宜兴三氿沉积物氮形态分布及其影响因素

为了解宜兴三氿(西氿、东氿和团氿)沉积物氮形态分布及其影响因素,采用连续分级提取法对三氿12个采样点表层沉积物样品中各种形态氮含量进行测定,探讨了不同形态氮的空间分布特征及影响因素。结果表明:总氮的空间分布与沉积物有机质分布存在明显的一致性,团氿含量较高,东、西氿含量较低且基本持平;可转化态氮含量占总氮的59.5%,对水体潜在危害较大,空间分布呈现出西氿最大、东氿次之、团氿最低的趋势;可转化态氮中4种形态氮含量大小顺序为弱酸可提取态氮、离子交换态氮、强碱可提取态氮、强氧化剂可提取态氮,弱酸可提取态氮为可转化态氮的优势形态;沉积物有机质与总氮和强氧化剂可提取态氮呈极显著正相关关系(P 0.01),pH值与总氮呈显著负相关关系(P 0.05);上覆水总氮与离子交换态氮呈极显著正相关关系(P 0.01),与可转化态氮呈显著正相关关系(P 0.05)。     

里下河水系九龙口湖荡沉积物性状的垂向特征及环境指示意义

对里下河水系九龙口湖荡沉积物中的碳和氮及其粒径进行测定,研究碳、氮元素的垂向分布与积累状况,分析沉积物的总氮(TN)、有机氮(ON)、铵态氮(NH₄⁺-N)、总有机碳(TOC)以及粒径之间的关系。结果表明:九龙口沉积物的中值粒径变化于13.44～82.01 μm,垂向变化可大致分为3段;九龙口沉积物中氮素主要为ON,无机氮以NH₄⁺-N为主,氮素质量的垂向分布特征与九龙口地区20世纪50年代以来人类活动的历史背景相一致;TOC质量比随深度的增加呈先增加后快速减小的趋势。沉积物的w(C)/w(N)介于5.67～26.08之间,指示出沉积物中有机质主要来自有纤维束的陆源植物。沉积物TOC和TN呈极显著相关,w(C)/w(N)对TOC质量比敏感,3个测点中南部湖区受人类活动影响较大。     

毛乌素沙地典型湖滨带湿地有机碳、氮素空间分布特征

通过对陕西毛乌素沙地典型湖滨带湿地有机碳和氮素的空间分布特征进行研究,为探讨湿地生态系统如何在沙化环境下发挥其特有的功能提供科学依据。在巴吓采当湖泊湖滨带A~F类型区采集土壤,测定土壤的有机碳、全氮、有机氮、硝态氮和铵态氮等指标。利用方差分析、Spearman相关性分析和主成分分析等方法分析对湖滨带有机碳、氮素空间分布特征进行研究。土壤表层0~10cm的有机碳和全氮含量随水位升高呈增加趋势。除了铵态氮外,有机碳、全氮、有机氮和硝态氮含量垂直分布上随着土壤深度增加呈降低趋势。土壤有机碳、全氮含量分别与全磷、土壤容重、含水率、水位显著相关。铵态氮和全磷、含水率、土壤容重、全氮、有机碳和水位等显著相关。硝态氮与微生物生物量碳、氮的相关系数分别为r=0.637和r=0.617(中度正相关)。有机碳及氮素的含量与土壤粘粒含量相关性不高。主成分分析提取3个主成分,累积贡献率达76.15%。土壤全磷、土壤含水率、土壤容重和水位是影响湖滨带土壤有机碳、氮素空间分布的主要因子。     

洪湖沉积物碳氮磷分布特征及污染评价

洪湖是中国第七大淡水湖,富营养化问题日益突出。全面了解洪湖沉积物氮、磷、有机质的含量及分布特征,对掌握其富营养化现状与氮磷污染生态风险具有重要意义。在湖区布设了8个采样点,2019年10月采集50 cm柱状沉积物,分别测定不同深度沉积物总氮(TN)、总磷(TP)以及有机质(OM)含量,分析了TN、TP 和OM 含量的空间分布特征及相关性,并运用综合污染指数法评价其对应的污染程度。结果表明:洪湖沉积物TN含量在467.8~8 454.5 mg/kg之间,平均值2 167 mg/kg,为重度污染,其中近一半的采样点表层沉积物TN含量>5 000 mg/kg;TP含量在502.7~1 252.4 mg/kg之间,平均值693.8 mg/kg,除杨柴湖为重度污染外,其他大部分地区为中度污染;有机质含量占比在5.0%~24.9%之间,平均值9.6%,为重度污染。在垂直空间上,TN、TP 和OM 均在沉积物表层垂向深度0~20 cm存在明显的积累,其含量随垂向深度的增加而迅速降低。研究成果可为洪湖富营养化的控制与治理提供科学数据支撑。     

