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101.
This 2‐year study (2000, 2001) reports annual nutrient (phosphorus, nitrate) export from a first‐order agricultural watershed in southern Ontario based on an intensive monitoring programme. The importance of storm and melt events in annual export estimates is demonstrated and the temporal variability in nutrient loading during events is related to processes occurring within the catchment. The feasibility of predicting event‐related nutrient export from hydrometric data is explored. The importance of sampling frequency throughout events is also shown. Export of total phosphorus (TP), soluble reactive phosphorus (SRP) and nitrate ( ) for 2000 and 2001 averaged 0·35 kg ha?1 year?1, 0·09 kg ha?1 year?1, and 35 kg ha?1 year?1 (as N) respectively. Approximately 75% of annual TP export, 80% of annual SRP export and 70% of annual export occurred during 28 events per year. A small number of large‐magnitude events (>34 mm) accounted for 18–42% of annual TP export, 0–61% of annual SRP export and 13–33% of annual NO export. Our results show that temporal variability in nutrient export is largely governed by discharge in this basin, and export can be predicted from discharge. SRP and TP export can also be predicted from discharge, but only for events that are not large in magnitude. The sampling interval throughout events is important in obtaining precise estimates of nutrient export, as infrequent sampling intervals may over‐ or under‐estimate nutrient export by ± 45% per event for P. This study improves our understanding of and P export patterns and our ability to predict or model them by relating temporal variability in event nutrient export to discharge and processes occurring within the basin, and also by exploring the significance of sampling interval in the context of the importance of individual events, season and temporal variability during events. Copyright © 2006 John Wiley & Sons, Ltd. 相似文献
102.
Huan-Xin Weng Ya-Chao Qin Xiang-Wei Sun Hailiang Dong Xiang-Hua Chen 《Estuarine, Coastal and Shelf Science》2007,73(3-4):501-509
Based on lab-culture experiments analyzing limitation and combination of iron and phosphorus on the growth of Cryptomonas sp. (Cryptophyceae), and the study of accumulation and release of Fe-bound P in sediment cores collected from the marine region of the Pearl River Estuary, China, reasons for the high frequency of phytoplankton bloom therein are discussed. Results show that the combined effect of Fe and P can obviously accelerate algal development, and the optimum culture conditions maintaining maximum growth rate are 0.05 μM Fe and 50 μM P. Cellular contents of Fe and P is consistent and the P:Fe molar ratio is 159:1. The optimum range of the P:Fe molar ratio in culture experiments for cell incubation is 500–1400. The vertical trends of total Fe and total P variations in sediments are parallel. Fe-bound P is the main species of inorganic sedimentary P. Through continuous leaching with agitation, 34–80% of exchangeable P and 4–23% of exchangeable Fe are concurrently released from the surficial sediments. This is a possible way by which nutrients are made available to phytoplankton. These factors might be responsible for a high frequency of harmful algal blooms in the Pearl River Estuary. 相似文献
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研究长江口和浙江近岸海域的水团流向、缺氧程度、潮汐作用以及养殖活动对表层沉积物中颗粒磷赋存形式的影响,对东海生态环境的可持续发展有着重要的意义。长江口以北和浙江近岸泥质区各存在一个缺氧中心,杭州湾属于强潮区,而象山港遍布养殖场。2018年8—9月在上述4个海域分别采集表层沉积物,采用SEDEX方法进行了颗粒磷的形态划分和含量测定。研究结果表明:在长江口外北部缺氧区和浙江近岸泥质区的南部缺氧区,由于沉积物-水界面的还原环境可以活化铁结合态磷,使之转变为生物可以直接利用的弱吸附态无机磷,因此表现出沉积物中铁结合态磷的低值和弱吸附态无机磷的高值;前者的缺氧程度高于后者,因此其铁结合态磷的含量相应更低。杭州湾和象山港海域均受潮汐作用影响,两者沉积物中磷的分布比较均匀。象山港表层沉积物中铁结合态磷含量均较低,这可能是因为养殖活动造成的水体缺氧通过潮汐活动扩散到整个港底。象山港废弃养殖场沉积物中的碎屑磷和残余有机磷含量显著低于非养殖区,可能是由于养殖活动累积的生物沉积稀释了陆源输入的碎屑颗粒。 相似文献
106.
