Anthropogenic impacts on natural nitrogen isotope variations in Pinus sylvestris stands in an industrially polluted area

Natural variations of the nitrogen isotopes 15N/14N (delta15N values) and the N concentrations of one-year-old needles from 7-12-year-old pine trees (Pinus sylvestris L.) were determined on 27 sites in the heavily polluted Leipzig-Halle region (former GDR). At three selected sites measurements were repeated over a period of 2 years. N concentrations and delta15N values in different needle age classes were compared at the three sites. The delta15N values of the N in the humus layer and the potential plant available N in the A(h) horizon of the local soil were determined. The 15N/14N isotope ratios (delta15N values) of one-year-old pine needles in the region of Leipzig-Halle were found to vary depending on their specific location by a factor of up to one order of magnitude (-9.6 per thousand to + 0.4 per thousand ). N concentrations in one-year-old pine needles varied between 0.71 and 1.38 mmol eq N g dw(-1). Pine stands with positive or slightly negative delta15N values and high N concentrations in one-year-old needles were concentrated around the cities of Leipzig and Halle and in the industrial areas. More negative delta15N values and lower N concentrations in one-year-old pine needles were found on sites at greater distances from the industrial agglomerations, mainly in the NE forested part. Site specific differences in the delta15N values of the N in the humus layer from three selected sites were similar to those found for the needles. No site specific differences, however, were found for the delta15N values of the water soluble nitrogen fraction from the mineral soil horizons of the same sites.     

Negative interactions between two SW Atlantic intertidal crabs in soft-bottom habitats

The intertidal crabs Chasmagnathus granulatus and Cyrtograpsus angulatus coexist across the SW Atlantic intertidal. Previous studies in this region suggest that C. granulatus displace C. angulatus in soft sediment, where C. granulatus build burrows (“burrowing beds”). We examined variation in abundance, size-frequency distribution, sex ratio, incidence of autotomies, and diet of both species in C. granulatus crab beds and adjacent areas without burrows. We also experimentally tested the hypothesis that in the absence of C. granulatus, C. angulatus will build burrows. Only large sized individuals of C. angulatus venture into C. granulatus crab beds. The sex ratio of C. angulatus was always biased towards females, with higher bias outside crab beds (1:8 outside, 1:2 inside). Although the items consumed in the crab beds did not differ from those consumed outside, the males of C. angulatus had a higher frequency of empty stomachs in crab beds. The incidence of limb autotomies of C. angulatus was higher outside C. granulatus crab bed areas. After a long rainy period in which C. granulatus was absent from these areas, the pattern of habitat use of C. angulatus changed. During this period C. angulatus showed higher abundance in the areas, where C. granulatus previously constructed burrows, and there were no differences between areas in any of the measured parameters. In the absence of C. granulatus, C. angulatus built their own burrows and never used C. granulatus burrows. The interaction between C. granulatus and C. angulatus may be a good example of competitive exclusion, when the shared resource is the access to surface soft-sediment.     

Midnight at the oasis: does restoration change the rigs-to-reefs debate in the North Sea?

ABSTRACT

In the North Sea, many oil and gas fields will reach the end of their productivity and their associated structures will be decommissioned. OSPAR decision 98/3 prescribes removal of all disused offshore structures as the only acceptable decommissioning option. This policy is the legacy of the 1995 Brent Spar incident, which resulted in the current dominant discourse of ‘Hands off the Oceans,’ ruling out the conversion of oil and gas rigs into artificial reefs (Rigs-to-Reefs (RtR)). The shift from a conservation to a restoration paradigm could open up the RtR debate. In this paper, a discourse analysis is carried out to discern whether and how ideas about RtR and ecosystem restoration are articulated to challenge the dominant ‘Hands off the Oceans’ discourse and thereby bring about change in North Sea decommissioning policy. A discourse analytic framework is applied to elucidate whether an ‘RtR as Restoration’ discourse can be distinguished and how competing claims are presented in the various storylines. Our analysis shows an ‘RtR as Restoration’ discourse, consisting of four different storylines. Given the fragmented nature of this discourse, the ‘RtR as Restoration’ discourse will not overcome the dominant ‘Hands off the Oceans’ discourse.     

Stratospheric ozone,global warming,and the principle of unintended consequences—An ongoing science and policy story

Supplemental Materials: Supplemental materials are available for this paper. Go to the publisher's online edition of the Journal of the Air & Waste Management Association.      

Effects of high atmospheric CO2 concentration on root hydraulic conductivity of conifers depend on species identity and inorganic nitrogen source

We examined root hydraulic conductivity (L_p) responses of one-year-old seedlings of four conifers to the combined effects of elevated CO₂ and inorganic nitrogen (N) sources. We found marked interspecific differences in L_p responses to high CO₂ ranging from a 37% increase in P. abies to a 27% decrease in P. menziesii, but these effects depended on N source. The results indicate that CO₂ effects on root water transport may be coupled to leaf area responses under nitrate (NO₃⁻), but not ammonium (NH₄⁺) dominated soils. To our knowledge, this is the first study that highlights the role of inorganic N source and species identity as critical factors that determine plant hydraulic responses to rising atmospheric CO₂ levels. The results have important implications for understanding root biology in a changing climate and for models designed to predict feedbacks between rising atmospheric CO₂, N deposition, and ecohydrology.     

Polychlorinated biphenyls in farmed and wild <Emphasis Type="Italic">Onchorhynchus kisutch</Emphasis> and <Emphasis Type="Italic">Onchorhynchus mykiss</Emphasis> from the Chilean Patagonia

Purpose  

This paper analyses the presence of polychlorinated biphenyls (PCBs) in escaped: farmed and wild salmons in southern Chile, analysing their concentrations and congener profiles in two species (Oncorhynchus kisutch and Oncorhynchus mykiss).     

Strategic environmental assessment of mining activities: A methodology for quantification of cumulative impacts on the air quality

Environmental impact assessments in Brazil have usually focused solely on project-related issues without considering the regional context. Although required by current environmental legislation, cumulative impact assessments have not been included in the overall environmental assessment of projects. However, in recent Strategic Environmental Assessment (SEA) studies of policies, plans, and programs undertaken on a voluntary basis in support of the decision-making process, this kind of assessment has been performed especially with respect to air quality. This paper presents the application of a methodology for the quantification of cumulative impacts on air quality under high uncertainty caused by various mining activities in a single region that is recommended for SEA studies. In this way, the methodology presented here is suitable for areas lacking detailed modeling information. The developed approach uses a relatively simplified mathematical model, lowering information gathering costs and requiring little processing time. The application of the methodology is illustrated in the case of a SEA of the Corumbá Mining and Industrial Complex Development Program. Despite the lack of data needed for a minimum characterization of conditions of the area surrounding the region modeled, the quantification of impact cumulativeness on air quality has played an important role in the context of the SEA.