Elevated methylmercury production in mercury-contaminated soil and its bioaccumulation in rice:key roles of algal decomposition  

作　　者：Di Liu Yan Wang Tianrong He Deliang Yin Shouyang He Xian Zhou Yiyuan Xu Enxin Liu 

机构地区：[1]Key Laboratory of Karst Georesources and Environment(Ministry of Education),Guizhou University,Guiyang 550025,China [2]College of Resources and Environmental Engineering,Guizhou University,Guiyang 550025,China [3]Guizhou Karst Environmental Ecosystems Observation and Research Station,Ministry of Education,Guiyang 550025,China

出　　处：《Frontiers of Environmental Science & Engineering》2023年第12期31-45,共15页环境科学与工程前沿（英文）

基　　金：supported by the National Natural Science Foundation of China(Nos.42007305,22166009,and 42267032);the Science and Technology Project of Guizhou Province(QKHJC[2020]1Y187 and QKHZC[2020]4Y031);the Guizhou Provincial Science and Technology Development Project(QKZYD[2022]4022).

摘　　要：Algal-derived organic matter(AOM)regulates methylmercury(MeHg)fate in aquatic ecosystems,whereas its role in MeHg production and bioaccumulation in Hg-contaminated paddies is unclear.Pot and microcosm experiments were thus performed to understand the response characteristics of MeHg concentrations in soil and rice in different rice-growing periods to algal decomposition.Compared to the control,algal decomposition significantly increased soil water-soluble cysteine concentrations during the rice-tillering and grain-filling periods(P<0.05).It also significantly lowered the molecular weight of soil-dissolved organic matter(SDOM)during the rice-tillering period(P<0.05)and SDOM humification/aromaticity during the grain-filling period.Compared to the control,AOM input increased the abundance of potential Hg and non-Hg methylators in soil.Furthermore,it also greatly increased soil MeHg concentrations by 25.6%-80.2%and 12.6%-66.1%during the rice-tillering and grain-filling periods,with an average of 42.25%and 38.42%,respectively,which were significantly related to the elevated cysteine in soil and the decrease in SDOM molecular weight(P<0.01).In the early stage(within 10 days of microcosm experiments),the MeHg concentrations in decayed algal particles showed a great decrease(P<0.01),suggesting a potential MeHg source in soil.Ultimately,algal decomposition greatly increased the MeHg concentrations and bioaccumulation factors in rice grains,by 72.30%and 16.77%,respectively.Overall,algal decomposition in Hg-contaminated paddies is a non-negligible factor promoting MeHg accumulation in soil-rice systems.

关 键 词：MERCURY METHYLMERCURY Algae Organic matter Rice(Oryza sativa L.) 

分 类 号：S15[农业科学—土壤学]