Reductive Dechlorination of Tetrachloroethylene by Soil Sulfate-Reducing Microbes under Various Electron Donor Conditions

Biotransformation of tetrachloroethylene (PCE) by soil sulfate-reducing bacteria was investigated using acetate, lactate and methanol as electron donors. Results show that the effectiveness of biotransformation of PCE by soil sulfate-reducing bacterial is dependent upon the type of electron donor used.     

Analysis of the small-scale spatial patterns of free-living marine nematodes from tidal flats in the East Frisian Wadden Sea

Serial samples with a multiple corer were taken in order to understand the small-scale aggregation patterns in the nematode community. A total of 77 species was found in the sample. Fifteen dominant nematode species were examined by means of a dispersion analysis. Only one species (Metachromadora scotlandica) may be considered randomly distributed. A variogram analysis gave no proof of aggregation in that species, but all the other (aggregated) species displayed different spatial patterns: (1) a maximum/aggregation at the sample's margin, (2) two maxima/aggregations in the centre of the sample, (3) aggregation of individuals distributed at random over the entire sample (Metalinhomoeus typicus) and (4) aggregation of individuals distributed at random only in the centre of the sample (Paralinhomoeus ilenensis). These results allow the prognosis that distribution patterns are repetitive in five species (Microlaimus conothelis, M. marinus, Odontophora rectangula, Oncholaimellus calvadosicus, Viscosia rustica). Finally, by means of MDS-ordination (based on cosine similarity) two nematode associations were distinguished: one group represented by diatom-feeders (sensu lato), the other one comprised of DOM-users (sensu lato). Received: 13 May 1998 / Accepted: 15 January 1999     

Use of Ammophila arenaria for Dune Stabilization in South Africa and Its Current Distribution—Perceptions and Problems

Ammophila arenaria (marram or European beach grass) for dune stabilization in South Africa in the past and present, its present distribution in South Africa, and the perceptions of coastal management agencies and the public about its further use. The planting of A. arenaria became the most important means of dune stabilization, by human intervention, along the South African Cape coast in this century. Its modern distribution from the semiarid west coast to the subtropical shores of the Eastern Cape extends through various climatic zones. Although historical data are missing for some areas, there is no indication of its unaided spread. A. arenaria occurs at most sites because of its prior planting. The South African climate appears to affect its vigor. However, concern about the use of the alien grass has been raised since it has proved to be a highly invasive species in other parts of the world, particularly along the North American west coast and in Tasmania. While the CSIR (Council of Scientific and Industrial Research) promotes its use, CNC (Cape Nature Conservation) follows a policy that restricts the use of any alien plant, including A. arenaria, and requests further research on its invasive properties. Although a questionnaire survey shows that stabilization sites featuring large areas of A. arenaria are accepted by the South African public, current coastal management practices need to be analyzed critically. A thorough investigation of the potential invasiveness of A. arenaria on South African coastal dunes will be essential and shed new light on the American A. arenaria problem.     

Evaluation of a respirometric test method to determine the heterotrophic yield coefficient of activated sludge bacteria

The heterotrophic yield coefficient of activated sludge bacteria is an important parameter in the field of wastewater degradation kinetics and the determination of degradation kinetics of defined chemicals. With the help of easily biodegradable organic compounds like glucose and acetate the respiration kinetics of degrading activated sludge bacteria was studied. The results of the respiration analysis were transformed to examine the degradation and respiration kinetics of municipal wastewaters at different food to microorganism ratios (F/M ratios). It was proved that the heterotrophic yield coefficient of aerobically degrading activated sludge bacteria could reliably be determined and that the heterotrophic yield coefficient was independent of the F/M ratio over a wide range.     

Inhibition of Na+/K+-ATPase and of active ion-transport functions in the gills of the shore crab Carcinus maenas induced by cadmium

