Nitrification in Kochi backwaters     

Joereen Miranda  K.K. Balachandran  R. Ramesh  Mohideen Wafar 《Estuarine, Coastal and Shelf Science》2008

Nitrification rates, as oxidation of ¹⁵N-labelled ammonium and loss of nitrite from N-Serve treated samples, were measured in Kochi backwaters during three seasons. Nitrification rates ranged from undetectable to 166 nmol N L⁻¹ h⁻¹ in the water column and up to 17 nmol N (g wet wt)⁻¹ h⁻¹ in sediments. Nitrification rates were higher in intermediate salinities than in either freshwater or seawater end. Within this salinity range, nitrification rates could be related to ammonium concentrations. As shown by the relation between ammonification and nitrification rates, it is also likely that nitrification is more regulated by renewal rates, rather than by in situ concentrations, of substrate. Among other environmental parameters, temperature and pH may have an influence on nitrification. Potential nitrification rates calculated from loss of nitrite from N-Serve treated, nitrite-enriched samples were about 800 nmol N L⁻¹ h⁻¹ in the water column and 40 nmol N (g wet wt)⁻¹ h⁻¹ in sediments. While these rates are in balance with those of biological ammonium production they may be inadequate to mitigate ammonium pollution in this estuary.  相似文献   

Growth of marine bacteria and ammonium regeneration from substrates in different C: N ratios     

WANG Jiangtao  YIN Xiaonan 《海洋学报(英文版)》2009,28(3):59-64

Natural assemblages of marine bacteria were chosen in a batch culture experiments. The impact of varying nitrogen substrate concentrations and the substrate C:N ratios (C:N_S) on the bacterial C:N ratio (C:N_B), the bacterial growth efficiency (BGE) and ammonium regeneration was mainly examined. The C:N_S ratios varied from 5:1 (carbon limitation) to 40:1 (nitrogen limitation) with varying combinations of glucose and NO₃^-. The C:N_B ratio had positive relationship with the C:N_S ratio (r=0.93, n=8), whose value was 3.77 when the C:N_S ratio was 5:1 but increased to 6.47 when the C:NS ratio was 40:1. These results indicate that the C:N_B ratio is a potential diagnostic tool for determining the bacterial growth in natural waters controlled by either, carbon or nitrogen. BGE decreased with the declining nitrate concentration and negatively related to C:N_s (r=-0.51, n=8). The average value of BGE was 0.20. This value was a little lower than other reports, which could be induced by the nitrogen source used in our experiments. Finally, regeneration time of ammonium delayed with the increasing C:N_S ratio, which indicates that there were different metabolism mechanisms when bacterial growth was limited by carbon source and nitrogen source.  相似文献   

海黍子(Sargassum muticum)池塘养殖及对氮磷去除效果的研究     

王翔宇  王志刚  吴海一 《海洋湖沼通报》2015,(1):91-95

初步研究了在海参养殖池塘中,不同养殖方式下,大型海藻海黍子(Sargassum muticum)的生长特性及对水体中氨氮和活性磷的去除作用。2012年3~5月,在山东莱州试验养殖海黍子60d,结果发现其长度最大从43.8cm增长到81.3cm,增长85.6%,日增长率(SGR)在14℃时最大,达到5.0%;每绳的平均质量从0.74kg增到2.59kg,增长3.5倍,SGR在12℃时最大,达4.3%;水体氨氮平均下降了25.9%,活性磷下降了37.5%。实验证明海黍子能在适合的池塘中养殖,并且能有效的去除水体中的氨氮和活性磷,是有效的近海生境修复大型工具种海藻。  相似文献   

沂源县田庄水库农业面源氮素淋滤行为研究   总被引：1，自引：0，他引：1  

宋辉  刘庆福 《地下水》2010,32(2):71-73

受农业面源影响,典型山区水库-田庄水库氮素超标,通过模拟土壤在不同降雨强度与不同降雨类型下的淋滤行为,探讨氮素淋溶释放规律,并对田庄水库农业面源氮素入库量进行了计算。结果表明,降雨类型和降雨强度只影响土壤中氨氮峰值浓度出现的时间,对其数值影响不大,由于土壤中硝氮含量较高,使降雨强度和类型对其淋出液中的硝氮峰值浓度产生的时间和数值都有所影响;农业面源氮污染通过田庄水库四条入库河流年均排入水库中的硝氮总量高达604．49t,氨氮为23．85t。  相似文献   

沼泽湿地土壤中硝态氮和铵态氮物理运移研究进展   总被引：1，自引：0，他引：1  

牟晓杰  孙志高  王玲玲 《海洋湖沼通报》2010,(1)

