Amendments of nitrogen and sulfur mitigate carbon-promoting effect on microbial mercury methylation in paddy soils.

The imbalance of nutrient elements in paddy soil could affect biogeochemical processes; however, how the key elements input influence microbially-driven conversion of mercury (Hg) to neurotoxic methylmercury (MeHg) remains virtually unknown. Herein, we conducted a series of microcosm experiments to explore the effects of certain species of carbon (C), nitrogen (N) and sulfur (S) on microbial MeHg production in two typical paddy soils (yellow and black soil). Results showed that the addition of C alone into the soils increased MeHg production approximately 2-13 times in the yellow and black soils; while the combined addition of N and C mitigated the C- promoting effect significantly.

Global distribution and environmental drivers of methylmercury production in sediments.

Neurotoxic methylmercury (MeHg) in environments poses substantial risks to human health. Saturated sediments are basic sources of MeHg in food chains; however, distribution patterns and environmental drivers of MeHg at a global scale remain largely unexplored. Here, we characterized global patterns of MeHg distribution and environmental drivers of MeHg production based on 495 sediment samples across five typical ecosystems from the literature (1995-2018) and our own field survey.