Denitrification potential and organic matter as affected by vegetation community, wetland age, and plant introduction in created wetlands

Denitrification potential (DP) and organic matter (OM) in soils were compared in three different vegetation communities-emergent macrophyte, open water, and forested edge-in two 10-yr-old created riverine wetlands. Organic matter, cold water-extractable organic matter (CWEOM), anaerobic mineralizable carbon (AnMC), and DP varied significantly (P<0.05) among vegetation communities. The surface (0 to 9 cm) soils in the emergent macrophyte community (EMC) showed highest DP (0.07+/-0.01 mg N h-1 kg-1), OM (84.90+/-5.60 g kg-1), CWEOM (1.12+/-0.20 g kg-1), and AnMC (1.50+/-0.10 mg C h-1 kg-1). In the deeper layer (9 to 18 cm), DP and CWEOM (0.04+/-0.01 mg N h-1 kg-1 and 1.13+/-0.20 g kg-1, respectively) were significantly higher in the open water community (OWC) than in the emergent macrophyte and forested edge communities. Plant introduction did not affect DP or OM content and characteristics. After 10 yr of wetland development, mean DP increased 25-fold in the surface layer (from 0.002 to 0.053 mg N h-1 kg-1); OM content more than doubled to 90.80+/-19.22 g kg-1, and CWEOM and HWEOM increased 2.5 and 2.7 times respectively from 1993 (prewetland conditions) to 2004. Humic acids were the most abundant form of OM in 2004 and 1993 samples. Significant (P<0.05) positive relationships between DP and OM, CWEOM, and AnMC were found in the surface layer; in the 9- to 18-cm layer, significant positive relationships were found between DP and CWEOM and AnMC.     

Influence of seat geometry and seating posture on NIC(max) long-term AIS 1 neck injury predictability

OBJECTIVE: Validated injury criteria are essential when developing restraints for AIS 1 neck injuries, which should protect occupants in a variety of crash situations. Such criteria have been proposed and attempts have been made to validate or disprove these. However, no criterion has yet been fully validated. The objective of this study is to evaluate the influence of seat geometry and seating posture on the NIC(max) long-term AIS 1 neck injury predictability by making parameter analyses on reconstructed real-life rear-end crashes with known injury outcomes. METHODS: Mathematical models of the BioRID II and three car seats were used to reconstruct 79 rear-end crashes involving 110 occupants with known injury outcomes. Correlations between the NIC(max) values and the duration of AIS 1 neck injuries were evaluated for variations in seat geometry and seating posture. Sensitivities, specificities, positive predictive values, and negative predictive values were also calculated to evaluate the NIC(max) predictability. RESULTS: Correlations between the NIC(max) values and the duration of AIS 1 neck injuries were found and these relations were used to establish injury risk curves for variations in seat geometry and seating posture. Sensitivities, specificities, positive predictive values, and negative predictive values showed that the NIC(max) predicts long-term AIS 1 neck injuries also for variations in seat geometry and seating postures. CONCLUSION: The NIC(max) can be used to predict long-term AIS 1 neck injuries.     

Persistent organochlorine pollutants in children working at a waste-disposal site and in young females with high fish consumption in Managua, Nicaragua

The aim of this study was to assess persistent organochlorine pollutant (POP) levels in serum collected from children (11-15 years old) working and sometimes also living at the municipal waste-disposal site in Managua, located at the shore of Lake Managua, and in nonworking children living both nearby and also far away from the waste-disposal site. The influence of fish consumption was further evaluated by assessing POPs levels in serum from young women (15-24 years old) with markedly different patterns of fish consumption from Lake Managua. 2,2-bis(4-chlorophenyl)-1,1,1-trichloro-ethane (4,4'-DDT) and 2,2-bis(4-chlorophenyl)-1,1-dichloro-ethene (4,4'-DDE), gamma-hexachlorocyclohexane (gamma-HCH), polychlorinated biphenyls, pentachlorophenol, and polychlorobiphenylols were quantified in all samples. In general, the levels observed were higher than those reported in children from developed countries, such as Germany and United States. Toxaphene, aldrin, dieldrin, and beta-HCH could not be identified in any sample. The children working at the waste-disposal site had higher levels of POPs compared with the nonworking reference groups. In children not working, there were also gradients for several POPs, according to vicinity to the waste-disposal site. Moreover, in children, as well as in young women, there were gradients according to fish consumption. The most abundant component was 4,4'-DDE, but at levels still lower than those reported in children from malarious areas with a history of recent or current application of 4,4'-DDT for vector control.     

Degradation and decolorization of a biodegradable-resistant polymeric dye by chelator-mediated Fenton reactions

Chelator-mediated Fenton reactions (CMFRs) were used to decolorize a biodegradable-resistant polymeric dye (Poly R-478). Screening of different iron chelators was performed on Fe(3+)-reduction activity. All chelators showed Fe(3+)-reduction activity over a wide range of pH (2-7) and each mol of catecholate chelators (3,4-dihydroxiphenilacetic acid--DOPAC and 2,3-dihydroxibenzoic acid--DHBA) reduced about 5-6 moles of Fe(3+) whereas hydroxamate chelators (acetohydroxamic acid-AHA and desferrioxamine B-DFB) reduced Fe(3+) stoichiometrically. The most effective decolorization of Poly R-478 was achieved by CMFR using catecholate chelators. In addition, a 2(4) factorial design was performed with the aim of evaluating the effects of the variables considered in this study (pH, [DOPAC], [Fe(3+)] and [H(2)O(2)]) and optimizing the dye decolorization, using response surface methodology. Statistical analysis of results showed that, in the range studied, except for Fe(3+), all variables have a significant effect on dye decolorization. A second-order model is proposed to represent the Poly R-478 decolorization. At optimum conditions, complete decolorization of the dye (degradation of the chromophoric group) and also complete chemical degradation of the dye was observed.     

