69 resultados para Water--Pollution--Ontario--Lake Gibson watershed.


Relevância:

100.00% 100.00%

Publicador:

Resumo:

为了进一步降低水中营养盐浓度、提高水体透明度,为湖泊生态系统的恢复创造条件,促进湖泊水体生态系统良性循环,以太湖五里湖富营养化水体为研究对象,采用中试规模的人工湿地技术来强化净化富营养化水体。重点研究了不同流态、不同基质、不同植物及植物有无条件下各人工湿地系统对富营养化水体的处理效果。此外,还对生长在人工湿地中的7种湿地植物芦苇(Phragmites communis)、香蒲(Typha angustifolia)、茭白(Zizania caduciflora)、水葱(Scirpus validus.)、菖蒲(Acorus calamus)、鸢尾(Iris pseudacorus)和千屈菜(Lythrum salicaria)的生长、生理生态特性如气体交换、叶绿素荧光、光合色素含量及氮、磷吸收能力进行了研究,旨在探索高等植物在富营养化水体净化过程中的机理和规律,为人工湿地污水净化机理奠定一定的科学和理论基础。主要研究结果如下: 通过对垂直潜流、水平潜流和自由表面流三种类型的人工湿地系统对富营养化水体净化效果的对比研究,我们发现在水力负荷0.64 m d-1,进水污染物浓度化学需氧量(COD) 7.37 mg L-1、氨氮(NH4+-N) 1.63 mg L-1、硝氮(NO3--N )1.41 mg L-1、总氮(TN) 4.82 mg L-1和总磷(TP) 0.15 mg L-1的条件下,三种不同流态的人工湿地对富营养化水体均有一定的净化功能。三种类型的人工湿地对主要污染物COD、NH4+-N、NO3--N、TN和TP的去除效果分别为:垂直潜流40.4%、45.9%、62.9%、51.6%和64.3%;水平潜流39.6%、32.0%、65.3%、52.1%和65.7%;自由表面流16.5%、22.8%、34.2%、19.8%和35.1%。相比之下,垂直潜流、水平潜流对主要的污染物的去除效果明显好于自由表面流人工湿地。除垂直潜流湿地NH4+-N的平均去除率显著大于水平潜流外,两人工湿地在其余指标的去除效果上无显著差异。考虑到土地面积的限制,就太湖五里湖富营养化水体治理而言,垂直潜流和水平潜流较自由表面流更为适合。 以沸石为基质的人工湿地较以砾石为基质的人工湿地对NH4+-N有很好的去除效果,除此之外两种基质类型的人工湿地在其余各污染指标的去除效果方面差异不显著。但随着湿地运行时间的延长,沸石对NH4+-N的吸收能力会逐渐减弱,考虑到湿地构建成本,建议就地取材,以当地较为廉价的砾石为人工湿地基质比较经济适用。 有无植物对有机污染物COD的去除效果影响差异不显著,但对TN和TP去除效果影响差异极显著,有植物的人工湿地对TN的去除率比无植物的分别高出12.5%和13.4%,对TP去除率分别高出16.9%和31.0%。不同植物对人工湿地处理效果的影响差异不显著,可见湿地流态对处理效果的影响大于植物的影响。 各湿地植物叶片的净光合速率(Pn)日变化均为双峰曲线,有光合“午休”现象。其中芦苇、茭白、鸢尾、菖蒲、水葱和千屈菜Pn的下降主要是由气孔导度(gs)的下降造成的,而香蒲则更多的受叶肉光合能力下降的影响。除千屈菜的Pn与gs之间呈显著正相关外,其余植物的Pn与gs之间均呈极显著正相关。气孔行为对湿地植物光合作用碳的固定显示了明显的主导控制作用。 各湿地植物的光补偿点(LCP)差异不显著,其均值都在10µmol m-2 s-1以上,显示了阳生植物的特性。但湿地植物的光饱和点 (LSP)差异极显著,LSP大小依次为香蒲1476.3µmol m-2 s-1>水葱1140.0µmol m-2 s-1>菖蒲753.7µmol m-2 s-1>芦苇751.7µmol m-2 s-1>茭白640.7µmol m-2 s-1>千屈菜567.3µmol m-2 s-1>鸢尾479.0µmol m-2 s-1。7种湿地植物的CO2补偿点差异极显著,CO2补偿点大小依次为水葱47.1µmol mol-1>茭白28.4µmol mol-1>香蒲23.7µmol mol-1>鸢尾16.8µmol mol-1>菖蒲16.7µmol mol-1>千屈菜15.2µmol mol-1>芦苇14.8µmol mol-1。与此相反,湿地植物的CO2饱和点差异不显著。 各湿地植物的Fv/Fm值大小差异也极显著,Fv/Fm值大小依次为千屈菜0.8168>水葱0.8348>香蒲0.8262>菖蒲0.8198>芦苇0.8168>茭白0.8040>鸢尾0.7930。由此可见千屈菜、水葱较芦苇和茭白有较高的PSⅡ效率。7种湿地植物叶片的叶绿素a、叶绿素b和类胡萝卜素含量水平差异极显著,芦苇和茭白叶片的叶绿素和类胡萝卜素含量水平都较高,这在客观上解释了他们为何拥有较强的光合能力。 不同湿地植物的生物量大小差异极显著,平均生物量(干重)变化范围在0.26-6.65 kg m-2之间。除香蒲和水葱的地下部生物量显著大于地上部外,其余植物都是地上部生物量大于地下部,这非常有利于人工湿地生态工程中通过收获植物地上部生物量来达到去除氮、磷污染目的。 不同湿地植物植株氮、磷含量差异极显著。湿地植物对氮吸收总量变化范围为6.09-93.96 g m-2,吸收氮最高是芦苇,最低是菖蒲;对磷吸收总量变化范围为0.51-8.95 g m-2,吸收磷最高是香蒲,最低是菖蒲。经测算,植物吸收的总氮量占人工湿地总氮去除量的0.6-17.1%,总磷量占人工湿地总磷去除量的1.4-40.5%。本次试验中香蒲和芦苇对氮、磷的吸收去除能力比较高,茭白、鸢尾、水葱和千屈菜的吸收去除能力中等,而菖蒲的吸收能力较弱。

