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1.
不同水生植物对富营养化水体无机氮吸收动力学特征 总被引：3，自引：2，他引：1
采用浓度梯度法,研究了鸢尾(Iris louisiana)、狐尾藻(Myriophyllum verticillatum)、茭白(Zizania latifolia)和水芹(Oenanthe clecumbens)对硝态氮(NO3--N)和铵态氮(NH4+-N)吸收动力学特征.结果表明:4种水生植物对水体NO3--N和NH4+-N吸收可用Michaelis-Menten酶动力学方程描述,随溶液NO3--N和NH4+-N浓度增加,植物吸收NO3--N和NH4+-N速率增加,当溶液NO3--N和NH4+-N浓度接近于2.0 mmol/L时,吸收速率增加趋缓;4种水生植物对NO3--N和NH4+-N的Vmax值大小为水芹 >茭白 >鸢尾 >狐尾藻,对NO3--N的Km值大小为水芹 >鸢尾=茭白=狐尾藻,对NH4+-N的Km值大小为水芹 >狐尾藻 >茭白=鸢尾.根据吸收动力学参数(Vmax,Km)判断水芹适宜于净化NO3--N和NH4+-N浓度较高的水体,茭白、鸢尾和狐尾藻适合净化NO3--N和NH4+-N浓度较低水体;4种水生植物对NO3--N、NH4+-N表现出不同的吸收偏好性,鸢尾吸收NO3--N的潜力大于吸收NH4+-N的,但对NH4+-N的亲和力大于NO3--N,表明能在NO3--N浓度较高环境中优先吸收NH4+-N.狐尾藻和水芹对NO3--N和NH4+-N能均衡吸收.茭白对NH4+-N具有较高的吸收潜力与亲和力. 相似文献
2.
浮游植物对氮的吸收与其生长繁殖密切相关，太湖梅梁湾湖区蓝藻水华频频暴发，对该水域浮游植物氮吸收进行研究具有重要意义.本文分别在冬、春、夏、秋4个季节于梅梁湾采样，对水体常规理化指标和浮游植物群落结构进行分析，并利用15N稳定同位素示踪技术研究了浮游植物对铵态氮（NH4+-N）、硝态氮（NO3--N）和尿素态氮（Urea-N）吸收的动力学特征.结果表明，太湖梅梁湾浮游植物群落除了秋季对NH4+-N的吸收不符合米氏方程外，其余均符合.冬季和春季3种形态氮最大吸收速率（Vmax）的大小依次为：NH4+-N > NO3--N > Urea-N，而夏季为：NH4+-N > Urea-N > NO3--N.3种形态氮Vmax的季节变化规律为夏季 > 秋季 > 春季 > 冬季.Vmax在不同季节以及不同形态氮之间的差异性可能与浮游植物群落组成以及水体中NH4+-N浓度不同有关.浮游植物对NH4+-N吸收的KS值在冬、春季高于夏季，对Urea-N吸收的Ks值则在夏、秋季高于冬、春季，而对NO3--N吸收的Ks值则在夏季显著高于其他3个季节.冬季和春季梅梁湾浮游植物群落最容易受到NO3--N限制，而最不容易受到Urea-N的限制；而夏季，则最容易受到NO3--N限制，而最不容易受到NH4+-N的限制，且浮游植物群落对NH4+-N的亲和力最高.与NO3--N相比，秋季浮游植物更容易受到Urea-N的限制.不同季节，容易对浮游植物产生限制作用的氮的形态不同. 相似文献
3.
为揭示冰封期氨氮（NH4+-N）在沉积物-水界面的迁移机制及内源性营养盐对全湖污染的贡献，于2018年2月初在乌梁素海湖区7个采样点采集了上覆水体与沉积物样品，得到了冰封期上覆水体与沉积物间隙水中的NH4+-N浓度，估算了沉积物-水界面NH4+-N的扩散通量.结果显示，上覆水体中NH4+-N浓度变化范围为0.55~1.60 mg/L，平均值为1.05 mg/L，0~5 cm表层沉积物间隙水中NH4+-N浓度是上覆水体中的10倍以上，其变化范围为6.64~18.63 mg/L，平均值为11.92 mg/L.估算沉积物间隙水NH4+-N向上覆水体的扩散通量为1.282~4.269 mg/（m2·d），表明在湖水冻结过程中，底泥沉积物接纳了大量的可溶性污染物成为内源污染源，会在冰封稳定期、融冰期和融冰后的一段时间内成为湖水的主要污染源. 相似文献
4.
