Plant communities in relation to flooding and soil contamination in a lowland Rhine River floodplain

Using canonical correspondence analysis (CCA), relationships were investigated between plant species composition and flooding characteristics, heavy metal contamination and soil properties in a lowland floodplain of the Rhine River. Floodplain elevation and yearly average flooding duration turned out to be more important for explaining variation in plant species composition than soil heavy metal contamination. Nevertheless, plant species richness and diversity showed a significant decrease with the level of contamination. As single heavy metal concentrations seemed mostly too low for causing phytotoxic effects in plants, this trend is possibly explained by additive effects of multiple contaminants or by the concomitant influences of contamination and non-chemical stressors like flooding. These results suggest that impacts of soil contamination on plants in floodplains could be larger than expected from mere soil concentrations. In general, these findings emphasize the relevance of analyzing effects of toxic substances in concert with the effects of other relevant stressors.     

Influencing factors and a proposed evaluation methodology for predicting groundwater contamination potential from stormwater infiltration activities.

To offset the detrimental effects of urbanization on groundwater recharge, stormwater managers are focusing on infiltrating much of the runoff from a site that was generated because of development. For this to be effective, tools are required to predict the potential for contamination resulting from this infiltration for many site conditions, because infiltration should be stressed in areas where the least potential for causing groundwater contamination exists. Factors that influence contamination potential include the pollutant concentration in the runoff directed to the infiltration device and the ability of the underlying soil to remove the pollutant. The groundwater contamination potential of some pollutants, even those with high concentrations and moderate-to-high mobilities, can be reduced with proper pretreatment before infiltration. This paper presents a methodology that can be used to evaluate infiltration as an management option and introduces two different levels of models that could be used to evaluate contamination potential.     

Quantitative–spatial assessment of soil contamination in S. Francisco de Assis due to mining activity of the Panasqueira mine (Portugal)

Through the years, mining and beneficiation processes produces large amounts of As-rich mine wastes laid up in huge tailings and open-air impoundments (Barroca Grande and Rio tailings) that are the main source of pollution in the surrounding area once they are exposed to the weathering conditions leading to the formation of AMD and consequently to the contamination of the surrounding environments, in particularly soils. In order to investigate the environmental contamination impact on S. Francisco de Assis (village located between the two major impoundments and tailings) agricultural soils, a geochemical survey was undertaken to assess toxic metals associations, related levels and their spatial distribution, and to identify the possible contamination sources. According to the calculated contamination factor, As and Zn have a very high contamination factor giving rise to 65.4 % of samples with a moderate to high pollution degree; 34.6 % have been classified as nil to very low pollution degree. The contamination factor spatial distribution put in evidence the fact that As, Cd, Cu, Pb, and Zn soils contents, downstream Barroca Grande tailing, are increased when compared with the local Bk soils. The mechanical dispersion, due to erosion, is the main contamination source. The chemical extraction demonstrates that the trace metals distribution and accumulation in S. Francisco de Assis soils is related to sulfides, but also to amorphous or poorly crystalline iron oxide phases. The partitioning study allowed understanding the local chemical elements mobility and precipitation processes, giving rise to the contamination dispersion model of the study area. The wind and hydrological factors are responsible for the chemical elements transport mechanisms, the water being the main transporter medium and soils as one of the possible retention media.     

ESF Workshop

Dioxin and PCB monitoring programs for food and feeding stuff in most countries of the world, including many European Countries are currently inadequate. Better control of food production lines and food processing procedures is needed to minimize entry of dioxin to the food chain and will help to avoid dioxin contamination accidents. This would also improve the ability to trace back a possible contamination to its source. European guidelines for monitoring programs should be established to ensure comparable and meaningful results. These guidelines should define the minimum requirements for the design of monitoring programs, analytical methods, and quality assurance. Though data from Northern Europe shows that the general population exposure to dioxin and PCB has decreased during the last ten years these compounds continue to be a risk of accidental contamination of the food chain. The most prominent recent example is the Belgian dioxin contamination of feeding stuff in 1999. The Belgian dioxin contamination was not detected due to dioxin monitoring programs but by their direct biological effects seen in animals. Four other cases of dioxin contamination have been detected in Europe since 1997 due to local monitoring programs. One of them (citrus pulp pellets 1998) was in a much larger scale than the Belgian dioxin contamination. The general population's exposure to dioxins and PCBs is still in the same range (1-4 pg WHO-TEQ/kg body weight and day) as the recently revised WHO tolerable daily intake (TDI). There is concern that short-term high level exposure to dioxins, furans, and PCB may cause biological effects on the human fetal development and further research is required. Further actions to control sources building on considerable advances already made in many countries may need to be supplemented by measures to prevent direct contamination of feeding stuff or food to reduce general population exposure further.     

