Soil microbial parameters and luminescent bacteria assays as indicators for in situ bioremediation of TNT-contaminated soils

In situ bioremediation is increasingly being discussed as a useful strategy for cleaning up contaminated soils. Compared to established ex situ procedures, meaningful and reliable approaches for monitoring the remediation processes and their efficiency are of special importance. The subject of this study was the significance of two bioassays for monitoring purposes. The work was performed within the scope of a research project on the in situ bioremediation of topsoil contaminated with 2,4,6-trinitrotoluene (TNT). To evaluate changes within different experimental fields during a 17-month remediation period, the results of soil microbial assays and luminescent bacteria assays were compared with chemical monitoring data. The luminescent bacteria assays showed a significant reduction of the water-soluble soil toxicants in the treated fields. This bioassay proved to be a sensitive screening indicator of toxicity and may effectively aid the ecotoxicological interpretation of chemical monitoring data. Microbial biomass (C(mic)), the metabolic quotient (qCO2), and the ratio of microbial to organic carbon (C(mic)/C(org)) showed a highly significant correlation with total concentrations of TNT in the soil. But, in contrast to luminescent bacteria assays, this approach did not reveal any recovery of the soil at the end of the remediation period. There is clear evidence for persistent adverse effects of chronic TNT contamination on the site-specific microbial community and the local carbon cycle in the soil. The study clearly exhibits the differences between, as well as the complementary value of both bioassay approaches for monitoring short-term and long-term effects of soil contamination and the efficiency of remediation.     

The impact of lynx and wolf on roe deer hunting benefits in Sweden

Large carnivores provide ecosystem and cultural benefits but also impose costs on hunters due to the competition for game. The aim of this paper was to identify the marginal impact of lynx (Lynx lynx) and wolf (Canis lupus) on the harvest of roe deer (Capreolus capreolus) in Sweden and the value of this impact. We applied a production function approach, using a bioeconomic model where the annual number of roe deer harvested was assumed to be determined by hunting effort, abundance of predators, availability of other game, and winter severity. The impact of the predators on the roe deer harvests was estimated econometrically, and carnivore marginal impacts were derived. The results showed that if the roe deer resource was harvested under open access, the marginal cost in terms of hunting values foregone varied between different counties, and ranged between 18,000 and 58,000 EUR for an additional lynx family, and 79,000 and 336,000 EUR for an additional wolf individual. Larger marginal costs of the wolf, in terms of the impact on roe deer hunting, were found in counties where the hunting effort was high and the abundance of moose (Alces alces) was low. If instead, hunters could exert private property rights to the resource, the average marginal cost was about 20% lower than it would have been if there was open access, and the difference in wolf impact between counties with high and low moose density was smaller. Together, results suggest that the current plan for expanding the wolf population in south Sweden can be associated with a substantial cost.

     

Ökotoxikologische Untersuchung von Sedimenten und Schwebstoffen

The potential risk of ground-water contamination through the infiltration of contaminants originating from suspended matter and sediments deposited within flood retention areas in the Upper Rhine valley, as well as subsequent problems for drinking water production, were analyzed by means of the bacterial dehydrogenase activity (DHA; sediment contact test) assay with Arthrobacter globiformis and in a prolonged embryo toxicity assay using zebrafish (Danio rerio). Since the direct uptake of contaminants from particle-bound sources has usually been assumed to play only a minor role in bioaccumulation, the availability of organic extracts to biota has generally been regarded as being overestimated. In order to confirm or discard this hypothesis, organic (acetone) extracts of recently suspended, freeze-dried matter, as well as freeze-dried sediments collected from Rhine flood plains (i.e. soil samples) were compared to corresponding native samples in order to screen for the relative availability of particle-bound contaminants. Whereas a significantly higher ecotoxicological burden was observed for some native soil samples, organic extracts of suspended matter proved to be more toxic than corresponding native samples when compared to organic extracts using each test system. With respect to organic extracts, the suspended matter samples were more toxic than soil samples taken from a rarely flooded site. In contrast to the native samples, the rarely flooded soils revealed a higher toxicity than suspended matter. Therefore, organic extracts did not necessarily overestimate the toxicity of soil and suspended matter samples. Moreover, considerable toxicity of particle-bound contaminants to both bacteria and fish embryos, even in native samples, corroborate the hypothesis that particle-bound contaminants may be more readily available than is generally assumed.     

Post-socialist forest disturbance in the Carpathian border region of Poland, Slovakia, and Ukraine.

Forests provide important ecosystem services, and protected areas around the world are intended to reduce human disturbance on forests. The question is how forest cover is changing in different parts of the world, why some areas are more frequently disturbed, and if protected areas are effective in limiting anthropogenic forest disturbance. The Carpathians are Eastern Europe's largest contiguous forest ecosystem and are a hotspot of biodiversity. Eastern Europe has undergone dramatic changes in political and socioeconomic structures since 1990, when socialistic state economies transitioned toward market economies. However, the effects of the political and economic transition on Carpathian forests remain largely unknown. Our goals were to compare post-socialist forest disturbance and to assess the effectiveness of protected areas in the border triangle of Poland, Slovakia, and Ukraine, to better understand the role of broadscale political and socioeconomic factors. Forest disturbances were assessed using the forest disturbance index derived from Landsat MSS/TM/ETM+ images from 1978 to 2000. Our results showed increased harvesting in all three countries (up to 1.8 times) in 1988-1994, right after the system change. Forest disturbance rates differed markedly among countries (disturbance rates in Ukraine were 4.5 times higher than in Poland, and those in Slovakia were 4.3 times higher than in Poland), and in Ukraine, harvests tended to occur at higher elevations. Forest fragmentation increased in all three countries but experienced a stronger increase in Slovakia and Ukraine (approximately 5% decrease in core forest) than in Poland. Protected areas were most effective in Poland and in Slovakia, where harvesting rates dropped markedly (by nearly an order of magnitude in Slovakia) after protected areas were designated. In Ukraine, harvesting rates inside and outside protected areas did not differ appreciably, and harvests were widespread immediately before the designation of protected areas. In summary, the socioeconomic changes in Eastern Europe that occurred since 1990 had strong effects on forest disturbance. Differences in disturbance rates among countries appear to be most closely related to broadscale socioeconomic conditions, forest management practices, forest policies, and the strength of institutions. We suggest that such factors may be equally important in other regions of the world.     

Polychlorinated naphthalenes in sediments from the industrial region of Bitterfeld

Bitterfeld (Germany) was a major site of chemical production in the former German Democratic Republic with chloralkali electrolysis as the basic process. Effluents were dumped via the creek Spittelwasser into the rivers Mulde and Elbe. Despite the fact that the chloralkali industry is known as a possible source of polychlorinated naphthalenes (PCNs), to date no data about PCN pollution in the region of Bitterfeld and downstream regions are available. Therefore, sediments of the creek Spittelwasser were isomer-specifically analysed for penta-, hexa- and heptachlorinated naphthalenes using GC/MS. Concentrations of 880, 543 and 1120 ng/g dry weight were found, respectively. The isomer pattern suggests chloralkali industry as the major source of PCN contamination. Because of their toxicological relevance we suggest to include PCNs into monitoring and risk assessment programs of the rivers Mulde and Elbe downstream of Bitterfeld.