Inhibition of Na⁺/K⁺-ATPase from gill plasma membranes of the shore crab Carcinus maenas by cadmium was investigated and compared with inhibitory effects by known antagonists (ouabain and Ca²⁺). For comparative considerations the Cd²⁺-inhibition of the enzyme from dog kidney was also tested. Na⁺/K⁺-ATPase from dog kidney and from crab gill differed greatly in sensitivity against ouabain. The inhibition constant K _i of the dog enzyme amounted to 9.1 × 10⁻⁷ mol l⁻¹, i.e. more than 300-fold smaller than the K _i of 2.9 × 10⁻⁴ mol l⁻¹ determined for the crab enzyme. Ca²⁺ inhibited the activity of Na⁺/K⁺-ATPase from crab gill plasma membranes with a K _i of 4.3 × 10⁻⁴ mol l⁻¹. The Na⁺/K⁺-ATPase from crab gill was inhibited by Cd²⁺ with a K _i of 9.1 × 10⁻⁵ mol l⁻¹. Cd²⁺ inhibited the Na⁺/K⁺-ATPase from dog kidney with a K _i (6.4 × 10⁻⁵ mol l⁻¹) comparable to that observed in the crab gill enzyme. Under experimental conditions Cd²⁺-inhibition of Na⁺/K⁺-ATPase was irreversible. Repeated washing, centrifugation and homogenization of the plasma membranes (four times) with Cd²⁺-free buffer did not restore any activity lost in the presence of 1 × 10⁻³ mol l⁻¹ Cd²⁺. Since ouabain-insensitive (nonspecific) ATPases in the plasma membrane fraction of crab gills were inhibited by Cd²⁺ in the same way as Na⁺/K⁺-ATPase, the heavy metal is considered as an unspecific ATPase inhibitor. Comparing these results with literature data on Cd²⁺-binding to electrophoretically separated proteins suggests that Na⁺/K⁺-ATPase is a Cd²⁺-binding enzyme. The results obtained on Na⁺/K⁺-ATPase were reflected by Cd²⁺-inhibition of the branchial ion-transport functions depending on this enzyme. The transepithelial short-circuit current of isolated gill half lamellae, a direct measure of area-specific active ion uptake, and the transepithelial potential difference of isolated, perfused whole gills, also indicative of active ion uptake, were inhibited by the heavy metal in a time- and dose-dependent mode. Remarkably these inhibitions were also irreversible. These findings are ecologically and biomedically significant: even when the actual environmental or tissue concentrations measured are low, biological microstructures such as Na⁺/K⁺-ATPase may accumulate the heavy metal by tight binding over prolonged periods until the first inhibitory effects occur. Received: 25 June 1997 / Accepted: 25 August 1997     

Sublethal impairment of respiratory control in plaice (Pleuronectes platessa) larvae induced by UV-B radiation, determined using a novel biocybernetical approach

The increasing amount of UV-B radiation (280 to 320 nm) reaching the earth's surface could endanger transparent fish and zooplankton in upper water layers. Previous studies on marine fish eggs and larvae focused mainly on the effects of high, lethal doses of ultraviolet irradiation. Now a sensitive test for accumulated, sublethal impairments of physiological performance has been established. In developing fish larvae (Pleuronectes platessa L.), the respiratory control responses to hypoxia were evaluated by combining a biocybernetical approach and a novel optical test system. Before testing respiratory control behavior, the larvae were irradiated with light containing UV-B (test individuals) or free from it (control individuals). Differences in the physiological reactions of these larvae were detected by biocybernetical analysis (linear systems analysis) of respiratory control. The analysis was based on the evaluation of changes in ventilatory rate caused by sinusoidally modulated partial pressures of ambient oxygen. The ventilatory movements of the larvae were recorded, analyzed and evaluated by video microscopy and digital image processing. After several days of irradiation with moderate UV-B doses or intensities (8.6 kJ m⁻² d⁻¹, corresponding to an irradiance of 0.24 W m⁻² for 10 h), sublethal impairments of respiratory control could be detected in plaice larvae by this method; both the linearity of respiratory control itself and the parameters of linear control behavior were affected by UV-B. Concerning environmental implications, the results must still be interpreted cautiously, because natural irradiation conditions are more complex than the artificial regimen. Our biocybernetical approach will be useful for further studies on sublethal impairments of physiological functions caused by UV-B in fish and other transparent marine or limnic animal groups. In addition, the method could be used to test the sublethal impact of chemical contaminants. Received: 4 November 1997 / Accepted: 6 May 1998     

Phthalates and their metabolites in breast milk--results from the Bavarian Monitoring of Breast Milk (BAMBI)