An appraisal of soil diffuse contamination in an industrial district in northern Italy

Soil diffuse contamination is one the major soil threats, especially in regions with a high population density and strong industrialization. In this work agricultural, natural, and periurban soils of an Italian Province (858 km(2)) were sampled and analyzed. Overall, 140 samples were taken at two depths and analyzed for 10 trace elements, 13 rare earth elements and for organic contaminants (PCBs, PCDDs and PAHs). The aim of this work was to obtain an appraisal of soil diffuse contamination in a large Italian Province by applying and validating available tools to quantify background values and evaluate the intensity of contamination. Data were processed, background values estimated, and enrichment and contamination factors calculated. For some contaminants the results allowed a discrimination between natural or anthropic-derived contaminants. Some contaminants revealed clear trends of enrichment in function of the land use (in particular for periurban soils). REEs were found to mostly derive from parent material. The results obtained in this study show the importance of merging the quantification of contaminants with the elaboration of indices of contamination. These require an accurate quantification of background values to be able to discriminate the anthropic contribution. Enrichment factor resulted to be more accurate than contamination factor but it cannot be applied to organic contaminants and requires a careful selection of the reference element to be adopted. This study revealed that some contaminants - Sb, Sn, Pb, and organic contaminants - can be used as tracers of diffuse contamination, and should be therefore always included in similar studies.     

中国蔬菜硝酸盐和亚硝酸盐污染因素及控制研究

本文综述了近十几年来我国城市蔬菜中硝酸盐和亚硝酸盐污染的研究结果,表明随着氮肥使用量的增大,蔬菜中硝酸盐污染较为严重而亚硝酸盐污染也不容忽视。探讨了蔬菜受硝酸盐和亚硝酸盐污染的影响因素及控制对策     

Sulfate contamination in groundwater from a carbonate-hosted mine

Sulfide oxidation in a carbonate environment produces groundwater contamination with high sulfate making the water unsuitable for drinking supplies. The zinc-lead mines near Shullsburg, Wisconsin are located in the Galena-Platteville Formation, a carbonate aquifer that was dewatered during mining. Sulfate levels have reached as high as 40 nmol/l in some local wells and eleven wells were abandoned.Geochemical modeling of chemical reactions and isotope effects using the USGS computer program PHREEQE showed the importance of dolomite, calcite, CO₂, and siderite or iron hydroxide in controlling the water chemistry. The decrease in sulfate levels with time indicated that dilution by incoming recharge water was an ongoing process. The results of carbon isotope reaction modeling are consistent with dilution of contaminated water. The evidence for localization of contamination and dilution means that area farmers have seen the worst of the contamination. The mechanism of contamination was further examined by microbiological sampling and sulfur isotope determinations, which indicated that bacteria of the Thiobacillus species that thrive under neutral pH conditions may have catalyzed sulfide oxidation.Research into the chemical evolution of contamination in this environment not only explains how sulfide oxidation causes contamination despite buffering by carbonate rocks, but also suggests how oxidation is initiated in the case of acid mine drainage.     

Effect of air-conditioner on fungal contamination

Air-conditioners (AC) produce much dew and wet conditions inside their apparatus, when in operation. We studied the fungal contamination in AC and found that the average fungal contamination of AC filters was about 5-fold greater than that of a carpet, and Cladosporium and Penicillium were predominant in AC filters. The fungal contamination inside AC, which were used everyday, increased more markedly than those not used daily, e.g. a few days per week or rarely. Moreover, the airborne fungal contamination in rooms during air-conditioning was about 2-fold greater than one in rooms without AC, and was highest when air-conditioning started and decreased gradually with time. We recognized that the airborne fungal contamination was controlled by the environmental condition of the rooms, in which AC were used. It is suggested that AC might promote mold allergies in users via airborne fungal spores derived from the AC. On the other hand, AC was estimated to remove moisture in the room atmosphere and carpets, and reduce the relative humidity in rooms. It was found that the average fungal contamination in the house dust of carpets with AC was suppressed by two-third of that in rooms without AC. The use of AC for suppressing fungal hazards was discussed.     