洋澜湖沉积物中磷的分布及污染评价

我国城市湖泊的生态系统功能下降,城市湖泊富营养化问题也日趋严重。城市湖泊的富营养化通常表现为磷限制,而湖泊沉积物是磷的主要归宿地。研究沉积物中磷的含量及分布特征,对探明其污染状况及湖泊富营养化的控制与治理具有重要的参考意义。洋澜湖作为典型的城市湖泊,近年来存在富营养化问题,以洋澜湖作为研究对象,分析其表层沉积物中的总磷(TP)浓度及空间分布特征,采用单因子指数法对沉积物中磷的污染情况进行评价,并选取3个代表性区域分析沉积物中磷的形态及垂向分布。结果表明,洋澜湖表层沉积物中TP的浓度为528~3 568 mg/kg,平均值1 096 mg/kg,其中西湖湖区的TP浓度最高,平均值1 362 mg/kg;洋澜湖表层沉积物总磷污染评价指数为0.88~5.95,表明整个湖区的沉积物均呈现一定程度的磷污染,其中轻度污染区域所占比例为9.38%,中度污染区域所占比例为32.81%,重度污染区域所占比例为57.81%。通过对沉积物中磷形态进行分析,沉积物中可交换态磷所占比例较小,铁铝结合态磷所占比例最高,是洋澜湖沉积物中磷释放的主要来源。     

潇河表层沉积物中氮素分布特征及其污染评价

为了研究河道表层沉积物中氮素分布特征,以潇河为研究区,选取7个采样点,研究表层沉积物中两种形态的氮素——氨氮和硝酸盐氮,测定分析其含量、分布特征及成因,并探究其与有机质之间的关系。其中氨氮用KCl浸提-靛酚蓝比色法测定,硝酸盐氮用酚二磺酸比色法测定,沉积物中有机质的测定用重铬酸钾法。在测定结果的基础上,采用单项指标标准指数法对沉积物中氮的污染程度进行评价。结果表明:1潇河表层沉积物中氮素总量表现为中下游段高于中上游段的特征。就两个河流段而言,同时呈逐渐下降的趋势。氮素总量受到上覆水体氮营养盐水平、溶解氧含量及沉积物的氧化还原电位、沉积物中有机质的降解影响。氨氮含量大于硝酸盐氮,二者平均值之比为1.38∶1,表明潇河沉积物还原程度较低。2利用线性回归分析可知,沉积物中硝酸盐氮和有机质含量呈显著正相关。3潇河沉积物中总氮的含量较高,一半以上采样点的标准指数超过1,说明潇河沉积物环境质量受氮的污染相对严重。     

江西省典型水库沉积物碳·氮·磷分布及污染评价

水体富营养化是水库、湖泊水污染问题最为严重的类型之一,为了解江西省水库沉积物的有机物污染水平,笔者测定了江西省15座中型水库沉积物中TP、TN、TOC含量,分析研究其分布特征和来源,并采用有机指数法进行综合评价.成果表明:江西省典型水库沉积物TP、TN总体处于轻度污染状态;在空间分布上,TN、TOC含量总体变幅不大,赣江上游及中游水库沉积物中TP、TN、TOC含量整体较低.TOC/TN比值表明,水生动物和陆地动物是沉积物有机质的主要来源.污染评价成果表明,有机指数IO平均值0.13,总体呈较清洁等级(II级);有机氮WON平均值0.09,总体呈尚清洁等级(III级).     

浅水湖泊沉积物-水界面可交换态氮赋存特征

以可交换态氮(EN)为主的负荷是湖泊水质的决定参数之一。以里下河地区受到不同人类活动方式影响的九龙口、大纵湖、蜈蚣湖和得胜湖4个浅水湖泊为研究对象,通过现场调查采样与实验测试方法,分析其沉积物-水界面中总氮(TN)和EN的分布特征。结果表明,EN的分布受人类活动方式影响明显;沉积物中的生物和微生物活动频繁,上覆水、间隙水和沉积物中的EN含量较低。另外,沉积物-水界面处的氧化还原条件对表层沉积物中EN的分布也有影响。     

