Urban environmental mercury in Changchun, a metropolitan city in Northeastern China: source, cycle, and fate

Mercury concentrations in each environmental compartment in Changchun City had obvious spatial and temporal trends. Particulate Hg (HgP) and total gaseous mercury (TGM) concentrations in air, total Hg (HgT) concentrations in precipitation and ratios of HgP to HgT (total Hg in air) in the atmosphere in heating season were higher than those in non-heating season, which resulted from civil heating. In contrast, reactive Hg (HgR) concentrations in precipitation were higher in non-heating season than those in heating season. TGM and SO2 in air had good agreement. HgP concentrations in the atmosphere were correlated with HgT concentrations in precipitation. Based on Hg concentrations in each environmental compartment, Hg exchange fluxes between environmental interfaces were estimated. Only 11.6% of Hg, emitted from coal combustion, deposited into land surface in urban district and the rest part participated in regional or global cycle, so urban district was the source of Hg global and regional cycle. Net fluxes of Hg into land surface and water were 34.26 kg year(-1) and 0.051 kg year(-1), respectively, which were clearly accumulated in the water and soil. Therefore considering urban local Hg cycle, each environmental compartment of urban ecosystem (water, air and soil) was the sink of Hg.     

Volatile organic compound (VOC) adsorption on material: influence of gas phase concentration, relative humidity and VOC type

This paper presents the results of a factorial experiment design analysis to investigate volatile organic compounds (VOC) adsorption on a ceiling tile. The impacts of three factors, VOC gas phase concentration, relative humidity, and VOC type, as single parameters and as a combination, on adsorption have been investigated. Cyclohexane, toluene, ethyl acetate, isopropyl alcohol and methanol were the five VOCs used in this study. A factor significant level was determined through evaluating its F value and comparing it with the critical value of F distribution at 95% confidence level. It was found that: (i) neither the relative humidity and gas phase concentration nor any interaction effect between them had significant impacts on toluene adsorption on the ceiling tile; (ii) the adsorption isotherm appeared to be linear for the non-polar compounds and non-linear for the semi-polar and polar compounds; (iii) no significant impact of relative humidity on adsorption was observed for most VOC compounds except for methanol; and (iv) the ceiling tile had the highest adsorption capacity toward the polar compounds, followed by the aromatic compounds and aliphatic compounds. In addition, the statistical analysis regarding the experimental results of toluene as a single compound or as a part of a mixture showed that toluene adsorption capacity on the ceiling tile as a single compound was higher than as a part of a mixture. PRACTICAL IMPLICATIONS: Building materials and furnishings may act as source and sink of VOCs in the indoor environment. In this study, a factorial experiment design analysis technique was used to show the impact of three factors, VOC gas phase concentration, relative humidity, and VOC type, as single parameters and as a combination, on the adsorption process (sink effect). The aim was to better understand the interaction between these parameters and to verify the common assumptions made in the model development and measurement of indoor air quality.     

An assay on the effect of preliminary restoration tasks applied to a large TENORM wastes disposal in the south-west of Spain

A large industrial wastes disposal site, where two phosphate rock processing plants release their wastes, located close to Huelva town (SW of Spain), has been partially submitted to restoration as a preliminary step in a possible decomissioning process. Due to the high natural radioactivity contents of these wastes, this repository is considered as a radiological anomaly, being actually considered as TENORM (technically enhanced naturally occurring radioactive materials). The efficiency of this restoration from the radiological point of view according to the new European regulatory framework was evaluated in this work. The results allow to conclude that, as a consequence of the partial restoration works, the external dose rate has been drastically reduced above the repository system. Nevertheless, special attention must be paid on the occupational factor to be applied to workers on the unrestored system. The application of a dosimetric model allows the prediction of the negative effects of using certain industrial wastes as a cover system in this restoration/mitigation task.     

Accumulation of heavy metals in circumpolar willow ptarmigan (Lagopus l. lagopus) populations

