First Observation of Mercury Species on an Important Water Vapor Channel in the Southeast Tibetan Plateau

The Tibetan Plateau is generally considered to be a significantly clean area owing to its high altitude; however, the transport of atmospheric pollutants from the Indian subcontinent to the Tibetan Plateau has infected the Tibetan environments. Nyingchi is located at the end of an important water vapor channel. In this study, continuous monitoring of gaseous elemental mercury (GEM), gaseous oxidized mercury (GOM), and particle-bound mercury (PBM) was conducted in Nyingchi from March 30 to September 3, 2019, to study the influence of the Indian summer monsoon (ISM) on the origin, transport and behavior of mercury. The atmospheric Hg concentrations during the preceding Indian summer monsoon (PISM) period (1.20 ± 0.35 ng m−3, 13.5 ± 7.3 pg m−3, and 11.4 ± 4.8 pg m−3 for GEM, GOM, and PBM, respectively) were relatively higher than those during the ISM period (0.95 ± 0.21 ng m−3, 12.7 ± 14.3 pg m−3 and 8.8 ± 6.0 pg m−3). The average annual total gaseous mercury concentration in the Nyingchi region was obtained using a passive sampler as 1.12 ± 0.28 ng m−3. The GEM concentration showed that the sampling area was very clean. The GEM has several patterns of daily variation during different periods. Stable high GEM concentrations occur at night during PISM, which may be related to the nocturnal boundary layer. High values occurring in the late afternoon during the ISM may be related to long-range transport. The results of the trajectory model demonstrate that the sources of pollutants at Nyingchi are different under the control of different airflow fields. During westerly circulation, pollutants mainly originate from northeast India or Nepal. During the ISM period, the pollutants mainly originate from northeast India, or the Bay of Bengal, and the Indian Ocean. The strong precipitation and vegetation effects on Hg during the ISM resulted in low Hg concentrations transmitted to Nyingchi during this period. Further, principal component analysis showed that long-distance transport, local emissions, meteorological factors, and snowmelt factors are the main factors affecting the local Hg concentration in Nyingchi.

Function Led Design of Aerogels: One-pot Self-assembly of 3D Macroscope Poly(vinyl alcohol) Aerogel for Mercury Species Removal in Aqueous Solution with Super-Fast Regeneration

Mercury pollutant, especially ionic mercury (Hg2+), has been ranked by the World Health Organization as one of the top ten chemicals that threatens the major public health. Absorption of Hg2+ on the solid phase is one of the effective ways for water remediation. In view of the disadvantages of most existing absorbents such as laborious preparation, secondary pollution, or time-consuming regeneration process, herein, we developed an aerogel absorbent based on poly(vinyl alcohol) and the auxiliary crosslinker of phytic acid, both of which can readily react through a self-assembly process in the hydrothermal condition. With good mechanical strength, tunable pore size and surface area, the aerogel is adequate in absorbing Hg2+ and organic mercury compound (MeHg+), and can be renewed in a super-fast process (~ 40 s). High removal rate of Hg2+ can be maintained even in presence of the competing ions (Mn2+, Cd2+, Cr2+, Cu2+ and Pb2+). The features of low-cost raw materials, straightforward synthesis, and the easy manipulation in remediation/regeneration process create a promising absorbent material to be used in the real scene.

Different Mercury Species Partitioning and Distribution in the Water and Sediment of a Eutrophic Estuary in Northern Taiwan

The total Hg and methyl Hg in waters and sediments, as well as particulate total Hg (PTHg), were analyzed to study their distribution and partitioning in the Danshuei River Estuary (DRE), northern Taiwan. TOC and grain size were also determined in the sediment samples. The dissolved total Hg (DTHg) in waters ranged from 24.0 to 45.8 ng/L. The dissolved methyl Hg (DMeHg) concentrations contributed 0.6–30.4% of the DTHg pool, with the higher percentage appearing in the upper estuary. The DMeHg concentration positively correlated with the Chl.a within the estuary, suggesting that phytoplankton plays an important role in influencing the DMeHg concentration. The partitioning results indicated that DTHg chiefly dominates the THg (DTH + PTHg) pool, especially at a salinity of >15 psu region. The value of partition coefficient, log(KD), was within a range of 3.54 to 4.68, and the value linearly decreased with increasing salinity. The sediment total Hg (STHg) concentrations ranged from 80 to 379 ng/g, and most data exceeded the NOAA guidelines value (ERL < 150 ng/g), indicating that the DRE is contaminated with Hg. The STHg concentrations inversely and positively correlated with the grain size and TOC content, respectively, suggesting that sediment Hg distributions are strongly influenced by the both parameters.

1243Quantitative risk-benefit assessment of fish and seafood consumption scenarios to support recommendations

Background Fish/seafood consumption has health benefits, namely due to its omega-3 fatty acids levels and risks due to methylmercury contamination. This study aims to quantify the health impact of hypothetical scenarios of fish/seafood consumption through a risk-benefit assessment and provide support for recommendations, using Portuguese food consumption data. Methods We used data from the National Food, Nutrition and Physical Activity Survey 2015-2016 (n = 5811) to estimate the mean exposure to methylmercury and EPA+DHA in the current and alternative scenarios. Alternative scenarios were modelled using probabilistic approaches to reflect substitutions from the current consumption in the type of fish/seafood (predatory vs low-mercury species) or its frequency (1-7x/week). The overall scenarios’ impact was quantified using Disability-Adjusted Life Years (DALYs). Results About 14% of the Portuguese population exceeds the methylmercury tolerable weekly intake, and this prevalence is higher among small children (36.6%). Nevertheless, if the fish/seafood consumption increased to once a day, ≈11450 DALYs could be prevented each year. However, such a scenario would result in higher risk for pregnant women (1398 extra DALYs). Moreover, excluding predatory species consumption resulted in small but significant health gains (-1078 DALYs). Conclusions For the general population, the maximum health gains are obtained by consuming fish/seafood up to 7x/week, but among children and pregnant women, the frequency should be limited to 3-5x/week. All population should preferably choose non-predatory species. Key messages Daily fish consumption results in the highest overall populational health gain, but children and pregnant women need to limit it to 3-5x/week, due to methylmercury exposure.