沼泽湿地土壤是氮的重要储库,发挥着源、汇和转化器的重要功能。湿地土壤中无机氮的物理运移不但影响着植物的养分供给状况,而且其对于湿地生态系统的结构、功能及健康状况等也有着深刻影响。综述了沼泽湿地土壤无机氮物理运移及影响因素的研究动态。当前湿地土壤无机氮物理运移的研究主要集中在硝态氮和铵态氮(特别是硝态氮)物理运移规律及部分影响因素(如水分条件、土壤物理性质等)的探讨上,缺乏无机氮物理运移的动力学、热力学机制与模型表征研究。鉴于当前研究中存在的问题,指出天然沼泽湿地是研究的薄弱点,其在今后应亟需加强的领域包括:①无机氮物理运移的驱动机制;②动力学、热力学与环境效应模型表征;③人类活动和全球变化对无机氮物理运移的影响。  相似文献   

Transformation of ammonium nitrogen and response characteristics of nitrifying functional genes in tannery sludge contaminated soil          下载免费PDF全文

Kong Xiang-ke  Zhang Zi-xuan  Wang Ping  Wang Yan-yan  Zhang Zhao-ji  Han Zhan-tao  Ma Li-sha 《地下水科学与工程》2022,10(3):223-232

High concentrations of ammonium nitrogen released from tannery sludge during storage in open air may cause nitrogen pollution to soil and groundwater. To study the transformation mechanism of NH₄⁺-N by nitrifying functional bacteria in tannery sludge contaminated soils, a series of contaminated soil culture experiments were conducted in this study. The contents of ammonium nitrogen (as NH₄⁺-N), nitrite nitrogen (as NO₂^?-N) and nitrate nitrogen (as NO₃^?-N) were analyzed during the culture period under different conditions of pollution load, soil particle and redox environment. Sigmodial equation was used to interpret the change of NO₃^?-N with time in contaminated soils. The abundance variations of nitrifying functional genes (amoA and nxrA) were also detected using the real-time quantitative fluorescence PCR method. The results show that the nitrification of NH₄⁺-N was aggravated in the contaminated silt soil and fine sand under the condition of lower pollution load, finer particle size and more oxidizing environment. The sigmodial equation well fitted the dynamic accumulation curve of the NO₃^?-N content in the tannery sludge contaminated soils. The Cr(III) content increased with increasing pollution load, which inhibited the reproduction and activity of nitrifying bacteria in the soils, especially in coarse-grained soil. The accumulation of NO₂^?-N contents became more obvious with the increase of pollution load in the fine sand, and only 41.5% of the NH₄⁺-N was transformed to NO₃^?-N. The redox environment was the main factor affecting nitrification process in the soil. Compared to the aerobic soil environment, the transformation of NH₄⁺-N was significantly inhibited under anaerobic incubation condition, and the NO₃^?-N contents decreased by 37.2%, 61.9% and 91.9% under low, medium and high pollution loads, respectively. Nitrification was stronger in the silt soil since its copy number of amoA and nxrA genes was two times larger than that of fine sand. Moreover, the copy numbers of amoA and nxrA genes in the silt soil under the aerobic environment were 2.7 times and 2.2 times larger than those in the anaerobic environment. The abundance changes of the amoA and nxrA functional genes have a positive correlation with the nitrification intensity in the tannery sludge-contaminated soil.  相似文献   

Wintertime rates of net primary production and nitrate and ammonium uptake in the southern Benguela upwelling system     

RF Flynn  JM Burger  K Pillay 《African Journal of Marine Science》2018,40(3):253-266

The elevated levels of primary productivity associated with eastern boundary currents are driven by nutrient- rich waters upwelled from depth, such that these regions are typically characterised by high rates of nitrate-fuelled phytoplankton growth. Production studies from the southern Benguela upwelling system (SBUS) tend to be biased towards the summer upwelling season, yet winter data are required to compute annual budgets and understand seasonal variability. Net primary production (NPP) and nitrate and ammonium uptake were measured concurrently at six stations in the SBUS in early winter. While euphotic zone NPP was highest at the stations nearest to the coast and declined with distance from the shore, a greater proportion was potentially exportable from open-ocean surface waters, as indicated by the higher specific nitrate uptake rates and f-ratios (ratio of nitrate uptake to total nitrogen consumption) at the stations located off the continental shelf. Near the coast, phytoplankton growth was predominantly supported by ammonium despite the high ambient nitrate concentrations. Along with ammonium concentrations as high as 3.6 µmol l^–1, this strongly suggests that nitrate uptake in the inshore SBUS, and by extension carbon drawdown, is inhibited by ammonium, at least in winter, although this has also been hypothesised for the summer.  相似文献   

