利用稳定同位素(15N)示踪技术研究浮游藻类氮素吸收速率特征     

韩菲尔  赵中华  李大鹏  张路 《海洋与湖沼》2019,50(4):811-821

浮游藻类对溶解态氮的吸收同化是湖泊氮生物循环和水体富营养化发生机制探讨的关键环节。本文通过~(15)N稳定同位素添加实验以铜绿微囊藻(Microcystis aeruginosa)、海链藻(Thalassiosira sp.)、卡德藻(Tetraselmis sp.)、剧毒卡尔藻(Karlodinium veneficum)以及盐水隐藻(Rhodomonas salina)为研究对象,从浮游藻类氮素吸收时间、营养盐基质以及藻种差异三个方面研究五种藻类对铵氮(NH_4~+-N)、硝氮(NO_3~--N)、尿素氮(Urea-N)三种形态氮的吸收特征。研究发现:(1)浮游藻类对三种形态氮的吸收均在1h时吸收速率最高,其氮素吸收过程为快速吸收。(2)浮游藻类优先吸收还原态氮,其中NH_4~+-N吸收速率最高,当培养周期为1d和4d时浮游藻类对NH_4~+-N吸收速率的均值分别为4.05和4.15μmol/(L·h);浮游藻类对Urea-N吸收相对偏好系数为25.18—713.42,表现出对小分子溶解态有机氮的特定偏好性。(3)不同藻种对氮素吸收具有不同特征,其中,剧毒卡尔藻对三种形态氮的吸收速率均为最高,而铜绿微囊藻的吸收速率均为最低;不同藻种不同培养时间氮素吸收速率差异与浮游藻类生长周期等特性有关。不同浮游藻类对不同形态氮素表现出吸收特异性,对水体氮负荷和浮游藻类水华优势种形成将产生重要影响。  相似文献   

Characteristics of the main inorganic nitrogen accumulation in surface water and groundwater of wetland succession zones          下载免费PDF全文

ZHOU Nian-qing  LI Tian-shui  ZHAO Shan  XIA Xue-min 《地下水科学与工程》2019,7(2):173-181

Based on the observation of a complete hydrological year from June 2014 to May 2015, the temporal and spatial variations of the main inorganic nitrogen(MIN, referring to NO_3~--N, NO_2~--N, NH_4~+-N) in surface water and groundwater of the Li River and the Yuan River wetland succession zones are analyzed. The Li River and the Yuan River are located in agricultural and non-agricultural areas, and this study focus on the influence of surface water level and groundwater depth and precipitation on nitrogen pollution. The results show that NO_3~-N in surface water accounts for 70%-90% of MIN, but it does not exceed the limit of national drinking water surface water standard. Groundwater is seriously polluted by H_4~+-N. Based on the groundwater quality standard of H_4~+-N, the groundwater quality in the Li River exceeds Class III water standard throughout the year, and the exceeding months' proportion of Yuan River reaches 58.3%. Compared with the Yuan River, MIN in groundwater of the Li River shows significant temporal and spatial variations owing to the influence of agricultural fertilization. The correlation between the concentrations of MIN and surface water level is poor, while the fitting effect of quadratic correlation between H_4~+-N concentration and groundwater depth is the best(R~2=0.9384), NO_3~-N is the next(R~2=0.5128), NO_2~--N is the worst(R~2=0.2798). The equation of meteoric water line is δD =7.83δ~(18) O+12.21, indicating that both surface water and groundwater come from atmospheric precipitation. Surface infiltration is the main cause of groundwater H_4~+-N pollution. Rainfall infiltration in non-fertilization seasons reduces groundwater nitrogen pollution, while rainfall leaching farming and fertilization aggravate groundwater nitrogen pollution.  相似文献   

Water quality modeling and sensitivity analysis using Water Quality Analysis Simulation Program (WASP) in the Shenandoah River watershed     

Mbongowo J. Mbuh  Richard Mbih  Comfort Wendi 《自然地理学》2019,40(2):127-148

This study used the Water Quality Analysis Simulation Program (WASP) to simulate nutrients, dissolved oxygen (DO), and chlorophyll-a dynamics in the Shenandoah River basin and performed an uncertainty analysis to examine the complexity of these variables in water quality estimation and their influence on the Shenandoah River. Significant progress has been made; however, nutrient loads emitted into the Shenandoah River from nonpoint sources remain high. Modeling of three points on the Shenandoah River in Virginia and West Virginia provides an ideal case study since the river is classified by the Virginia Department of Environmental Quality as being impaired. The results of a sensitivity test show that model error decreases with increasing model complexity and sensitivity. The model predicted DO values that tended to be close to the measured data, while total nitrogen and phosphorus tended to be overemphasized. Our results examine the importance of temperature, stream flow, and velocity in influencing water quality between seasons and levels on the different sections of the watershed.  相似文献   

