Methylmercury and sulfate-reducing bacteria in mangrove sediments from Jiulong River Estuary, China

Estuaries are important sites for mercury (Hg) methylation, with sulfate-reducing bacteria (SRB) thought to be the main Hg methylators. Distributions of total mercury (THg) and methylmercury (MeHg) in mangrove sediment and sediment core from Jiulong River Estuary Provincial Mangrove Reserve, China were determined and the possible mechanisms of Hg methylation and their controlling factors in mangrove sediments were investigated. Microbiological and geochemical parameters were also determined. Results showed that SRB constitute a small fraction of total bacteria (TB) in both surface sediments and the profile of sediments. The content of THg, MeHg, TB, and SRB were (350 150) ng/g, (0.47 0.11) ng/g, (1.4 1011 4.1 109) cfu/g dry weight (dw), and (5.0 106 2.7 106) cfu/g dw in surficial sediments, respectively, and (240 24) ng/g, (0.30 0.15) ng/g, (1.9 1011 4.2 1010) cfu/g dw, and (1.3 106 2.0 106) cfu/g dw in sediment core, respectively. Results showed that THg, MeHg, TB, MeHg/THg, salinity and total sulfur (TS) increased with depth, but total organic matter (TOM), SRB, and pH decreased with depth. Concentrations of MeHg in sediments showed significant positive correlation with THg, salinity, TS, and MeHg/THg, and significant negative correlation with SRB, TOM, and pH. It was concluded that other microbes, rather than SRB, may also act as main Hg methylators in mangrove sediments.     

恒定和波动盐度增加对河口淡水感潮湿地间隙水溶解性甲烷和间隙水化学特征的影响

以闽江河口区塔礁洲河岸分布的短叶茳芏(Cyperus malaccensis)淡水感潮沼泽湿地及其比邻的光滩为研究对象,通过采集土芯和土壤-植物连续体,构建中型生态系统(Mesocosm),并2016年12月—2017年10月模拟持续恒定盐度增加及波动短期盐度增加两种情景,测定间隙水溶解性甲烷(CH_4)浓度及其它理化因子,探讨持续恒定和短期波动盐度增加对河口淡水感潮湿地间隙水溶解性CH_4浓度的影响.结果表明:①2种处理均显著抑制了短叶茳芏沼泽及光滩湿地间隙水溶解性CH_4浓度,波动盐度对于短叶茳芏湿地间隙水溶解性CH_4浓度的抑制效果明显高于光滩;②恒定盐度及波动盐度增加主要通过提高间隙水SO_4~(2-)、Cl~-、NH~+_4-N和TN浓度,降低间隙水pH值,抑制间隙水溶解性CH_4浓度;③短叶茳芏沼泽间隙水溶解性CH_4浓度受间隙水pH值影响最为显著,而光滩间隙水溶解性CH_4浓度则受间隙水NH~+_4-N浓度及气温影响显著.研究表明,未来盐水入侵情景下,河口淡水感潮湿地间隙水溶解性CH_4浓度将下降,且在盐度短期增加情景下,河口淡水感潮沼泽湿地间隙水溶解性CH_4浓度下降幅度大于光滩湿地.     

太湖出入湖河口水质和水生植物中氮、磷含量及其相关性分析

以太湖蠡湖区和贡湖湾区的13个主要出入湖河口为研究对象,分析了其水质及水生植物的分布情况,结果表明:河口的主要水质指标,即总氮(TN)、氨氮(NH_4~+-N)、总磷(TP)、高锰酸盐指数(COD_(Mn))的浓度分别为0. 48～4. 17,0. 26～1. 09,0. 04～0. 29,5. 80～18. 30 mg/L,出入湖河口有机物和氮普遍污染严重;河口广布种的水生植物为芦苇、茭草、香蒲和水鳖,它们对氮、磷的吸收量排序为:芦苇茭草香蒲水鳖;水生植物茎叶TN含量与水体TN含量无明显相关性,而TP的正相关性显著,即在一定浓度范围内,水生植物体内磷的积累量随水体磷含量的增加而增加。     

Distribution and habitat characteristics of fishes in the Pearl River Estuary北大核心CSCD

To explore the current situation and distribution of fish in the eight major estuaries of the Pearl River Estuary in China, acoustic detection and water quality monitoring were conducted in 2018. The results showed that almost living in eight major estuaries were juvenile, the proportion of strong echo was higher in winter, and Jiaomen and Modaomen Estuary were relatively rich in adult fish. In winter, the Humen, Jiaomen, and Yamen Estuary had a high density relatively, for 46.05 (± 50.30), 33.12 (± 93), and 32 (± 78) ind/103 m3, respectively. However, the fish densities of the Hengmen, Modaomen, and Hutiaomen estuaries were higher in summer at 55.72 (± 83.23), 37.52 (± 55) and 36 (± 99) ind/103 m3, respectively. Thus, fish are mainly concentrated in the flood tidal estuary in winter and in the ebb tidal estuary in summer. In addition, fish density was higher in flood tide than in ebb tide, and the strong echo proportion was lower. In winter, the key water quality factors affecting the biodiversity of estuary fish Shannon were chlorophyll a (P < 0.05), while what affected the fish density were turbidity and salinity (P < 0.05). This study showed that the Pearl River estuary was still the main habitat for juvenile fish. However, habitat variability is obvious; hence, it is important to flexibly carry out the delimitation of estuarine fish reserves and ecological restoration. © 2022 Authors. All rights reserved.     

