Mercury (Hg) methylation could occur in freshwater ecosystems with low or high salinity. However, few studies are available about the effects of salinity change on mercury(Hg) release and methylation. In-situ experiments using Suaeda heteroptera wetland soil column from the Liaohe estuary were performed to decipher how total mercury (THg) and methylmercury (MeHg) contents change under fluctuant salinity and wet and dry soil conditions. Salinity gradients were set to 0.50% (S1), 1.00% (S2), 1.50% (S3) and 1.80% (S4), and pure deionized water was used as a blank control (CK). Wet and dry soil conditions were set to full inundation condition (WD1) and naturally dried treatment (WD2). Results indicated that the highest THg and MeHg contents were found in surface and bottom soil when water salinity treatment was CK under WD1. THg and MeHg decreased with salinity under WD1. THg contents in overlying water varied from 0.854 to 1.243 µg L⁻¹ under WD1 treatments and increased with salinity change. When under WD2 treatment, THg contents in both soil layers gradually decreased with rising salinity. Meanwhile, MeHg contents in both soil layers reached the lowest level at CK (1.666 μg kg⁻¹and 2.520 μg kg⁻¹) and increased gradually with the rising salinity. By comparison, THg content of the soil was much lower in WD1 than that in WD2. Under the WD1 condition, the MeHg contents and %MeHg decreased with rising salinity and showed significantly different in different salinity treatment, however, its showed an opposite trend with rising salinity under the WD2 condition.

中文翻译：

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湿润和干燥条件下，翅果碱蓬湿地土壤的总汞和甲基汞对盐度梯度的响应。

低盐度或高盐度的淡水生态系统中可能发生汞甲基化。但是，关于盐度变化对汞（Hg）释放和甲基化的影响的研究很少。Suaeda heteroptera的原位实验用辽河口湿地土壤柱分析了盐度波动和干湿土壤条件下总汞（THg）和甲基汞（MeHg）含量的变化。盐度梯度设置为0.50％（S1），1.00％（S2），1.50％（S3）和1.80％（S4），并将纯去离子水用作空白对照（CK）。将潮湿和干燥的土壤条件设置为完全淹没条件（WD1）和自然干燥的处理条件（WD2）。结果表明，在WD1条件下，水盐度为CK时，表层和表层土壤的THg和MeHg含量最高。在WD1下，THg和MeHg随盐度降低。上覆水中的THg含量为0.854至1.243 µg L ^-1在WD1处理下，随着盐度变化而增加。当进行WD2处理时，两个土壤层中的THg含量随着盐度的升高而逐渐降低。同时，两个土壤层中的MeHg含量在CK达到最低水平（1.666μgkg ^-1和2.520μgkg ^-1），并随着盐度的升高而逐渐增加。相比之下，WD1中土壤的THg含量要比WD2中的低得多。在WD1条件下，MeHg含量和％MeHg随盐度升高而降低，并且在不同盐度处理下表现出显着差异，但在WD2条件下，其与盐度升高呈相反的趋势。