Effects of soil nitrate：ammonium ratio on plant carbon：nitrogen ratio and growth rate of Artemisia sphaerocephala seedlings     

Rong Li  XingDong He  PingPing Xue  HuaCong Ci  Wei Wu  YuBao Gao  HaLin Zhao 《寒旱区科学》2010,2(5):0445-0454

Can soil nitrate： ammonium ratios influence plant carbon： nitrogen ratios of the early succession plant？ Can plant carbon： nitrogen ratios limit the plant growth in early succession？ To address these two questions, we performed a two-factor （soil nitrate： ammonium ratio and plant density） randomized block design and a uniform-precision rotatable central composite design pot experiments to examine the relationships between soil nitrate： ammonium ratios, the carbon： nitrogen ratios and growth rate of Artemisia sphaerocephala seedlings. Under adequate nutrient status, both soil nitrate： ammonium ratios and plant density influenced the carbon： nitrogen ratios and growth rate of A. sphaerocephala seedlings. Under the lower soil nitrate： ammonium ratios, with the increase of soil nitrate： ammonium ratios, the growth rates of plant height and shoot biomass of A. sphaerocephala seedlings decreased significantly; with the increase of plant carbon： nitrogen ratios, the growth rates of shoot biomass of A. sphaerocephala seedlings decreased significantly. Soil nitrate： ammonium ratios affected the carbon： nitrogen ratios of A. sphaerocephala seedlings by plant nitrogen but not by plant carbon. Thus, soil nitrate： ammonium ratios influenced the carbon： nitrogen ratios of A. sphaerocephala seedlings, and hence influenced its growth rates. Our results suggest that under adequate nutrient environment, soil nitrate： ammonium ratios can be a limiting factor for the growth of the early succession plant.  相似文献   

基于次溴酸钠氧化-氨基磺酸还原测定沉积物15N加富培养样品中的15NH+4的方法探索     

徐颢铭  宋国栋  刘素美  梁生康  张桂玲 《海洋学报》2022,44(1):147-154

沉积物中的异化硝酸盐还原过程是海洋中活性氮转化的关键过程之一.不同于反硝化和厌氧铵氧化,异化硝酸盐还原为铵(DNRA)是将硝酸盐直接还原为铵,而不是以氮气的形态移除,这有可能会加重水体富营养化和缺氧.目前测定沉积物中异化硝酸盐还原过程的主要手段是15N标记培养技术.为了准确评估DNRA的潜在速率,首先要准确测定加富样品...  相似文献   

The Interaction of Natural Organic Matter with Iron in a Wetland (Tennessee Park, Colorado) Receiving Acid Mine Drainage   总被引：3，自引：0，他引：3  

Stefan Peiffer  Katherine Walton-Day  Donald L. Macalady 《Aquatic Geochemistry》1999,5(2):207-223

Pore water from a wetland receiving acid mine drainage was studied for its iron and natural organic matter (NOM) geochemistry on three different sampling dates during summer 1994. Samples were obtained using a new sampling technique that is based on screened pipes of varying length (several centimeters), into which dialysis vessels can be placed and that can be screwed together to allow for vertical pore-water sampling. The iron concentration increased with time (through the summer) and had distinct peaks in the subsurface. Iron was mainly in the ferrous form; however, close to the surface, significant amounts of ferric iron (up to 40% of 2 mmol L-1 total iron concentration) were observed. In all samples studied, iron was strongly associated with NOM. Results from laboratory experiments indicate that the NOM stabilizes the ferric iron as small iron oxide colloids (able to pass a 0.45μm dialysis membrane). We hypothesize that, in the pore water of the wetland, the high NOM concentrations (>100 mg C L-1) allow formation of such colloids at the redoxcline close to the surface and at the contact zone to the adjacent oxic aquifer. Therefore, particle transport along flow paths and resultant export of ferric iron from the wetland into ground water might be possible. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

The origin and distribution of nitrate in groundwater from village wells in Kotagede, Yogyakarta, Indonesia     