Phthalates have long been used as plasticizers to soften plastic products and, thus, are ubiquitous in modern life. As part of the Bavarian Monitoring of Breast Milk (BAMBI), we aimed to characterize the exposure of infants to phthalates in Germany. Overall, 15 phthalates, including di-2-ethylhexyl phthalate (DEHP), di-n-butyl phthalate (DnBP), di-isobutyl phthalate (DiBP), di-isononyl phthalate (DiNP), three primary metabolites of DEHP [mono-(2-ethylhexyl) phthalate (MEHP), mono-isobutyl phthalate (MiBP), and mono-n-butyl phthalate (MnBP)], and two secondary metabolites of DEHP were analyzed in 78 breast milk samples. We found median concentrations of 3.9 ng/g for DEHP, 0.8 ng/g for DnBP, and 1.2 ng/g for DiBP, while other parent phthalates were found in only some or none of the samples at levels above the limit of quantitation. In infant formula (n=4) we observed mean values of 19.7 ng/g (DEHP), 3.8 ng/g (DnBP), and 3.6 ng/g (DiBP). For MEHP, MiBP, and MnBP, the median values in breast milk were 2.3 μg/l, 11.8 μg/l, and 2.1 μg/l, respectively. The secondary metabolites were not detected in any samples. Using median and 95th percentile values, we estimated an "average" and "high" daily intake for an exclusively breast-fed infant of 0.6 μg/kg body weight (b.w.) and 2.1 μg/kg b.w., respectively, for DEHP, 0.1 μg/kg b.w. and 0.5 μg/kg b.w. for DnBP, and 0.2 μg/kg b.w. and 0.7 μg/kg b.w. for DiBP. For DiNP, intake values were 3.2 μg/kg b.w. and 6.4 μg/kg b.w., respectively, if all values in milk were set half of the detection limit or the detection limit. The above-mentioned "average" and "high" intake values corresponded to only about 2% to 7%, respectively, of the recommended tolerable daily intake. Thus, it is not likely that an infant's exposure to phthalates from breast milk poses any significant health risk. Nevertheless, other sources of phthalates in this vulnerable phase have to be considered. Moreover, it should be noted that for infants nourished with formula, phthalate intake is of the same magnitude or slightly higher (DEHP) than for exclusively breast-fed infants.     

Bisphenol A content in fish caught in two different sites of the Tyrrhenian Sea (Italy)

Bisphenol A (BPA) is an endocrine disruptor (ED) that is abundant in the environment because of its extensive use in human-manufactured products. In this study, the BPA concentration was measured in the muscle and liver of five edible fish, characterized by different habitat and habits, caught in two different sites of the Tyrrhenian Sea (Italy). Our results show that: (i) fish livers are about 2.5 times more polluted than muscle; (ii) fish caught in the Gulf of Naples are more polluted than those from the Latium coasts, ranging from 1.2-fold more for White Bream to 6.6-fold for Grey Mullet; and (iii) the percentages of fish found to be BPA-polluted in the Gulf of Naples ranged from 73% (for Bass) to 90% (for Mullet), while the Latium fish range from 60% (for Bass) to 90% (for Mullet). These data indicate that consumers of fish caught in the Gulf of Naples are at a greater risk for BPA-induced endocrine pathologies compared to those who consume fish caught along the Latium coasts.     

Growth responses and metal accumulation capabilities of woody plants during the phytoremediation of tannery sludge

Five woody plants species (i.e. Terminalia arjuna, Prosopis juliflora, Populus alba, Eucalyptus tereticornis and Dendrocalamus strictus) were selected for phytoremediation and grow on tannery sludge dumps of Common Effluent Treatment Plant (CETP), Unnao (Uttar Pradesh), India. Concentration of toxic metals were observed high in the raw tannery sludge i.e. Fe-1667 > Cr-628 > Zn-592 > Pb-427 > Cu-354 > Mn-210 > Cd-125 > Ni-76 mg kg⁻¹ dw, respectively. Besides, physico-chemical properties of the raw sludge represented the toxic nature to human health and may pose numerous risks to local environment. The growth performances of woody plants were assessed in terms of various growth parameters such as height, diameter at breast height (DBH) and canopy area of plants. All the plant species have the capabilities to accumulate substantial amount of toxic metals in their tissues during the remediation. The ratio of accumulated metals in the plants were found in the order Fe > Cr > Mn > Pb > Zn > Cu > Cd > Ni and significant changes in physico-chemical parameters of tannery sludge were observed after treatment. All the woody plants indicated high bioconcentration factor for different metals in the order Fe > Cr > Mn > Ni > Cd > Pb > Zn > Cu. After one year of phytoremediation, the level of toxic metals were removed from tannery sludge up to Cr (70.22)%, Ni (59.21)%, Cd (58.4)%, Fe (49.75)%, Mn (30.95)%, Zn (22.80)%, Cu (20.46)% and Pb (14.05)%, respectively.