Isolation of novel bacteria able to degrade alpha-halocarboxylic acids by enrichment from environmental samples

In order to isolate novel bacteria able to degrade alpha-halocarboxylic acids a variety of culturing strategies were implemented. Eight pure cultures were obtained and were found to be associated with the Gram negative Proteobacteria and the Gram positive Bacillus and Enterococcus genera. Furthermore, several strains were obtained which were able to degrade the DL-halocarboxylic acids anaerobically. Molecular analysis of the pure cultures led us to conclude that they may possess novel enzymes involved in the biodegradation of the alpha-halocarboxylic acids. These results are the first for nearly 40 years to describe the isolation of Gram positive isolates on an alpha-halocarboxylic acid as the sole source of carbon and energy, which also show the ability to de-toxify the test substrate by releasing chloride.     

Possible chemical causes of skeletal deformities in grey heron nestlings (Ardea cinerea) in North Nottinghamshire, UK

Dead and deformed grey heron (Ardea cinerea) chicks were reported at a large heronry in North Nottinghamshire, UK between 1996 (when systematic visits to the heronry started) and 2002. Many of the birds died for no obvious reason but deformities in others included multiple fractures of the tarsus and tibia and metacarpal bones (angel wings). This study aimed to investigate possible chemical causes of these deformities. Analysis of eggs and nestling tissue for a range of metals showed no levels of concern and no significant differences between unaffected and deformed birds. However, the levels of polychlorinated biphenyls (PCBs), polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) detected in affected heron nestlings in 2002 and in eggs taken from nests in 2003 were sufficiently high to suggest that this may be the underlying cause of the deformities, possibly due to effects on deposition of calcium in bone. Further work is underway to identify where the parent birds of the affected nestlings are feeding and identify the possible source of the pollution.     

Baseline mercury and zinc concentrations in terrestrial and coastal organisms of Admiralty Bay, Antarctica

This paper provides the first quantitative information on mercury in soil, coastal sediment, and in characteristic organisms of terrestrial and shallow coastal marine ecosystems from Admiralty Bay (King George Island, Antarctica). As expected for a remote area, mercury content is low in abiotic components of the ecosystem, and probably similar to natural levels. Mercury also occurs in very low concentrations in the vegetation, invertebrates and fish. These low mercury levels may be due to sulphide formation in reducing sediments of this environment. Higher concentrations of mercury occurred in bird feathers and mammal hair, indicating biomagnification. This was not found for Zinc. These results may be useful as a reference background to detect future inputs of trace elements in this remote area of the earth. Terrestrial vegetation and bird feathers are suggested as target regional biomonitors.     

Use of hydra for chronic toxicity assessment of waters intended for human consumption

Methods developed with the cnidarian, Hydra attenuata (Pallas), have proven effective for screening acute toxicity in aqueous samples, whereas their use in revealing (sub)chronic toxic effects have had mitigated success. We therefore sought to explore manifestations of hydra mortality and abnormal morphological changes, as well as the reproductive capacity of hydras to further enhance the bioassay sensitivity and to assess (sub)chronic toxicity. These parameters were recorded following the onset of experiments after 8, 12 and 19-21 days of hydra exposure. Results obtained with potable waters (30 brands of bottled waters and artesian waters from 9 wells) showed chronic sublethal and lethal effects or reproduction rate inhibition for most samples. The effectiveness of the hydra toxicity test was demonstrated in comparison with other widely used bioassays. Our previous and present investigations suggest that hydra is a reliable and relevant test organism for the assessment of acute and chronic water toxicity.     

Influences of wetland plants on weathered acidic mine tailings

Establishment of Carex rostrata, Eriophorum angustifolium and Phragmites australis on weathered, acidic mine tailings (pH approximately 3) and their effect on pH in tailings were investigated in a field experiment. The amendments, sewage sludge and an ashes-sewage sludge mixture, were used as plant nutrition and their influence on the metal and As concentrations of plant shoots was analysed. An additional experiment was performed in greenhouse with E. angustifolium and sewage sludge as amendments in both weathered and unweathered tailings. After one year, plants grew better in amendments containing ashes in the field, also in those plants the metal and As shoot concentrations were generally lower than in other treatments. After two years, the only surviving plants were found in sewage sludge mixed with ashes. No effect on pH by plants was found in weathered acidic mine tailings in either field- or greenhouse experiment.     

Remediation efficiency of vapour extraction of sandy soils contaminated with cyclohexane: Influence of air flow rate, water and natural organic matter content

This work reports the analysis of the efficiency and time of soil remediation using vapour extraction as well as provides comparison of results using both, prepared and real soils. The main objectives were: (i) to analyse the efficiency and time of remediation according to the water and natural organic matter content of the soil; and (ii) to assess if a previous study, performed using prepared soils, could help to preview the process viability in real conditions. For sandy soils with negligible clay content, artificially contaminated with cyclohexane before vapour extraction, it was concluded that (i) the increase of soil water content and mainly of natural organic matter content influenced negatively the remediation process, making it less efficient, more time consuming, and consequently more expensive; and (ii) a previous study using prepared soils of similar characteristics has proven helpful for previewing the process viability in real conditions.