A circumpolar survey of heavy metals in willow ptarmigan liver and kidney revealed considerable variations in Cd content in Canada and Scandinavia. The Cd content in central Canada was comparable with that in Scandinavia and Russia, at least for kidney. However, in both liver and kidney the median for Canada as a whole was much higher than in the other countries. Some Canadian locations had exceptionally high levels, several birds having >50 mg kg(-1) in liver and >400 mg kg(-1) in kidney. In Norway, the Cd content was highest in central mountain areas in south Norway and inland locations in the two northernmost counties. Five locations in central and north Norway showed mean Cd levels in kidney above 100 mg kg(-1). It is difficult to evaluate regional differences in Sweden, but most locations had the same Cd level as moderately contaminated locations in Norway. Cd levels in Russia were comparable to moderately contaminated locations in the other countries. Due to a high intake of willow, naturally rich in Cd, direct comparison of the Cd level in willow ptarmigan from different locations cannot reveal the effects of long-range pollution. The Pb concentration in willow ptarmigan kidney and liver varied significantly in Norway and Canada, but not in Sweden and Russia. Levels in Sweden and Russia were comparable to those in Canada and low levels in Norway. The highest median value from all locations within countries was found in Norway, both in liver and kidney. The highest Pb content was found in south Norway, indicating an effect of long-range pollution in willow ptarmigan. The level in western Canada was significantly higher than in central Canada. The Hg content in liver varied significantly from one location to another in all the countries and in kidney everywhere except Sweden. In Scandinavia, there is no distinct regional pattern. Canada had a significantly higher Hg level in central than western regions in both tissues the opposite of that found for Cd and Pb. Cu and Zn showed significant variations from one location to another in liver and kidney in Canada and Norway, but only in kidney in samples from Sweden. Comparison between western and central Canada revealed a significant difference for Cu in liver, samples from central Canada having more. There are no significant differences from one country to another, but some localities in Canada seem to have higher Cu concentrations in kidney than are found in Scandinavia and Russia.     

Atmospheric mercury depletion event study in Ny-Alesund (Svalbard) in spring 2005. Deposition and transformation of Hg in surface snow during springtime

A field campaign was conducted in Ny-Alesund (78 degrees 54'N, 11 degrees 53'E), Svalbard (Norway) during April and May 2005. An Atmospheric Mercury (Hg) Depletion Event (AMDE) was observed from the morning of April 24 until the evening of April 27. Transport of already Hg and ozone (O3) depleted air masses could explain this observed depletion. Due to a snowfall event during the AMDE, surface snow Hg concentrations increased two fold. Hg deposition took place over a short period of time corresponding to 3-4 days. More than 80% of the deposited Hg was estimated to be reemitted back to the atmosphere in the days following the event. During the campaign, we observed night and day variations in surface snow Hg concentrations, which may be the result of gaseous elemental mercury (GEM) oxidation to divalent Hg at the snow/air interface by daylight surface snow chemistry. Finally, a decrease in the reactive Hg (HgR) fraction of total Hg (HgT) in the surface snow was observed during spring. We postulate that the transformation of HgR to a more stable form may occur in Arctic snow during spring.     

Selecting a battery of bioassays for ecotoxicological characterization of wastes

This study was conducted in France within the context of waste classification (Hazardous Waste Council Directive 91/689/EEC), and focused on "ecotoxic" property (H14). In 1998, an experimental test strategy was developed to assess ecotoxicological properties of wastes using a battery of six standardized bioassays. This combined direct and indirect approaches integrating two solid-phase tests: emergence and growth inhibition of Lactuca sativa (14 days), mortality of Eisenia fetida (14 days) and four standardized tests performed on water extracts from wastes: growth inhibition of Pseudokirchneriella subcapitata (3 days), inhibition of mobility of Daphnia magna (48 h), inhibition of reproduction of Ceriodaphnia dubia (7 days), inhibition of light emission of Vibrio fischeri (30 min). This study aimed to set up preliminary conclusions on relevancy of this experimental test strategy, based on data obtained since 1998. Results were analyzed from the combined use of Hierarchical Cluster Analysis, Principal Component Analysis and Nonlinear Mapping. These multivariate analyses clearly showed that it was possible to reduce this number of tests without changing the typology of the wastes. A battery of bioassays including one solid phase test and two tests performed on water extracts (L. sativa, V. fischeri and C. dubia) was found as an optimal solution for characterizing the toxicity of the studied wastes. This optimal battery represents a good basis for determining the H14 property.     

Bioaugmented membrane bioreactor (MBR) with a GAC-packed zone for high rate textile wastewater treatment

The long-term performance of a bioaugmented membrane bioreactor (MBR) containing a GAC-packed anaerobic zone for treatment of textile wastewater containing structurally different azo dyes was observed. A unique feeding strategy, consistent with the mode of evolution of separate waste streams in textile plants, was adopted to make the best use of the GAC-zone for dye removal. Dye was introduced through the GAC-zone while the rest of the colorless media was simultaneously fed through the aerobic zone. Preliminary experiments confirmed the importance of coupling the GAC-amended anaerobic zone to the aerobic MBR and also evidenced the efficacy of the adopted feeding strategy. Following this, the robustness of the process under gradually increasing dye-loading was tested. The respective average dye concentrations (mg/L) in the sample from GAC-zone and the membrane-permeate under dye-loadings of 0.1 and 1 g/L.d were as follows: GAC-zone (3, 105), permeate (0, 5). TOC concentration in membrane-permeate for the aforementioned loadings were 3 and 54 mg/L, respectively. Stable decoloration along with significant TOC removal during a period of over 7 months under extremely high dye-loadings demonstrated the superiority of the proposed hybrid process.     

