Suchergebnisse

Organic contaminants in polar regions have become significant concerns because of their persistence, bioaccumulation and toxicity potential. Climate change can alter the biogeochemical cycling of persistent organic pollutants (POPs) and emerging organic contaminants (EOCs) and amplify their effects on polar ecosystems. Occurrences of POPs and EOCs from long-range transport and local discharge have left impacts on fragile polar ecosystems. Therefore, actions are urgently needed to monitor the temporal trends of POPs and to investigate novel EOCs in polar regions. The data on legacy POPs in environmental media and biota exhibit declining trends in both the Arctic and the Antarctic by virtue of the global endeavor in banning their manufacture and usage. However, the reemission of POPs that previously accumulated in the polar environment has been observed, and these POPs can enter the global cycle again following the processes of ice retreat, glacier melting and permafrost thawing driven by global warming. Therefore, continual monitoring should be conducted for legacy POPs in polar areas. Screening surveys for EOCs in environmental and biological matrices have been carried out through national and regional research programs. The long-range environmental transport of EOCs has been highlighted with their occurrences in ice cores, snow, and lake waters in polar regions. Therefore, the investigation of EOCs in the Antarctic needs to be strengthened through national and international research programs. Glacial ice and snow acted as secondary emission sources in the polar regions and released POPs and EOCs into the atmosphere and ocean. Thus, future research will need to understand the various biogeochemical and geophysical processes under climate change and anthropogenic pressures to be able to predict the environmental fates and toxicity risk of EOCs in polar regions.

Global and regional change clearly affects the structure and functioning of ecosystems in shelf seas. However, complex interactions within the shelf seas hinder the identification and unambiguous attribution of observed changes to drivers. These include variability in the climate system, in ocean dynamics, in biogeochemistry, and in shelf sea resource exploitation in the widest sense by societies. Observational time series are commonly too short, and resolution, integration time, and complexity of models are often insufficient to unravel natural variability from anthropogenic perturbation. The North Sea is a shelf sea of the North Atlantic and is impacted by virtually all global and regional developments. Natural variability (from interannual to multidecadal time scales) as response to forcing in the North Atlantic is overlain by global trends (sea level, temperature, acidification) and alternating phases of direct human impacts and attempts to remedy those. Human intervention started some 1000 years ago (diking and associated loss of wetlands), expanded to near-coastal parts in the industrial revolution of the mid-19th century (river management, waste disposal in rivers), and greatly accelerated in the mid-1950s (eutrophication, pollution, fisheries). The North Sea is now a heavily regulated shelf sea, yet societal goals (good environmental status versus increased uses), demands for benefits and policies diverge increasingly. Likely, the southern North Sea will be re-zoned as riparian countries dedicate increasing sea space for offshore wind energy generation - with uncertain consequences for the system's environmental status. We review available observational and model data (predominantly from the southeastern North Sea region) to identify and describe effects of natural variability, of secular changes, and of human impacts on the North Sea ecosystem, and outline developments in the next decades in response to environmental legislation, and in response to increased use of shelf sea space