Trend analysis of nutrient loadings in a large prairie catchment     

Luis Alejandro Morales-Marín  Kwok Pan Chun  Howard Simon Wheater  Karl-Erich Lindenschmidt 《水文科学杂志》2017,62(4):657-679

Nutrient loadings in many river catchments continue to increase due to rapid expansion of agriculture, urban and industrial development, and population growth. Nutrient enrichment of water bodies has intensified eutrophication which degrades water quality and ecosystem health. In this study, we carried out a trend analysis of total phosphorus and total nitrogen loads in the South Saskatchewan River (SSR) catchment using a novel approach to analyse nutrient time series. Seasonal analysis of trends at each of the water quality stations was performed to determine the relationships between annual flow regimes and nutrient loads in the catchment, in particular, the influence of the high spring runoff on nutrient export. Decadal analysis was also performed to determine the long-term relationships of nutrients with anthropogenic changes in the catchment. Although it was found that seasonal and historical variability of nutrient load trends is mainly determined by streamflow regime changes, there is evidence that increases in nitrogen concentration can also be attributed to anthropogenic changes.  相似文献   

Effect of seasonal flushing on nutrient export characteristics of an urbanizing,remote, ungauged coastal catchment   总被引：1，自引：0，他引：1  

Gayan L. Gunaratne  Ryan I.J. Vogwill 《水文科学杂志》2017,62(5):800-817

Urbanization is a primary driver of nutrient export in coastal catchments; however, estimating the rate of export from urbanizing, remote and ungauged communities with episodic rainfall characteristics has rarely been reported in tropical and subtropical areas. In this study, the coastal catchment of Roebuck Bay near Broome, northwestern Australia, was instrumented to elucidate the effect of seasonal flushing on nutrient export. A cost-effective framework involving temporary gauging and community participation led to a quantitative estimate of surface hydrology and nutrient dynamics from this urbanizing, remote and ungauged catchment. The contribution of nutrient export was larger from the older Broome town site sub-catchments compared to sub-catchments that have been progressively urbanized since 2000. A distinctive seasonal first flush phenomenon, with an initial 30% of runoff volume containing 40–70% of the nutrient load was a key feature. This indicates there are opportunities for storm-water management to minimize impacts through adopting water-sensitive urban design principles.  相似文献   

The effects of wastewater discharges on the functioning of a small temporarily open/closed estuary     

Robynne A. Lawrie  Derek D. Stretch  Renzo Perissinotto 《Estuarine, Coastal and Shelf Science》2010

Wastewater discharges affect the functioning of small temporarily open/closed estuaries (TOCEs) through two main mechanisms: (1) they can significantly change the water balance by altering the quantity of water inflows, and (2) they can significantly change the nutrient balance and hence the water quality. This study investigated the bio-physical responses of a typical, small TOCE on the east coast of South Africa, the Mhlanga Estuary. This estuary receives significant inflows of treated effluent from upstream wastewater treatment works. Water and nutrient budgets were used together with biological sampling to investigate changes in the functioning of the system. The increase in inflows due to the effluent discharges has significantly increased the mouth breaching frequency. Furthermore, when the mouth closes, the accumulation of nutrients leads to eutrophication and algal blooms. A grey water index, namely the proportion of effluent in the estuary and an indicator of the additional nutrient inputs into the estuary, reached high values (?50%) during low flow regimes and when the mouth was closed. In these hyper-eutrophic conditions (DIN and DIP concentrations up to 457 μM and 100 μM respectively), field measurements showed that algal blooms occurred within about 14 days following closure of the mouth (chlorophyll-a concentrations up to 375 mg chl-a m⁻³). Water and nutrient balance simulations for alternative scenarios suggest that further increases in wastewater discharges would result in more frequent breaching events and longer open mouth conditions, but the occurrence of hyper-eutrophic conditions would initially intensify despite more frequent openings. The study indicates how water and nutrient balance simulations can be used in the planning and impact assessment of wastewater treatment facilities.  相似文献   