海岸带盐度过渡区域水体中氮、磷的准确测定对陆海统筹及海岸带管理起着至关重要的作用。为探究盐度对氮、磷测定准确度的影响,进而明确河口海岸带淡水-咸水盐度过渡区不同形式氮、磷测定方法的选择依据,分别采用淡水和海水的相关国家标准方法,测定不同盐度下不同质量浓度氮、磷的人工海水和天然海水水样中氨氮、亚硝氮、总氮、活性磷酸盐和总磷的质量浓度。结果表明,盐度对某些氮、磷的淡水法和海水法测定结果有一定程度的影响。对氨氮的测定,当S≤4.0时淡水法或海水法均可准确测定水体中的氨氮,S>4.0时应对水样进行pH 调整预处理后用海水法进行测定;对亚硝氮的测定,淡水法和海水法的测定结果无明显差异;对总氮的测定,当S≤5.0时应采用操作简单、测定准确的淡水法测定,S>5.0时应采用海水法。对水体中的活性磷酸盐的测定,在低盐低磷(S≤35.0且ρPO3-4 ≤0.2mg·L-1)的情况下盐度对淡水法和海水法测定结果的影响微乎其微,而对于高盐高磷(S>35.0且ρPO3-4 > 0.2mg·L-1)的水样选择灵敏度更高的海水法测定更准确;对总磷的测定,选取海水法测定准确度更高。研究结果为海岸带水体不同形式氮、磷质量浓度的准确测定与方法选择提供了科学依据。 相似文献
107.
The nitrogen(N) and phosphorus(P) budget and the ecological efficiency of a polyculture system of sea cucumber(Apostichopus japonicus), jellyfish(Rhopilema esculenta) and shrimp(Fenneropenaeus chinensis) were studied in a cofferdam, 120.2 ha in size. The nutrients were supplied by spring tide inflow. In total, 139600 kg N yr-1 and 9730 kg P yr-1 input to the system; while 118900 kg N yr-1 and 2840 kg P yr-1 outflowed from the system concurrently, thus the outflow was 85.7%(N) and 29.2%(P) of inflow. The production of N and P was 889.5 kg yr-1 and 49.28 kg yr-1(sea cucumber) and 204 kg yr-1 and 18.03 kg yr-1(jellyfish and shrimp), respectively. The utilization rate of N and P by polycultured animals was 7.8‰ and 6.9‰, respectively, 21.9% and 38% higher than that of monocultured sea cucumber. Our results indicated that the polyculture system was an efficient culture system of animals and a remediation system of coastal environment as well; it scavenged 14.3% and 70.8% of N and P, respectively. Such an ecological efficiency may be improved further by increasing either the stocking density or the size of sea cucumber or both. 相似文献
108.
贵州省瓮福磷矿沉积环境及矿床成因探讨 总被引:1,自引:0,他引:1
瓮福磷矿沉积的有利场所是潮下海湾浅滩环境,而不是潮坪。海湾的大小又控制着矿床的规模,海滩能量的差异影响着磷矿石的不同结构成因类型。矿石的结构,从凝胶―细砂屑与砂屑颗粒由细变粗;岩石的颜色由灰褐、黑色(多陆屑、富有机炭及黄铁矿)变为浅灰、灰白色;矿层中P2O5含量随之渐增,而且CaO含量变化与P2O5含量变化同步,说明水动力条件由弱渐强,反映了沉积环境由潮汐作用为主的海湾环境。为此,陡山沱组以浅水碳酸盐优势岩相的地层条件是成磷的前提;温暖、干燥的古气候提供了有利于磷质的析出及沉积;适宜的海滩古地理环境提供了最佳的成矿场所;"黔中隆起"的古构造条件是磷矿的分布及富矿形成的最主要的控制因素。 相似文献
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为研究海水养殖对海湾沉积物的累积影响, 对大亚湾的大鹏澳养殖区沉积物柱状样中总氮、总磷和有机碳的含量及剖面分布特征进行了研究, 并探讨了海水养殖区沉积物中氮、磷的污染状况。结果表明, 网箱养殖区、贝类养殖区和对照区等3个区域柱状样中总氮的含量范围分别为638.2—3803.9mg.kg-1、740.9—2152.1mg.kg-1和343.2—471.9mg.kg-1, 总磷的含量范围分别为344.7—3233.9mg.kg-1、297.9—497.5mg.kg-1和650.2—1327.2 mg.kg-1, 有机碳的含量范围分别为0.96%—2.22%、0.87%—1.13%和0.69%—0.95%。该三个因子的含量均从底层至表层呈增加趋势, 但网箱养殖区上层增加幅度最为剧烈, 贝类区次之, 对照区变化幅度最小。所有柱状样中, 总氮含量均超标, 但网箱养殖区总氮污染最为严重, 贝类养殖区次之, 对照区最轻; 网箱养殖区的总磷在上层的不同深度超标, 而贝类养殖区及对照区柱状样的总磷含量均未超标。 相似文献