Relevância:

100.00% 100.00%

Publicador:

Resumo:

从抚仙湖入湖河流选择了9个点的水样进行分析,同时对抚仙湖入湖河流两栖动物的种类及分布作了调查,共采集标本530号,计14种,隶属1目5科10属.结果显示,在抚仙湖入湖河流中,蟾蜍科代表以及牛蛙分布相对广泛,蛙科的种类较多,但是分布狭窄,且总体来看,污染较重的河流两栖动物很少,甚至没有,而在水质状况较好的河流及人工湿地中,两栖动物的种类及数量相对较多.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

为了比较抚仙湖不同区域的水质及其致突变性, 从抚仙湖周围水域采取7 个样点的水样。用电感 耦合氩等离子发射光谱法对水样中的无机污染物作定性和定量分析。另外使用蝌蚪( B uf o buf o andrewsi) 红细 胞微核试验检测抚仙湖水样的致突变性。结果显示: 禄冲采样点水样带有微核的红细胞率增高, 表明这个点水 样有致突变活性物质。

Relevância:

100.00% 100.00%

Publicador:

Resumo:

The Yangtze finless porpoise (Neophocaena phocaenoides asiaeorientalis) is currently limited to the middle and lower reaches of the Yangtze River from Yichang to Shanghai, China, and the adjoining Poyang and Dongting Lakes. Its population size has decreased remarkably during the last several decades due to the heavy impact of human activities, including overfishing of prey species, water development projects that cause attendant habitat loss and degradation, water pollution, and accidental deaths caused by harmful fishing gear and collisions with motorized vessels. It was estimated that the number of remaining individuals was down to approximately 1800 in 2006, a number that is decreasing at a rate as high as 5% per year. Three conservation measures - in situ and ex situ conservation and captive breeding have been applied to the protection of this unique porpoise since the early 1990s. Seven natural and two "semi-natural" reserves have so far been established. Since 1996, a small group of finless porpoises has been successfully reared in a facility at the Institute of Hydrobiology of the Chinese Academy of Sciences; three babies were born in captivity on July 5, 2005, June 2, 2007 and July 5, 2008. These are the first freshwater cetaceans ever born in captivity in the world. Several groups of these porpoises caught in the main stream of the Yangtze River, or rescued, have been introduced into the Tian'e-Zhou Semi-natural Reserve since 1990. These efforts have proven that, not only can these animals survive in the area, they are also to reproduce naturally and successfully. More than 30 calves had been born in the reserve since then, with one to three born each year. Taking deaths and transfers into account, there were approximately 30 individuals living in the reserve as of the end of 2007. Among eight mature females captured in April 2008, five were confirmed pregnant. This effort represents the first successful attempt at off-site protection of a cetacean species in the world, and establishes a solid base for conservation of the Yangtze finless porpoise. A lesson must be drawn from the tragedy of Chinese River Dolphin (Lipotes vexillifer), which has already been declared likely extinct. Strong, effective and appropriate protective measures must be carried out quickly to prevent the Yangtze finless porpoise from becoming a second Chinese River Dolphin, and save the biodiversity of the Yangtze River as a whole.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