黄河中游土壤有机质与氮磷相关性分析

在对渭河、泾河、洛河、无定河、窟野河和皇甫川6条黄河支流进行广泛采样和室内分析的基础上，对土壤养分数据进行标准化处理后，研究了土壤有机质含量与全氮、全磷、矿质态氮含量之间的相关关系。结果表明：全氮与有机质含量标准化后的数据基本一致，全磷含量与有机质含量变化趋势也相接近；有机质含量与全氮、全磷含量分别呈直线相关。与矿质态氮含量呈二次性相关；有机质含量与全氮、全磷和矿质态氮含量的逐步回归相关模型中，仅有渭河流域四种养分含量全被引进且相关关系达到极显著，泾河、洛河和窟野河流域矿质态氮被剔出后相关性也达到极显著，皇甫川流域仅有全氮被引进。     

底泥吸附水体中可转化态氮研究进展

对底泥中可转化态氮的赋存形态及提取方法进行了归纳,同时讨论了p H值、温度、泥水比、粒径、有机质和水动力条件等因素对底泥吸附可转化态氮的影响,针对底泥吸附可转化态氮的动力学及热力学规律进行总结,并展望了未来的研究重点。     

Nutrient concentrations in the surface sediments of Lake Chivero,Zimbabwe: A shallow,hypereutrophic, subtropical artificial lake

A lake‐wide survey in Lake Chivero, Zimbabwe, was performed to (i) examine the spatial distribution of three sediment grain sizes; (ii) determine their nutrient concentrations; and (iii) analyse the relationships between the measured surface sediment variables in the three sediment grain sizes. The results of this study indicated sand, silt and mud sediments occupied about 24, 22 and 54%, respectively, of the lake area. All the measured physicochemical variables varied significantly among the three sediment grain sizes (P < 0.05, anova ). High values for pH, dissolved oxygen and NO₃ were observed in the sand sediments, while water depth, electrical conductivity, soluble reactive phosphorus, NH₄, total phosphorus, total nitrogen and total organic carbon were observed in the mud sediments. In the silt sediments, most measured variables showed intermediate values. Intervariable correlation indicated varied correlation patterns among the three sediment grain sizes. Information generated in this study is essential for an accurate delineation of the spatial extent of nutrient and contaminant distribution in the sediment of Lake Chivero and will facilitate the ability of lake managers to derive a comprehensive nutrient budget of the lake as a means of establishing realistic target conditions for lake restoration.     

沙颍河表层沉积物中氮与重金属的分布特征及污染评价

为揭示沙颍河沉积物中氮及重金属的分布和污染特征,于2015年6—9月采集了沙颍河干支流主要站点的表层沉积物及上覆水样品,分析了其中氮的赋存形态和重金属的分布,探讨了水体-沉积物氮的转化机制及重金属的来源。结果表明:沙颍河表层沉积物中NO-3-N、NH+4-N、ON(有机氮)和TN的质量比分别为21.47~53.60 mg/kg、1.702 3~3.066 1 mg/kg、1 050~2 390 mg/kg和1 071~2 488 mg/kg,ON占TN的97.17%以上;表层沉积物中Cd、Cu、Zn和As质量比分别为1.583~3.533 mg/kg、21.98~64.60 mg/kg、148.5~165.5 mg/kg和1.527~2.416 mg/kg。Pearson相关性分析表明:表层沉积物中氮主要存在于有机物中,表层沉积物释放NH+4-N已经成为影响沙颍河水体NH+4-N浓度的一个重要因素;沙颍河大部分站点的表层沉积物有机指数和ON分别处于Ⅱ、Ⅳ级,有机碳污染较轻,ON污染严重;潜在生态评价中重金属Cd已经达到了很强-极强的污染程度,其余重金属则处于轻微污染水平;重金属潜在生态风险指数IR显示沙颍河表层沉积物重金属潜在风险已经到了很强-极强的水平,其中Cd对IR的贡献达97.22%。     

Stable carbon and nitrogen isotopic signatures of organic matter sources in near-shore areas of Lake Victoria,East Africa

Stable isotope ratios of organic carbon and nitrogen (δ¹³C and δ¹⁵N) were measured in suspended particulate matter (SPM) and sediment in the near-shore areas of Tanzanian waters of Lake Victoria (LV) to identify the various sources of organic matter in different areas of the lake. Spatial variations in δ¹³C, δ¹⁵N, and C/N ratios in SPM and sediments in inshore areas were due to differences in the proportions and sources of autochthonous or allochthonous matter. Watershed characteristics, such as urbanization, and lake characteristics, such as algal blooms, also immensely influenced the stable isotope signal of the organic matter in sediments. Stable C and N ratios showed that inshore areas in bays without pronounced fluvial input were dominated by autochthonous planktonic organic matter; conversely, for bays receiving significant fluvial inflows, the composition of organic matter depended on the extent of preservation of shoreline vegetation. Signals resulting from input of anthropogenic organic waste as a result of urbanization were distinguishable from natural sources. This work demonstrates the potential to discriminate between input sources of organic material into lakes using stable isotope signals in sediment and suspended particulate matter.     

