Occurrence and distribution of phthalate esters (PAEs) in wetland sediments

This study investigated the occurrence and distribution of 15 phthalate esters (PAEs) in sediments collected from Qixinghe wetlands, northeast China. Total concentration of PAEs in all sediments ranged from 128.41 to 502.79 mu g kg(-1), with the mean value of 284.61 mu g kg(-1). PAEs significantly differed among wetland types; the average PAEs concentration of surface sediments were as follows: Phragmites australis wetland (PAW, 419.87 +/- 73.61 mu g kg(-1)) > Carex lasiocarpa wetland (CLW, 304.18 +/- 56.47 mu g kg(-1)) > Deyeuxia angustifolia wetland (DAW, 129.78 +/- 18.24 mu g kg(-1)). Dimethyl phthalate (DMP), diisobutyl phthalate, di-n-butyl phthalate, and di-(2-ethylhexyl) phthalate (DEHP) were found in all sediments, DEHP was the most abundant PAEs congeners with concentrations varying from 37.62 to 294.9 mu g kg(-1). DMP and DEHP exhibited relatively higher concentrations in CLW and PAW wetlands than in DAW, indicating that the different deoxidization and biodegradation conditions could have important implications for the distribution patterns of PAEs in wetland sediments. The variation of PAEs concentrations in horizontal and vertical sediments with wetland types could be attributed to the migration of contaminants by surface water, groundwater and atmospheric deposition. The occurrence and distribution of PAEs in wetlands also suggests that contamination in natural ecosystems should not be overlooked.

Spatial Distribution Characteristics of Heavy Metals Cu and Zn in Coastal Wetland Sediments

The content of Cu,Zn in the sediments from coastal wetlands of the Yellow River Delta was determined.The results showed that:(i)The content of Cu,Zn range was 16.70-50.40 mg/kg,18.15-48.80 mg/kg,respectively.The mean content of Cu,Zn was 31.12mg/kg,36.74 mg/kg,respectively.Compared with the soil environmental background values of Shandong Province,the content of Cu was excessive,while the content of Zn was below the background.(ii)The concentrations of Cu,Zn in sediment in the coast of the Yellow River Delta were higher than in the other two areas.(iii)Vertical distribution characteristics of the concentrations of Cu,Zn were increasing with depth.The maximum content of Cu,Zn was 80-100 cm,in general,the content of Cu,Zn in the bottom sediments was higher than that in the surface sediments.The growth and decline trends of Zn in Tamarix and Suaeda areas were much the same and all higher than in the Phragmites communis area.(iv)The distribution characteristics of Cu concentration in different vegetation cover in sediment is Suaeda>Phragmites communis>Tamarix,which reflected different effects on retention of Cu in the sediments because of the different vegetation types.The highest content of Zn in the 0-20 cm sediments in Tamarix area was 44.07 mg/kg.

COMPARISON OF HEAVY METAL CONCENTRATIONS IN SURFACE SEDIMENT OF TANJUNG PIAI WETLAND WITH OTHER SITES RECEIVING ANTHROPOGENIC INPUTS ALONG THE SOUTHWESTERN COAST OF PENINSULAR MALAYSIA

S:Tanjung Piai wetland has now been proclaimed to be a wetland of international importance since 2003. Therefore, its heavy metal pollution status should be known and recorded. In this study, sediments in Tanjung Piai wetland were collected in 2002 and 2005 and were analysed for Cd, Cu, Ni, Pb and Zn. For comparison purpose, sediments were also collected for metal analysis from a known polluted site at Kg. Pasir Puteh, four jetties and a river. A comparison with the polluted sediment collected from Kg. Pasir Puteh and the established Sediment Quality Criteria showed that Tanjung Piai was not polluted with Cd, Cu, Ni, Pb and Zn. These background concentrations or baseline data of heavy metals in the sediment is important for future reference. Therefore, Tanjung Piai wetland is a suitable site for sanctuary and wetland conservation and it should be conserved for its pristine conditions in order to support its high biodiversity.

