Bioaccumulation of PCDD/Fs,PCBs and PBDEs by earthworms in field soils of an E-waste dismantling area in China

A total of 60 paired samples of earthworm, corresponding soil and wormcast were collected to investigate the bioaccumulation tendency of polychlorinated dibenzo-p-dioxins/dibenzofurans (PCDD/Fs), polychlorinated biphenyls (PCBs) and polybrominated diphenyl ethers (PBDEs) in earthworms from a typical E-waste dismantling area in east China. Significant correlations were observed for the total concentrations among different matrix types except for PCDD/Fs in soil and earthworm. The bioaccumulation tendency showed some differences among the contaminants. Calculated biota–soil accumulation factors (BSAFs) indicated that PCBs and PBDEs had higher bioaccumulation potential compared to PCDD/Fs, which was somewhat different from laboratory studies. The plot of mean BSAFs versus log K_ow values for PCBs and PBDEs was well fitted by a second-order polynomial with the maximum BSAF at approximately log K_ow of 6.5. While for PCDD/Fs, only a slightly decreasing trend was observed with increasing log K_ow. Composition analysis indicated that tetra-, penta- and hexa-halogenated homologs had higher bioaccumulation levels, indicating that medium-halogenated congeners with log K_ow around 6.5 are more easily accumulated by earthworms. Furthermore, the ratios of BDE-47/-99 and BDE-99/-100 showed some discrepancies with the technical products and other biotic species, suggesting different bioaccumulation potential of PBDEs in earthworm.     

Effects of earthworm activity on fertility and heavy metal bioavailability in sewage sludge

The potential for using earthworms (Eisenia fetida) to improve fertility and reduce copper and cadmium availability in sewage sludge was tested by laboratory incubation experiments. Results comparing sewage sludge with and without earthworm treatment showed that earthworm activity decreased the contents of organic matter, total nitrogen, but increased the contents of available nitrogen and phosphorus and had no significant effect on the contents of total phosphorus, total potassium and available potassium. After incubation of the sewage sludge with earthworms for 60 days, the contents of Cu and Cd in the earthworms increased with the increase of additional Cu up to 250 mg kg(-1) and Cd up to 10 mg kg(-1). Bioconcentration factors (BCF) were higher than 1 only for Cd when the addition rate was lower than 5 mg kg(-1), which indicates that the earthworms can only accumulate Cd when the concentration of Cd is low in sewage sludge. Bioavailability of Cd and Cu was evaluated by applying sewage sludge with and without earthworm treatment to soil and then growing cabbage plants. The results showed that earthworm treatment increased the biomass of cabbage and decreased the bioaccumulation of Cd and Cu in the cabbage plants.     

Comparative chronic toxicity of nanoparticulate and ionic zinc to the earthworm Eisenia veneta in a soil matrix

Manufactured nanoparticles (NPs) are increasingly being used in a range of consumer products and are already entering the environment. NP ZnO is one of the most widely used and potentially toxic NPs in aquatic exposures. It is likely that ZnO nanoparticles will also be bioavailable to soil organisms, studies on ZnO NP toxicity in a soil matrix are lacking. We exposed the earthworm Eisenia veneta to uncoated NP ZnO (<100 nm) dosed to soil and food at 250 and 750 mg Zn kg(-1) for 21 d. Concurrent exposures of equivalent ionic Zn were conducted with ZnCl(2) and for both forms effects on life history traits, immune activity and Zn body concentrations were compared. Despite slightly higher measured body concentrations, NP ZnO generally had less impact than ZnCl(2) on measured traits. At 750 mg Zn kg(-1), reproduction declined by 50% when exposed to NP ZnO but was almost completely inhibited by ZnCl(2). Similarly, immune activity was unaffected by NP ZnO but was suppressed by 20% when exposed to ZnCl(2). Scanning electron microscopy analysis of worm tissues following 24h aqueous exposure showed the presence of ZnO particles suggesting that NPs can be taken up in particulate form. This may explain the reduced effects at similar body concentrations seen in the soil study. Our findings suggest that risk assessments do not need to go beyond considering the metal component of NP ZnO in soils at least for the larger size uncoated particles considered here.     