海洋生物固氮作用研究进展   总被引：1，自引：0，他引：1  

张润  陈敏 《台湾海峡》2010,29(3):428-433

近年来,海洋生物固氮作用研究已成为海洋氮循环研究热点之一,因为它补充了海洋中的结合态氮,影响着海洋氮储库的收支平衡,进而调控海洋的初级生产力,并因此与海洋颗粒有机碳的迁出以及海洋对大气CO2的吸收密切相关.海洋生物固氮作用的研究主要是在近30a开展起来的,现有观点认为全球海洋生物固氮速率为100～200 Tg/a.15↑N2示踪法和乙炔还原法是最重要的生物固氮速率实测方法,而硝酸盐异常指数法、15↑N同位素收支平衡法、卫星遥测法等则是重要的间接估测方法.束毛藻曾被认为是全球海洋最重要的固氮生物,但近年来也发现了固氮生物在微微（pi-co）级和微（nano）级的分布,表明以往基于束毛藻的固氮速率可能是被低估的.海洋生物固氮作用营养盐限制的研究主要集中在铁和磷这2个元素的作用,但目前尚无定论.在中国边缘海生物固氮作用的研究还很匮乏,少数研究表明除黑潮区外,由束毛藻所支持的固氮速率并不高.就海洋固氮作用研究的未来发展,指出今后必须在更大时空尺度上开展海洋生物固氮作用研究,以弥补现有实测数据的不足,并获取固氮微生物种类组成的准确信息,在确定海洋生物固氮作用控制因素的同时,追踪新固定氮的流向,进而为海洋氮循环提供准确信息.  相似文献   

Nutrient Fluxes in Rainfall,Throughfall, and Stemflow in Pinus densata Natural Forest of Tibetan Plateau     

《洁净——土壤、空气、水》2017,45(7)

  相似文献   

光纤光谱仪的研制及其在海水营养要素检测中的应用   总被引：1，自引：0，他引：1       下载免费PDF全文

李彩  曹文熙  程远月  孙兆华  杨跃忠 《热带海洋学报》2010,29(2):12-16

基于交叉非对称的czerny-Turner结构, 研制了一种微型光纤光谱仪, 采用光栅分光、线阵CCD探测光, 基于复杂可编程逻辑器件及PC104设计CCD数据采集电路, 采样结果通过PC104总线上传至PC104工控机, 光谱仪及数据采集电路集成为一光谱仪模块, 约为96mm(宽)×104mm(长)×18mm(高), 该模块与PC104工控机之间通过PC104总线以“针”和“孔”形式层叠连接, 在具有体积小、功耗低、采样速度快等优点的同时还具有极好的抗震性, 非常适合于野外恶劣工作环境下的在线使用。将其应用于海水中铁等痕量元素及营养盐在线检测仪, 试验结果良好。  相似文献   

Production of Pacific White Shrimp Polycultured with Swimming Crab at Different Densities,and Nutrient Budget in the Enclosure System     

ZHOU Yangen  BAO Weiyang  SU Yuepeng  HUANG Ming  WANG Xingqiang  YAN Binlun  MA Shen 《中国海洋大学学报(英文版)》2022,21(1):171-178

This study was to evaluate the effect of stocking densities on the nitrogen and phosphorus budgets for a polyculture of the crab Portunus trituberculatus and the Pacific white shrimp Litopenaeus vannamei.The shrimps(initial weight,0.012 g)were cultured at a density of 45 shrimp m^-2,and juvenile crabs(initial weight,0.024 g)were cultured at five densities of 0,3,6,9,and 12 crabs m^-2.The treatments were grouped as C0S45,C3S45,C6S45,C9S45,and C12S45,respectively.Water quality parameters,growth of shrimp and crabs,and nitrogen and phosphorus budget were measured.The results indicated that the shrimp performances in polyculture treatments C3S45 and C6S45 were superior to those in the crab-free treatment(C0S45).The crab in treatments C3S45 and C6S45 exhibited a significantly higher final mean weight and carapace width/length than those in treatments C9S45 and C12S45.The final size and survival of crabs had a negative correlation with the increasing crab stocking density.The contents of total phos-phorus and total nitrogen and the comprehensive contamination index values were higher in the C9S45 and C12S45 treatments than in the other treatments.The conversion ratios of nitrogen for crab and shrimp growth in treatment C3S45 were significantly higher than those in the crab-free treatment.These findings indicate that polyculturing shrimp with crabs at suitable densities can improve productivity,profitability,nutrient utilization,and the environmental quality.From the 60-day treatments,the optimal culture densi-ties were 3-6 crabs m^-2 and 45 shrimps m^-2.  相似文献   