Study on the Purification Effect of Phosphorus in Sewage from Sediments in Coastal Wetland of Yellow River Delta

[Objectives] This study was conducted to explore whether the coastal wetlands in the Yellow River Delta have become secondary pollution sources. [Methods] With a coastal reed wetland in the Yellow River Delta as a research object, the SMT method and DGT technology were combined to study the vertical distribution of different forms of phosphorus in the sediment and the distribution characteristics of phosphorus at the sediment-interstitial/overlying water interface of the wetland to clarify the receiving and purification capabilities of wetlands in this region. [Results] The total phosphorus content in the wetland’s water intake area, dense reed area and water outlet area increased with the depth increasing;and the wetland phosphorus accumulated in the deep layer, and the total phosphorus content in the wetland sediments was as high as 936.30 mg/kg. The research on the phosphorus forms in the wetland sediments found that the content of Ca phosphorus was the highest in the wetland sediments, followed by the content of Fe/Al-bonded phosphorus, and the exchangeable phosphorus content was the lowest. The DGT sampling technology was used to investigate the distribution characteristics of phosphorus at wetland sediment-interstitial/overlying water micro-interface. It was found that the concentrations of phosphorus in the overlying water of the water intake area, dense reed area and water outlet area were significantly higher than that in the interstitial water. The wetland pollution level in this research area was high and had an obvious cumulative effect. [Conclusions] The results show that the wetland sediments in this region have a strong ability to retain phosphorus, and can control the migration and transformation of endogenous phosphorus, and the wetland has not become a secondary pollution source.

Partitioning of heavy metals in the surface sediments of Quanzhou Bay wetland and its availability to Suaeda australis

In order to investigate distributions of heavy metal pollution in Quanzhou Bay wetland, the total concentration and chemical partitioning of a number of heavy metals （Cu, Zn, Cd, Pb, Cr, Hg） in sediments of three sampling sites of Quanzhou Bay wetland and their availability to Suaeda australis were analyzed. The Geoaccumulation Index （Igeo） values reveal that the sediments of three sampling sites may all be considered as moderately contaminated for Pb and Zn, and all sediments might be strongly contaminated with cadmium. The partitioning analyses revealed the measured heavy metals in three sites are bound to the exchangeable fraction at lower concentrations. The measured metals in a considerable amount are bound to the reducible and oxidizable fractions, and a high proportion of the measured heavy metals were distributed in the residual fraction in the sediment samples. The concentrations of Cd in each chemical phase extracted from the sediments are above natural global background levels and should be further investigated because of its toxicity. Suaeda australis has different accumulation abilities for the measured heavy metals. For the root and stem, the bioaccumulation ability assessed by bioaccumulation factor （BAF） for the measured heavy metals follows the decreasing order as： Cu〉Cr〉 Zn〉Cd, Pb, Hg. In the leaf, stronger bioaccumulation ability for Hg is exhibited. The heavy metal concentrations in Suaeda australis roots have positive correlations with their available fractions, while the exchangeable fraction of Cu and Cd might have be more important to both mature plant roots and seedling roots uptake than other fractions; as for Cr, the oxidizable fraction might make a greater contribution to the plant root uptake; as for Zn, the reducible fraction might make so contribution ; and for Pb, the oxidizable fraction might make a significant contribution to the mature plant root uptake, however, the exchangeable fraction might have a significant contribution to the seedling root uptake.

Spatial Distribution Characteristics of Nitrogen and Phosphorus in Sediments of Coastal Wetlands