Effect of Earthworm（Pheretima sp.） Density on Revegetation of Lead/zinc Metal Mine Tailings Amended with Soil

The objective of this study was to investigate the effects of earthworm density on the availability of nutrients and heavy metals in metal contaminated soils. Pb/Zn mine tailings were mixed throughly with a red yellow podzolic soil at the ratio （w/w） of 75：25. Earthworms （Pheretima sp.） were introduced to the mixture at four different densities, zero, three, six and nine individuals per pot planted with ryegrass （Loliun multiflorum）. The results indicated that earthworm activity significantly enhanced ryegrass shoot biomass. However, as denser earthworm population was introduced, shoot biomass tended to decrease. Earthworm activity significantly increased soil pH and availability of N, P and K in the tailings and soil mixture. There was a general tendency that uptake of Zn by ryegrass increased after earthworm inoculation, although the increase in extractable Zn in tailings and soil mixture was not significant. On the contrary, there seemed to be a lower uptake of Pb by ryegrass under earthworm inoclation, despite the fact that higher extractable Pb concentrations were observed. The present project indicated that the improved growth of ryegrass was due to improved nutrient availability and other soil conditions, by inoculation of earthworms at an appropriate rate. Further studies are needed to illustrate the relationship between metal availability and earthworm activity in the field.     

Effect of Earthworm(Pheretima sp.) Density on Revegetation of Lead/zinc Metal Mine Tailings Amended with Soil

Abstract

The objective of this study was to investigate the effects of earthworm density on the availability of nutrients and heavy metals in metal contaminated soils. Pb/Zn mine tailings were mixed throughly with a red yellow podzolic soil at the ratio (w/w) of 75:25. Earthworms (Pheretima sp.) were introduced to the mixture at four different densities, zero, three, six and nine individuals per pot planted with ryegrass (Loliun multiflorum). The results indicated that earthworm activity significantly enhanced ryegrass shoot biomass. However, as denser earthworm population was introduced, shoot biomass tended to decrease. Earthworm activity significantly increased soil pH and availability of N, P and K in the tailings and soil mixture. There was a general tendency that uptake of Zn by ryegrass increased after earthworm inoculation, although the increase in extractable Zn in tailings and soil mixture was not significant. On the contrary, there seemed to be a lower uptake of Pb by ryegrass under earthworm inoclation, despite the fact that higher extractable Pb concentrations were observed. The present project indicated that the improved growth of ryegrass was due to improved nutrient availability and other soil conditions, by inoculation of earthworms at an appropriate rate. Further studies are needed to illustrate the relationship between metal availability and earthworm activity in the field.     

The co-application of earthworms (Dendrobaena veneta) and compost to increase hydrocarbon losses from diesel contaminated soils

The feasibility of using composted civic waste for the remediation of a soil contaminated with petroleum hydrocarbons (extractable petroleum hydrocarbons (EPH) 10+/-1.8 g kg(-1) and total 16 USEPA PAH 1.62+/-0.5 g kg(-1)) was assessed. The effects of compost to soil ratio, in combination with and without earthworm presence (Dendrobaena veneta), upon the loss of contaminants were determined for EPH (GC-FID) and PAH (GC-MS), respectively. Increasing the ratio of compost substrate to hydrocarbon impacted soil (1:0.5, 1:1, 1:2 and 1:4 (soil:compost wt/wt)) in the absence of earthworms resulted in significantly (p<0.05) greater losses of both EPH and SigmaPAH after an 84 d incubation period, when compared to the soil only control. Where earthworms were present without compost, EPH losses were significantly (p<0.05) enhanced in the soil only treatment (33.4+/-5.3% residual) compared to the soil only control (54.4+/-5.3% residual). However, PAH loss in the soil only treatment (with-earthworm presence) were only slightly enhanced (65.3+/-9.3% residual), with respect to the soil only control (69.2+/-6.4% residual). Synergistic benefits of both earthworm and compost presence were most significant for PAHs (p<0.05), and less so for EPH. (14)C-respirometer studies, to establish catabolic competence in terms of microbial mineralisation of key hydrocarbons, complemented the hydrocarbon analysis.     

