瓦埠湖沉积物中氮与磷赋存形态分析

利用连续提取法研究了瓦埠湖沉积物中磷的赋存形态和氮的组成特征。结果显示:瓦埠湖沉积物中总磷含量为293～874 mg/kg,平均为470 mg/kg,总磷主要由无机磷组成;在沉积物的提取磷中铁结合态磷为主要赋存形态;铁磷、钙磷、铝磷的相对百分含量指示出该湖泊的磷源自污染较少的区域。瓦埠湖沉积物中总氮的含量为208～464 mg/kg,平均为265 mg/kg,氮的主要组成为有机氮,有机氮、有机指数等显示该湖泊属于清洁类型,未遭受污染。瓦埠湖流域的社会与自然状况的调查结果、湖泊底泥的有机碳氮比等均表明湖泊营养物质来自面源,各指标含量在空间分布的特点与相关性的差异,说明了物质沉积存在重力分离与水动力作用的过程。     

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%。     

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...     

淮北平原地下水三氮浓度分布规律及其影响因素分析

对淮北平原浅层地下水103个样品进行三氮及其他相关指标测定分析,揭示该区三氮的空间分布规律、来源及形成机理,并对其影响因素进行分析。结果表明:淮北平原浅层地下水三氮浓度逐年增大,并与其水位埋深呈负相关关系,丰水期的三氮浓度明显大于枯水期。农业含氮肥料的过量使用和流失是导致该区三氮浓度增高的主要原因。此外,三氮浓度还受到包气带的厚度大小的影响,pH值的变化范围、溶解氧浓度的高低也影响着三氮的转化方向和速度,高浓度的Fe2+是导致局部NO2--N严重超标的重要因素。     

升钟湖夏季水和沉积物中磷形态分布特征

为探究升钟湖水和沉积物中磷污染情况,于2019年8月(夏季),采集了升钟湖湖区15个样点的水样和沉积物样品,测定了升钟湖表层水、间隙水及沉积物的磷形态,并分析各种形态磷之间的相关性。结果表明:①升钟湖表层水总磷含量介于0.033～0.085 mg/L,各形态的磷含量由高到低依次为DTP(61.93%)、DOP(40.00%)、PP(38.07%)和DIP(21.93%);②间隙水的总磷含量介于3.49～7.57 mg/L,是水体磷的“源”,正磷酸盐仅占总磷的1.9%;③沉积物总磷含量介于299.04～1 138.69 mg/kg,Psenner法连续分级提取出表层沉积物共有5种形态的磷,各形态磷含量由高到低依次为残渣磷(Res-P:44.78%)、金属氧化物结合态磷+有机碎屑腐殖酸磷(NaOH-P:22.92%)、钙结合态磷(HCl-P:14.82%)、可还原态磷(BD-P:13.39%)和弱吸附态磷(NH₄Cl-P:4.09%),各形态磷含量均表现一定的空间分布差异,其中,总磷含量整体为西北部高于东南部;④相关性分析结果显示,沉积物中磷的释放主要通过BD-P、N...     

开放水体脱氮过程及其影响因素研究进展

中国已建各类水库近10万座,水库建设改变了原河流水动力条件,影响了水体物质场、能量场、化学场和生物场,究竟是"削减了水体净化功能"还是"强化了水体去污能力"目前尚不明确.本文系统总结了开放水体脱氮过程研究进展,主要包括:(1)厌氧反硝化(Denitrification)、厌氧氨氧化(Anaerobic ammonium...     

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。     

石河子地区地下水“三氮”空间分布特征及影响因素分析

地下水是新疆石河子地区居民生活饮用、农业灌溉、工业生产的主要水源,研究该地区地下水中"三氮"空间分布特征及影响因素,对控制和治理当地地下水污染、保障用水安全等具有重要的意义。本研究运用SPSS23、Sufer8及Mapgis67等软件,综合分析了该地区地下水中"三氮"含量的空间变异特征以及其影响因素。结果表明:43组水样"三氮"含量均达到《地下水质量标准(DZ/T 0290-2015)》Ⅲ类标准限值的要求。研究区地下水"三氮"含量空间分布特征显著,其平面分布特征表现为:以石河子市区为中心,"三氮"含量向四周研究区界线逐渐降低,整体上北低南高。在垂直方向上,浅层承压水中NO-3—N含量大于深层承压水的含量,但小于潜水的含量;而深层承压水中NO-2—N和NH+4—N含量大于浅层承压水的含量,但也小于潜水的含量;"三氮"含量极大值的采样点均位于潜水含水层。该地区地下水"三氮"含量主要受氧化还原环境、酸碱环境、潜水埋深、包气带及含水层岩性等自然因素以及土地利用类型、农业污染、生活污染、畜牧养殖及农产品加工污染等人为因素的影响。     