Taking the typical coastal wetlands in the Yellow River Delta as the research object,( i) three parallel strips A1,A2 and A3 were set up along the vertical coastline in the newborn wetland at 60 km south of the Dongwenliu Management Station in the Yellow River Delta Nature Reserve.( ii) Sample plots B( Phragmites communis area),C( Suaeda glauca area),and D( Tamarix chinensis area) were set up near the field ecological station of the coastal wetlands.Through collecting sediment samples and measuring nitrogen and phosphorus contents,the spatial distribution characteristics of nitrogen and phosphorus in sediments of coastal wetlands were studied.Following results were obtained.( i) The concentration of TN in the 0-20 cm surface sediments of the coastal wetlands in the Yellow River Delta was in the range of130-695 mg/kg,the concentration of TP was in the range of 589-778 mg/kg,and the average content of TN and TP was 372.18 and 660.82 mg/kg respectively.( ii) From the remote coastal area of the Yellow River to the near coastal area,the horizontal distribution of TN in the sediments was different at each level,and the TN content in the surface sediments gradually decreased; the content of TP generally increased.( iii) At the profile level,the content of TN and TP generally showed a trend of decreasing gradually from the surface layer and tending to be stable,and the peak appeared at the outermost layer.( iv) In the sediments under different vegetation cover,TN was more evenly distributed on each profile,and the distribution of TP on each profile was different.TN showed the largest distribution in the 0-20 cm surface sediments in the T.chinensis area,while TP had the largest distribution in the 80-100 cm bottom sediments in the T.chinensis area.

Levels and Potential Ecological Risk Assessment of Heavy Metals in Sediments of Longjiang Wetland in Binzhou City

Wetland is a unique habitat with great biodiversity and important ecological functions between land and water on the earth. With the irrational utilization of wetland resources, the ecological destruction and pollution of wetland are becoming more and more serious. To evaluate the pollution of heavy metals in the sediments of Longjiang Wetland in Binzhou City, chromium(Cr), copper(Cu), zinc(Zn), cadmium(Cd) and lead(Pb) were measured by inductively coupled plasma mass spectrometry. Concentrations of Cr, Cu, Zn, Cd and Pb in the sediments were 5.3–13.6, 5.6–15.0, 16.6–33.0, 0.1–0.4 and 7.9–24.9 mg/kg dry weight, respectively. The concentrations of heavy metals in Longjiang Wetland was lower than soil background values of Shandong Province and in lower level compared with those reported in sediments/soils of wetlands in some other locations. Based on geo-accumulation index(Igeo), Cr, Cu, Zn and Pb showed low levels of contamination at all stations, while Cd was observed at a moderate pollution degree. Potential ecological risk factor(E_r^i) and risk index(RI) values showed low ecological risk of heavy metals in sediments of the wetland.

Stable Carbon Isotope and Long-Chain Alkane Compositions of the Major Plants and Sediment Organic Matter in the Yellow River Estuarine Wetlands

Elemental(TOC,TN,C/N)and stable carbon isotopic(δ^13C)compositions and long-chain alkane(n C16-38)concentrations were measured for eight major plants and a sediment core collected from the Yellow River estuarine wetlands.Our results indicate that both C3(-25.4‰to-29.6‰)and C4(-14.2‰to-15.0‰)plants are growing in the wetlands and C3 plants are the predominant species.The biomass of the wetland plants had similar organic carbon(35.5-45.8%)but very different organic nitrogen(0.35-4.15%)contents.Both C3 and C4 plants all contained long-chain alkanes with strong odd-to-even carbon numbered chain predominance.Phragmites australis,a dominant C3 plant contained mainly n C29 and n C31 homologues.Aeluropus littoralis,an abundant C4 plant were concentrated with n C27 and n C29 homologues.Organic matter preserved in the Yellow River estuarine sediments showed strong terrestrial signals(C/N=11-16,δ^13C=-22.0‰to-24.3‰).The distribution of long-chain n-alkanes in sediments also showed strong odd-to-even carbon chain predominance with n C29 and n C31 being the most abundant homologues.These results suggest that organic matter preserved in the Yellow River estuarine sediments were influenced by the wetland-derived organic matter,mainly C3 plants.The Yellow River estuarine wetland plants could play important role affecting both the carbon and nutrient cycling in the estuary and adjacent coastal waters.