Analysis of soil characteristics of different land uses and metal bioaccumulation in wheat grown around rivers: possible human health risk assessment

The present study was conducted to determine the physico-chemical properties and heavy metal contents in soils under three land uses (agricultural, riverbank and roadside) from areas situated around rivers (Beas and Sutlej) in Punjab, India. Heavy metal contents in wheat samples (grain and fodder) growing in the area were also analyzed in order to find out potential human health risk through wheat consumption. The studied soils under the three land uses were found to be basic in nature with sandy texture, low soil organic matter and other soil nutrients. Comparatively higher amounts of soil nutrients were observed in soils under agricultural land use as compared to riverbank and roadside land uses. The amounts of heavy metals (Cr, Cu, Co and Pb) analyzed in soils were lower than the various national and international maximum permissible limits, but heavy metal contents observed in wheat fodder samples exceeded the maximum permissible limits for fodder. The soil-to-plant metal bioaccumulation factor was found to be highest for Cu (3.812 for soil–wheat grain and 1.874 for soil–wheat fodder), which showed the bioaccumulation of heavy metals from soils to crops, and the wheat straw-to-grain translocation factor was found to be highest for Co (4.375). The hazard index calculated to assess non-carcinogenic health risks was found above 1 for children, meaning that the wheat grains can pose health risks to children.     

Enchytraeus albidus (Enchytraeidae): a test organism in a standardised avoidance test? Effects of different chemical substances

Enchytraeids (Enchytraeus albidus) directly improve the pore structure of the soil and are indirectly involved in regulating the degradation of organic matter. Due to their behavior they are able to avoid unfavorable environmental conditions. Avoidance tests allow a first assessment of toxicity of a contaminated or spiked soil within 48 h, by using the reaction of the enchytraeids as measurement endpoint. In this period, the organisms can choose between the control soil and the test soil. In the tests reported here, enchytraeids were exposed to LUFA 2.2 soil spiked with the following set of toxic substances: copper chloride, zinc chloride, cadmium chloride, phenmedipham, benomyl, carbendazim, dimethoate, atrazine, pentachlorophenol, chlorpyriphos, lindane, TBTO, Linear Alkylbenzene Sulfonates (LAS) and boric acid. Different chemical concentrations were tested. EC50s ranged from 8 mg/kg (Carbendazim) to >1000 mg/kg (e.g. LAS). While the tested heavy metals showed clear dose-response relationships, the effect pattern differed considerably in the tests with organic chemicals, e.g. no avoidance behaviour was observed in LAS, even at very high doses. Here we proposed to standardize the Enchytraeid avoidance test in a way similar to what is currently done for the earthworm and collembolan avoidance tests by the International Standardisation Organisation (ISO).     

Environmental effects of new herbicides for vegetation control in forestry

Environmental fate of and toxicity data for ammonium ethyl carbamoylphosphonate [fosamine ammonium], N-(phosphonomethyl)glycine [glyphosate], and 3-cyclohexyl-6-(dimethylamino)-1-methyl-1,3,5-triazine-2,4(1H, 3H)-dione [hexazinone] which appear promising for vegetation control in forestry are reviewed. None of the three herbicides is very persistent in soil, with half-lives reported of about 7–10 days for fosamine ammonium, 8–19 weeks for glyphosate, and 1–6 months for hexazinone, depending on soil type and climatic conditions. Degradation in soil is primarily via microbial routes. Whereas hexazinone is a very mobile herbicide (with mobility dependent on soil type), fosamine ammonium and glyphosate are strongly adsorbed and not readily leached in many soil types. Based on bioassay results, the three herbicides exhibit “very low” to “low” toxicity. Fosamine ammonium is not mutagenic and was not teratogenic when fed to pregnant rats at 10,000 ppm. Data on hexazinone indicate no carcinogenic effect in rats, negative in bacterial and mammalian point mutation assays, and not embryotoxic or teratogenic at up to 5000 ppm in diet of rats. The three herbicides have minimum-to-nil effect on soil microorganisms and exhibit little or no potential for bioaccumulation. Limitations of the available data are discussed and suggestions are made for future studies.     