DPQAC-PAC-MC复合改性粘土在不同介质中的絮凝行为研究     

吴婷  曹西华  俞志明  宋秀贤  姜文彬  袁涌铨  吴在兴  贺立燕  范子初 《海洋与湖沼》2021,52(1):106-113

改性粘土法絮凝消除浮游微藻是我国迄今唯一得到大规模应用的有害赤潮应急处置方法,研发安全高效的改性粘土材料是该方法发展的重要方向之一。本文研究了双烷基聚氧乙烯基三季铵盐(DPQAC)与聚合氯化铝(PAC)复合改性粘土获得新材料DPQAC-PAC-MC在去离子水、海水及东海原甲藻藻液(Prorocentrum donghaiense)等不同介质中的絮凝行为,分析了水体中硫酸根离子和藻源胞外有机质(extracellular organic matters,EOMs)对其影响,探讨了该复合改性粘土高絮凝性能的成因与机制,为该类型改性粘土进一步增效优化及应用推广提供参考。研究结果表明,与双烷基聚氧乙烯基三季铵盐改性粘土(DPQAC-MC)、聚合氯化铝改性粘土(PAC-MC)等单组分改性粘土相比,DPQAC-PAC-MC表现出更强的絮凝能力,但在不同介质中其絮凝行为差异明显。其中,在藻液中形成的絮凝体颗粒更大、强度更高、再生能力更强、生长速度更快。介质中的硫酸根离子或胞外有机质都可促进DPQAC-PAC-MC的絮凝,并且具有最佳促凝浓度,硫酸根离子浓度为10^-3mol/L,EOMs浓度为50%含量,在此浓度之前随浓度增加,絮凝体生长时间缩短、强度增加、絮凝效果提升;超过最佳浓度后,促凝效果随浓度的进一步增加而降低。对影响DPQAC-PAC-MC在藻液中絮凝行为的分析发现:(1)复合改性有效提高了颗粒的表面正电性,长链大分子增强了颗粒间的桥联聚结作用,从而增强了粘土颗粒的自身絮凝能力;(2)赤潮暴发水体中大量存在的硫酸根离子、EOMs可以进一步增效复合改性粘土颗粒的絮凝聚结能力。  相似文献   

光照和黑暗条件下苦草(Vallisneria natans)和穗花狐尾藻(Myriophyllum spicatum)对铵态氮的吸收   总被引：1，自引：0，他引：1  

钟爱文  曹特  张萌  倪乐意  谢平 《湖泊科学》2013,25(2):289-294

在室内模拟实验中,研究了光照(50μmol/(m²·s))和黑暗条件下苦草(Vallisneria natans)和穗花狐尾藻(Myrio-phyllum spicatum)对铵态氮(NH₄⁺-N)的吸收速率与去除效果.结果表明,随着外源铵态氮浓度(0,0.01,0.1,1和10 mg/LNH₄⁺-N)的增加,苦草和穗花狐尾藻对铵态氮的吸收速率都是先增加后又逐渐降低,在外源铵态氮浓度为1 mg/L时吸收速率达到最大.同种植物在光照条件下对铵态氮的吸收率不低于黑暗条件下的吸收率;相同光强条件下穗花狐尾藻对铵态氮的吸收率不低于苦草的吸收率.在黑暗条件下,在外源铵态氮浓度为1 mg/L时,穗花狐尾藻对铵的吸收速率是苦草的2.42倍;在光照条件下,在外源铵态氮浓度为1和10 mg/L时,穗花狐尾藻对铵态氮的吸收速率分别是苦草的2.47和1.79倍.因此,在富营养湖泊治理过程中,在沉水植物可耐受铵态氮浓度范围内,可以优先考虑把穗花狐尾藻作为植物修复的先锋物种.  相似文献   

有机改性粘土对铜绿微囊藻的絮凝去除   总被引：3，自引：1，他引：2  

刘国锋  钟继承  张雷  范成新  任小龙 《湖泊科学》2009,21(3):363-368

如何有效的去除富营养化水体中频繁出现的藻华,已成为湖泊环境治理中的一个迫切问题.通过用表面活性剂十六烷基三甲基溴化铵改性的原位沉积物为介质,利用搅拌器和沉积物再悬浮发生装置来研究烷基铵盐改性物质絮凝去除铜绿微囊藻细胞的作用和效果.结果表明,烷基铵盐和粘土的添加量分别为0.3g/L和0.2g/L,搅拌停止30min后,其去除效率达83.9%:在絮凝沉降500min后,水体中藻细胞去除率可达98.9%,较能有效的絮凝沉降藻细胞;同时水体的浊度也有相应的提高.电镜扫描表明这种活性剂形成的网捕包膜作用对藻细胞的沉降起到了重要作用.但烷基铵盐的杀菌作用可能会造成藻细胞内含物向水体释放的风险.  相似文献