Spatial Distribution of Heavy Metals in Sediments of Tamarix chinensis Wetland on the South Bank of Bohai Bay

In order to understand the spatial distribution of heavy metals in coastal wetlands,Tamarix chinensis wetlands on the south bank of Bohai Bay were selected as the research object.The content of Cr,Mn,Ni,Zn and Cu in soil was determined by sampling method in April 2018.The spatial distribution characteristics of heavy metals and causes were studied.The results showed that except for Cr,Ni and Zn,the content of other heavy metals in this area did not exceed the background value of soil environment in Shandong Province.The study area was slightly polluted by these three heavy metals.In the vertical direction,the content of Cr,Mn,Cu and Ni followed the law of surface layer>middle layer>bottom layer,while the content of Zn was higher in the bottom layer,which needed to be further studied.In the horizontal direction,the content of the five heavy metals was not significantly different according to the distance from the coastline.There was no significant difference in the content of heavy metals between rhizosphere soil and non-rhizosphere soil.There was a significant correlation between the content of heavy metal elements,except Mn,the content of heavy metals was significantly correlated with the content of soil organic matter.The content of some heavy metals was significantly correlated with the content of available phosphorus and ammonium nitrogen.

Bacterial Community Structure of Sediment in Upstream Ecological Wetland of Guanting Reservoir under the Action of Different Plants in Winter

In order to study the effect of reed and cattail on the bacterial community structure of surface sediments of wetland in winter,highthroughput sequencing technology was used to analyze the bacterial composition. The results showed that 134 228 high-quality gene sequences were obtained by high-throughput sequencing in sediments of natural wetland in winter,and there were 13 866 OTUs,in which the number of OUT in sediments of reed wetland and cattail wetland was 6 677 and 7 189 respectively. The richness and diversity of bacterial communities in sediments of cattail wetland in winter were higher than those in sediments of reed wetland. Relative abundance of Proteobacteria in sediments of reed wetland and cattail wetland was 0. 54 and 0. 52,respectively. The dominant classes of bacteria were Betaproteobacteria,Deltaproteobacteria,Gammaproteobacteria and Epsilonproteobacteria,which belonged to gram-negative bacteria,indicating that the rhizosphere of wetland was easier to enrich gram-negative bacteria. Under the genus level,the dominant bacteria in the sediments were not obvious.

Sedimentation rates in the Wanggang salt marshes,Jiangsu

Coastal salt-marshes represent an important coastal wetland system. The total area of coastal wetlands exceeds 5000 km2 in Jiangsu Province, China, but it is decreasing rapidly in response to the intense reclamation activities and coastal erosion along a part of the coastline. Hence, two types of plants, Spartina angelica and Spartina alterniflora, were introduced successively into the Jiangsu coastal areas, in order to protect the coastline from erosion and to increase the accumulation rate. Pb-210 and Cs-137 analyses were carried out for sediment samples from the salt-marshes of Wanggang to determine the sedimentation rate, on the basis of an evaluation of the background activity values and the factors affecting the enrichment of Pb-210. Analysis of a typical sediment column of the tidal flat shows that there is weak absorption of Pb-210 in the silt-dominated sediment. Because of the influences of factors such as storm events, bioturbation, material sources and analytical error, some abnormal data points appear in the Pb-210 record. After ignoring these data the calculated sedimentation rate was 3.3 cm yr-1 on average. Based upon analysis of the Cs-137 dating, the rate since 1963 was 3.1 cm yr-1 on average, similar to the data by Pb-210 dating and the previous studies. The dating results show that there were three stages of sedimentation, with the most rapid accretion being taking place after Spartina angelica was introduced into the area. The study also shows that at the stage of Spartina alterniflora growth, the accretion rate was higher than on the flat surface with the same elevation without the cover of this plant.