Soil-water distribution coefficients and plant transfer factors for (134)Cs, (85)Sr and (65)Zn under field conditions in tropical Australia

Measurements of soil-to-plant transfer of (134)Cs, (85)Sr and (65)Zn from two tropical red earth soils ('Blain' and 'Tippera') to sorghum and mung crops have been undertaken in the north of Australia. The aim of the study was to identify factors that control bioaccumulation of these radionuclides in tropical regions, for which few previous data are available. Batch sorption experiments were conducted to determine the distribution coefficient (K(d)) of the selected radionuclides at pH values similar to natural pH values, which ranged from about 5.5 to 6.7. In addition, K(d) values were obtained at one pH unit above and below the soil-water equilibrium pH values to determine the effect of pH. The adsorption of Cs showed no pH dependence, but the K(d) values for the Tippera soils (2300-4100 ml/g) exceeded those for the Blain soils (800-1200 ml/g) at equilibrium pH. This was related to the greater clay content of the Tippera soil. Both Sr and Zn were more strongly adsorbed at higher pH values, but the K(d) values showed less dependence on the soil type. Strontium K(d)s were 30-60 ml/g whilst Zn ranged from 160 to 1630 ml/g for the two soils at equilibrium pH. With the possible exception of Sr, there was no evidence for downward movement of radionuclides through the soils during the course of the growing season. There was some evidence of surface movement of labelled soil particles. Soil-to-plant transfer factors varied slightly between the soils. The average results for sorghum were 0.1-0.3 g/g for Cs, 0.4-0.8 g/g for Sr and 18-26 g/g for Zn (dry weight) with the initial values relating to Blain and the following values to Tippera. Similar values were observed for the mung bean samples. The transfer factors for Cs and Sr were not substantially different from the typical values observed in temperate studies. However, Zn transfer factors for plants grown on both these tropical soils were greater than for soils in temperate climates (by more than an order of magnitude). This may be related to trace nutrient deficiency and/or the growth of fungal populations in these soils. The results indicate that transfer factors depend on climatic region together with soil type and chemistry and underline the value of specific bioaccumulation data for radionuclides in tropical soils.     

Modelling chronic exposure to contaminated soil: a toxicokinetic approach with the terrestrial snail Helix aspersa

To enlarge the possibilities of using organisms of the soil fauna to assess the bioaccumulative potential of chemicals, the kinetic of soil cadmium (Cd) transfer to the terrestrial gastropod Helix aspersa was investigated under laboratory conditions during a long-term experiment (6 months). During the exposure phase (3 months), juvenile snails were subjected to three different concentrations of Cd spiked in artificial ISO soil (ISO 0, 20 and 100 mg Cd kg(-1)) and to a field soil (ME4) industrially contaminated by 20 mg Cd kg (-1). For both soils, internal steady-state Cd concentrations were reached in the viscera of the snails, the main storage organ for Cd, after 2 weeks of exposure whatever the Cd concentration in soil. The equilibrium concentrations in the viscera were 0.7 (+/-0.1), 11.3 (+/-2.4), 73.3 (+/-4.8) and 6.3 (+/-1.3) mg Cd kg(-1) dry mass for ISO 0, ISO 20, ISO 100 and ME4, respectively. During the depuration phase (3 months), from 0 to 52% of the accumulated Cd in the viscera were removed by excretion or relocation in the foot. However, the snails were not able to depurate down to initial concentrations. Data were modelled by integrating a specific growth rate constant into one-compartment toxicokinetic models. This allowed the calculation of Cd uptake rates that can be used as indicators of metal bioavailability. Since this parameter was found to be lower for snails exposed to the field soil ME4, we concluded that lower Cd bioavailability in this field soil was responsible of the lower transfer to the snails compared to the ISO 20 soil, even though they were polluted to similar extents. Internal validation showed that the toxicokinetic models could be applied for predictive purposes, promising for the development of a bioaccumulation directive for terrestrial environment.     