The distribution and turnover of benthic organic matter in a lowland river: influence of hydrology,seston load and impoundment

The standing stocks of benthic organic matter (BOM) and some of its biochemical compounds (particulate organic carbon, particulate nitrogen, protein, and chlorophyll a) were investigated in the upper 12 cm of the sediments at several sampling sites in a free‐flowing and in an impounded river section of the lowland River Spree (Germany). Several environmental variables were recorded, in order to determine their potential influence on the organic matter content in the sediments. It was shown that the organic matter content in the upper sediment layers was mainly determined by the local hydrological regime, which was best reflected by the particle size distribution at the sampling sites. For the deepest investigated sediment strata, no influencing factors could be determined. The amount and quality of suspended matter was of minor importance to sediment composition. Also seasonal effects could not be detected. The impounded river section exhibited less seasonal variation in organic matter storage, as well as shorter carbon turnover lengths, longer carbon turnover times and lower rates of annual organic matter recycling than the free‐flowing river section, which indicates that changes in river hydraulics result in alterations to the organic matter budget. These alterations could be related to the changed mesohabitat composition and to the higher standing stocks of organic matter in the impounded river reach. We conclude that both morphological and hydrological alterations affect the structure and function of running water ecosystems because of their negative effect on the organic matter cycling. Copyright © 2002 John Wiley & Sons, Ltd.     

Diagenesis of Organic Matter in the Sediments of Lakes Ontario,Erie, and Huron

The organic matter in the modern sediments of Lakes Ontario, Erie, and Huron is composed of humic compounds (68 to 83%), amino acids (19 to 20%), lipids (2 to 8%), carbohydrates (2 to 6%), and amino sugars (0.5 to 4%). Amino acid and carbohydrate concentrations are high in plankton samples, which are the primary source of the sedimentary organic matter. These compounds are decomposed during their passage through the food chains and while resting at the sediment-water interface with the concurrent formation of humic compounds. The degree of diagenesis of the modem sedimentary organic matter is related to both the trophic state of the lake and to the water depth, with the greatest amount in the most eutrophic lake basins and in the shallowest water depths. Diagenesis of the organic matter is rapid prior to burial in the sediments and is slow after burial. The decomposition rates of the sedimentary organic matter are in the following order: amino acids>>amino sugars>carbohydrates>humic compounds>lipids.     

Sediment Toxicity from Copper in the Torch Lake (MI) Great Lakes Area of Concern

Torch Lake (MI) is a Federal Superfund Site and a Great Lakes Area of Concern. Torch Lake was impacted by over 200 million tons of copper rich mine tailings that were deposited in and along the shores of the lake. Twenty percent of the volume of the lake was displaced and the sediments have high concentrations of copper (1,000 mg/kg dry weight on average).Pore water from four sediment cores was analyzed at incremental depths for copper, total organic carbon, and toxicity using the Microtox^® 90% Comparison Test. Cores were also analyzed for copper and organic matter in the dry sediments. Statistical evaluation of data indicated that the upper sediments compared to the deeper sediments: 1) were less toxic (49% light loss versus 68%); 2) contained less pore water copper (0.59 mg/L vs. 0.81 mg/L); 3) had a higher percent organic matter (2.2% vs. 1.6%); and, 4) had no difference in the solid phase copper concentrations.Further evaluation of the sediment toxicity through direct comparison to copper chloride standards demonstrated that all pore water samples had reduced toxicity. The reduced toxicity of the pore water samples was reproduced by adding synthetic organic carbon to the copper chloride standards. These findings have implications for the EPA's No Action alternative for the sediments of Torch Lake. In making their recommendation, the EPA cites that preliminary data (believed to be obtained from nearby Portage Lake) shows that the sediments of Torch Lake are being covered and detoxified by natural sedimentation. However, total copper concentrations in the sediments from the south basin of Torch Lake do not indicate that the sediments are being covered and diluted by natural organic matter laden particles. Also, detoxification may be difficult to demonstrate without a baseline of sedimentation readings for comparison. In fact, solid phase copper concentrations may remain high due to scouring and erosion of surrounding stamp sand beaches or the steep side walls of the lake. This instability of particles has important implications for future restoration and monitoring activities in Torch Lake.     