A study on PCB, PCDD/PCDF industrial contamination in a mixed urban-agricultural area significantly affecting the food chain and the human exposure. Part I: soil and feed

This study deals with a PCB, PCDD and PCDF contamination in Brescia, a city in the North-West of Italy, affecting an area with about 11000 inhabitants. The area is close to an industrial plant that produced, in total, some 31,000 ton of PCB. A relevant part of the polluted area is agricultural soil, where cattle were fed with polluted forage and farmers were consuming their own products, so that contamination led eventually to human exposure. Total levels of PCDD/Fs varied from 8 to 592 pgTE(WHO)/g for soil samples and when the dioxin-like PCBs (dl-PCBs) are included, the levels varied from 14.6 to 1033.7 pgTE(WHO)/g. In several cases, the legal limit was exceeded by more than one order of magnitude, with the highest contamination in some agricultural areas and in the surrounding zones. For the forage samples, total levels of PCDD/Fs varied from 0.29 to 2.04 pgTE(WHO)/g and, when dl-PCBs are included, this range increased from 2.04 to 4.75 pgTE(WHO)/g. PCB contamination of the forage through vapor condensation seemed to be relevant. The toxic contribution of dl-PCBs is always relevant and must be considered for risk management. The main component of the contamination source is probably a heavy PCB mixture, such as Aroclor 1262. The study dealt generally with the contamination transfer of PCBs, PCDDs and PCDFs from soil up to humans across the food chain. Results on soils and forages are shown, while measurements concerning the contamination of the animals fed with contaminated forage, and the exposure of the farmers (through human serum analyses), as compared to general population, will be reported in a dedicated paper.     

Combining a finite mixture distribution model with indicator kriging to delineate and map the spatial patterns of soil heavy metal pollution in Chunghua County, central Taiwan

This study identifies the natural background, anthropogenic background and distribution of contamination caused by heavy metal pollutants in soil in Chunghua County of central Taiwan by using a finite mixture distribution model (FMDM). The probabilities of contaminated area distribution are mapped using single-variable indicator kriging and multiple-variable indicator kriging (MVIK) with the FMDM cut-off values and regulation thresholds for heavy metals. FMDM results indicate that Cr, Cu, Ni and Zn can be individually fitted by a mixture model representing the background and contamination distributions of the four metals in soil. The FMDM cut-off values for contamination caused by the metals are close to the regulation thresholds, except for the cut-off value of Zn. The receiver operating characteristic (ROC) curve validates that indicator kriging and MVIK with FMDM cut-off values can reliably delineate heavy metals contamination, particularly for areas lacking background information and high heavy metal concentrations in soil.     

Heavy metals, PCDD/F and PCB in sewage sludge samples from two wastewater treatment facilities in Rio de Janeiro State, Brazil

Two sewage sludge samples collected from an urban as well as a rural area in Brazil and one sludge sample originating from the city of Balingen, Baden-Württemberg, South Germany, were investigated in respect to contamination with heavy metals, PCDD/F and PCB. The results were compared to PCDD/F and indicator-PCB mean values found in the region of Baden-Württemberg. The observed toxicity equivalents of PCDD/F found in the Brazilian samples, were below the upper limit specified by German legislation for final disposal or agricultural use in soils. Both the PCB and heavy metal values exceeded this limit. The PCDD/F congener/homologue profiles found in the Brazilian samples indicated that the urban sewage sludge shows a contamination where both chlorophenols and depositional sources appear to be contributing to the contamination pool. The enrichment of highly chlorinated PCDD/F groups in the sludge of semi-rural origin is probably due to transport phenomena effects. For the German sludge sample, depositional sources seem to be the main PCDD/F contamination pathway. Regarding PCB, both Brazilian samples show a homologue profile that indicates a contamination stemming from technical PCB formulations like Clophen A50 and Clophen A60 or equivalent.     