湖光岩玛珥湖水体中营养盐的时空分布特征及其影响因素 总被引：1，自引：0，他引：1
湖光岩玛珥湖是世界上最大的玛珥湖，它几乎是封闭的，受外界的干扰小.目前有关玛珥湖的研究主要集中在古气候及生态环境研究方面，而有关玛珥湖营养盐在一年中的生物地球化学循环的研究较少，因此研究湖光岩玛珥湖营养盐的生物地球化学过程具有重要意义.于2015年10月-2016年9月对湖光岩玛珥湖全水柱的营养盐及其他相关参数进行逐月调查，分析营养盐的结构特征、垂直分布特征和时间变化情况，并讨论营养盐时空变化的影响因素.结果表明，湖光岩玛珥湖水中的无机氮（DIN）以铵态氮（NH4+-N）为主（>60%），其次是硝态氧（NO3--N），亚硝态氮（NO2--N）所占比利最低.湖光岩玛珥湖水中的硅酸盐（SiO32--Si）浓度较高，水体浮游植物生长受磷限制.冬季风期间，水体垂直混合较均匀，导致营养盐的垂直分布比较均匀；夏季风期间，水体层化，营养盐浓度在浅层水体较低，在深层水体较高.湖光岩玛珥湖表层水中的NO3--N、NH4+-N和SiO32--Si具有明显的时间变化规律：NO3--N浓度从10月-次年3月升高，从3-9月降低；NH4+-N浓度从10月-次年5月降低；SiO32--Si浓度从11月-次年5月降低，从5-9月持续升高.营养盐浓度的时间变化受有机质的矿化分解、水体的季节性混合、浮游植物的吸收、降雨的输入等多种因素的综合影响. 相似文献
5.
A model on a physico-biological engineering experiment for purifying water in Wulihu Bay of Lake Taihu by using Trapa natans var. bispinosa was constructed. The state variables in water in the physico-biological engineering were ammonium nitrogen (NH4+-N); nitrate nitrogen (NO3--N); nitrite nitrogen (NO2--N); phosphate phosphorus (PO43--P); dissolved oxygen (DO); nitrogen (N) and phosphorus (P) in detritus; biomass density, N and P in phytoplankton and in Trapa natans var. bispinosa, N and P in the substance adsorbed by the membrane of the engineering and the rootstocks of Trapa natans var. bispinosa. The state variables in bottom mud layer were PO43--P in the core water,exchangeable P and N. The external forcing functions were solar radiation, water temperature, NH4+-N; NO3--N; NO2--N; PO43--P; N and P in detritus; DO; phytoplankton concentrations in inflow water and the retention time of the water in physico-biological engineering channel. The main physical, chemical and biological processes considered in the model were:growth of Trapa natans var. bispinosa and phytoplankton; oxidation of NH4+-N and NO2--N, of detritus break down; N and P sorption by the enclosure cloth of the experimental engineering and by the rootstocks of Trapa natans var. bispinosa in water; reaeration of water; uptake of P, NH4+-N, NO3--N by phytoplankton and Trapa natans var. bispinosa:mortality of the phytoplankton and Trapa natans var. bispinosa:settling of detritus; and nutrient release from sediment. Comparison of calculated results and observed results showed that the model was constructed reasonably for the experiment. The mechanism of purifying lake water in the experiment engineering was discussed by the use of the model. 相似文献
6.