The Habitat Structure of Lukanga Ramsar Site in Central Zambia: An Understanding of Wetland Ecological Condition

A field survey was carried out to determine the vegetation structure of the Lukanga Swamp Ramsar site in central Zambia. The aim of the study was to identify the different vegetation communities, species composition and distribution patterns for improved habitat management. Sampling was conducted in all recognizable vegetation communities. The results of the survey showed that the swamp was a littoral palustrine wetland predominantly characterized by the dominance of Leersia hexandria Swartz (42.02%), Typha capensis Rohrb (62.43%), Phragmites australis (Cav.) Trin. ex Steud (33.61%), Aeschynomeme fluitans Peter (31.58%) and Polygonum senegalense Meisn (48.8%). The occurrence of Vossia cuspidata Griff and Cyperus papyrusL was restricted to small and isolated locations. Short Termitaria was generally covered by Acrocerus macrum Stapf (35.25%) while tall Termitaria was dominated by Panicum maximum Jacq. (26.00%). The most important woody plant species included Combretum ghasalense Engl. et Diels (I. V = 62.88), Pseudolachnostylis maprouneifolia Pax ((I. V = 90.48), Albizia adianthifolia (Schmacher) W.F. Wight (I. V = 135.63) Isoberlinia angolensis Hyle and Brenan (I. V = 87.25). The current structure of the hydrophytes composition observed in this study was an indication of a generally silting wetland, while the dominant occurrence of understorey woody plants in the surrounding vegetation signified degraded miombo vegetation. It was concluded that the ecological status of wetland habitat was potentially threatened by mainly anthropogenic activities such as;wildfires, and unsustainable exploitation of surrounding vegetation. Further research is required to examine water flows, eutrophication and the long-term effects of deforestation on the ecological functioning of the wetland.

基于APCS-MLR模型的西藏茶巴朗湿地表层沉积物重金属分布特征及来源解析

湿地作为介于水体和陆地之间的第三生态系统,有着重要的生态功能。由于特殊的地理位置和自然环境条件,西藏地区形成了众多独具特色的天然高原湿地,在拉萨河流域湿地聚集现象尤为显著,茶巴朗湿地就是该流域的重要成员之一。近年来,随着城市旅游业、农牧业大力发展,湿地面积、动植物资源丰富度和湿地功能等方面出现了不同程度的退化。为了解西藏茶巴朗湿地表层沉积物的重金属分布特征与污染状况,于2021年8月共采集湿地表层沉积物样品19个,分别测定了沉积物样品中重金属含量,同时利用内梅罗污染指数和潜在生态风险指数对研究区重金属污染现状进行评价,并通过绝对主成分得分-多元线性回归模型(APCS-MLR)进行重金属来源解析。结果发现,茶巴朗湿地表层沉积物中Cu、Cr、Ni、Zn、Pb、Cd、As和Hg元素含量分别是西藏背景值的1.71、0.56、0.65、1.02、1.31、1.52、0.92、1.48倍,但远低于《土壤环境质量农用地土壤污染风险管控标准(试行)》(GB 15618—2018)中筛选值,与西藏其他高原湿地相比,沉积物重金属富集水平较低;研究区内梅罗污染指数均值为1.68,属轻度污染水平;潜在生态风险指数RI均值为134.45,属于轻微生态风险。绝对主成分得分-多元线性回归模型结果表明,茶巴朗湿地沉积物中Cu、Zn、Pb、Hg来源于交通运输和农业活动混合源,Cr、Ni来源于土壤母质源,As来源于地热源,Cd来源于地热源、交通运输和农业活动混合源,研究区湿地的沉积物重金属主要影响途径为交通运输和农业活动混合输入。本研究揭示了茶巴朗湿地沉积物中重金属元素的赋存现状、空间分布特征和生态风险等级,以及重金属的可能来源,客观了解湿地环境质量现状,为茶巴朗湿地和其他区域高原湿地后续的污染防治工作和可持续发展提供科学依据和理论支撑。

长江中游牛轭湖湿地含水层沉积物中铁和有机质组成对砷赋存形态的影响

以长江中游天鹅洲故道牛轭湖湿地为研究对象,研究了长江中游牛轭湖湿地内外侧C3、C5两个典型钻孔沉积物中砷、铁赋存形态和有机质组成差异,并结合内外侧沉积环境的差异,查明了牛轭湖湿地内外侧不同沉积环境中铁-有机质耦合作用对含水层沉积物中砷赋存形态的影响。结果表明:牛轭湖湿地外侧C3钻孔0~<10m浅层沉积物中含有更多的吸附在无定形铁氧化物和腐殖质类有机质上的强吸附态砷,牛轭湖湿地内侧C5钻孔沉积物中含有更多与硅酸盐铁结合的低活性砷;牛轭湖湿地外侧浅层沉积物中富含黏土矿物以及粒径偏细、风化程度较高的湖相沉积环境使得铁-有机质-砷共同富集,牛轭湖湿地内侧沉积物粒径偏粗、风化程度偏低的河流相沉积环境不利于活性砷和黏土矿物、有机质的赋存。

