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1.
瓦埠湖沉积物氮的赋存特征以及环境因子对NH4+-N释放的影响 总被引：9，自引：1，他引：8
采用现场采样和室内测试的方法,研究了瓦埠湖沉积物各层的TN、NH4^＋-N、NO3^--N的赋存特征。结果发现,TN上层比底层低,随着沉积深度的增加,硝化作用相对减弱,NO3^-N随着沉积深度的增加而减少,NH4^＋-N的含量随着沉积深度的增加而增加。pH〈9时,pH对NH4^＋-N释放的影响规律不是很明显,pH〉9时,NH4^＋-N释放随着pH的增加而增加。随着温度的升高,NH4^＋-N的释放量增大。好氧、厌氧条件下,NH4^＋-N都有释放,且在好氧条件下NH4^＋-N呈低释放状态,厌氧状态下NH4^＋-N呈高释放状态。 相似文献
2.
利用1980年地形图、1988/1990年Landsat TM、2000年Landsat ETM＋、2007年ALOS AVNIR-2遥感资料和近41年（1967-2007年）的气温、降水量资料对喜马拉雅东段洛扎地区的冰川、冰湖变化特征及变化原因进行了研究。结果表明：1）1980-2007年,本区冰川面积从491.64... 相似文献
3.
洞庭湖红壤坡地减氮控磷对玉米产量和径流氮磷的影响 总被引：4，自引：1，他引：3
坡地氮磷流失是洞庭湖农业面源污染的重要来源。以湖南省湘阴县红壤坡耕地土壤为研究对象,通过田间小区试验,探讨玉米减量施肥对产量、化肥利用率和氮磷流失量的影响。结果表明,NP常规施肥量在减少20%范围内对玉米产量没有十分显著的影响,但达到30%时玉米表现减产。减量施肥不仅一定程度提高NP化肥肥效和肥料利用率,而且降低土壤NP流失量。氮的径流量减少了12.54%～28.68%,磷减少了1.3%～30.1%。在各种减量施肥处理中,以控释肥减氮处理效果最佳,有效减少农业面源污染。 相似文献
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Background River and lake sediments constitute complex and difficult analytical samples. On the other hand, sediments play a fundamental
role in the distribution of toxic compounds in aquatic systems and in the evaluation of the current state and the course of
changes taking place in the environment.
Among elements present in the environment in trace concentrations, but having well-elaborated toxic properties, one of most
dangerous is arsenic. The element occurs in the environment in several chemical forms, predominant are inorganic forms of
As(V) and As(III), and methylated forms such as monomethylarsonic acid (MMAA) and dimethylarsinic acid (DMAA).
Objectives Reported herein are experiments, which were undertaken with the aim of examining the dynamics of arsenic sorption in sediments
and its dependence on speciation of the element and the pH in the environment. Simultaneously, influence of organic matter
content and chemical composition of the sediments on As sorption, were investigated.
Methods Sediment samples (upper 10 cm layer) were collected from three sites located in the vicinity of Cracow:
Using XRD and IR methods, mineral composition of sediments was analysed. Concentrations of iron, manganese, aluminium and
arsenic as well as organic matter content in solid samples were analysed.
Sorption experiment 100 g of dry sediment sample was placed in a 400 ml volume glass beaker. 300 ml of arsenic containing solution was poured
into the beaker. Every 30 min (total experiment time span equalled 7 to 7.5 hours), 0.5 ml of the suspension’ (the beaker
content was constantly mixed) was collected and centrifuged, and the concentration of arsenic was determined in the supernatant.
In the series of experiments, solution contained about 0.05 μg/ml of arsenic in organic (DMAA) and inorganic forms, at different
pH values — 3, 5, 7 and 9.
Results and Discussion Examined sediments of Vistula river and Dobczyce Lake were characterised by relatively high concentrations of arsenic, iron,
manganese and aluminium.Rudawa river. At pH 3, the concentration of inorganic As in solution decreased from an initial value of 0.049 μg/ml to 0.012 μg/ml in
7.5 hours time. The same decreasing tendency was found at pH 5 (initial value 0.046 μg/ml, after 7.5 hours - 0.015 μg/ml).
Less distinct sorption effects were noted at pH 7 and 9.
Vistula river. At all pH values, a very significant decrease of inorganic As concentration up to 80% of the initial value, as well as a
short time of achieving an equilibrium state (1 – 2.5 hours), was found.
Dobczyce lake. Inorganic As was distinctly accumulated in sediments at pH 3 (decrease of As concentration in solution from 0.052 to 0.007
μg/ml after 7.5 hours of the experiment) and at pH 5. At pH 7, about 40% of As was accumulated in sediments (solution As concentration
decrease from 0.050 to 0.030). Only 20% of As adsorbed on sediments at pH 9.Very weak accumulation of organic form of As (DMAA)
was found in all examined sediments at pH 3 and 5. At higher pH values no sorption was registered.
