Effect of Salinity on Mercury Methylation in Sediments of A Typical Coastal Wetland

doi:10.16258/j.cnki.1674-5906.2022.09.018

Ecology and Environment ›› 2022, Vol. 31 ›› Issue (9): 1876-1884.DOI: 10.16258/j.cnki.1674-5906.2022.09.018

• Research Articles • Previous Articles Next Articles

Effect of Salinity on Mercury Methylation in Sediments of A Typical Coastal Wetland

WANG Zhao¹^,²^,³(), ZHANG Manyin¹^,²^,³^,^*(), HU Yukun¹^,²^,³, LIU Weiwei¹^,²^,³, ZHANG Miaomiao¹^,²^,³

1. Beijing Key Laboratory of Wetland Services and Restoration, Institute of Wetland Research, Chinese Academy of Forestry, Beijing 100091, P. R. China
2. Institute of Ecological Conservation and Restoration, Chinese Academy of Forestry, Beijing 100091, P. R. China
3. Hebei Hengshuihu National Wetland Ecosystem Research Station, Hengshui 053000, P. R. China

Received:2022-04-06 Online:2022-09-18 Published:2022-11-07
Contact: ZHANG Manyin

盐度对典型滨海湿地沉积物汞甲基化的影响

王钊¹^,²^,³(), 张曼胤¹^,²^,³^,^*(), 胡宇坤¹^,²^,³, 刘魏魏¹^,²^,³, 张苗苗¹^,²^,³

1.中国林业科学研究院湿地研究所/湿地生态功能与恢复北京市重点实验室,北京 100091
2.中国林业科学研究院生态保护与修复研究所,北京 100091
3.河北衡水湖湿地生态系统国家定位观测研究站,河北衡水 053000

通讯作者: 张曼胤
作者简介:王钊（1996年生）,男,硕士研究生,主要研究方向为湿地生态学。E-mail: wangz435@nenu.edu.cn
基金资助:
中国林科院湿地所项目(CAFIWRTC2020003);国家重点研发计划项目(2017YFC0506205)

Abstract

Abstract:

Salinity is one of the most typical environmental features in coastal wetlands. However, how salinity affects the process of mercury methylation under anaerobic condition in coastal wetland sediments remains unclear. Using a microcosm experiments, we investigated the effects of simulated salinity (0, 0.6%, 1.2%, 1.8%, 2.4% and 3.0%) on methylmercury contents and absolute abundance of sulfate-reducing bacteria in sediments from the coastal wetland of Yancheng, Jiangsu Province, China. The results showed that the methylmercury content in the sediments had an overall increase at the beginning and then decreased during the entire incubation period (1-29 d), and it reached the highest value at the 8th day. In addition, the methylmercury content first increased and then decreased with the increase of salinity, and was the highest at the salinity of 1.2%. Similarly, the absolute abundance of sulfate-reducing bacteria showed a unimodal pattern with the incubation time. The salinity used in this study probably did not cause salt stress to the growth of sulfate-reducing bacteria. However, the abundance of sulfate-reducing bacteria decreased after being incubated for 15 days. There was no significant linear correlation between the absolute abundance of sulfate-reducing bacteria and methylmercury content. Dissolved organic carbon could explain a large proportion of the changes in the methylmercury content over time. These findings highlight the important role of the spatio-temporal changes in salinity for the production of methylmercury in coastal wetlands, and can provide a basis for predicting the ecological risk of methylmercury caused by the variation in salinity.

Key words: salinity, coastal wetland, methylmercury, sulfate-reducing bacteria, dissolved organic carbon, anaerobic condition