Both arsenic pollution and eutrophication are prominent environmental issues when considering the problem of global water pollution. It is important to reveal the effects of arsenic species on cyanobacterial growth and toxin yields to assess ecological risk of arsenic pollution or at least understand naturally occurring blooms. The sensitivity of cyanobacteria to arsenate has often been linked to the structural similarities of arsenate and phosphate. Thus, we approached the effect of arsenate with concentrations from 10(-8) to 10(-4) M on Microcystis strain PCC7806 under various phosphate regimes. The present study showed that Microcystis strain PCC7806 was arsenate tolerant up to 10(-4) M. And such tolerance was without reference to both content of intra- and extra-cellular phosphate. It seems that arsenate involved the regulation of microcystin synthesis and cellular polyphosphate contributed to microcystin production of Microcystis responding to arsenate, since there was a positive linear correlation of the cellular microcystin quota with the exposure concentration of arsenate when the cells were not preconditioned to phosphate starvation. It is presumed that arsenate could help to actively export microcystins from living Microcystis cells when preconditioned to phosphate starvation and incubated with the medium containing 1 mu M phosphate. This study firstly provided evidence that microcystin content and/or release of Microcystis might be impacted by arsenate if it exists in harmful algal blooms. (C) 2008 Wiley Periodicals, Inc. Environ Toxicol 24:97 94, 2009.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

Both organic pollution and eutrophication are prominent environmental issues concerning water pollution in the world. It is important to reveal the effects of organic pollutants on algal growth and toxin production for assessing ecological risk of organic pollution. Since nonylphenol (NP) is a kind of persistent organic pollutant with endocrine disruptive effect which exists ubiquitously in environments, NP was selected as test compound in our study to study the relationship between NP stress and Microcystis growth and microcystin production. Our study showed that responses of toxic and nontoxic Microcystis aeruginosa to NP stress were obviously different. The growth inhibition test with NP on M. aeruginosa yielded effect concentrations EbC50 values within this range of 0.67-2.96 mg/L. The nontoxic M. aeruginosa strains were more resistant to NP than toxic strains at concentration above 1 mg/L. Cell growth was enhanced by 0.02-0.2 mg/L NP for both toxic and nontoxic strains, suggesting a hormesis effect of NP on M. aeruginosa. Both toxic and nontoxic strains tended to be smaller with increasing NP. But with the increased duration of the experiment, both the cell size and the growth rate began to resume, suggesting a quick adaptation of M. aeruginosa to adverse stress. NP of 0.05-0.5 mg/L significantly promoted microcystin production of toxic strain PCC7820, suggesting that NP might affect microcystin production of some toxic M. aeruginosa in the field. Our study showed that microcystin excretion was species specific that up to 75% of microcystins in PCC7820 were released into solution, whereas > 99% of microcystins in 562 remained in algal cells after 12 days' incubation. NP also significantly influenced microcystin release into cultural media. The fact that NP enhanced growth and toxin production of M. aeruginosa at low concentrations of 0.02-0.5 mg/L that might be possibly found in natural freshwaters implies that low concentration of NP may favor survival of M. aeruginosa in the field and may play a subtle role in affecting cyanobacterial blooms and microcystin production in natural waters. (c) 2006 Elsevier Inc. All rights reserved.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

