergoes rapid biodegradation in aerobic and anaerobic environments (approximately 100% removal of EG within 24 h to 28 days). In air, EG reacts with photo-chemically produced hydroxyl radicals with a resulting atmospheric half-life of 2 days. Acute toxicity values (LC(50)s and EC(50)s) were generally >10,000 mg/l for fish and aquatic invertebrates. The data collectively show that EG is not persistent in air, surface water, soil, or groundwater, is practically non-toxic to aquatic organisms, and does not bioaccumulate in aquatic organisms. Potential long-term, quasi-steady state regional concentrations of EG estimated with a multi-media model for air, water, soil, and sediment were all less than predicted no effect concentrations (PNECs).     

PLATIN (plant-atmosphere interaction) I: A model of plant-atmosphere interaction for estimating absorbed doses of gaseous air pollutants

A PLant-ATmosphere INteraction model (PLATIN) was developed for estimating air pollutant absorbed doses under ambient conditions. PLATIN is based on the canopy energy balance combined with a gas transport submodel. The model has three major resistance components: (1) a turbulent atmospheric resistance Rah(zm) that describes the atmospheric transport properties between a measurement height above the canopy and the conceptual height z=d+z0m which represents the sink for momentum according to the big-leaf concept; (2) a quasilaminar layer resistance R(b,A) that quantifies the way in which the transfer of sensible heat and matter (e.g. latent heat, ozone) differs from momentum transfer; (3) a canopy or surface resistance R(c,A) that describes the influences of the plant/soil system on the exchange processes. Soil water content is simulated by a Force-Restore model. By a simple interception submodel precipitation and dew are partitioned into intercepted water and water reaching the soil surface. PLATIN can be run in a prognostic or a diagnostic mode. It is also intended for on-line use in air quality monitoring networks.     

Modelling the accumulation of hydrophobic organic chemicals in earthworms

In this paper a method is developed which can be used to estimate the body burden of organic hydrophobic chemicals in earthworms. In contrast to the equilibrium partitioning theory, two routes of uptake are incorporated: uptake from interstitial water and dietary uptake. Although many uncertainties still remain, calculations show that for earthworms steady state body burdens are mainly determined by uptake from interstitial water. Under most circumstances, the contribution of dietary uptake is small, except for hydrophobic chemicals (log K_ow > 5) in soils with a high organic matter (OM) content of ≈ 20 %. Under those conditions, estimates of the steady state body burden calculated with the equilibrium partitioning model, in which only uptake from interstitial water is taken into account, might result in a small underestimation of the real body burden of chemicals in earthworms.     

Acidification, metals and macrophytes

Plant-specific and metal-specific uptake of Al, Cd, Pb and Hg are reviewed, using examples from bryophytes, lichens, wetland plants, woody plants and crop plants. Ranges of plant metal concentration, toxic thresholds and effects, and effects of metal on biomass are derived from the literature. Relationships of metal in plants to metals in sediment, soil water and air are discussed. Plant Al is negatively correlated with pH of water in lakes and with soil pH. Cadmium in crop plants is negatively related to soil pH. Lead in submergents is related negatively to sediment pH at 4.5 to 6. Little information on plant Hg was available. Factors affecting plant uptake include soil or sediment organic content, carbon exchange capacity, oxide and carbonate content, and Eh as well as total metal content.     

Review of recent advances in research on the toxicity,detection, occurrence and fate of cyclic volatile methyl siloxanes in the environment

The fate and behavior of cyclic volatile methylsiloxanes (cVMS) octamethylcyclotetrasiloxane (D4), decamethylcyclopentasiloxane (D5), and dodecamethylcyclohexasiloxane (D6) in the environment were reviewed. We evaluated their usage data and patterns, physico-chemical properties, toxicology, partitioning and degradation, methods of detection, and concentrations. The use of cVMS as an intermediate in the formation of silicone polymers, personal care and household products has resulted in their widespread environmental exposure; they have been detected in biogas, air, water, soil, biosolid, sediment, and biota samples. Modeled and experimental results suggest that cVMS may be subject to long-range atmospheric transport, but have low potential to contaminate the Arctic. For D4 and D5, there was no evidence of trophic biomagnification in aquatic food webs, while some aquatic organisms demonstrated a high degree of bioconcentration and bioaccumulation. High concentrations of cVMS observed in indoor air and biosolids resulted from point sources. Concentrations of cVMS in water, sediment, and soil were all below their no-observed-effect-concentrations.     

Large-scale fires and time trends of PCDDS/DFs in sediments

Drastic increases in PCDDs/DFs concentrations were identified in the uppermost layers of a sediment core sample taken from the coastal area of Kobe City. As large-scale fires caused by the Great Hanshin-Awaji earthquake were deemed to be a possible cause, we performed additional sampling of sediment cores and surface sediment samples, estimating the total amount of PCDDs/DFs released from fires and presuming the load to sediments by individual transport routes, such as air and water, using an air diffusion model to investigate the influence of fires. The total amount of PCDDs/DFs released from fires was estimated at 2000 g-total PCDDs/DFs, 22 g-TEQ. Increases in PCDDs/DFs generated in fires were principally transported through water rather than air. If 20% of the total PCDDs/DFs formed in fires had entered water, it would correspond to the entire increase of PCDDs/DFs concentration in sediment cores.