洞庭湖湿地短尖薹草(Carex brevicuspis)种群克隆生长对泥沙淤积的适应

泥沙淤积是影响湿地植物生存和生长的重要因素。克隆植物是湿地生态系统的主要植物类型之一。在自然水文条件下,湿地克隆植物种群对不同淤积速率的响应研究相对较少。本研究以洞庭湖湿地优势克隆植物短尖薹草(Carex brevicuspis)为对象,通过连续3年的野外控制实验,研究了不同淤积速率(0、2、4、6 cm/a,分别对应对照组,低、中和高淤积速率组)对湿地克隆植物种群的影响。结果表明:淤积速率对短尖薹草的种群密度影响显著,淤积处理的密度显著低于对照处理。随着淤积速率的增加,密度下降,地下/地上生物量比增加,高淤积速率下种群的密度最低,地下/地上生物量比最高。与对照处理相比,泥沙淤积促进了更多的短根(<10 cm)、长根茎(≥1 cm)和游击型克隆分株的形成,长根茎的长度随淤积速率的增加而增加。高淤积速率下的长根茎数量较低,但其根长最长,表明其克隆生长策略由密集型向游击型转变。由此可见,短尖薹草种群可通过对密度、生物量分配、根系长度和克隆生长策略的调节,有效地应对不同泥沙淤积速率的影响。

人工湿地中沉积物溶解性有机质与Cd结合机制——以株洲市某人工湿地为例

为探究人工湿地不同季节的溶解性有机质(DOM)组分变化以及与Cd之间的相互作用及差异,本研究利用紫外光谱、荧光光谱、傅里叶变换红外光谱(FTIR)和X射线光电子能谱(XPS)等多种光谱表征技术,并结合平行因子分析(PARAFAC)和二维相关光谱(2D-COS)分析对春秋两季湿地沉积物中DOM进行深入探讨。研究发现,湿地沉积物DOM主要来源于微生物活动、植物凋落物和根系分泌物,亲水性强且芳香性较低。春季与秋季的DOM含量分别为434 mg·kg^(-1)和700 mg·kg^(-1),其中春季主要由两种类蛋白和两种腐殖质组成,而秋季则为一种类蛋白和三种腐殖质。各组分与Cd的淬灭过程主要是静态淬灭,其中春季的蛋白质残基表现出最为明显的淬灭效果,存在两类以上结合位点,而秋季的类蛋白和类富里酸为单齿络合物。类蛋白和类富里酸与Cd的结合比其他组分更为强烈且稳定,并且类蛋白质组分与Cd优先结合。结合过程中,Cd主要与DOM的酰胺、酚羟基、羧基官能团相互作用,其中酰胺的结合速率最快,其次是酚羟基和羧基。

