Heavy metal accumulation in Littoraria scabra along polluted and pristine mangrove areas of Tanzania

The periwinkle Littoraria scabra was collected at polluted and pristine mangrove sites along the Tanzanian coastline, including Msimbazi, Mbweni (i.e. Dar es Salaam) and Kisakasaka, Nyamanzi and Maruhubi (i.e. Zanzibar). Periwinkles were morphologically characterized, sexed and their heavy metal content was determined using ICP-MS. Analysis revealed that L. scabra from polluted areas contained higher soft tissue heavy metal levels, were significantly smaller and weighed less compared to their conspecifics from the unpolluted mangroves. The current morphological observations may be explained in terms of growth and/or mortality rate differences between the polluted and non-polluted sites. Although a variety of stressors may account for these adverse morphological patterns, our data suggest a close relationship with the soft tissue heavy metal content. Compared to soft tissue heavy metal levels that were measured in L. scabra along the same area in 1998, most metals, except for arsenic, chromium and iron have decreased dramatically.     

Monitoring contaminants from oil production at sea by measuring gill EROD activity in Atlantic cod (Gadus morhua)

An ex vivo gill EROD assay was applied in Atlantic cod (Gadus morhua) as a biomarker for waterborne CYP1A-inducing compounds derived from oil production at sea. Exposure to nominal concentrations of 1 ppm or 10 ppm North Sea crude oil in a static water system for 24 h caused a concentration-dependent gill EROD induction. Further, exposure of cod for 14 days to environmentally relevant concentrations of produced water (PW, diluted 1:200 or 1:1000) from a platform in the North Sea using a flow-through system resulted in a concentration-dependent induction of gill EROD. Crude oil (0.2 ppm) from the same oil field also proved to induce EROD. Finally, gill EROD activity in cod caged for 6 weeks at 500-10 000 m from two platforms outside Norway was measured. The activities in these fish were very low and did not differ from those in fish caged at reference sites.     

Nitrogen deposition increases the acquisition of phosphorus and potassium by heather Calluna vulgaris

Increased plant productivity due to nitrogen pollution increases the strength of the global carbon sink, but is implicated in plant diversity loss. However, modelling and experimental studies have suggested that these effects are constrained by availability of other nutrients. In a survey of element concentrations in Calluna vulgaris across an N deposition gradient in the UK, shoot concentrations of N and more surprisingly phosphorus and potassium were positively correlated with N deposition; tissue N/P ratio even decreased with N deposition. Elevated P and K concentrations possibly resulted from improved acquisition due to additional enzyme production or mycorrhizal activity. Heather occurs on organic soils where nutrient limitations are likely due to availability constraints rather than small stocks. However, if this effect extends to other plant and soil types, effects of N deposition on C sinks and plant competition may not be as constrained by availability of other nutrients as previously proposed.     

Sulphur transformation and deposition in the rhizosphere of Juncus effusus in a laboratory-scale constructed wetland

Sulphur cycling and its correlation to removal processes under dynamic redox conditions in the rhizosphere of helophytes in treatment wetlands are poorly understood. Therefore, long-term experiments were performed in laboratory-scale constructed wetlands treating artificial domestic wastewater in order to investigate the dynamics of sulphur compounds, the responses of plants and nitrifying microorganisms under carbon surplus conditions, and the generation of methane. For carbon surplus conditions (carbon:sulphate of 2.8:1) sulphate reduction happened but was repressed, in contrast to unplanted filters mentioned in literature. Doubling the carbon load caused stable and efficient sulphate reduction, rising of pH, increasing enrichment of S(2-) and S(0) in pore water, and finally plant death and inhibition of nitrification by sulphide toxicity. The data show a clear correlation of the occurrence of reduced S-species with decreasing C and N removal performance and plant viability in the experimental constructed wetlands.     

