Isotopic analysis of snow from Dome C indicates changes in the source of atmospheric lead over the last fifty years in East Antarctica

Pollution revealed by stable lead isotopes in recent snow from the northern and central Tibetan Plateau

Lead (Pb) isotopes are less fractionated than those from different sources, and thus were used to trace the sources of Pb in the environment. To investigate the sources of Pb in the atmosphere of the Tibetan Plateau, stable Pb isotopes (206Pb, 207Pb and 208Pb) in acidified snow pit samples collected from five glaciers (i.e., Qiyi-QY, Meikuang-MK, Yuzhufeng-YZF, Hariqin-HRQ and Xiaodongkemadi-XDKMD) in May 2016 of the northern and central Tibetan Plateau were measured. The results showed narrow ranges of 1.158-1.187 for 206Pb/207Pb and 2.450-2.489 for 208Pb/207Pb respectively. The 206Pb/207Pb ratios in all samples were obviously lower than the environmental background value of 1.196, indicating the primary contributions of anthropogenic sources. At least 60% of Pb was contributed by various human activities, which was supported by the Pb isotopes in the snow pit samples from the QY, MK, YZF, HRQ and XDKMD glaciers. By comparing Pb isotope data, we found that the primary anthropogenic sources are coal combustion, mining and smelting activities in northwestern China and mixed emissions from cities located in western China and close to the glaciers. These sources contributed to the Pb in the northern glaciers (QY and MK) in particular. Coal combustion in India probably contributes to the central glaciers (HRQ and XDKMD). Another potential source could be parts of central Asia (e.g., Kyrgyzstan and Uzbekistan) through long range transport. The above potential source areas of contaminants were traced further by the air mass back-trajectory tracing method.

Microplastic Interactions and Possible Combined Biological Effects in Antarctic Marine Ecosystems

Antarctica and the Southern Ocean are the most remote regions on Earth, and their quite pristine environmental conditions are increasingly threatened by local scientific, tourism and fishing activities and long-range transport of persistent anthropogenic contaminants from lower latitudes. Plastic debris has become one of the most pervasive and ubiquitous synthetic wastes in the global environment, and even at some coastal Antarctic sites it is the most common and enduring evidence of past and recent human activities. Despite the growing scientific interest in the occurrence of microplastics (MPs) in the Antarctic environment, the lack of standardized methodologies for the collection, analysis and assessment of sample contamination in the field and in the lab does not allow us to establish their bioavailability and potential impact. Overall, most of the Southern Ocean appears to be little-affected by plastic contamination, with the exception of some coastal marine ecosystems impacted by wastewater from scientific stations and tourist vessels or by local fishing activities. Microplastics have been detected in sediments, benthic organisms, Antarctic krill and fish, but there is no clear evidence of their transfer to seabirds and marine mammals. Therefore, we suggest directing future research towards standardization of methodologies, focusing attention on nanoplastics (which probably represent the greatest biological risks) and considering the interactions of MPs with macro- and microalgae (especially sea-ice algae) and the formation of epiplastic communities. In coastal ecosystems directly impacted by human activities, the combined exposure to paint chips, metals, persistent organic pollutants (POPs), contaminants of emerging interest (CEI) and pathogenic microorganisms represents a potential danger for marine organisms. Moreover, the Southern Ocean is very sensitive to water acidification and has shown a remarkable decrease in sea-ice formation in recent years. These climate-related stresses could reduce the resilience of Antarctic marine organisms, increasing the impact of anthropogenic contaminants and pathogenic microorganisms.