镇江市古运河和金山湖河湖上覆水体和沉积物氮及有机质分布特征及污染评价

镇江市位于长江和京杭大运河"十字黄金水道"的交汇处,是我国历史上最为重要的水上交通枢纽之一,区域内水量充沛、河网密布.近年来,该区域水环境存在不同程度的退化,故调查镇江市主要河湖水体及沉积物污染现状,将为当地水环境质量的改善提供重要的基础数据.基于此,本研究选择镇江市典型河湖水体共21个点位（金山湖10个点位,古运河及其支流共11个点位）,在冬夏两季采集上覆水及沉积物样品测定其理化指标和氮素含量,并通过有机指数及有机氮对沉积物污染程度进行评价.结果表明：①上覆水总氮（TN）浓度在冬夏季节分别介于1.95~15.71 mg·L^-1和0.64~12.09 mg·L^-1之间,平均值为4.01 mg·L^-1和4.07 mg·L^-1,平均值浓度高于地表水Ⅴ类标准.上覆水氨氮（NH₄⁺-N）浓度在季节上均表现为冬季<夏季,空间上则表现为河流>湖泊;②沉积物TN含量在冬夏两季分别介于394.61~3288.09 mg·kg^-1和869.21~3598.04 mg·kg^-1之间,平均值为1928.58 mg·kg^-1和2068.40 mg·kg^-1.湖泊沉积物TN、NH₄⁺-N、硝态氮（NO₃^--N）和有机氮（Org-N）含量均表现为冬季>夏季,而河流沉积物TN平均含量为冬季<夏季,NH₄⁺-N和NO₃^--N则表现为冬季>夏季,表明河流沉积物在季节上的分布规律更为复杂;空间上,冬夏两季沉积物NO₃^--N表现为湖泊>河流,NH₄⁺-N含量则表现为湖泊<河流.C/N结果表明研究区域沉积物有机质主要来源于内源污染;③湖泊和河流沉积物超过60%点位属于有机氮污染Ⅳ水平,即存在有机氮污染,而超过70%和54.55%的湖泊和河流沉积物处于有机指数Ⅱ类水平,即较清洁水平,表明镇江市河湖沉积物主要为氮素污染.以上研究结果将为镇江市河流水体及沉积物氮素控制提供重要的基础数据.     

鸭绿江口汞的污染状况及其防治对策

本文以对鸭绿江口水中、沉积物中以及１６种鱼鱼体中Ｈｇ含量的实测结果,阐明了鸭绿江口Ｈｇ的污染状况,在找出该江口Ｈｇ的主要污染源的基础之上,提出了三项Ｈｇ的污染防治对策,以其中的Ｈ２Ｓ除Ｈｇ的实验结果,阐述了该法技术经济上的可行性。     

汛期暴雨情景下鄱阳湖流域水质时空分布特征与污染成因分析

基于2019年和2020年鄱阳湖流域降水及水质监测数据,利用线性倾向估计法和累积距平法对2020年汛期暴雨情景下的湖区及入湖河流开展水质时空分布特征及污染成因分析,量化湖区地表水水质评价指标在不同降水量级情景下的响应。结果表明:①从时间上看,TP为主要超标污染物。2020年汛期,出湖口水质为Ⅲ类的月份占比同比上升8.3%,有机污染强度同比显著加重,暴雨情景下的指标浓度变幅大于非汛期降水情景。②从空间上看,湖区水质自南向北改善明显。入湖支流汛期水质主要受有机污染强度增加的影响而有所下降,TP浓度在南部入湖口和出湖口变幅较小,NH₃-N浓度与场次降水量存在强正相关性,污染负荷变化对场次暴雨量的累积响应较同步且迅速。③降水量级会影响污染来源结构。暴雨洪水的稀释作用可能是湖区水质年内波动的主要控制因素,暴雨可能导致湖体出现富营养化。     

滨海沼泽湿地转化为养殖塘对其碳储量的影响

以闽江河口为研究区域,配对采集芦苇(Phragmites australis)湿地、短叶茳芏(Cyperus malaccensis)湿地和互花米草(Spartina alterniflora)湿地的植物、土壤(0～100cm)及由其围垦而成的水产养殖塘沉积物(0～100cm)样品,测定其有机碳含量,计算生态系统碳储量...     

不同溶氧条件下九龙江口湿地沉积物一水界面氨氮释放与氧化规律

摘要：沉积物中氨氮（NH4^＋-N）的释放与氧化是河口湿地生态系统氮素生物地球化学循环的关键过程。本文通过室内模拟,构建饱和（BH）、好氧（HY）、缺氧（QY）和厌氧（YY）等四种上覆水溶氧（DO）条件,研究九龙江口湿地两种沉积物（红树林、光滩）中NH4^＋-N在沉积物-水界面的释放与氧化规律。结果表明,不同溶氧条件下,两种沉积物氨氮的释放、氧化存在显著差异。首先,红树林沉积物上覆水NH4^＋-NN的累积释放量是光滩沉积物的1．9-4．5倍,其中红树林沉积物上覆水NH4LN释放量分别达到1．64mg（BH）、2．07mg（HY）、3．47mg（QY）和3．20mg（YY）,而光滩沉积物则分别为0．85mg（BH）、1．00mg（HY）、0．77mg（QY）和1．27mg（YY）。在较高DO条件下两种沉积物NH。’一N均呈低释放状态,而在较低DO条件下则呈高释放状态。另外,四种溶氧条件下红树林沉积物NH4^＋-NN的释放速率（N43．73-78．51mg-m^-2-d^-1）和氧化速率（N26．19-40．68mg-m^-2-d^-1）均高于光滩（分别为N14．50-19．22mg-m^-2-d^-1和N8．89-22．53mg-m^-2-d^-1）,原因可能是红树林沉积物微生物种类丰富,群落多样性更高,矿化和硝化作用强烈。本文明晰了不同溶氧条件下河口红树林湿地沉积物NH4^＋-N的迁移转化过程,可促进滨海湿地的生态保护以及近海水域富营养化的控制。