Distribution of Pb, As, Cd, Sn and Hg in soil, sediment and surface water of the tropical river watershed, Terengganu (Malaysia)

Hydrogeochemistry and distribution of Pb, As, Cd, Sn and Hg in soils (n = 53), sediments (n = 42) and surface waters (n = 51) of the tropical Terengganu River basin, northeast coast of Peninsular Malaysia, were investigated. The order of abundance of the elements in soils followed granite > metasedimentary > Quaternary deposit ? volcanic with slight enrichment as compared to the upper continental crust. Both soils and sediments registered the order of concentration of Pb > Sn > As ? Cd ? Hg with an enrichment factor (EF) < 6 for sediments indicating slight enrichment representing the regional background and less likely due to the anthropogenic activity related input. SEM analysis revealed the presence of Malayaite (CaSnOSiO₄) explaining elevated Sn concentration (up to ∼34 mg/kg; 3 times the upper continental crust) in soils. Soil Pb distribution showed the geology as the primary control.Dissolved concentrations of As showed an increasing and Cd decreasing with distance from upstream to downstream along the river flow path. Lake surface waters registered 16 times higher Cd concentrations (average ∼ 14.21 μg/L) than the river waters, but lake sediments registered lower Cd concentration than the river sediments (average ∼ 0.45 mg/kg) revealing Eh, pH and TDS control. Dissolved average Hg concentration (∼0.04 μg/L) was measured to be lower than the tropical river waters from the Central Africa river, but higher than the Mekong and the Amazon Rivers.     

周村水库大气湿沉降氮磷及溶解性有机物特征

为揭示周村水库大气湿沉降中污染物的污染特征,通过收集周村水库2016年3月至2017年2月大气湿沉降样品,测定了大气湿沉降中氮磷以及溶解性有机物的质量浓度,分析了污染物的污染特征及大气湿沉降量的变化规律。结果表明:周村水库的降水主要集中在夏秋季,占全年的68.50%;降水中总氮质量浓度在1.67~7.63 mg/L之间,氨氮和硝氮是其主要组分,分别占总氮的52.91%和28.49%;降水中的硝氮和氨氮年湿沉降通量分别为772.45mg/m^2和1411.99 mg/m^2,且与降水量呈显著正相关关系(P<0.01);单因子水质评价法和综合污染指数法评价得出大气湿沉降中的降水大多为劣Ⅴ类的重度污染水体;总磷和有机物的湿沉降通量最大值出现在夏季,与降水量也呈显著正相关关系(P<0.01);大气湿沉降中的溶解性有机物以富里酸为主,呈现较强的自生源特征。     

Distribution,sources, and behavior of trace elements in the Clinton River Watershed,Michigan

The Clinton River watershed near Detroit, Michigan, USA was separated in six different land uses: agricultural, residential, mixed industrial and residential, downstream industrial, Clinton River Spillway, and Lake St. Clair, utilizing As, Cd, Cu, Ni, Pb, and Zn contents of the sediment that has median values of 3, 0.3, 15, 14, 13, and 57 mg kg^− 1, respectively. However, trace element concentrations in the lower Clinton River rivaled those in the most contaminated watersheds of the world. Enrichment factors and principal component analysis (PCA) separated trace elements into 2 categories: anthropogenic (Cd, Cu, Ni, Pb, and Zn) and geogenic (Al, As, Ca, Fe, K, Mg, TOC) sources. PCA linked agricultural, residential, and mixed industrial and residential land uses to anthropogenic Cd, Cu, Ni, Pb, and Zn, and lake sediments to geogenic elements, organic matter and clay contents. The downstream industrial zone has a unique source signature. Trace element concentrations varied with land use. The upper Clinton River (> 20 km from mouth; residential land use; median concentrations up to 25 mg kg^− 1) appeared to meet delisting criteria. Partitioning was also land use and element specific with: (1) exchangeable fraction (up to 94% of total) related to road salt and mobile chloride complex formation; (2) carbonate-bound fraction (up to 100%) resulting from Ca substitution or adsorption; (3) presence of immobile (hydr)oxide-bound fraction (up to 90%) instead of potentially mobile organic matter and sulphide-bound fraction (up to 20%); and (4) residual fraction (up to 65%) originating from geogenic and/or anthropogenic sources.