小流域氮流失特征及其影响因素

由非点源流失的氮是造成水体污染的主要因子之一,而土地利用方式往往对氮的流失产生重要影响。本课题在福建省九龙江流域遴选了4个不同土地利用方式的小流域,通过在自然降雨条件下现场采样与室内分析相结合,研究不同土地利用结构的小流域氮的流失特征和影响因素。研究结果表明：总氮、可溶态氮和泥沙结合态氮的浓度通常比径流先达到峰值,然后开始降低;氮的流失以可溶态氮为主(占73%～98.3％),因此其流失量主要受径流量的影响与雨强关系不大;土地利用方式对氮的流失有明显影响,一般植被覆盖度提高可以降低流失,而农业活动会加剧流失;此外,在高植被覆盖度的天然林地,氮的流失呈现出以泥沙结合态为主。通过本研究可以看出土地利用结构的调整和合理布置是九龙江流域非点源污染控制的重点。     

广州城市河涌氮、磷污染研究

对广州市区典型河涌氮、磷污染进行分析研究。结果表明:上覆水中氨氮质量浓度为6.21~22.40 mg/L,间隙水中氨氮质量浓度为19.9~152.0 mg/L。河涌上覆水以及间隙水中的氮污染主要是无机氮污染,且以氨氮为主,占总无机氮的90%以上。各河涌的氨氮和总氮值之间表现出很强相关性,但上覆水的氨氮和总氮值与间隙水的氨氮和总氮值之间,却不存在明显相关性。底泥间隙水与上覆水磷形态差异较大,间隙水中可溶性正磷酸盐与总磷具有较好的相关性,且有机磷质量浓度比上覆水要高;底泥中可溶性磷(Psol)、铝结合磷(PAl)质量浓度较低,铁结合磷(PFe)质量浓度较高。悬浮物中各形态磷质量浓度整体上均比底泥样品要高。     

Spatial variations in sedimentary organic matter in surficial lake sediments of Nyanza Gulf (Lake Victoria,Kenya) after invasion of water hyacinth

No detailed studies have been conducted on the spatial distribution of sediment characteristics within Nyanza Gulf of Lake Victoria, especially after the invasion of water hyacinth. Accordingly, a rapid, inexpensive method was used to determine the spatial sediment organic matter variations, expressed as loss on ignition (LOI). Surficial sediments were collected during different survey periods from about thirty‐two sampling sites between 1994 and 2012, in order to characterize the sediments. Although the deeper (>40 m) depositional areas are located in the open lake, visual observations indicate that most of the offshore sediments consist of muddy deposits, plus significant shell remains, with a more sandy type of sediments located in some areas off the inflowing river mouths. The surficial sediments were characterized by a relatively high water content, with over 89% of the samples containing water contents greater than 75%. The sediment organic matter contents from the 2012 survey were more variable, ranging from 1.90% to 33.47%. The sediment organic carbon contents varied spatially, although there were no significant variations between the different sampling periods. Evaluating the SOM at different heating durations at a constant temperature (550 °C) and a very high temperatures (950 °C) did not identify any significant differences. High primary production and greater settling in the deeper areas contribute to the nature of sediments deposited, also being reflected in the relatively high OC contents. Spatially, it is thought that detritus from water hyacinth and terrestrial external loads are important sources of organic matter deposited on the lake bottom within the gulf and may support its growth because of enrichment of nutrient elements. The importance of sediments in adsorption of contaminant substances and influencing geochemical processes within the lake is also emphasized.     

太原市用水量影响因素的灰色关联分析

城市用水紧张已经成为城市经济发展的瓶颈。本文运用灰色关联分析法,对影响太原市用水量的因子进行排序后发现:水的重复利用率是影响太原市用水量的主要因子,其次为人口数量和水价,而人均收入和工业总产值的影响较小。据此提出提高水资源重复利用率实现水循环;控制人口数量,协调供需矛盾;调节水价,推动节水工作等措施。从而达到节约用水,促进经济发展的目的。     

玄武湖沉积物磷形态的垂向变化和生物有效性

采用不同的化学提取法,分析玄武湖西北湖区沉积物中各形态磷、生物可利用磷(BAP)的垂向变化,探讨了各层沉积物中磷的生物有效性。结果表明,沉积物中总磷以无机磷为主,BAP占总磷的20%~52.6%,玄武湖底泥的磷有较好的生物可利用性。不同地点沉积物各磷形态和BAP的垂向变化有较大的差异。1号采样点的总磷、无机磷、铁磷和BAP质量比在沉积0~20 cm处较高,20~40 cm逐渐减小,说明0~20 cm内释磷潜力较大;2号采样点的总磷和无机磷质量比先减小,20~40 cm逐渐增加,而BAP和铁磷质量比随深度增加呈上升趋势,说明2点深层具有较大的释磷潜力。铁磷与BAP相关性较好,这部分磷具有较大的潜在释放风险。     

