Applicability of Fenton and H2O2/UV reactions in the treatment of tannery wastewaters

In this paper we evaluated the H2O2/UV and the Fenton's oxidation processes for the treatment of tannery wastewater under different experimental conditions. Efficiencies were judged by the amounts of organic substances degraded or eliminated under these treatment techniques. Daphnia magna and Vibrio fischeri were used to monitor toxicity. Organic compounds contained in the untreated and treated tannery wastewater were determined and identified using substance specific techniques. Gas chromatography-mass spectrometry (GC-MS) in positive electron impact (EI(+)) mode was applied to determine volatile organics. Atmospheric pressure ionization (API) mass (MS) and tandem mass spectrometry (MS-MS) coupled with flow injection analysis (FIA) or liquid chromatography (LC) were used to detect or identify polar organic pollutants. The experimental results indicated that both oxidation processes--H2O2/UV at pH 3 and Fenton at pH 3.5--are able to reduce TOC content by mineralisation of the organic compounds.     

Trichloroacetic acid cycling in Sitka spruce saplings and effects on sapling health following long term exposure

Trichloroacetic acid (TCA, CCl(3)COOH) has been associated with forest damage but the source of TCA to trees is poorly characterised. To investigate the routes and effects of TCA uptake in conifers, 120 Sitka spruce (Picea sitchensis (Bong.) Carr) saplings were exposed to control, 10 or 100 microg l(-1) solutions of TCA applied twice weekly to foliage only or soil only over two consecutive 5-month growing seasons. At the end of each growing season similar elevated TCA concentrations (approximate range 200-300 ng g(-1) dwt) were detected in both foliage and soil-dosed saplings exposed to 100 microg l(-1) TCA solutions showing that TCA uptake can occur from both exposure routes. Higher TCA concentrations in branchwood of foliage-dosed saplings suggest that atmospheric TCA in solution is taken up indirectly into conifer needles via branch and stemwood. TCA concentrations in needles declined slowly by only 25-30% over 6 months of winter without dosing. No effect of TCA exposure on sapling growth was measured during the experiment. However at the end of the first growing season needles of saplings exposed to 10 or 100 microg l(-1) foliage-applied TCA showed significantly more visible damage, higher activities of some detoxifying enzymes, lower protein contents and poorer water control than needles of saplings dosed with the same TCA concentrations to the soil. At the end of each growing season the combined TCA storage in needles, stemwood, branchwood and soil of each sapling was <6% of TCA applied. Even with an estimated half-life of tens of days for within-sapling elimination of TCA during the growing season, this indicates that TCA is eliminated rapidly before uptake or accumulates in another compartment. Although TCA stored in sapling needles accounted for only a small proportion of TCA stored in the sapling/soil system it appears to significantly affect some measures of sapling health.     

Environmental impact assessment of salmonid feeds using Life Cycle Assessment (LCA)

Understanding the environmental burdens associated with aquafeeds is a critical component for assessing and improving the environmental performance of aquaculture. The aim of the study was to assess the environmental impacts associated with feeds for rainbow trout production in France, using Life Cycle Assessment (LCA). The stages assessed are: the extraction of the raw materials, the production and transformation of the primary ingredients used, the manufacturing of the feeds, the use of the feeds at the farm, transport at all stages, and the production and use of energy resources. The assessment revealed that the use of fishery resources (such as biotic resource use) and nutrient emissions at the farm (such as eutrophication potential) contribute most to the potential environmental impacts of salmonid aquafeeds. Improvements in feed composition and management practices seem to be the best ways for improving the environmental profile of aquafeeds.     

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Heavy metal concentrations in soil and earthworms in a floodplain grassland

We determined accumulated heavy metal concentrations (Cd, Pb, Cu, Zn) of earthworms in moderately contaminated floodplain soils. Both soil and mature earthworms were sampled before and after flooding and earthworm species were identified to understand species specific differences in bioconcentration. Accumulated metal concentrations in floodplain earthworms differed before and after flooding. Differences in uptake and elimination mechanisms, in food choice and living habitat of the different earthworm species and changes in speciation of the heavy metals are possible causes for this observation. Regression equations taken from literature, that relate metal accumulation by earthworms in floodplains as a function of metal concentration in soil, performed well when all species specific data were combined in an average accumulation, but did not address differences in accumulation between earthworm species.     

