互花米草入侵对滨海盐沼土壤甲基汞的影响

本研究跨越11个纬度选取了4个典型滨海盐沼湿地，通过对比分析互花米草湿地和其他盐沼湿地（没有互花米草的本地种单优或者共优群落湿地）的汞（THg）和甲基汞（MeHg）含量特征及环境因子，探究互花米草入侵对我国滨海盐沼湿地土壤甲基汞的影响.结果表明：（1）4个研究区THg含量高低顺序为闽江口（（115.327±18.220）μg/kg） > 杭州湾（（37.792±3.761）μg/kg） > 黄河三角洲（（27.690±4.359）μg/kg） > 盐城（（8.843±1.688）μg/kg）；MeHg含量为杭州湾（（0.589±0.134）μg/kg） > 黄河三角洲（（0.511±0.059）μg/kg） > 闽江口（（0.361±0.065）μg/kg） > 盐城（（0.191±0.027）μg/kg）.（2）综合4个研究区进行分析发现，互花米草入侵对盐沼湿地土壤MeHg和% MeHg的均没有显著影响，但是互花米草入侵著增加了黄河三角洲的MeHg含量（95.0%）.（3）在两种湿地类型中，% MeHg（甲基化率）和THg均呈现极显著的负相关关系，且二者之间的关系存在一个临界值（20~30μg/kg之间），当THg小于临界值时，% MeHg与环境因子相关性较弱；当THg大于临界值时，% MeHg与环境因子显著相关.本研究从较大的空间尺度回答了互花米草入侵对滨海盐沼湿地甲基汞特征的影响，为全面评价互花米草入侵对我国滨海地区的影响提供了数据支持，为研究滨海滩涂地区汞的迁移转化提供了依据.

Effects of Spartina alterniflora invasion on soil methylmercury in coastal salt marshes

Four coastal salt marshes invaded by Spartina alterniflora spanning 11 degrees of latitudes were selected, and soil totalmercury (THg), methylmercury (MeHg) contents and environmental factors were compared and analyzed between S.alterniflora marshes and other salt marshes (native specieswith no mutual growth of S.alterniflora). The aim was to explore the effects of S.alterniflora invasion on the characteristics of soil methylmercury in coastal salt marshes in China. First, among four study sites, the rank of THg content was Minjiang Estuary ((115.327±18.220) μg/kg) > Hangzhou Bay ((37.792±3.761) μg/kg) > Yellow River Delta ((27.690±4.359) μg/kg) > Yancheng ((8.843±1.688) μg/kg); the rank of MeHg content was Hangzhou Bay ((0.589±0.134) μg/kg) > Yellow River Delta ((0.511±0.059) μg/kg) > Minjiang Estuary ((0.361±0.065) μg/kg) > Yancheng (0.191±0.027 μg/Kg). Second, the overall effect of S.alterniflora invasionhad no significant effect on soil MeHg and%MeHg of coastal salt marshes except for the Yellow River Delta where S.alterniflora invasion increased the MeHg content(95.0%). Third, among those two types of salt marshes, the correlation between%MeHg and THg was highly negative, and there was a threshold for this relationship (20~30μg/kg):when THg was lower than the threshold, the correlation between%MeHg and environmental factors was weak; while when THg was higher than the threshold,%MeHg was significantly correlated with environmental factors. This study investigated the effects of S.alterniflora invasion on soil methylmercury of coastal salt marshes with a large spatial span. Out study provided data supports for a more comprehensive evaluation of the impacts of S.alterniflora invasion on China's coastal areas, and also provided a basis for studying the migration and transformation of mercury in coastal wetlands.