气候变化对黄土高原的水资源有重要影响,对其影响进行评估可以为区域发展提供重要的决策依据。基于分布式水文模型SWAT和4种全球环流模式的各3种排放情景,评估了2010~2039年黄土高塬沟壑区黑河流域水资源对气候变化的潜在响应。结果表明,黑河流域2010~2039年的年均降水变化-2.3%~7.8%,年均最高和最低温度分别升高0.7~2.2℃和1.2~2.8℃,年均径流量变化-19.8%~37.0%,1.2m剖面年均土壤水分含量变化-5.5%~17.2%,年均蒸散量普遍增长0.1%~5.9%;水文气象变量变化趋势复杂,但T检验表明年降水、径流、土壤水分和蒸散增长的概率较大。对于季节变化,降水可能在12~7月份和9月份增长,8月份和10~11月份减少;径流在4~7月份和9~10月份增加,11~3月份和8月份减少;土壤水分在各月都增长;蒸散11~6月份普遍增长,7~10月份减少的可能性较大。未来气候将发生显著变化并对水资源有重要影响,需采取必要的措施来减缓其不利影响。

Relevância:

100.00% 100.00%

Publicador:

Resumo:

造纸行业是造成我国水环境有机污染物的重要污染源之一,其水污染的特点是小厂多、草浆多、工艺落后、污染扩散面广、造成废 水排放量大,每年排放的废水量约39亿立方米,占全国工业废水排放量的1/6,其中有机污染物(以BOD5计)160万吨左右,约占全 国工业废水中有机污染物总量的1/4。尤以占全国制浆造纸行业90%以上的碱法草浆造纸厂的蒸煮黑液量大面广,除含有机物外,还 含有木质素、残碱、硫化物、氯化物等污染物,属于PH值高、色度深、难于治理的高浓度有机废水,对水体污染特别严重,各地要 求治理呼声很高,急待研究并尽快找出各种有效的治理途径。对于碱法草浆蒸煮,黑液高浓度废水的治理,有各种方法,根据国内 的研究进展和我们已有试验工作表明,最经济有效,具有实用价值,在生产上可获得成功是厌氧处理法。近10多年来,国外关于高 效厌氧处理技术研究进展迅速,并出现了多种多样的工艺设备,如高效厌氧生物反应器,并在实用化方面取得了很大成绩,建立了 生产性装置,达到了高负荷运行,效果良好。本试验是根据我们已有研究基础,针对我国国情,对小型制浆造纸厂水污染防治除了 开发碱回收及各种综合利用技术外,要特别加强废水(废液)实用技术研究的指导思想,本试验采用改进型的上流式厌氧污泥床反应 器,设计了两种试验方案,通过试验结果如下。1. 试验方案I—碱法草浆黑液酸化和厌氧发酵I号UASB反应器动态模型试验结果表 明:(1). 采用中温35℃±1℃高效厌氧反应器USAB内装有填料(陶粒)和三相分离器,具有保持高浓度生物量和防止污泥流失的特点 ,污泥浓度Vs 可达30%以上,因而具有高效、节能、产能、滞留期短的优点,当进水CODcr在7500-10000mg/l,HRT由7天缩短到3天 ,有机容积负荷在1.22gCODcr/l·d-3.43gCODcr/l·d时,CODcr平均去除率可达55%-45.5%,最高CODcr去除率可达60.2-63.5%, BOD5去除率可达75.9-83.2%,沼气容积产气率可达0.29-0.67l/l·d,每克CODcr转化为沼气产率达0.39-0.48l/gCODcr·d,CH4含量 65.8-75.5%。厌氧发酵出水再用化学法进行后处理脱除难降解的木质素,CODcr总去除率达80%以上。(2). 动态试验结果表明:采 用酸化—厌氧发酵处理黑液工艺合理,技术路线可行。2. 试验方案II—黑液用化学法(Hcl)去除木质素进行厌氧发酵,II号UASB反 应器动态模型试验结果表明:(1). 采用中温35℃±1℃高效厌氧反应器UASB(内有软填料),当进水CODcr7000-13000mg/l左右,HRT 由6天缩短到1天,有机负荷由0.98gCODcr/l·d增加到11gCODcr/l·d时,COD平均去除率均可稳定在70-77%,BOD5去除率为87.3- 93.1%,沼气容积产气率0.21-2.6l/l·d,每克CODcr转化为沼气产率为0.39-0.48l/gCODcr·d,高的可达0.53l/gCODcr·d,转化 率较高,CH4含量63-70%。(2). 试验证明碱法草浆黑液物化预处理—厌氧发酵处理的技术路线也是可行的,工艺合理、效果较好。 在有条件的工厂可采用。3.厌氧发酵阶段几大类群微生物计数表明:(1). 当发酵工艺和运行处于相对稳定状态时,微生物群体的 组成也达到相对的稳定,各类微生物之间保持动态平衡关系。当产乙酸菌的数量为107-108个/ml时,产甲烷菌的数量为105-106 个/ml,当产乙酸菌数量为106-107个/ml时,产甲烷菌的数量为103-105个/ml。(2).稳态运行条件下,黑液预处理为甲烷发酵创造 了有利的生态环境,获得了较好的处理效果和较高的COD转化为沼气的产率0.39-0.48l/g·CODcr·d,反应器中形成较为稳定而数 量较下水污泥中高1-2个数量级的厌氧发酵微生物区系组成。这一结果为黑液厌氧发酵提供了微生物理论依据。