Effect of Long-Term Low-Salinity Culture on the Survival,Growth, and Nutrient Composition of Mud Crab Scylla paramamosain     

JI Zilu  LI Ronghua  WANG Chunlin  ZHANG Zhouyi  ZHANG Weijia  MU Changkao  SONG Weiwei 《中国海洋大学学报(英文版)》2022,21(1):179-185

This study investigated the effects of long-term low-salinity on the growth performance,proximate composition,amino acid and fatty acid profiles of Scylla paramamosain.The salinity of the low-salinity-culture group(LC)and maintained-salinity-cul-ture group(MC)were set at 5 and 25 respectively.After rearing for 30 d,the survival rate(SR)of the LC group was significantly lower,whereas the average daily molting frequency(ADMF)was significantly higher than those in MC group(P<0.05).There were no significant difference for weight gain rate(WGR)and specific growth rate(SGR)between the two groups.The moisture content of the LC group was slightly higher than the MC group without significant difference.The contents of ash,crude lipid and crude pro-tein in the LC group were lower than those in the MC group,but no significant differences were found except for ash content.A total of 17 free amino acids and 23 fatty acids were identified from the muscle of S.paramamosain.The total amino acids(TAA),essen-tial amino acids(EAA)and essential amino acid index(EAAI)had no significant difference between the two groups.The crabs from LC group had a significantly higher HUFA,including EPA,DHA,ARA.The percentage of n-3 PUFA and the ratio of n-3/n-6 PUFA were significantly higher in the LC group.These results indicated that S.paramamosain rearing at low salinity had significantly de-creased SR;however,the low-salinity environment significantly promoted the accumulation of unsaturated fatty acids(UFAs),espe-cially the n-3 PUFA,which might be related to the osmoregulation mechanism.  相似文献   

Modelling nitrogen and phosphorus cycles and dissolved oxygen in the Zhujiang Estuary Ⅰ.Model results     

管卫兵  王丽娅  许东峰 《海洋学报(英文版)》2001,(4)

rmIoxThe averag annual dischaIge of the Zhujiang Xiver is 3. 32 x l0ll m3, which ranks theZhujiang River just end to the Changjiang River in China. The dischnye occutring duringthe fltal m between APril and ffepteTnber accounts for 80% of the yearly total. The Zhu-jiang hiver has a yeaIy sediment load of about 1 x l08 tons, which also concentrates in theM arn (Zhao, l990; Chen et al., 1998). The Zhujiang Xiver delta,which has l2 cities ofdifferent sizes and more than 40 towns with a po…  相似文献   

2000年夏季莱州湾主要观测要素的分布特征   总被引：10，自引：1，他引：10  

万修全  吴德星  鲍献文  姜华 《中国海洋大学学报(自然科学版)》2004,34(1):7-12

在 2 0 0 0年夏季莱州湾加密大面调查资料的基础上 ,研究了莱州湾海域海水的温度、盐度、溶解氧、浊度、叶绿素、无机氮、磷酸盐和硅酸盐的分布特征 ,初步讨论了它们之间的相互关系。结果表明 ,莱州湾盐度值与以前相比有显著升高 ;叶绿素南部的高值区对应于溶解氧的低值区 ,温度的高值区 ;浊度受黄河径流的影响较大 ;无机氮西部浓度高 ,东部浓度低 ,且相差很大 ;浮游植物生长的限制因素东部与西部海域不同 ,东部为氮限制 ,而西部为磷限制。  相似文献