Application of SO(4)(2-)/TiO2 solid superacid in decontaminating radioactive pollutants

Polyaniline doped with SO(4)(2-)/TiO(2) superacid shows good conductive ability. When used in a strippable coating film for decontaminating radioactive pollutants, the SO(4)(2-)/TiO(2) solid superacid replacing HCl exhibits higher electrical conductivity (7.01 s/cm) and a decontamination ratio higher than 97%. Coating and electrolyzing the film in solution or in dry medium were effective methods, the latter was more promising for decontaminating radioactive pollutants which were attached to the surface or within the body of equipments used in nuclear industry.     

The effect of ageing on the bioaccessibility and fractionation of cadmium in some typical soils of China

Ingestion of contaminated soil has been recognized as an important exposure pathway of cadmium (Cd) for humans, especially for children through outdoor hand-to-mouth activities. The effect of ageing process following the input of Cd into soil on the bioaccessibility of Cd in five typical soils of China was investigated using physiologically based in vitro test in this study. A sequential extraction procedure was employed with attempt to identify the bioaccessible fraction(s) of Cd in soils. The bioaccessibility of Cd in strongly acidic (approximately pH 4.5) soils reached nearly steady levels (76.5-76.9% and 52.0-52.6% in the gastric and small intestinal phases, respectively) after a sharp decline in the first week of ageing. In contrast, the bioaccessibility of Cd in higher pH (>6.0) soils was found to be much lower (53.3-72.7% and 29.9-43.4% in gastric and small intestinal phases, respectively) and took 2 weeks of ageing to reach steady levels. The freshly spiked Cd was more labile than native Cd. The main proportion of spiked Cd was found in exchangeable Cd which was higher in strongly acidic soils (68.6-71.8%) than in higher pH soils (53.4-61.4%) at day 120 after a sharp decline to the nearly steady state in the first 1 and 2 weeks, respectively. Significant correlations between Cd bioaccessibility and either water soluble and exchangeable Cd individually, or the sum of water soluble and exchangeable Cd throughout the incubation period for all soils, indicate that these forms of Cd are likely to constitute the main proportion of bioaccessible Cd in soils.     

Revegetating fly ash landfills with Prosopis juliflora L.: impact of different amendments and Rhizobium inoculation

A revegetation trial was conducted to evaluate the feasibility of growing a legume species, Prosopis juliflora L., on fly ash ameliorated with combination of various organic amendments, blue-green algal biofertilizer and Rhizobium inoculation. Significant enhancements in plant biomass, photosynthetic pigments, protein content and in vivo nitrate reductase activity were found in the plants grown on ameliorated fly ash in comparison to the plants growing in unamended fly ash or garden soil. Higher growth was obtained in fly ash amended with blue-green algae (BGA) than farmyard manure or press mud (PM), a waste from sugar-processing industry, due to the greater contribution of plant nutrients, supply of fixed nitrogen and increased availability of phosphorus. Nodulation was suppressed in different amendments of fly ash with soil in a concentration-duration-dependent manner, but not with other amendments. Plants accumulated higher amounts of Fe, Mn, Cu, Zn and Cr in various fly ash amendments than in garden soil. Further, inoculation of the plant with a fly ash tolerant Rhizobium strain conferred tolerance for the plant to grow under fly ash stress conditions with more translocation of metals to the above ground parts. The results showed the potential of P. juliflora to grow in plantations on fly ash landfills and to reduce the metal contents of fly ash by bioaccumulation in its tissues.     

Evaluation of chemical and ecotoxicological characteristics of biodegradable organic residues for application to agricultural land