Geoffrey D. Smith  Robbert Wetselaar  James J. Fox  Robert H. M. van de Graaff  Doeljachman Moeljohardjo  Joko Sarwono  Wiranto  Sri Rahajoe Asj'ari  Suharto Tjojudo  Basuki 《Hydrogeology Journal》1999,7(6):576-589

The causes and nature of nitrate pollution of wells in a village within Kotagede, a subdistrict of the city of Yogyakarta, Indonesia, were investigated in a detailed hydrological study. Nitrate concentrations in groundwater frequently exceeded the WHO recommended limit of 50 mg L^− 1. Groundwater nitrate concentrations were measured over a 19-month period in monitoring wells and in piezometers placed strategically in relation to sewage tanks within the village. Results indicate that the tanks are major sources of nitrate in the groundwater and that the input is markedly dependent on rainfall, resulting in a surge of nitrate into the groundwater at the beginning of each wet season. That the tanks are a major source was confirmed by measuring nitrate in soil cores obtained by augering close to selected tanks. Washrooms, where people wash themselves, are not significant sources of nitrate. Faecal coliform counts in groundwater from a random selection of wells are very high. The results have implications for the siting of wells and toilets within villages in Indonesia. Received, January 1999/Revised, August 1999/Accepted, August 1999  相似文献   

Spring time sources and sinks of Peroxyacetyl Nitrate in the UK and its contribution to acidification and nitrification of cloud water     

G. G. McFadyen  J. N. Cape 《Atmospheric Research》1999,50(3-4)

During spring the atmospheric concentration of Peroxyacetyl Nitrate, PAN, in the UK varies over three orders of magnitude due to long range transport and local photochemical production. An experiment at Great Dun Fell was used to determine which of these sources of PAN controlled spring time concentrations and to quantify the contribution of PAN to oxidised nitrogen in cloud water. The gas phase mixing ratio of a wide range of trace gas pollutants, including PAN, along with cloud water chemical composition and aerosol/cloud droplet distributions were measured. A chemical model was developed to determine the contribution of PAN hydrolysis to cloud water nitrification and to quantify the sink strengths of PAN. Chemical reaction following thermal decomposition was found to be the dominant sink mechanism in the model but transport was the most important factor controlling PAN concentration. During cloud episodes PAN concentrations varied from 100 ppt to over 1 ppb but the calculated inorganic oxidised nitrogen loading in the cloud due to PAN dissolution and hydrolysis was an insignificant fraction of the observed total oxidised nitrogen loading of the cloud. Extrapolation of the model to persistent cloud in marine conditions showed that PAN has a negligible effect on cloud nitrification. It was concluded that PAN concentrations were heavily influenced by regional concentrations and that the hydrolysis of PAN in cloud water was an insignificant source of oxidised nitrogen in cloud water.  相似文献   

硝酸盐氮氧同位素在不同生态系统中的研究进展   总被引：1，自引：0，他引：1  

张金  马金珠  陈春武  潘昆  包磊 《干旱区地理》2015,38(2):312-319

硝酸盐作为氮循环中的重要物质之一,已成为地下水污染的主要形式。硝酸盐的来源分为自然源和人为源。不同来源的硝酸盐具有不同的同位素特征,因此可以利用N、O同位素来识别硝酸盐的来源、迁移和转化。本文通过综述硝酸盐的主要来源及其同位素特征,简要介绍了硝酸盐同位素检测技术的发展历程,影响同位素分馏的相关作用过程;同时简述了硝酸盐同位素在农业、沙漠、森林、城市生态系统中开展的相关研究,概述了研究中存在的问题,并展望了今后的发展方向。  相似文献   

Laminaria gametophyte clone culture and its application in sporeling cultivation   总被引：1，自引：0，他引：1  