Variation of MCPA, metribuzine, methyltriazine-amine and glyphosate degradation, sorption, mineralization and leaching in different soil horizons

Pesticide mineralization and sorption were determined in 75 soil samples from 15 individually drilled holes through the vadose zone along a 28 km long transect of the Danish outwash plain. Mineralization of the phenoxyacetic acid herbicide MCPA was high both in topsoils and in most subsoils, while metribuzine and methyltriazine-amine was always low. Organic matter and soil pH was shown to be responsible for sorption of MCPA and metribuzine in the topsoils. The sorption of methyltriazine-amine in topsoil was positively correlated with clay and negatively correlated with the pH of the soil. Sorption of glyphosate was tested also high in the subsoils. One-dimensional MACRO modeling of the concentration of MCPA, metribuzine and methyltriazine-amine at 2 m depth calculated that the average concentration of MCPA and methyltriazine-amine in the groundwater was below the administrative limit of 0.1 μg/l in all tested profiles while metribuzine always exceeded the 0.1 μg/l threshold value.     

Spatial variability of arsenic concentration in soils and plants, and its relationship with iron, manganese and phosphorus

Spatial distribution of arsenic (As) concentrations of irrigation water, soil and plant (rice) in a shallow tube-well (STW) command area (8 ha), and their relationship with Fe, Mn and P were studied. Arsenic concentrations of water in the 110 m long irrigation channel clearly decreased with distance from the STW point, the range being 68-136 μg L⁻¹. Such decreasing trend was also noticed with Fe and P concentrations, but the trend for Mn concentrations was not remarkable. Concerning soil As, the concentration showed a decreasing tendency with distance from the pump. The NH₄-oxalate extractable As contributed 36% of total As and this amount of As was associated with poorly crystalline Fe-oxides. Furthermore only 22% of total As was phosphate extractable so that most of the As was tightly retained by soil constituents and was not readily exchangeable by phosphate. Soil As (both total and extractable As) was significantly and positively correlated with rice grain As (0.296 ± 0.063 μg g⁻¹, n = 56). Next to drinking water, rice could be a potential source of As exposure of the people living in the As affected areas of Bangladesh.     

In field arsenic removal from natural water by zero-valent iron assisted by solar radiation

An in situ arsenic removal method applicable to highly contaminated water is presented. The method is based in the use of steel wool, lemon juice and solar radiation. The method was evaluated using water from the Camarones River, Atacama Desert in northern Chile, in which the arsenic concentration ranges between 1000 and 1300 μg L⁻¹. Response surface method analysis was used to optimize the amount of zero-valent iron (steel wool) and the citrate concentration (lemon juice) to be used. The optimal conditions when using solar radiation to remove arsenic from natural water from the Camarones river are: 1.3 g L⁻¹ of steel wool and one drop (ca. 0.04 mL) of lemon juice. Under these conditions, removal percentages are higher than 99.5% and the final arsenic concentration is below 10 μg L⁻¹. This highly effective arsenic removal method is easy to use and inexpensive to implement.     

Long term changes in atmospheric N and S throughfall deposition and effects on soil solution chemistry in a Scots pine forest in the Netherlands

In a Scots pine forest the throughfall deposition and the chemical composition of the soil solution was monitored since 1984. (Inter)national legislation measures led to a reduction of the deposition of nitrogen and sulphur. The deposition of sulphur has decreased by approximately 65%. The total mineral-nitrogen deposition has decreased by ca. 25%, which is mainly due to a reduction in ammonium-N deposition (−40%), since nitrate-N deposition has increased (+50%). The nitrogen concentration in the upper mineral soil solution at 10 cm depth has decreased, leading to an improved nutritional balance, which may result in improved tree vitality. In the drainage water at 90 cm depth the fluxes of NO₃⁻ and SO₄²⁻ have decreased, resulting in a reduced leeching of accompanying base cations, thus preserving nutrients in the ecosystem. It may take still several years, however, before this will meet the prerequisite of a sustainable ecosystem.     

Levels of perfluorochemicals in water samples from Catalonia,Spain: is drinking water a significant contribution to human exposure?