入湖河口湿地四种植物群落类型的土壤氮素空间分布特征 总被引：1，自引：0，他引：1
对江苏省溧阳市大溪水库的洙漕河河口湿地中香蒲、水蓼、灯心草和芦苇四种植物生物量、氮含量及植物群落的土壤氮素分布特征进行研究,结果表明:四种植物地上生物量、地上组织氮含量、地下生物量、地下组织氮含量存在显著差异;土壤烧失量(LOI)、总氮(TN)、硝态氮(NO3--N)在垂直分布上表现为由表层向下减少的总体分布趋势,铵态氮(NH4+-N)浓度的剖面变化呈现先减少后增加的趋势;四种植物群落土壤氮浓度各不同,但均大于对照,以有机氮为主,说明湿地具有一定的储氮能力;不同的植物群落影响湿地氮素的分布.相关性分析显示,土壤LOI与TN、NO3--N和NH4+-N均存在极显著相关性,无机氮构成比例较小,仅为1.41%,表明土壤中的氮素主要以有机氮的形式存在;土壤氮浓度与植物生物量及组织氮含量相关性不大,说明土壤氮形态浓度不仅受到植物生长的影响,同时也可能受到植物根区环境、微生物数量与活性等的影响. 相似文献
7.
城市湖泊不同水生植被区水体温室气体溶存浓度及其影响因素 总被引：2，自引：1，他引：1
为了解城市湖泊不同水生植被区水体温室气体的溶存浓度及其影响因素，于2015年4-11月按每月2次的频率采用顶空平衡法对聊城市铃铛湖典型植被区——菹草区、莲藕区和睡莲区表层水中CO2、CH4和N2O的溶存浓度进行监测，计算水中温室气体的饱和度和排放通量，并测定水温（T）、pH、溶解氧（DO）、叶绿素a及营养盐浓度等理化指标，以探究水体环境因子对温室气体溶存浓度的影响.结果表明，铃铛湖各植被区水体温室气体均处于过饱和状态，是大气温室气体的"源"；莲藕区CH4浓度、饱和度和排放通量均显著高于菹草区，而各植被区N2O和CO2均无显著性差异；不同植被区湖水中DO、总氮（TN）、总磷（TP）和硝态氮（NO3--N）浓度具有显著差异，其中DO、TN和NO3--N浓度均表现为菹草区最高，莲藕区最低，而TP浓度则正好相反；各植被区温室气体浓度和水环境参数间的相关分析和多元回归分析的结果表明，水生植物可通过影响水体的理化性质对温室气体的产生和排放产生显著差异影响，在菹草区亚硝态氮（NO2--N）、NO3--N、T和DO是控制水体温室气体浓度的主要因子；睡莲区为TP和pH；莲藕区则为pH、NO2--N和DO. 相似文献
8.
为揭示太湖流域降雨和湖水酸根阴离子长期变化特征及环境意义，通过历史数据收集和采样分析，对太湖流域降雨和湖水中的SO42-、NO3-变化特征和来源进行了研究.结果表明：自1990s以来太湖流域降雨中SO42-呈显著下降趋势，年平均下降率为0.28 mg/（L·a）；NO3-浓度却呈显著上升趋势，年平均增长率为0.05 mg/（L·a），降雨中氮污染呈现加重的趋势.与之相反，湖水中SO42-呈显著上升趋势，年平均增长率为1.24 mg/（L·a）；NO3-浓度却呈显著下降趋势，年平均下降率为0.02 mg/（L·a）.30年以来，太湖水体SO42-/NO3-比值不断升高，远高于降水SO42-/NO3-比值.研究认为：流域SO2排放引起的酸沉降是湖水SO42-浓度增长的最重要原因，但氮氧化物排放并未引起湖水NO3-浓度升高，说明太湖流域对大气沉降的氮氧化物有滞留作用，而太湖水体是流域大气沉降硫酸盐的重要汇.综合治理太湖流域酸性物质排放对防止太湖水体酸化和治理富营养化都具有重要意义. 相似文献
9.