Modeling dissolution and volatilization of LNAPL sources migrating on the groundwater table

A vertically averaged two-dimensional model was developed to describe areal spreading and migration of light nonaqueous-phase liquids (LNAPLs) introduced into the subsurface by spills or leaks from underground storage tanks. The NAPL transport model was coupled with two-dimensional contaminant transport models to predict contamination of soil gas and groundwater resulting from a LNAPL migrating on the water table. Numerical solutions were obtained by using the finite-difference method. Simulations and sensitivity analyses were conducted with a LNAPL of pure benzene to study LNAPL migration and groundwater contamination. The model was applied to subsurface contamination by jet fuel. Results indicated that LNAPL migration were affected mostly by volatilization. The generation and movement of the dissolved plume was affected by the geology of the site and the free-product plume. Most of the spilled mass remained as a free LNAPL phase 20 years after the spill. The migration of LNAPL for such a long period resulted in the contamination of both groundwater and a large volume of soil.     

Characterization of heavy metal concentrations in the sediments of three freshwater rivers in Huludao City, Northeast China

Wuli River, Cishan River, and Lianshan River are three freshwater rivers flowing through Huludao City, in a region of northeast China strongly affected by industrialization. Contamination assessment has never been conducted in a comprehensive way. For the first time, the contamination of three rivers impacted by different sources in the same city was compared. This work investigated the distribution and sources of Hg, Pb, Cd, Zn and Cu in the surface sediments of Wuli River, Cishan River, and Lianshan River, and assessed heavy metal toxicity risk with the application of two different sets of Sediment Quality Guideline (SQG) indices (effect range low/effect range median values, ERL/ERM; and threshold effect level/probable effect level, TEL/PEL). Furthermore, this study used a toxic unit approach to compare and gauge the individual and combined metal contamination for Hg, Pb, Cd, Zn and Cu. Results showed that Hg contamination in the sediments of Wuli River originated from previous sediment contamination of the chlor-alkali producing industry, and Pb, Cd, Zn and Cu contamination was mainly derived from atmospheric deposition and unknown small pollution sources. Heavy metal contamination to Cishan River sediments was mainly derived from Huludao Zinc Plant, while atmospheric deposition, sewage wastewater and unknown small pollution were the primary sources for Lianshan River. The potential acute toxicity in sediment of Wuli River may be primarily due to Hg contamination. Hg is the major toxicity contributor, accounting for 53.3-93.2%, 7.9-54.9% to total toxicity in Wuli River and Lianshan River, respectively, followed by Cd. In Cishan River, Cd is the major sediment toxicity contributor, however, accounting for 63.2-66.9% of total toxicity.     

Heavy metal contamination of roadside soils in the Greater Athens area

The airborne contamination of roadside soils with Pb, Cd, Zn and Ni was evaluated for the Greater Athens Area of Greece. High levels of lead enrichment were found in the upper 0-5 cm soil layer along roads with heavy traffic loads. The central section of the study area appeared to have soils with the highest levels of lead enrichment. The contamination decreased exponentially with the distance from the road edge and dropped to a background level at about 50 m. Most of the lead was concentrated in the upper 5 cm of the soil and was associated with carbonates and crystalline oxides. The main source of contamination was automobile exhausts. Roadside soils were also enriched with airborne Cd and Zn, but to a lesser degree than with Pb. The enrichment of the soil with these two elements fell rapidly and exponentially with distance. No evidence of Ni contamination of roadside soils was obtained.     

Total mercury concentrations in an industrialized catchment,the Thur River basin (north-eastern France): geochemical background level and contamination factors

River bottom sediments and soils were collected from the industrialized Thur River basin (north-eastern France) to assess mercury contamination. The regional geochemical background level of total mercury was evaluated to calculate mercury contamination factors (Fc) in soils and river bottom sediments. Our estimate of the mean background mercury levels in river sediments and soils, not affected by human activities, was 232 ng x g(-1) (range: 27-406 ng x g(-1)). Sediments contaminated by the effluent from a chlor-alkali plant yielded the highest contamination factors (Fc=1784). Contamination factors of surficial soils within 1 km of the industrial site range from 6.3 to 43.6. This contamination is attributed to diffuse atmospheric deposition from this local plant. However, even upstream from this industrial area elevated contamination factors were recorded for river bottom sediments (Fc=3.2 to 26.4) and for one alluvial soil profile (Fc=10). This is possibly due to past pollution resulting from waste water discharges. Mercury contamination in the different horizons of alluvial soils is not correlated with soil organic carbon content, but may be the result of occasional accidental pollution arising from the introduction of contaminated suspended particulate matter by the Thur River during periods of flooding.     