Effects of atmospheric ammonia on vegetation--a review

Atmospheric ammonia does not only cause acute injuries at vegetation close to the source, but significantly contributes to large scale nitrogen eutrophication and acidification of ecosystems because the amount of sources is high and after conversion to ammonium it can reach remote areas by long-range atmospheric transport. Besides having acute toxic potential, NH(3) and NH(4)(+) (= NH(y)) may disturb vegetation by secondary metabolic changes due to increased NH(y) uptake and assimilation leading to higher susceptibility to abiotic (drought, frost) and biotic (pests) stress. Prevention of damage to natural and semi-natural ecosystems will only be achieved if NH(3) emissions are drastically reduced. In this paper, the current knowledge on NH(y) emission, deposition, and its effects on vegetation and ecosystems are reviewed. Critical levels and critical loads for nitrogen deposition are discussed.     

Exploiting plant metabolism for the phytoremediation of persistent herbicides

Weed control by herbicides has helped us to create the green revolution and to provide food for at least the majority of human beings living today. However, some herbicides remain in the environment and pose an ecological problem. The present review describes the properties and fate of four representative herbicides known to be presistent in ecosystems. Metabolic networks are depicted and it is concluded that removal of these compounds by the ecologically friendly technique of phytoremediation is possible. The largest problem is seen in the uptake of the compounds into suitable plants and the time needed for such an approach.     

Concentration of LAS and boron in the Itter. Comparison of measured data with results obtained by simulation with the GREAT-ER software

The GREAT-ER software was used to calculate linear alkylbenzene sulphonate [LAS] and boron concentrations in the Itter stream in North Rhine-Westfalia, Germany. The aim was to investigate the predictive strength of this newly developed tool and to compare its results to measured data. Substance-specific input data which were used in this scenario were partly generic (e.g. LAS and sodium perborate tetrahydrate consumption figures for Germany) and partly (site-)specific data (e.g. half-life time for LAS elimination). The comparison with the measured data reveals that the model predictions for LAS and boron are correct at least within a factor of two, only if generic German consumption data is applied. By using refined input data, the accuracy can be increased further.     

Genetic engineering in the improvement of plants for phytoremediation of metal polluted soils

Metal concentrations in soils are locally quite high, and are still increasing due to many human activities, leading to elevated risk for health and the environment. Phytoremediation may offer a viable solution to this problem, and the approach is gaining increasing interest. Improvement of plants by genetic engineering, i.e. by modifying characteristics like metal uptake, transport and accumulation as well as metal tolerance, opens up new possibilities for phytoremediation. So far, only a few cases have been reported where one or more of these characteristics have been successfully altered; e.g. mercuric ion reduction causing improved resistance and phytoextraction, and metallothionein causing enhanced cadmium tolerance. These, together with other approaches and potentially promising genes for transformation of target plants are discussed.     

Anaerobic incorporation of the radiolabeled explosive TNT and metabolites into the organic soil matrix of contaminated soil after different treatment procedures

Four bioreactor designs were performed to evaluate the level of incorporation of 14C-labeled 2,4,6-trinitrotoluene (TNT) and metabolites into the organic soil matrix of different anaerobically treated contaminated soils. The contaminated soils were amended with molasses slivers (80:20% per weight) as auxiliary substrate to enhance microbial activity. After 5 weeks (bioreactors 1 and 2), 8 weeks (bioreactor 3) and 12 weeks (bioreactor 4) of anaerobic incubation, we determined 41%, 58%, 72%, and 54%, respectively, of the initially applied radioactivity immobilized in various soil fractions. After alkaline hydrolyses of the solvent-extracted soils, low quantities of radiolabel were found in the humic and fulvic acid fractions, whereas the bulk of 14C activity was found to be strongly bound to the humin fraction (solid soil residues). The amounts of solvent extractable radioactivity were 53%, 40%, 16%, and 29% for bioreactors 1, 2, 3, and 4, respectively. The level of TNT transformation at the end of the experiments was within 90-94%. Regarding the results presented in this study, we can assume that there is the possibility of high incorporation levels of TNT metabolites into the soil organic matrix mediated by microbial cometabolism under strictly anoxic conditions.