Conclusions The following facts were established:
Recommendations The presented method of analysis of As sorption in sediments and results visualization (based on a newly defined coefficient)
provides a useful tool for the characterization of sorptive properties of sediments and may be used for other compounds as
well. Crucial, functional information — how much of a given element may be accumulated in sediments at a certain pH — is obtained
without digestion of the sediment sample, in an experiment taking less than one day. 相似文献
| • | Rudawa river — 37 km long river, flowing mainly through the suburban area; |
| • | Vistula river — heavily contaminated, main Polish river; |
| • | Dobczyce reservoir — artificial reservoir on Raba river, total capacity of 125,000,000 m3, supplying about 60% of drinking water to the city of Cracow. |
| • | inorganic form of arsenic was effectively accumulated in all analysed sediments; |
| • | inorganic As sorption in sediments strongly depended on pH — for sediments of Rudawa river and Dobczyce lake, the highest sorption was found at pH 3, and a decrease of accumulated As was noted with an increase of pH (at pH 9, the lowest amount of As was immobilised in sediments); in the case of Vistula river sediments, a reverse tendency was found; |
| • | organic form of arsenic (DMAA) was accumulated only at pH 3 in all sediments and less significantly at pH 5 (Vistula river sediments); no sorption of that form of As was found in the other sediment samples; |
| • | state of equilibrium (no change in inorganic As concentration in liquid medium) was achieved in 1 hour for Vistula river sediments, after about 2 hours for Rudawa river and after about 4 hours for Dobczyce lake sediments. |
7.
2012年7月和10月分别对白云湖中华鳖养殖池塘的浮游植物群落结构进行了调查.结果表明：7月采集到浮游植物5门23种,10月采集到5门36种,种类组成上均以绿藻门种类最多,其次是蓝藻门或者硅藻门;7月池塘浮游植物优势种的优势度为0.02～0.32,优势种数共10种;10月份优势种的优势度为0.02～0.37,优势种数共13种;7月份池塘浮游植物平均密度为4.70×107 ind/m3,变化范围为（0.75～12.5）×10^7 ind/m3,10月平均密度为13.16×107 ind/m3,变化范围为（2.88～18.2）×10^7 ind/m3;7月份浮游植物生物量8.10～90.70 mg/L,平均为35.57 mg/L,10月份生物量为23.10～295.86 mg/L,平均为165.55 mg/L,浮游植物优势种的种类种群、密度和生物量都存在时间和空间上的差异. 相似文献
8.
亚洲中部干旱区的湖泊 总被引：12，自引：8，他引：12
采用系统论的观点,对亚洲中部的干旱区湖泊（包括咸海、巴尔喀什湖、博斯腾湖、艾比湖、玛纳斯湖、艾丁湖与罗布泊等）的水分循环与其他物质循环进行综合研究,其结果不仅丰富了生态循环的理论,而且深刻地揭示了干旱区湖泊与湿润区湖泊截然不同的特征;表现出水分循环的独特性、形态测量学的复杂性、风生湖流的奇特性与泥沙运行的规律性以及内陆湖水化学特征和别具一格的水生态循环系统等。干旱区湖泊作为陆地水圈的组成部分,他是一个完整的生态系统。他由湖泊中的生物和水两大亚系统组成,相互作用而又相互联系。尽管大陆性气候严酷和强烈,风生湖流强劲（有时还多亏他的作用）,蒸发量大,但内陆湖能生存数千年,即在现代时间尺度上是无IL尽的。 相似文献
9.
袁洪州 《中国农村水利水电》2013,(8)
以《太湖流域水环境综合治理总体方案》提出的太湖2012年水质保护目标为基础,结合太湖分湖区实测水质浓度,确定太湖各湖区水质保护目标;提出太湖污染物限制排污总量曲线的概念,采用太湖二维水量水质模型,计算不同入湖水量条件下满足太湖2012年水质保护目标时的太湖污染物限制排污总量,结合入湖水量特征拟定太湖污染物限制排污总量曲线,并以实际入湖污染负荷量和太湖实测水质对太湖污染物限制排污总量曲线进行了检验,为严格限制纳污红线管理提供依据. 相似文献
10.
湖州市是一座江南古城,有着浓厚的文化底蕴.湖州太湖旅游度假区位于湖州市境内,其区域内河道网络纵横交错,产生了众多的桥梁和滨水地带.为进一步提升湖州滨湖度假区环境品质,增加度假休闲氛围,打造国内一流休闲旅游度假区,现对滨湖休闲景现带的景观设计理念进行研究探讨. 相似文献