三峡大坝上下游水质时空变化特征 总被引：6，自引：2，他引：4
为探索三峡大坝上下游（坝上99.9 km、坝下63.0 km、全长162.9 km）水质时空变化特征，运用主成分分析和方差分析对2016年近坝段水质时空变化特征进行了分析.主成分分析表明，水文因子流量（Q）、气温（T）、水位（Z）和水质因子（水温（WT）、pH、电导率（EC）、溶解氧（DO）、悬浮物（SS）、高锰酸盐指数（CODMn）、硫酸盐（SO42-）、氟化物（F-）、总硬度（T-Hard）、硝态氮（NO3--N）、总氮（TN）和硒（Se））的变化主导着研究区域水质变化；各采样点主成分得分和双因素方差分析结果显示研究区域水质因子时间变化主要呈现出季节和不同水库运行时期的差异.消落期（2-5月），T-Hard、F-、SO42-和EC是影响河流水质变化的主导因子；汛期（7-8月），Q、SS、CODMn、NO3--N、TN和Se是影响河流水质变化的主导因子；T和WT主导着汛末（9月）河流水质变化，并引起了DO等理化特性的变化；高水位运行期（12月），Cl-是影响河流水质变化的主导因子.现阶段，DO、有机污染物（CODMn）、无机盐（SO42-和F-）、营养盐类（NO3--N和TN）、类金属元素（Se）和水体的矿化程度（T-Hard）的变化主导着区域水质的变化，是三峡大坝近坝段水域水质的控制因子.方差分析表明，河流的理化特性（DO、pH和SS）、营养盐组分构成（NH3-N和NO3--N）、无机盐类（EC和Cl-）、石油类有机污染物及粪大肠菌群（FC）等指标在坝上与坝下断面存在显著性差异.气温、水温、降雨、含沙量的季节性影响因素和水库调度运行模式是影响近坝段水质时间差异的主要因子；空间差异主要受城区污染排放和三峡水库调度引起的坝上和坝下水文和水动力学条件差异影响.因此控制研究区域因人类活动等造成的外源性污染，并针对不同类污染物质的季节变化特征实施合理的水库运行方式是近坝段水质提升的关键. 相似文献
10.
基于2019年夏季(8月)对岱海水样的实测数据分析,通过运用克里金插值、相关性分析、多元线性逐步回归、主成分分析方法,探究了叶绿素a(Chl.a)的空间分布特征及其与水环境因子的相关关系,并讨论了相应的防治措施。研究显示:Chl.a空间分布呈现由岸边向湖心递减的趋势,总氮(TN)、总磷(TP)、氨氮(NH3-N)、硝态氮(NO-3-N)、正磷酸盐(PO3-4-P)空间分布特征与Chl.a空间分布特征相近,采样期内岱海湖局部区域水质状况已达到富营养状态;Chl.a与浊度(Turbidity)、TP、TN、悬浮物(SS)、pH、NO-3-N、NH3-N、PO3-4-P、蓝绿藻丰度(CYANO)呈极显著正相关,与溶解氧(DO)呈显著负相关,与电导率(Cond.)呈正相关、与氮磷比(TN/TP)呈负相关;各湖区Chl.a与环境因子相关关系不同,全湖逐步线性回归方程为YChl.a=-21.42+8.658XpH-0.865XDO+0.779XNH3-N+0.699XTurbidity+0.502XCYANO;岱海不同湖区因子对Chl.a浓度的影响存在差异,各湖区Chl.a与环境因子相关关系不同,通过岱海与我国其他湖泊Chl.a与环境因子的相关性关系对比分析,湖泊地理属性差异及营养物质输入浓度是影响Chl.a变化的重要因素;本研究岱海的TN/TP平均值为12.23,说明夏季岱海湖Chl.a变化为氮磷共同限制。 相似文献
11.
