The bioaccumulation of Molybdenum in the earthworm Eisenia andrei: influence of soil properties and ageing

Mo bioaccumulation in the earthworm Eisenia andrei was determined after 28 d exposure in ten different European field soils (pH 4.4-7.8) and an artificial soil, freshly spiked with Na₂MoO₄ at concentrations between 3.2 and 3200 mg Mo kg⁻¹ dry soil. Three field soils were also tested after ageing for 11 months. Earthworm Mo concentrations generally levelled off at high exposure levels but in most soils showed a (nearly) linear increase with increasing soil concentrations in the lower, non-toxic range (below EC10 or NOEC for reproduction effects). Bioaccumulation (BAF) and Bioconcentration factors (BCF) were calculated as the ratio of earthworm concentration to soil and estimated porewater concentrations, respectively. BAFs (0.35-3.44) and BCFs (1.31-276) did not seem much affected by soil concentration, suggesting that earthworms are not capable of regulating their internal Mo concentrations. BAF was best predicted by ammonium oxalate-extractable iron (Fe_ox) and phosphor (P_ox) contents of the soils.     

Review on the use of enzymes for the detection of organochlorine, organophosphate and carbamate pesticides in the environment

Pesticides are released intentionally into the environment and, through various processes, contaminate the environment. Three of the main classes of pesticides that pose a serious problem are organochlorines, organophosphates and carbamates. While pesticides are associated with many health effects, there is a lack of monitoring data on these contaminants. Traditional chromatographic methods are effective for the analysis of pesticides in the environment, but have limitations and prevent adequate monitoring. Enzymatic methods have been promoted for many years as an alternative method of detection of these pesticides. The main enzymes that have been utilised in this regard have been acetylcholinesterase, butyrylcholinesterase, alkaline phosphatase, organophosphorus hydrolase and tyrosinase. The enzymatic methods are based on the activation or inhibition of the enzyme by a pesticide which is proportional to the concentration of the pesticide. Research on enzymatic methods of detection, as well as some of the problems and challenges associated with these methods, is extensively discussed in this review. These methods can serve as a tool for screening large samples which can be followed up with the more traditional chromatographic methods of analysis.     

Aggregation and ecotoxicity of CeO₂ nanoparticles in synthetic and natural waters with variable pH, organic matter concentration and ionic strength

The influence of pH (6.0-9.0), natural organic matter (NOM) (0-10 mg C/L) and ionic strength (IS) (1.7-40 mM) on 14 nm CeO₂ NP aggregation and ecotoxicity towards the alga Pseudokirchneriella subcapitata was assessed following a central composite design. Mean NP aggregate sizes ranged between 200 and 10000 nm. Increasing pH and IS enhanced aggregation, while increasing NOM decreased mean aggregate sizes. The 48 h-E_rC20s ranged between 4.7 and 395.8 mg CeO₂/L. An equation for predicting the 48 h-E_rC20 (48 h-E_rC20 = −1626.4 × (pH) + 109.45 × (pH)² + 116.49 × ([NOM]) − 14.317 × (pH) × ([NOM]) + 6007.2) was developed. In a validation study with natural waters the predicted 48 h-E_rC20 was a factor 1.08-2.57 lower compared to the experimental values.     

Functional redundancy and food web functioning in linuron-exposed ecosystems

An extensive data set describing effects of the herbicide linuron on macrophyte-dominated microcosms was analysed with a food web model to assess effects on ecosystem functioning. We showed that sensitive phytoplankton and periphyton groups in the diets of heterotrophs were gradually replaced by more tolerant phytoplankton species as linuron concentrations increased. This diet shift--showing redundancy among phytoplankton species--allowed heterotrophs to maintain their functions in the contaminated microcosms. On an ecosystem level, total gross primary production was up to hundred times lower in the treated microcosms but the uptake of dissolved organic carbon by bacteria and mixotrophs was less sensitive. Food web efficiency was not consistently lower in the treated microcosms. We conclude that linuron predominantly affected the macrophytes but did not alter the overall functioning of the surrounding planktonic food web. Therefore, a risk assessment that protects macrophyte growth also protects the functioning of macrophyte-dominated microcosms.     

Integrated evaluation of the performance of a more than seven year old permeable reactive barrier at a site contaminated with chlorinated aliphatic hydrocarbons (CAHs)

An important issue of concern for permeable reactive iron barriers is the long-term efficiency of the barriers due to the long operational periods required. Mineral precipitation resulting from the anaerobic corrosion of the iron filings and bacteria present in the barrier may play an important role in the long-term performance. An integrated study was performed on the Vapokon permeable reactive barrier (PRB) in Denmark by groundwater and iron core sample characterization. The detailed field groundwater sampling carried out from more than 75 well screens up and downstream the barrier showed a very efficient removal (>99%) for the most important CAHs (PCE, TCE and 1,1,1-TCA). However, significant formation of cis-DCE within the PRB resulted in an overall insufficient efficiency for cis-DCE removal. The detailed analysis of the upstream groundwater revealed a very heterogeneous spatial distribution of contaminant loading into the PRB, which resulted in that only about a quarter of the barrier system is treating significant loads of CAHs. Laboratory batch experiments using contaminated groundwater from the site and iron material from the core samples revealed that the aged iron material performed equally well as virgin granular iron of the same type based on determined degradation rates despite that parts of the cored iron material were covered by mineral precipitates (especially iron sulfides, carbonate green rust and aragonite). The PCR analysis performed on the iron core samples indicated the presence of a microbial consortium in the barrier. A wide range of species were identified including sulfate and iron reducing bacteria, together with Dehalococcoides and Desulfuromonas species indicating microbial reductive dehalogenation potential. The microbes had a profound effect on the performance of the barrier, as indicated by significant degradation of dichloromethane (which is typically unaffected by zero valent iron) within the barrier.     

