Emerging Issue Summary
Within that framework, the STAP considered more specific management questions, concerns, and needs as they related to these six categories:
Many of the questions that need to be answered involve information needs that can be satisfied only by long-term observations, detailed familiarity with the environment, and continued sampling and monitoring. There is also a growing recognition that traditional knowledge can contribute effectively to program planning and management.
Human activities are the main sources of contaminants to the Arctic. Therefore, accurate data are required on the release and distribution of contaminants into the aquatic and terrestrial environment, as well as into the biota, so that managers can understand sources, pathways, and fates and develop effective strategies to reduce the input to the Arctic.
Within the total contaminant loading to the Arctic, the specific proportion and effects of anthropogenic versus natural sources of specific contaminants can be difficult to determine or may not have yet been measured. For example, localized naturally elevated concentrations of heavy metals in areas undisturbed by human activities may result in elevated concentrations in resident biota, but appear to have little consequence to the health of the biota. Detectable levels of radioactivity appear to result mostly from natural radioactivity decay from uranium and thorium minerals, but the impact of ocean disposal of nuclear waste remains unmeasured.
Generally, levels of radionuclides in air, water and soil in the Alaskan Arctic are similar to or lower than levels in more temperate areas.
Local sources of contaminants include industrial areas, abandoned radar sites, northern mining activities, and garbage dumps. Although such sites are not the principal cause of widespread distribution of contaminants in the Alaskan Arctic, they are of concern to the health of local ecosystems because they emit a variety of contaminants (including heavy metals and persistent organic pollutants (POPs)). The atmosphere is the most important pathway to the Arctic for POPs, heavy metals, and radionuclides and their transport is dependent on a number of factors, including temperature, the process of cold condensation, and the circulation patterns of global and arctic air masses.
An increase in arctic air temperature results in a corresponding increase in the carrying potential of the arctic air mass. However, a build-up in moisture and increase in rainfall may remove contaminants from air masses and deposit them on the ground and in the water.
Oceans, rivers, sea ice, and migratory fauna are additional transporters of contaminants to the Arctic, but the atmosphere is the most significant. Contaminants released into the atmosphere in other parts of the world reach the Arctic in a matter of days, whereas transport by ocean currents and sea ice takes considerably longer.
Marine mammals, fish, and other native species are staples across the Arctic. Organochlorine levels are generally higher in marine mammals that feed at high levels in the food chain and tend to accumulate large fat reserves. Average intakes of organochlorines may thus be higher in people who consume more of these higher trophic level marine mammals than terrestrial mammals. The major organochlorines in the marine biota are polychlorinated biphenyls (PCBs) and toxaphene and their concentrations are similar among most marine mammals. There are opportunities to monitor contaminants in the tissues of fishes, seabirds, and marine mammals through co-management councils – for example, the Alaska Marine Mammal Tissue Archival Project (AMMTAP) at the National Institute of Standards and Technology.
Hexachlorobenzene and PCBs seem to be the most consistently distributed contaminants in snow samples. However, reported levels are subject to large variations attributed to a combination of factors, such as methods of analysis, seasonality, dust contamination of snow pack, and depositional trends.
Conflicting evidence from sediment core data for mercury highlights the difficulty in determining whether its source is anthropogenic or natural. However, global atmospheric concentrations of mercury have been increasing for the past several hundred years and anthropogenic releases to the atmosphere have been identified as the cause of increases in global air and ocean surface water concentrations. Many freshwater fish have high mercury levels; however, based on very limited studies, no adverse health effects to the fish or human populations have been noted thus far in the Alaskan Arctic. Nevertheless, it is imperative that we continue to monitor contaminant levels in the Arctic if we are to understand more completely the extent to which the people and environment are exposed.
There is a positive linear relationship between increasing rates of organic carbon remineralization and methylated mercury concentrations. The near-term rise in Asian anthropogenic emissions and deposition in coastal waters of the western Pacific may now be affecting basin-wide mercury levels of the North Pacific Ocean. Such increases could have serious implications for resulting contaminant burdens in pelagic marine fish in the Arctic. Both air and water monitoring should be developed and implemented, and observations should be made of the concentration of methylated mercury species in sub-surface, low-oxygen thermocline waters known to have high levels of bacterial activity.
Evidence for ecosystem effects in the Arctic as a result of contaminants is currently derived from comparisons of contaminant levels in arctic wildlife with those in the same or similar species in locations where effects have been observed, and from studies of biological responses based on biochemical indicators. While some research has been done to identify biological responses to ecosystem stress in the Arctic, significant dose-response data for arctic animals is too limited to draw clear conclusions. The effects of organochlorines on the health of arctic wildlife, in particular marine mammals at the individual or population level, are inconclusive. The reports on the effects of exposure to heavy metals are also inconclusive, but it may be that the arctic biota have adapted to the relatively high levels of heavy metals naturally occurring in the Arctic.
Indigenous people and scientists across the circumpolar Arctic agree that a diet based on traditional foods has important nutritional, cultural, and economic benefits. At present, the literature suggests there may be some risk associated with the consumption of traditionally harvested foods due to exposure to certain organochlorines, especially chlordane, toxaphene, and PCBs, and to the heavy metals including cadmium and mercury. Concern about these contaminants has led to assessments of human health risk. Very little is known about the inter-generational effects associated with long-term exposure to these contaminants. However, decisions based on risk management procedures do not always result in recommendations to limit consumption, in part because known benefits of a traditional diet are often judged to outweigh uncertainties and risks with such a diet.
The STAP identified certain contaminants, but not all, of concern for further monitoring and investigation. These contaminants include methyl mercury, total mercury, organochlorine and pesticides, PCBs, dioxins, polycyclic aromatic hydrocarbons (PAHs), brominated fire retardants, and the metals arsenic, cadmium, chromium, lead, nickel, and selenium. An appropriate management strategy would be to sample polybrominated diphenyl ethers (PBDEs) and polychlorinated dibenzofurans (PCDFs). POPs have been identified around the globe, including the Arctic. In addition, because there are known international anthropogenic sources, radionuclides should be monitored in the air, land, and sea.
Airborne contaminants can cause serious health threats to wildlife and humans. Some airborne toxic compounds tend to “biomagnify.” Biological effects include impacts on reproductive success, growth, behavior, disease and survival. Airborne contaminants of concern that accumulate by the cold-condensation effect include POPs, dichlorodiphenyltrichloroethane (DDT), hexachlorocyclohexanes (HCHs), and mercury.
Among the primary concerns about contaminants from offshore oil and gas activities are anthropogenic inputs of metals and hydrocarbons. To the extent that it has not been done through programs such as the MMS Arctic Nearshore Impact Monitoring in the Development Area (ANIMIDA), there is a particular need to measure and statistically characterize the concentrations of 12 metals (vanadium, chromium, copper, nickel, zinc, arsenic, cadmium, lead, antimony, barium, iron, manganese) in the mud fractions and mercury and hydrocarbons in gross sediments for the past several decades across the Beaufort and Chukchi Seas.
The earlier MMS Outer Continental Shelf Environmental Assessment Program-sponsored monitoring design workshops recommended that MMS develop multiyear contaminant guidelines prior to offshore development. In 2008, MMS initiated the “Chukchi Offshore Monitoring in Drilling Area (COMIDA): Chemistry and Benthos” project that implemented a two-year sampling strategy to collect offshore sediments for baseline measurements of Polyaromatic Hydrocarbons, EPA priority metals, and other parameters such as diagnostic hydrocarbon ratios.
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