Seasonal and annual trends of changes in rainfall, rainy days, heaviest rain and relative humidity have been studied over the last century for nine different river basins in northwest and central India. The majority of river basins have shown increasing trends both in annual rainfall and relative humidity. The magnitude of increased rainfall for considered river basins varied from 2–19% of mean per 100 years. The maximum increase in rainfall is observed in the Indus (lower) followed by the Tapi river basin. Seasonal analysis shows maximum increase in rainfall in the post‐monsoon season followed by the pre‐monsoon season. There were least variations in the monsoon rainfall during the last century and winter rainfall has shown a decreasing trend. Most of the river basins have experienced decreasing trends in annual rainy days with a maximum decrease in the Mahanadi basin. The heaviest rain of the year has increased from 9–27 mm per 100 years over different river basins with a maximum of 27 mm for the Brahamani and Subaranrekha river basins. A combination of increase in heaviest rainfall and reduction in the number of rainy days suggest the possibility of increasing severity of floods. Such information is useful in the planning, development and management of water resources in the study area. Further, the majority of river basins have also experienced an increasing trend in relative humidity both on seasonal and annual scales. An increase in annual mean relative humidity for six river basins has been found in the range of 1–18% of mean per 100 years, while a decrease for three river basins from ? 1 to ? 13% of mean per 100 years was observed, providing a net increase in the study area by 2·4% of mean per 100 years. It is understood that an increase in areal extent of vegetation cover as well as rainfall over the last century has increased the moisture in the atmosphere through enhanced evapotranspiration, which in turn has increased the relative humidity. Copyright © 2007 John Wiley & Sons, Ltd. 相似文献
12.
Although changes in rainfall characteristics have been noted across the world, few studies have reported those in mountainous areas. This study was undertaken to clarify spatial and temporal variations in rainfall characteristics such as annual rainfall amount (Pr), mean daily rainfall intensity (η), and ratio of rain days (λ) in mountainous and lowland areas in Taiwan. To this aim, we examined spatial and year‐to‐year variations and marginal long‐term trends in Pr, η, and λ, based on rainfall data from 120 stations during the period 1978–2008. The period mean rainfall () at the lowland stations had strong relationships with the period mean daily rainfall intensity () and the period mean ratio of rain days () during those 31 years. Meanwhile, was only strongly related to at mountainous stations, indicating that influences on spatial variations in were different between lowland and mountainous stations. Year‐to‐year variations in Pr at each station were primarily determined from the variation in η at most stations for both lowland and mountainous stations. Long‐term trend analysis showed that Pr and η increased significantly at 10% and 31% of the total 120 stations, respectively, and λ decreased significantly at 6% of the total. The increases in Pr were mostly accompanied by increases in η. Although stations with significant η increases were slightly biased toward the western lowland area, increases or decreases in Pr and λ were not common. These results contribute to understanding the impacts of possible climate changes on terrestrial hydrological cycles. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
13.
Phosphorus dynamics in water and sediments in urbanized and non-urbanized rivers in Southern Brazil 总被引：1，自引：0，他引：1
Pagliosa PR Fonseca A Bosquilha GE Braga ES Barbosa FA 《Marine pollution bulletin》2005,50(9):965-974
Phosphorus flux models show that the removal tends to be a common feature in polluted estuarine systems whereas the release of P to the adjacent coastal area occurs in pristine environments. This study analyzes the distribution of P in water and sediments along six rivers in the south coast of Brazil. Three rivers located inside protected areas were considered non-polluted and used as a control of urbanization. The other three, situated within urbanized areas, were considered as having highly elevated concentrations of P. Results showed a different behavior of P in water and sediments located in urbanized and non-urbanized areas. The concentrations of dissolved organic (P-org) and inorganic (P-inorg) phosphorus in water, and the total phosphorus (P-tot) and polyphosphate (P-poly) in sediments where higher in the urbanized rivers compared to the non-urbanized ones. Both P of punctual origin and of diffuse origin contributed to the maintenance of elevated concentrations and disturbed the natural fluxes along the polluted rivers. The