Contaminants in the coastal karst aquifer system along the Caribbean coast of the Yucatan Peninsula, Mexico

Intensive land development as a result of the rapidly growing tourism industry in the “Riviera Maya” region of the Yucatan Peninsula, Mexico may result in contamination of groundwater resources that eventually discharge into Caribbean coastal ecosystems. We deployed two types of passive sampling devices into groundwater flowing through cave systems below two communities to evaluate concentrations of contaminants and to indicate the possible sources. Pharmaceuticals and personal care products accumulated in the samplers could only have originated from domestic sewage. PAHs indicated contamination by runoff from highways and other impermeable surfaces and chlorophenoxy herbicides accumulated in samplers deployed near a golf course indicated that pesticide applications to turf are a source of contamination. Prevention and mitigation measures are needed to ensure that expanding development does not impact the marine environment and human health, thus damaging the tourism-based economy of the region.     

Effects of atmospheric ammonia and ammonium sulphate on Douglas fir (Pseudotsuga menziesii)

Three-year-old Douglas firs (Pseudotsuga menziesii) were fumigated with 180 microg m(-3) NH3 or clean (charcoal-filtered) air. During these fumigations the plants received 15 mm artificial rain weekly, supplemented with 20, 500 or 2500 micromol litre(-1) (NH4)2SO4. Exposure to NH3 and NH4+ for 14 weeks resulted in a change of the nutrient status of the needles. The most remarkable effect was the increase in the N/K ratio, due to both uptake of N and leaching of K. The action of NH3 was stronger than that of NH4+. Both NH3 and (NH4)2SO4 affected the epicuticular wax layer and decreased mycorhiza frequency. Following fumigation and artificial rain treatments, needles were incubated for 8 h in a medium containing 0, 50, 250, 500 and 2500 micromol litre(-1) (NH4)2SO4. Almost no exchange of Ca, Mg and K for NH4+ was found. Therefore this ion exchange probably explains only a minor part of the changes in nutrient status of the whole trees.     

Satellite derived trends in NO2 over the major global hotspot regions during the past decade and their inter-comparison

We assessed satellite derived tropospheric NO₂ distribution on a global scale and identified the major NO₂ hotspot regions. Combined GOME and SCIAMACHY measurements for the period 1996-2006 have been used to compute the trends over these regions. Our analysis shows that tropospheric NO₂ column amounts have increased over the newly and rapidly developing regions like China (11 ± 2.6%/year), south Asia (1.76 ± 1.1%/year), Middle East (2.3 ± 1%/year) and South Africa (2.4 ± 2.2%/year). Tropospheric NO₂ column amounts show some decrease over the eastern US (−2 ± 1.5%/year) and Europe (0.9 ± 2.1%/year). We found that although tropospheric NO₂ column amounts decreased over the major developed regions in the past decade, the present tropospheric NO₂ column amounts over these regions are still significantly higher than those observed over newly and rapidly developing regions (except China). Tropospheric NO₂ column amounts show some decrease over South America and Central Africa, which are major biomass burning regions in the Southern Hemisphere.     

Oxidative properties of ambient PM2.5 and elemental composition: Heterogeneous associations in 19 European cities

We assessed the extent to which constituents of PM_2.5 (transition metals, sodium, chloride) contribute to the ability to generate hydroxyl radicals (OH) in vitro in PM_2.5 sampled at 20 locations in 19 European centres participating in the European Community Respiratory Health Survey. PM_2.5 samples (n = 716) were collected on filters over one year and the oxidative activity of particle suspensions obtained from these filters was then assessed by measuring their ability to generate OH in the presence of hydrogen peroxide. Associations between OH formation and the studied PM constituents were heterogeneous. The total explained variance ranged from 85% in Norwich to only 6% in Albacete. Among the 20 centres, 15 showed positive correlations between one or more of the measured transition metals (copper, iron, manganese, lead, vanadium and titanium) and OH formation. In 9 of 20 centres OH formation was negatively associated with chloride, and in 3 centres with sodium. Across 19 European cities, elements which explained the largest variations in OH formation were chloride, iron and sodium.     

Industrial and urban symbiosis in Japan: Analysis of the Eco-Town program 1997–2006

Japan's Eco-Town Program spearheaded in Japan the integration of Industrial Symbiosis and Urban Symbiosis, seeking to maximise the economic and environmental benefit from close geographic proximity of industrial and urban areas, through the use of previously discarded commercial, municipal and industrial waste materials in industrial applications. The program established 26 Eco-Towns around Japan. Approximately 1.65 billion USD was invested in 61 innovative recycling projects, with an average government subsidy of 36%. In addition at least 107 other recycling facilities have been constructed without government subsidy. 14 Eco-Towns primarily contributed to improving industry's productivity, whilst 10 Eco-Towns primarily contributed to improving environmental amenity. In 16 Eco-Towns the private sector was the most important actor supporting local government in the realisation of the Eco-Town, whilst in 9 Eco-Towns this was civil society. The availability of investment subsidies, the coming into force of ambitious recycling legislation with quantified, product-specific targets, access to the significant technological resources of the private sector, and widespread recognition of the urgency to act on environmental issues, all contributed to the success of the Eco-Town Program.