A Probability Model for Evaluating Building Contamination from an Environmental Event

ABSTRACT

Asbestos dust and bioaerosol sampling data from suspected contaminated zones in buildings allowed development of an environmental data evaluation protocol based on the differences in frequency of detection of a target contaminant between zones of comparison. Under the assumption that the two test zones of comparison are similar, application of population proportion probability calculates the significance of observed differences in contaminant levels. This was used to determine whether levels of asbestos dust contamination detected after a fire were likely the result of smoke-borne contamination, or were caused by pre-existing/background conditions.

Bioaerosol sampling from several sites was also used to develop the population proportion probability protocol. In this case, significant differences in indoor air contamination relative to the ambient conditions were identified that were consistent with the visual observations of contamination. Implicit in this type of probability analysis is a definition of “contamination” based on significant differences in contaminant levels relative to a control zone. Detection of a suspect contaminant can be assessed as to possible sources(s) as well as the contribution made by pre-existing (i.e., background) conditions, provided the test and control zones are subjected to the same sampling and analytical methods.     

基于可视角度下重金属污染物在介质中的迁移规律

介质中污染物迁移的可视化研究有助于厘清污染物及介质间微观作用机制。依托透明土的可视化理念,以Cu(Ⅱ)、Cr(Ⅵ)污染土为研究对象,分析电场及温度场驱动作用下重金属污染物在透明土及实际土体中的迁移分布规律,探讨可视化研究的可靠性并建立重金属污染物的界面迁移机制。结果表明,透明土可用于研究多孔介质中重金属污染物的迁移扩散性,电场及温度场作用下同点位污染物质量分数的波动率均在10%以内;电场作用下污染物的迁移由离子赋存状态所带电荷决定,Cu(Ⅱ)、Cr(Ⅵ)分别以阳离子、酸根阴离子状态存在,迁移方向相反。Cu(Ⅱ)因铜胶体絮凝物生成易产生聚集效应,迁移受阻;温度场作用下污染物的迁移取决于温度梯度,因土颗粒高低温处结合水厚度的差异及水分子间的吸力会促使孔隙流体迁移以达平衡,重金属污染物在对流和分子扩散的协调作用下,均表现为向低温处迁移趋势。在同外力驱动作用下,重金属污染物间的迁移存在差异性,Cr(Ⅵ)的迁移性均强于Cu(Ⅱ)的,化学沉淀物质的产生及重金属阳离子静电吸附作用是影响迁移效率的内在关键。本研究结果可为土壤污染预测及修复研究提供参考。     

Evaluating contamination of dredges and disposal criteria in Greek coastal areas

Sediments were collected from areas that were going to be dredged located at six small Greek ports, as well as from possible disposal areas. In order to assess the contamination level of dredged material, the samples were analysed for pH, organic matter, the metals Cd, Pb, Hg, Cr, Ni, Cu, Zn and major organic compounds (PAHs, PCBs). The sediments' quality was evaluated by two approaches: (i) by classifying each area according to two sets of Sediment Quality Guidelines (SQGs) and (ii) by calculating the contamination factors and degree for each area. The results showed that organic compounds were detected in trace amounts in 14% of the port samples belonging to the PAHs group. The characterization of the sediment samples was based on the metals' concentration showing that the majority of the areas to be dredged (80%) are classified as of medium-low contamination according to the SQGs. However, according to the contamination degree, only 30% of the areas are classified as of low contamination, while 40% as of moderate contamination and 30% of the areas as of considerable contamination. From the point of view of "no disturbance" of the ecosystem, decisions about dumping should be taken only after evaluating the material to be dredged. If the SQGs are exceeded, dumping must be forbidden. Otherwise, further evaluation is needed based on the comparison with the receiving area, i.e. by estimating the contamination degree. Dumping could be allowed if the contamination degree is found to be below moderate.     

粘土覆盖层对防治污水渗漏污染地下水作用的研究

本文通过实际类比的研究方法 ,对粘土覆盖层防治污水明渠渗漏污染地下水的作用进行了探讨 ,并确定了粘土覆盖层防止地面污水渗漏污染地下水所必需的临界厚度范围。     

室内环境污染研究进展

介绍了室内环境污染问题的由来及危害、研究对象及内容 ,并对国内外在室内环境这一新兴学科领域所开展的研究工作进行了综述 ,同时指出了我国进行室内环境污染系统研究的必要性。