Anthropogenic land-use signals propagate through stream food webs in a California,USA, watershed     

《Limnologica》2014

Human development of watersheds can change aquatic ecosystems via multiple pathways. For instance, human rural development may add nutrients to ecosystems. We used naturally occurring stable isotopes in stream food webs to investigate how land use affects stream ecosystems across a gradient of land development in the San Lorenzo watershed, California. Road density was used as a proxy for land development. We found that streams in watersheds with higher road densities had elevated concentrations of phosphate and nitrate. Furthermore, algal δ¹⁵N values increased as a function of nitrate concentration, but saturated at approximately 6‰. This saturating pattern was consistent with a two-source mixing model with anthropogenic and watershed sources, fit using Bayesian model fitting. In sites that had >2.6 km roads km⁻², anthropogenic sources of N were estimated to represent >90% of the N pool. This anthropogenic N signal was propagated to stream consumers: rainbow trout (Oncorhynchus mykiss), signal crayfish (Pacifasticus leniusculus), and benthic invertebrate δ¹⁵N were positively correlated with algal δ¹⁵N. Even relatively low density rural human land use may have substantial impacts on nutrient cycling of stream ecosystems.  相似文献   

广东雷州半岛土壤氮、磷、钾元素地球化学特征及其土壤肥力评价          下载免费PDF全文

汪实  朱鑫  黎旭荣  罗思亮 《中国地质》2021,48(4):1177-1187

广东雷州半岛位于中国大陆最南端,是中国菠萝、香蕉、甘蔗等农产品重要产地。土壤氮、磷、钾等养分是作物生长需要最多的营养元素,对农业发展至关重要。文章通过对雷州半岛土壤取样,首次对该地区土壤氮磷钾的背景特征进行了分析,研究了不同成土母质、不同土地利用类型氮磷钾的含量水平,探讨了氮磷钾人为影响因素和时空演化规律,并进行了土壤肥力评价。研究发现,雷州半岛土壤中氮、磷、钾分布受地质背景制约,并受人为活动干扰强烈,氮、磷受人类活动影响显著,钾受人为扰动程度较轻。与20世纪90年代相比,表层土壤磷元素含量增幅较大,钾元素含量与前期相当。土壤肥力评价结果表明,雷州半岛土壤富磷,缺钾,局部缺氮。  相似文献   

Confronting the nitrogen challenge: Options for governance and target setting     

《Global Environmental Change》2019

The release of excessive anthropogenic nitrogen contributes to global climate change, biodiversity loss, and the degradation of ecosystem services. Despite being an urgent global problem, the excess nitrogen is not governed globally. This paper considers possible governance options for dealing with excessive nitrogen through target setting, which is an approach commonly adopted to address global environmental problems. The articulation of the nitrogen problem and the numerous international institutions dealing with it, provide evidence of a nitrogen regime characterised by limited coordination and targets covering sources and impacts only partially. This calls for improving the nitrogen governance in the direction of more integrated approaches at the global scale. In this vein, the paper investigates two opposite governance options – here labelled as ‘holistic’ and ‘origin-based’ – and evaluates them for their capability to define solutions and targets for human-induced nitrogen. From the analysis, it emerges that origin-based solutions can be preferable to holistic solutions as they can be more specific and potentially have greater immediate results. Independent from which governance arrangement is chosen, what matters most is the speed at which an arrangement can deploy solutions to combat (fast-growing) nitrogen pollution.  相似文献   

First observations of jelly-falls at the seafloor in a deep-sea fjord     

Andrew K. Sweetman  Annelise Chapman 《Deep Sea Research Part I: Oceanographic Research Papers》2011,58(12):1206-1211