摘要：

盐度是滨海湿地最重要的环境特征之一,然而滨海湿地盐度的变化如何影响汞甲基化过程目前仍缺乏相关研究。基于室内培养的方法,研究了厌氧条件下江苏盐城滨海湿地沉积物甲基汞质量分数和硫酸盐还原菌绝对含量随盐度梯度（0、0.6%、1.2%、1.8%、2.4%和3.0%）的变化特征。结果表明,海盐处理下,随着盐度的升高,甲基汞质量分数总体呈现先增加后减少的趋势,1.2%盐度下,沉积物汞甲基化程度最高;随着培养时间（1-29 d）的增长,甲基汞质量分数总体也呈现出先增加后减少的趋势,培养8 d时,沉积物汞甲基化程度最高。海盐处理下,随着盐度的升高,硫酸盐还原菌的绝对含量总体增加,表明海水盐度未对硫酸盐还原菌生长产生盐胁迫;随着培养时间（1-29 d）的增加,硫酸盐还原菌的绝对含量表现为先增加后减少的趋势,当培养时间超过15 d时,硫酸盐还原菌的生长会受到抑制。该实验条件下,硫酸盐还原菌绝对含量与甲基汞质量分数间无显著线性相关,可溶性有机碳对甲基汞质量分数随时间的变化具有较高的解释度。该研究表明滨海湿地盐度的时空变化对汞甲基化过程有较重要的影响。研究结果可为预测盐度变化所带来的甲基汞生态风险提供了依据。

关键词: 盐度, 滨海湿地, 甲基汞, 硫酸盐还原菌, 可溶性有机碳, 厌氧

CLC Number:

WANG Zhao, ZHANG Manyin, HU Yukun, LIU Weiwei, ZHANG Miaomiao. Effect of Salinity on Mercury Methylation in Sediments of A Typical Coastal Wetland[J]. Ecology and Environment, 2022, 31(9): 1876-1884.

王钊, 张曼胤, 胡宇坤, 刘魏魏, 张苗苗. 盐度对典型滨海湿地沉积物汞甲基化的影响[J]. 生态环境学报, 2022, 31(9): 1876-1884.

Figures/Tables 7

Figure 1 Distribution of study region and sampling sites in the field

Table 1 Description of sample collection in the field

样地 Sample plots	样本量 Sample size	经纬度 Longitude and latitude	主要植被类型 Main vegetation type
新洋港北 North of Xinyang Port	5	120.5660°-120.5666°E, 33.6356°-33.6362°N	芦苇 Phragmites australis、盐度碱蓬 Suaeda salsa
核心保护区 Core Reserve	10	120.5537°-120.6141°E, 33.5778°-33.6090°N	芦苇 Phragmites australis、互花米草 Spartina alterniflora、盐地碱蓬 Suaeda salsa
大丰麋鹿区 Dafeng Elk Natural Reserve	5	120.8491°-120.8622°E, 33.0529°-33.0550°N	互花米草 Spartina alterniflora、白茅 Imperata cylindrica

Figure 2 Differences in pH and DOC among different salinity levels and incubation time Mean±SE, n=5. Different lowercase letters indicate that the same incubation time has significant differences among different salinity levels at 0.05 level; different capital letters indicate that the same salinity has significant differences among different incubation time at 0.05 level. The same below

Table 2 Differences in methylmercury contents between the sediments under simulated salinity and the background level

时间 Time/d	盐度 Salinity/%
	0		0.6		1.2		1.8		2.4		3.0
	t	P	t	P	t	P	t	P	t	P	t	P
1	4.016	0.057^ns	21.496	0.002**	18.796	0.003**	2.219	0.157^ns	9.591	0.011*	9.148	0.012*
8	8.331	0.014*	9.705	0.010*	11.241	0.008**	13.096	0.006**	21.224	0.002**	8.727	0.013*
15	10.371	0.009**	20.370	0.002**	34.204	<0.001***	5.398	0.033*	29.100	0.001**	5.408	0.033*
22	5.620	0.030*	3.402	0.080^ns	11.017	0.008**	11.568	0.007**	4.376	0.048*	5.456	0.032*
29	7.526	0.017*	3.243^ns	0.083^ns	-2.752	0.111^ns	2.349	0.143^ns	6.092	0.03*	4.673	0.043*

Figure 3 Differences in methylmercury content and absolute abundance of sulfate-reducing bacteria among different salinity levels and incubation time

Figure 4 Relationships between pH, DOC and methylmercury content n=3. r represents the correlation coefficient; P represents the value of significant test

Figure 5 Relationship between absolute abundance of SRB and methylmercury content n=3. r represents the correlation coefficient; P represents the value of significant test. Logarithmic transform points to the base 10 logarithm

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Effect of Salinity on Mercury Methylation in Sediments of A Typical Coastal Wetland

盐度对典型滨海湿地沉积物汞甲基化的影响

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