陈桥湿地土壤和沉积物碳、氮、磷分布及沉积物污染评价

【目的】探究陈桥湿地土壤和沉积物养分状况及沉积物污染水平。【方法】分别对陈桥湿地非水体(泥滩区)土壤和水体沉积物进行采样,分析样品中总氮(total nitrogen,TN)、总磷(total phosphorus,TP)、有机质(organic matter,OM)、总无机态氮(total inorganic nitrogen,TIN)、铵态氮(NH_(4)^(+))、硝态氮(NO_(3)^(−))和亚硝态氮(NO_(2)^(−))含量及化学计量特征,并通过综合污染指数法和有机污染指数法评价沉积物污染水平。【结果】(1)沉积物OM、TN、TP和TIN含量远高于土壤;(2)土壤C/N、C/P和N/P均值分别为25.31、16.39和0.66;沉积物C/N均值为18.08,C/P和N/P样点间差异大;(3)各样点沉积物TN、TP和OM均值分别为(1723.35±1562.50)mg/kg、(754.28±98.94)mg/kg和(5.00±4.26)%,综合污染指数和有机污染指数均为轻度或重度污染水平;(4)TP与OM、各氮素指标无显著相关性(P>0.05),TN与OM呈显著正相关(P<0.05)。【结论】陈桥湿地水体沉积物OM和氮磷含量高于非水体土壤,沉积物污染水平较高,水体生态环境受氮素影响较大,需加强管理,控制水体内源负荷。

微塑料在我国典型湿地沉积物中的污染特征、分布及分离检测进展

中国是塑料使用大国.微塑料作为其破碎后的产物,因多类型、多形态、小体积、难降解的特点,存在潜在生态风险,进而成为国内外学者研究的热门问题.沉积物是湿地污染的“源”和“汇”,我国对湿地沉积物中微塑料的污染和分布了解十分有限.同时,完整、有效的分离和检测技术是开展环境介质微塑料研究的前提.本文综述了微塑料在我国典型湿地沉积物中的污染特征、分布状况,系统分析了当前沉积物中微塑料的分离与检测技术,并对未来相关工作提出展望,以期对深入认识微塑料对我国典型湿地环境的影响以及形成标准、统一的湿地沉积物中微塑料鉴别方法提供参考.

洱海罗时江湿地表层沉积物氨氮释放特征及影响因素

以洱海上游的罗时江湿地为研究对象,基于为期半年的野外监测,弄清湿地水体和表层沉积物中氨氮(NH_(3)-N)的时空分异规律,借助摇瓶试验法探究湿地入口沉积物NH_(3)-N的释放特征及水体离子强度(IS)和pH的影响.结果表明:(1)罗时江湿地上覆水和表层沉积物NH_(3)-N浓度变化范围分别为0.14-1.45 mg·L^(−1)和0.23-8.89 mg·kg^(−1),干湿季差异均不显著(P>0.05);上覆水和表层沉积物NH_(3)-N浓度均沿水流方向显著下降(P<0.05),出水口NH_(3)-N平均浓度分别是入水口的59.2%和49.9%,湿地对水体NH_(3)-N有截留效果.(2)模拟试验条件下,沉积物NH_(3)-N累积释放量的变化范围为412.9-653.7 mg·kg^(−1),随提取次数的增加单次释放量逐渐降低;NH_(3)-N累积释放量湿地入口显著高于其他样点,干季高于湿季.(3)上覆水IS升高促进沉积物NH_(3)-N的持续释放,增加快速释放NH_(3)-N占比;上覆水处于弱酸条件下更利于沉积物NH_(3)-N的持续释放,同时提高快速释放NH_(3)-N占比.研究结果显示,表流湿地入水口沉积物是NH_(3)-N的主要富集场所,水化学条件变化导致NH_(3)-N向上覆水释放可能引起二次污染.

滨海湿地中多溴联苯醚的污染特征及生态风险评价研究进展

系统梳理了多溴联苯醚(PBDEs)在滨海湿地中的种类和浓度、沉积物中的分布特征、与沉积物理化因子的关系、生态风险评价等方面的研究进展,分析了滨海湿地沉积物和生物体内PBDEs的种类和浓度,总结了PBDEs在滨海湿地中的水平分布与垂向分布规律,阐述了滨海湿地沉积物理化因子对其分布影响,归纳了滨海湿地中PBDEs的生态风险评价方法。后期研究需进一步厘清滨海湿地沉积物和生物体内的PBDEs同系物及富集浓度等问题,加强滨海城市排污口附近区域的PBDEs归趋研究,解析滨海湿地沉积物理化因子(如铁、硫、氮等元素)与PBDEs的关系,探究PBDEs生态风险阈值与评价方法,为滨海湿地污染控制与评价提供技术支撑。