The use of organic waste and compost as a source of organic matter and nutrients is a common practice to improve soil physico-chemical properties, meanwhile reducing the need for inorganic fertilisers. Official guidelines to assess sewage sludge and compost quality are mostly based on total metal content of these residues. Measurement of the total concentration of metals may be useful as a general index of contamination, but provides inadequate or little information about their bioavailability, mobility or toxicity when the organic residue is applied to the soil. However, ecotoxicity tests provide an integrated measure of bioavailability and detrimental effects of contaminants in the ecosystem. In the present study, three different types of biodegradable organic residues (BORs) have been considered: sewage sludge from municipal wastewater treatment (SS), compost from the organic fraction of unsorted municipal solid waste (MSWC), and garden waste compost (GWC). The BORs were subjected to chemical characterisation and total metal quantification (Cd, Cr, Cu, Ni, Pb and Zn), in order to verify their suitability for land application. Water leachability was determined through the DIN 38414-S4 method, while the modified BCR sequential extraction procedure was used for metal speciation. Ecotoxicity of the BORs was studied by direct and indirect bioassays. Direct toxicity bioassays were: plant growth tests with cress (Lepidium sativum L.) and barley (Hordeum vulgare L.), and earthworm (Eisenia fetida) mortality. On the other hand, indirect exposure bioassays, with leachate from the residues, took into account: luminescent bacteria (Vibrio fischeri), seed germination (L. sativum and H. vulgare) and Daphnia magna immobilization. As far as total metal concentration is concerned, with particular reference to Zn, SS resulted neither suitable for the use in agriculture nor compatible to be disposed of as an inert material into landfill, according to the Directive 1999/31/EC. Zinc in SS was mainly present in exchangeable form (28.5%), appearing as highly bioavailable. As a consequence, SS exhibited either high ecotoxicity effects with the indirect exposure bioassays or significant mortality with the earthworm bioassay. Total content of metals in MSWC allowed its classification as "stabilised biowaste", according to 2nd draft [DG Env.A.2. Working document of Biological treatment of biowaste - 2nd draft. Directorate-General Environment, Brussels, 12th February; 2001. accessed in:http://europa.eu.int/comm/environment/waste/facts_en.htm, at 10/09/2002] while leachate, on the basis of the concentration of these contaminants, could be classified as "inert waste". This residue showed significant ecotoxicity effects with direct exposure bioassays as well as with the luminescent bacteria bioassay. However, it resulted less toxic than SS. Finally, GWC could be classified as a Class 2 compost, with no detectable toxic effects on the organisms used in the bioassays, except for the luminescent bacteria. In this case, an EC(50) of 73.0% was observed. Considering the results, the use of a battery of toxicity test in conjunction with chemical analysis should be suggested, in order to correctly assess possible environmental risks deriving from disposal or land application of biodegradable organic residues.     

Assessment of ecotoxicological risks related to depositing dredged materials from canals in northern France on soil

The implementation of an ecological risk assessment framework is presented for dredged material deposits on soil close to a canal and groundwater, and tested with sediment samples from canals in northern France. This framework includes two steps: a simplified risk assessment based on contaminant concentrations and a detailed risk assessment based on toxicity bioassays and column leaching tests. The tested framework includes three related assumptions: (a) effects on plants (Lolium perenne L.), (b) effects on aquatic organisms (Escherichia coli, Pseudokirchneriella subcapitata, Ceriodaphnia dubia, and Xenopus laevis) and (c) effects on groundwater contamination. Several exposure conditions were tested using standardised bioassays. According to the specific dredged material tested, the three assumptions were more or less discriminatory, soil and groundwater pollution being the most sensitive. Several aspects of the assessment procedure must now be improved, in particular assessment endpoint design for risks to ecosystems (e.g., integration of pollutant bioaccumulation), bioassay protocols and column leaching test design.     

Can barium and strontium be used as tracers for radium in soil-plant transfer studies?

Radium is one of the prominent potential contaminants linked with industries extracting or processing material containing naturally occurring radionuclides. In this study we investigate if 133Ba and 85Sr can be used as tracers for predicting 226Ra soil-to-plant transfer. Three soil types were artificially contaminated with these radionuclides and transfer to ryegrass and clover was studied. Barium is considered a better tracer for radium than strontium, given the significant linear correlation found between the Ra and Ba-TF. For strontium, no such correlation was found. The relationship between soil characteristics and transfer factors was investigated. Cation exchange capacity, exchangeable Ca+Mg content and soil pH did not seem to influence Ra, Ba or Sr uptake in any clear way. A significant relation (negative power function) was found between the bivalent (Ca+Mg) concentration in the soil solution and the Ra-TF. A similar dependency was found for the Sr and Ba-TF, although less significant.     

