A 300-Year High-Resolution Greenland Ice Record of Large-Scale Atmospheric Pollution by Arsenic in the Northern Hemisphere.

We report the first high-resolution record of arsenic (As) observed in Greenland snow and ice for the periods 1711-1970 and 2003-2009 AD. The results show well-defined large-scale atmospheric pollution by this toxic element in the northern hemisphere, beginning as early as the 18th century. The most striking feature is an abrupt, unprecedented enrichment factor (EF) peak in the late 1890s, with an ∼30-fold increase in the mean value above the Holocene natural level. Highly enriched As was evident until the late 1910s; a sharp decline was observed after the First World War, reaching a minimum in the early 1930s during the Great Depression. A subsequent increase lasted until the mid-1950s, before decreasing again. Comparisons between the observed variations and Cu smelting data indicate that Cu smelting in Europe and North America was the likely source of early anthropogenic As in Greenland. Despite a significant reduction of ∼80% in concentration and ∼60% in EF from the 1950s to the 2000s, more than 80% of present-day As in Greenland is of anthropogenic origin, probably due to increasing As emissions from coal combustion in China. This highlights the demand for the implementation of national and international environmental regulations to further reduce As emissions.

Characteristics of elemental and Pb isotopic compositions in aerosols (PM10-2.5) at the Ieodo Ocean Research Station in the East China Sea.

A total of 82 aerosol samples (PM10-2.5) were collected from June 18, 2015 to October 1, 2016 at the remote sea site, the Ieodo Ocean Research Station (IORS), in the East China Sea. Samples were analyzed for 10 elements (Al, Fe, Cu, Zn, As, Mo, Cd, Sb, Tl, and Pb) as well as Pb isotopic composition to characterize temporal variations in elemental concentration levels, and to identify the potential source regions of atmospheric pollutants transported over the remote East China Sea. The results showed that the annual average element concentrations were lowest compared to those at different sites in East Asia, suggesting a very clean background area of IORS, with values ranging from 114 ng m-3 for Al to 0.045 ng m-3 for Tl. Concentrations averaged seasonally for all the elements revealed the highest levels occurring between winter and spring, and the lowest levels in summer. High enrichment factors (EF) of more than 100 for trace elements suggest that these elements originated mostly from anthropogenic sources. Coupling the Pb isotopic composition with a back trajectory analysis identified the potential source regions for each sample. Our approach identified China as a dominant contributor affecting atmospheric composition changes at IORS, the remote area of the East China Sea. As the largest anthropogenic emission source in East Asia, China contributed to almost 100% of the elemental concentration levels in winter and spring, ∼53% in summer and ∼63% in autumn. Because IORS's ambient air is sensitive to even slight changes in pollutant loading due to the significantly low pollution levels, long-term monitoring of air quality at IORS will provide invaluable information on the progress and efforts of atmospheric pollution management linked to emission controls in East Asian countries, especially China.