广州车陂涌底泥重金属污染及生态风险评价

合理处置重金属污染超标的底泥,是河道清淤工程的重点。以车陂涌清淤工程为例,通过原位测试、化学检验等,掌握河道清淤段不同位置底泥的污染特征。采用潜在生态危害指数法进行底泥污染潜在生态风险评价,得出河涌底泥低风险占31.71%、中等风险占29.27%、较高风险占2.44%、极高风险占36.59%,说明大多底泥需要处理。采用内梅罗综合污染指数法来评价底泥作为农用地土壤的适宜性,73.2%样点属于清洁,尚清洁、轻微污染各占9.8%,中度及严重污染共占7.2%,说明大部分底泥可用于农田。最后提出了该清淤工程应注意的问题,为车陂涌水环境治理提供科学依据。     

Effects of Hydrological Flow Regime on Sediment-water Interface and Water Column Nitrogen Dynamics in a Great Lakes Coastal Wetland (Old Woman Creek,Lake Erie)

Sediment-water interface nitrogen (N) transformations and water column ammonium cycling rates were measured along a stream to lake gradient at three sites within Old Woman Creek (OWC) and one near-shore Lake Erie site during two hydrological regimes: one with open flow to the lake after a rain event (July 2003), and another with a sand barrier blocking flow (July 2004). Net N2 effluxes in OWC at all times and at the near-shore Lake Erie site in July 2003 suggest that sediments are a N sink via denitrification. Observed dissimilatory nitrate reduction to ammonium (DNRA) may counteract some of this N removal, particularly when the creek mouth is closed. Upstream, a closed creek mouth led to higher sediment oxygen demand, net N₂ flux, potential DNRA, and potential denitrification rates. The lake site exhibited lower rates of these processes with the creek mouth closed except denitrification potential, which was unchanged. Denitrification in OWC appeared to drive N limitation in the lower wetland when the sand barrier was blocking flow to the lake. Higher potential versus in situ denitrification estimates imply that water column NO₃⁻ limits and drives denitrification in OWC. Water column to sediment regeneration ratios suggest that sediment recycling may drive primary production in the OWC interior when the creek mouth is closed and new N inputs from runoff are absent, but more data are needed to confirm these apparent trends. Overall, hydrological regime in OWC appeared to have a greater impact on sediment N processes than on water column cycling.     

Nitrogen and phosphorus changes and optimal drainage time of flooded paddy field based on environmental factors

While many controlled irrigation and drainage techniques have been adopted in China, the environmental effects of these techniques require further investigation. This study was conducted to examine the changes of nitrogen and phosphorus of a flooded paddy water system after fertilizer application and at each growth stage so as to obtain the optimal drainage time at each growth stage. Four treatments with different water level management methods at each growth stage were conducted under the condition of ten-day continuous flooding. Results show that the ammonia nitrogen (NH⁺₄-N ) concentration reached the peak value once the fertilizer was applied, and then decreased to a relatively low level seven to ten days later, and that the nitrate nitrogen (NO^-₃-N) concentration gradually rose to its peak value, which appeared later in subsurface water than in surface water. Continuous flooding could effectively reduce the concentrations of NH⁺₄-N, NO^-₃-N , and total phosphorus (TP) in surface water. However, the paddy water disturbance, in the process of soil surface adsorption and nitrification, caused NH⁺₄-N to be released and increased the concentrations of NH⁺₄-N and NO^-₃-N in surface water. A multi-objective controlled drainage model based on environmental factors was established in order to obtain the optimal drainage time at each growth stage and better guide the drainage practices of farmers. The optimal times for surface drainage are the fourth, sixth, fifth, and sixth days after flooding at the tillering, jointing-booting, heading-flowering, and milking stages, respectively.     

里下河地区代表性浅水湖泊表层沉积物可转化态氮的赋存特征

以受人类活动影响剧烈的小型富营养化湖泊为研究对象,研究湖泊表层沉积物可转化态氮的赋存特征,探索环境因子与各形态可转化态氮之间的关系。结果表明:14个湖泊表层沉积物中各形态可转化态氮质量比次序为强氧化剂可提取态氮(SOEF-N)离子交换态氮(IEF-N)弱酸提取态氮(WAEF-N)强碱可浸取态氮(SAEF-N);2w(IEF-N)与黏粒、壤粒、砂粒、w(Ca)呈显著的相关性;w(WAEF-N)与含水率、w(有机质)、w(TP)、w(Ca)、w(Zn)呈显著相关性;w(SOEF-N)与黏粒、w(有机质)、w(TOC)、w(NH+4)、w(Mn)呈显著的相关性;w(SAEF-N)仅与w(TP)和w(Ca)存在一定的相关性。3受人类活动影响较大的湖泊w(IEF-N)和所占TN百分比最高;表层沉积物中的w(WAEF-N)与w(有机质)多寡一致。