Faunal communities at the deep-sea floor mainly rely on the downward transport of particulate organic material for energy, which can come in many forms, ranging from phytodetritus to whale carcasses. Recently, studies have shown that the deep-sea floor may also be subsidized by fluxes of gelatinous material to the benthos. The deep-sea scyphozoan medusa Periphylla periphylla is common in many deep-sea fjords in Norway and recent investigations in Lurefjorden in western Norway suggest that the biomass of this jellyfish currently exceeds 50000 t here. To quantify the presence of dead P. periphylla jellyfish falls (hereafter termed jelly-falls) at the deep seafloor and the standing stock of carbon (C) and nitrogen (N) deposited on the seafloor by this species, we made photographic transects of the seafloor, using a ‘Yo-Yo’ camera system during an opportunistic sampling campaign in March 2011. Of 218 seafloor photographs taken, jelly-falls were present in five, which resulted in a total jelly-fall abundance of 1×10^-2 jelly-falls m⁻² over the entire area surveyed. Summed over the entire area of seafloor photographed, 1×10^-2 jelly-falls m⁻² was equivalent to a C- and N-biomass of 13 mg C m⁻² and 2 mg N m⁻². The contribution of each jelly-fall to the C- and N-amount of the sediment in the immediate vicinity of each fall (i.e. to sediment in each 3.02 m² image in which jelly-falls were observed) was estimated to be 568±84 mg C m⁻² and 88±13 mg N m⁻². The only megafaunal taxon observed around or on top of the jelly-falls was caridean shrimp (14±5 individuals jelly-fall⁻¹), and shrimp abundance was significantly greater in photographs in which a jelly-fall was found (14±5 individuals image⁻¹) compared to photographs in which no jelly-falls were observed (1.4±0.7 individuals image⁻¹). These observations indicate that jelly-falls in this fjord can enhance the sedimentary C- and N-amount at the deep-sea floor and may provide nutrition to benthic and demersal faunas in this environment. However, organic enrichment from the jelly-falls found in this single sampling event and associated disturbance was highly localized.  相似文献   

不同黏土对中肋骨条藻的絮凝去除研究   总被引：1，自引：0，他引：1  

王洪亮  曹西华  宋秀贤  俞志明 《海洋科学》2011,35(12):15-20

比较了不同种类黏土对中肋骨条藻的絮凝去除效率, 分析了黏土理化特征对絮凝去除效率的影响。结果表明, 不同种类黏土的Zeta 电位为？36.1～？15.9 mV, BET 比表面积为0.31～60.76 m2/g, 硅铝比为1.35～3.62。当黏土用量均为0.50 g/L 时, 不同黏土对中肋骨条藻的絮凝去除速度和去除...  相似文献   

Differential utilization of a shallow-water pulse by six shrub species in the Patagonian steppe     

E. KowaljowR.J. Fernández 《Journal of Arid Environments》2011,75(2):211-214

A field experiment was performed to improve understanding of the functional diversity of western Patagonian shrubs. Anarthrophyllum rigidum, Adesmia volckmanni, Berberis heterophylla, Mulinum spinosum, Schinus poligamus and Senecio filaginoides were compared in their capacity to absorb water from a 10-mm pulse enriched in deuterium and applied at the beginning of the dry summer. Xylem-water enrichment 14 days after watering was rather subtle, but the upper-soil signal was clear enough to distinguish shallow from deeper absorption. According to a linear mixing model, the proportion of surface-pulse water relative to total water uptake was maximum for Senecio (29-38%) and Mulinum (22-32%), both relatively shallow-rooted species, intermediate for Berberis (16-17%) and Schinus (6-9%), and negligible for the two N-fixing Fabaceae: Adesmia (<1%) and Anarthrophyllum (<3%), despite this last one having a dimorphic (tap + shallow) root system. It is hypothesized that shallow-water pulses may be more profitable in terms of nitrogen than of water, and thus constitute a higher-quality resource for those species only able to use N from soil sources.  相似文献   

京津唐都市经济圈浅层地下水三氮含量评价的协克里格法     

郭丽峰  罗阳  郭勇  刘德文  林超 《测绘与空间地理信息》2011,34(4):17-22,25

对京津唐地区浅层地下水240个样本点的氨氮和硝酸盐氮含量进行了测定,应用地统计学方法对数据进行了分析,结果表明地下水中氨氮和硝酸盐氮含量符合对数正态分布。采用简单协克里格方法对未观察点进行了估值,并绘制了氨氮和硝酸盐氮含量空间分布图。将氨氮和硝酸盐氮含量分成8个等级,利用GIS空间分析方法分别统计了各个等级的面积。结果...  相似文献