Bacillus thuringiensis, nucleopolyhedrosis virus,and pheromones: Environmental considerations and uncertainties in large-scale insect control

The mode of action, extent of use, and the current knowledge on environmental fate and toxicity of three biological insecticides [Bacillus thuringiensis (B.t.), nucleopolyhedrosis virus (NPV), and pheromones] are reviewed. Data gaps, environmental uncertainties in any large-scale use, and proposed registration guidelines which may lead to more extensive use are discussed. B.t. disappears rapidly from plant foliage on exposure to sunlight and/or moisture, although it may persist in dry soil for several months or years. Foliar-applied NPVs are also inactivated by sunlight; the halflife on cotton leaves is 20–25 h. In the soil, NPVs may remain active for several years. Pheromones volatilize readily and do not persist in plant or in soil. Limited available data indicate that B.t. and pheromones do not persist in aquatic environments; quantitative data are unavailable for NPVs. Based on bioassay data, the three insecticides exhibit undetectable to low toxicity to nontarget organisms; there are also no reports of human disease or injury due to exposure to these pesticides and no bioaccumulation is expected with normal application. Except for B.t. which has been used in a limited large-scale applications, pest control uses of NPVs and pheromones are still in experimental stages. Areas of uncertainties requiring research and development include potential adverse health and ecological impacts in any large-scale and widespread use and efficacy and cost relative to synthetic chemical pesticides.     

Study on the contamination of heavy metals and their correlations in mollusks collected from coastal sites along the Chinese Bohai Sea

Mollusks living in seas can accumulate heavy metals, and may serve as excellent passive biomonitors. During a period of 1 year, bioaccumulation of As, Cd, Co, Cr, Cu, Fe, Hg, Mn, Ni, Pb, Se, and Zn was examined in nine kinds of mollusks (Rapana venosa, Neverita didyma, Scapharca subcrenata, Mytilus edulis, Amusium, Crassostrea talienwhanensis, Meretix meretrix, Ruditapes philippinarum, and Mactra veneriformis), which were collected at eight coastal sites along the Chinese Bohai Sea. Metal concentrations were directly determined by inductively coupled plasma mass spectrometer (ICP-MS). Two certified reference materials, dogfish muscle (DORM-2) and mussel (GBW 08571), were used to validate the methods, and the recoveries were within 83.72-112.30% of the certified values. Bioaccumulation of metals varied strongly among sampling sites and species. Statistical analysis (one-way ANOVA) indicated that different species examined showed different bioaccumulation of metals, and perhaps they could be used as potential biomonitors to investigate the contamination levels of heavy metals. Principal component analysis (PCA) and correlation analysis were used to study the relationships between these heavy metals. The results showed that, in nine mollusks' tissues, there are significant correlations between these elements in adjacent main group or subgroup in periodic table of elements.     

The precautionary principle and chemicals management: The example of perfluoroalkyl acids in groundwater

Already in the late 1990s microgram-per-liter levels of perfluorooctane sulfonate (PFOS) were measured in water samples from areas where fire-fighting foams were used or spilled. Despite these early warnings, the problems of groundwater, and thus drinking water, contaminated with perfluoroalkyl and polyfluoroalkyl substances (PFASs) including PFOS are only beginning to be addressed. It is clear that this PFAS contamination is poorly reversible and that the societal costs of clean-up will be high. This inability to reverse exposure in a reasonable timeframe is a major motivation for application of the precautionary principle in chemicals management. We conclude that exposure can be poorly reversible; 1) due to slow elimination kinetics in organisms, or 2) due to poorly reversible environmental contamination that leads to continuous exposure. In the second case, which is relevant for contaminated groundwater, the reversibility of exposure is not related to the magnitude of a chemical's bioaccumulation potential. We argue therefore that all PFASs entering groundwater, irrespective of their perfluoroalkyl chain length and bioaccumulation potential, will result in poorly reversible exposures and risks as well as further clean-up costs for society. To protect groundwater resources for future generations, society should consider a precautionary approach to chemicals management and prevent the use and release of highly persistent and mobile chemicals such as PFASs.