Zhou Zhigang  Li Dapeng  Wu Chaoyuan  Liu Haihang 《海洋学报(英文版)》2000,19(2):89-95

IN~UCrIOXIn China, the total annual production of cultivated ham maria japonica reached half milliontons in dry weight these few years. All the sporelings used for artificial cultivation were culturedin greenhouses with controlled temperature. This technique was developed in the mid 1950s(Tseng et al., 1955). The key point of this method is to collect ~spores in summer instead Ofautumn. The garnetophytes and the resulting young sporophytes are cultured at 6 -- 10t generally with sufficient…  相似文献   

基于镀铜镉柱海水中硝酸盐氮的检测技术的研究     

刘春晖  黄存款  张政  袁方  王思长  郑策 《海洋科学》2021,45(8):40-46

镀铜镉柱还原——重氮偶氮染色法在检测海水领域具有重要的位置,算法的不断创新优化成为海水水质检测质量的的关键。本研究以硝酸钾作为标准溶液,海水作溶剂做相关实验,并且在实际海水检测应用中得到良好的效果。通过对实验原理的分析及实验过程的探究,确定了本研究的最佳还原与显色条件。并采用偏最小二乘法（partial least squares regression,PLS）算法模型对实验数据进行预处理,利用浊度对其进行补偿,最终得到硝酸盐氮的最优模型。经实验结果比对,该方法确定的检测系统线性范围宽、检出限低,符合海水的快速检测要求。在此基础上设计了一套在线自动检测装置,解决了海水在线、实时监测的难题。  相似文献   

Impacts of land-use changes on watershed discharge and water quality in a large intensive agricultural area in Thailand   总被引：1，自引：0，他引：1  

Srilert Chotpantarat  Satika Boonkaewwan 《水文科学杂志》2018,63(9):1386-1407

The objectives of this research were to evaluate the effect of land-use change on streamflow, sediment and water quality data along the Lower Yom River, Thailand, covering an intensively agricultural area of 14 613.6 km², and to assess the relative impact of point and non-point sources of pollution from multiple-land-use watersheds. Long-term calibration and validation of the SWAT (Soil and Water Assessment Tool) model was performed on data for 2000–2013. Land-use change led to a 13–49% increase in runoff in the basin and resulted in 37–427% increased sediment yield. The amount of NO₃-N load doubled in the upper and middle parts of the study area, while the increase in PO₄^3– ranged from 37 to 377%, reflecting the increase in agricultural lands and urban areas. It is concluded that the changed land use is closely associated with the quantity of runoff, sediment yield and the NO₃-N and PO₄^3– concentrations.  相似文献   

Prediction of regional-scale groundwater recharge and nitrate storage in the vadose zone: A comparison between a global model and a regional model     

Tuvia Turkeltaub  Matthew. J. Ascott  Daren C. Gooddy  Xiaoxu Jia  Ming-An Shao  Andrew Binley 《水文研究》2020,34(15):3347-3357

Extensive nitrogen loads at the soil surface exceed plant uptake and soil biochemical capacity, and therefore lead to nitrogen accumulation in the deep vadose zone. Studies have shown that stored nitrogen in the vadose zone can eventually reach the water table and affect the quality of groundwater resources. Recently, global scale models have been implemented to quantify nitrate storage and nitrate travel time in the vadose zone. These global models are simplistic and relatively easy to implement and therefore facilitate analysis of the considered transport processes at a regional scale with no further requirements. However, the suitability of applying these models at a regional scale has not been tested. Here, we evaluate, for the first time, the performance and utility of global scale models at the regional scale. Applied to the Loess Plateau of China, we compare estimates of groundwater recharge and nitrate storage derived from global scale models with results from a regional scale approach utilizing the Richards and advection-dispersion equations. The estimated nitrate storage was compared to nitrate observations collected in the deep vadose zone (>50 m) at five sites across the Loess Plateau. Although both models predict similar spatial patterns of nitrate storage, the recharge fluxes were three times smaller and the nitrate storage was two times higher compared with the regional model. The results suggest that global scale models are a potentially useful screening tool, but require refinement for local scale applications.  相似文献