Background, aim, and scope  In recent years, due to a high persistence, biomagnification in food webs, presence in remote regions, and potential toxicity, perfluorochemicals (PFCs) have generated a considerable interest. The present study was aimed to determine the levels of perfluorooctane sulfonate (PFOS), perfluorooctanoic acid (PFOA), and other PFCs in drinking water (tap and bottled) and river water samples from Tarragona Province (Catalonia, Spain). Materials and methods  Municipal drinking (tap) water samples were collected from the four most populated towns in the Tarragona Province, whereas samples of bottled waters were purchased from supermarkets. River water samples were collected from the Ebro (two samples), Cortiella, and Francolí Rivers. After pretreatment, PFC analyses were performed by HPLC-MS. Quantification was done using the internal standard method, with recoveries between 68% and 118%. Results  In tap water, PFOS and PFOA levels ranged between 0.39 and 0.87 ng/L (0.78 and 1.74 pmol/L) and between 0.32 and 6.28 ng/L (0.77 and 15.2 pmol/L), respectively. PFHpA, PFHxS, and PFNA were also other detected PFCs. PFC levels were notably lower in bottled water, where PFOS could not be detected in any sample. Moreover, PFHpA, PFHxS, PFOA, PFNA, PFOS, PFOSA, and PFDA could be detected in the river water samples. PFOS and PFOA concentrations were between <0.24 and 5.88 ng/L (<0.48 and 11.8 pmol/L) and between <0.22 and 24.9 ng/L (<0.53 and 60.1 pmol/L), respectively. Discussion  Assuming a human water consumption of 2 L per day, the daily intake of PFOS and PFOA by the population of the area under evaluation was calculated (0.78–1.74 and 12.6 ng, respectively). It was found that drinking water might be a source of exposure to PFCs as important as the dietary intake of these pollutants. Conclusions  The contribution of drinking water (tap and bottled) to the human daily intake of various PFCs has been compared for the first time with data from dietary intake of these PFCs. It was noted that in certain cases, drinking water can be a source of exposure to PFCs as important as the dietary intake of these pollutants although the current concentrations were similar or lower than those reported in the literature for surface water samples from a number of regions and countries. Recommendations and perspectives  Further studies should be carried out in order to increase the knowledge of the role of drinking water in human exposure to PFCs.     

Acute toxic hazard evaluations of glyphosate herbicide on terrestrial vertebrates of the oregon coast range

GOAL, SCOPE AND BACKGROUND: The degree to which dose responses of model organisms (lab rodents) can adequately predict dose responses of free-ranging wild mammals or amphibians is unknown, and the relative sensitivity of such species to body loading of a toxicant such as glyphosate is seldom reported. For relative effects of dosage, we compare sensitivity of nine wild vertebrate species to effects of high doses of glyphosate in Swiss-Webster laboratory mice both by gavage and by intraperitoneal injection. We also evaluate sublethal effects of herbicide exposure on behavior and reproductive success of one mammal and one amphibian species. METHODS: Comparisons of acute toxicity of glyphosate were made with intraperitoneal dosings of technical glyphosate isopropylamine salt to nine species of terrestrial vertebrates (five amphibians, four mammals) and compared with responses in Swiss-Webster laboratory mice. Animals collected from sites that had no recent herbicide application were allowed 7-14 days to equilibrate in captivity before treatment. RESULTS: Median lethal dose ranged from 800 to 1,340 mg kg(-1) in mammals, and 1,170 to >2,000 mg kg(-1) in amphibians, with Oregon vole being the most sensitive. White lab mice were in the middle of the mammalian range. Tailed frog, at >2,000 mg kg(-1) was the least sensitive. Calibration of IP sensitivity to oral administration by gavage indicated that roughly four times as much glyphosate must be administered to obtain a comparable estimate of lethality. Administration by gavage in highly concentrated solutions tended to cause physical injury, hence may prove less useful as a relative indicator of toxicity. When sublethal dosages were given to roughskin newts or chipmunks, mobility and use of cover appeared largely unaffected. DISCUSSION: Direct toxic effects of spraying glyphosate under normal forest management seem unlikely for the nine species examined. Nor could we detect significant indirect effects of exposure on behavior and use of cover features in two species. There may be effects on other aspects of the field biology of these animals, such as reproductive rates, which we did not investigate. Recent field data indicate that changes in habitat quality following herbicide application can result in high reproductive activity in species associated with the grasses and forbs that proliferate following field applications. CONCLUSIONS: When compared to field data on body burdens of wild mammals exposed after aerial application of glyphosate at maximum rates in forests, there seems to be a large margin of safety between dosages encountered and those causing either death or limitation of movement, foraging or shelter. RECOMMENDATIONS AND PERSPECTIVES: Margins of safety for small mammals and amphibians appear to be large under any probable exposure scenarios, however our results indicate high variability in responses among species. Uncertainty introduced into field studies from unknown sources of mortality (e.g, likely predation) must be considered when interpreting our results.