minimum and maximum concentrations in urbanized areas varied from 0.39 to 12.45 (microM) for P-org and 0.00 to 5.92 (microM) for P-inorg in water, and in sediments from 89.90 to 808.16 (microM g(-1)) for P-tot and 0.00 to 76.51 (microM g(-1)) for P-poly. In non-urbanized areas concentrations in water varied from 0.22 to 1.20 (microM) for P-inorg and 4.43 to 5.56 (microM) for P-org, and in sediments from 45.91 to 652.26 (microM g(-1)) for P-tot and 0.00 to 8.61 (microM g(-1)) for P-poly. Using a hierarchical sampling design and a simple model of variation of P (K(d) model) it was possible to demonstrate that urbanized and non-urbanized estuaries may act as sinks or sources of P. The variation of P analysis in different points along each of the six rivers showed that release and removal areas may occur within a same river independently of its urbanization. 相似文献
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Jurassic and Lower Cretaceous radiolarian zonation in Japan and in the western Pacific 总被引：7，自引：0，他引：7
Abstract A radiolarian zonal scheme for the entire Jurassic and Lower Cretaceous using biostratigraphic data from both Japanese Island sections and the western Pacific seafloor is documented. The zonation is applicable to low and middle paleolatitude portions of the Paleo-Pacific ocean. Radiolarian bio-events such as the evolutionary first appearance biohorizon, first occurrence biohorizon, and last occurrence biohorizon were used to define zones. The 11 zones proposed are, in ascending order, Parahsuum simplum, Trillus elkhornensis, Laxtorum(?) jurassicum, Tricolocapsa plicarum, Tricolocapsa conexa, Stylocapsa(?) spiralis, Hsuum maxwelli, Pseudodictyomitra primitiva, Pseudodictyomitra carpatica, Cecrops sep-temporatus, and Acanthocircus carinatus zones. Preliminary age assignments for these zones are presented. 相似文献
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This Special Issue of Earth Surface Processes and Landforms develops from the ‘Geomorphology: a 2020 Vision’ Annual Conference of the British Society for Geomorphology, organised at the University of Birmingham, UK, in July 2007. Entitled ‘New Developments in Process Understanding and Modelling in Geomorphology’, the Issue comprises a vibrant selection of 10 ‘process’ papers from leading researchers in geomorphological processes who presented at Birmingham. It aims to provide a readily accessible source of new and emerging ideas in understanding different landform processes across a range of space and time scales, based on innovations in geomorphological modelling and monitoring. The last few years have seen significant and exciting changes in geomorphology, especially in conceptual developments, numerical simulations, monitoring methodologies, data‐acquisition strategies and dating techniques. The resultant empirical datasets, theory development and modelling results have generated substantial advances in the understanding of geomorphological processes, form‐process feedbacks, scale impacts, long‐term landform evolution, the effects of climate and environmental change, and human impacts and management strategies. The Special Issue attempts to address the following key challenges: (a) to build on our Conference theme ‘Geomorphology: a 2020 Vision’, by identifying fundamental areas where doors need to be opened, for example in theory development, conceptual understanding, model evaluation, integration of the chemistry, physics, biology and mathematics of geomorphological processes, experimental validation, data needs and monitoring requirements; (b) to look forward to the next decade and beyond, and critically examine some of the approaches we will need for the questions ahead; and (c) to stimulate new research in the geomorphological sciences by highlighting both research gaps and promising developments, including emerging process modelling approaches, monitoring technologies and robust datasets. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
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本文对中国石油、天然气资源作了重点的介绍.强调了这些资源对我国国民经济和国防建设的重要性.目前,我国油气资源短缺的现象日益严重.作者指明了在前第三纪海相残留盆地中勘探这些资源,会带来光明的前景. 相似文献
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Numerous soil pipes are reported from a small catchment in an area of kandoid (kaolin-rich) soils and 2375 mm annual rainfall in the humid tropical volcanic island of Dominica, West Indies. Two spot surveys in August 1982 at baseflow during the wet season indicated that pipes contributed at least 14–16 per cent of streamflow. Sampled pipeflow was of similar chemical composition to the baseflow-dominated streamwater. Specific conductance (249–420 μS cm?1) and silica (75 mg l?1) levels of pipeflow were high and suggested that the pipes tapped solute-rich water close to the soil-rock interface. The principal pipes flow perennially and showed little response to daily rainfalls of up to 43 mm during the monitoring period. 相似文献