Assessment of copper bioavailability and toxicity in vineyard runoff waters by DPASV and algal bioassay

The aim of this study was to assess the toxicity of runoff waters in an agricultural multipollution context through an in-depth assessment of copper bioavailability and toxicity. Runoff waters were screened for major ions, metals and diuron. The potential environmental impact of these runoff waters was evaluated using the conventional 72-h growth inhibition test with the green alga Pseudokirchneriella subcapitata. The results suggested that the toxicity detected in the calcareous vineyard field was due to the presence of diuron, whereas the non-calcareous runoff waters were non-toxic. Chemical speciation modelling by MINEQL revealed that most of the copper present in the non-toxic natural runoff waters was complexed by organic matter. These samples were spiked with copper, and then the toxicity and the electrochemically bioavailable copper fraction were measured. Differential pulse anodic stripping voltammetry (DPASV) was used to detect labile complexes and free copper. This combined approach highlighted the presence of some labile copper complexes in samples reaching the EC10-these could have contributed to the copper toxicity.     

Sorption and redox processes controlling arsenic fate and transport in a stream impacted by acid mine drainage

Reigous acid creek originating from the Carnoulès tailings impoundment supplies high concentrations of arsenic under soluble (up to approximately 4 mg/l) and particulate (up to 150 mgAs/g) phases to the Amous river, situated at the drainage basin of the Rh?ne river (Southern France). The metalloid is present as As(III) (>95%) in Reigous creek water while As(V) predominates (50-80%) in the solid phase, i.e. schwertmannite. At the confluence between acid (pH<5) creek and alkaline Amous river, As(III) concentrations decrease ten-fold through dilution and formation of As-rich ferrihydrite (As/Fe=0.02-0.1) containing 10-30% As(III). However, these attenuation processes are not efficient in the summer heatwave of 2003 since As concentrations in Amous river water (>or=20 microg/l) and As/Fe ratios in particulate matter (>or=0.07) are closed to those of Reigous creek (相似文献   

Levels and spatial and temporal trends of contaminants in Greenland biota: an updated review

Knowledge of contaminant levels in Greenland biota has increased substantially in recent years, particularly for persistent organic pollutants. This paper reviews and updates knowledge of spatial and temporal trends of Cd, Hg and organochlorines (PCBs, DDTs, HCHs, HCB and chlordane-related compounds) in Greenland terrestrial, freshwater and marine biota. The most comprehensive studies of spatial trends of Cd and Hg in the terrestrial ecosystem concern lichens, with relatively complete coverage, and caribou (Rangifer tarandus), with coverage mainly in different regions of central West Greenland and Southwest Greenland. The Arctic char (Salvelinus alpinus) is the only freshwater organism for which studies of spatial trends of Hg levels have been completed. Information on spatial trends of Cd and Hg in the marine environment is available from studies of fish, seabirds, ringed seals (Phoca hispida) and polar bears (Ursus maritimus). Geographical patterns of Cd and Hg in Greenland biota were not always consistent among different species or different studies. In landlocked Arctic char the concentrations of Hg decreased from south to north. In marine animals levels of Hg tended to be higher in East Greenland than in West Greenland and Cd levels were highest in biota from Disko Island in central West Greenland. The observed regional differences are difficult to explain but in most cases the causes appear to be natural rather than anthropogenic. Only a few time series covering the last 20 years exist for Cd and Hg. The one time series indicating a temporal change is for ringed seals in Northwest Greenland, which shows an increasing trend of Hg and a decreasing trend of Cd since 1984. Whether the changes reflect anthropogenic inputs, seal behaviour or other environmental factors is unknown. The most significant new insights have concerned organochlorines. In general, levels of these compounds were very low in terrestrial biota compared to marine species. Concentrations in landlocked Arctic char were highest in Southeast Greenland and lowest in Northwest and Northeast Greenland. Marine species from East Greenland had consistently higher levels of SigmaPCB, SigmaDDT and SigmaHCH than marine species from West Greenland. Very few data exist to evaluate temporal changes of organochlorine levels in Greenland biota, and this is the most significant knowledge gap at present. The most pronounced change observed was a decrease of 78% in SigmaPCB levels in polar bears from East Greenland from 1990 to 2000. Levels of SigmaHCH in shorthorn sculpins (Myoxocephalus scorpius) and seals from both central West Greenland and central East Greenland appear to have decreased since 1994. Increasing trends of SigmaDDT from 1994 until now were found in both sexes of seals as well as in male sculpins from central West Greenland.