Paper industry is one of the important pollution source of water environment in our country. Its character of water pollution is many small factories, much grass pulp, disadvantageous technique, large preading area of pullution. Its effluent makes up 1/6 of whole country's industry wastwater. Its organic pollutant accounts 1/4 of whole country's. Alkaline grass paper pulp effluent with pollutants such as ligoin, remaining alkali sulfide, chloride besides organic material, is a kind of high concentrate organic wastewater which has high PH walug, dark colour and is difficult in treatment. There is urgent require to find ways to treat the wastewater. There are different ways to treat alkaline paper grass pulp effluent. According to the research advances and our experiment work, the most economical and useful way is anaerobic degradation which was advanced quick in last ten years. In the control of waste water of small pulp paper mill, the study of wastewater utilization technology should be emphasized, besides alkaline retrieving and different kinds of comprehensive utilization technology. Our experiment used modified UASB(Upflow Anaerobic Sludge Blanket Reactor). Two kinds of plan were disgned. The results are lined below. 1. The first experiment plant-aciding black pulp effluent and methanogenic digestion. The dynamic model experiment results of I-UASB reactor showed: (1)The mesophilic(35℃±1℃)high effect UASB reactor having haydite and threee state seperation in it had the character of keeping high bioimass concentration and preventing losss of sludge. It had advantages of high effect, energe saving, energe prodcing and short HRT(Hydroulic retention time). When the influent COD was 7500-10000mg, HRT was shortened from 7 days to 3days, organic loading rate was 1.22g-3.43COD/l· d, the average COD removal efficiency was 55%-45%. The highest COD efficiency was 60.2-63.5%, BOD removal of 75.9 -83.4% was achieved. Biogass production rate were up to 0.29-0.67l/l·d. Biogass converted efficiency from every gram of COD could reach 0.39-0.48l/gCOD·d. Methane content was 65.0-75.5%. Chemical method was used to deplate lignin in anaerobic digestion effluent. Total COD removal efficiency could be more than 80%. (2)Using aciding annaerobic digestion to treat the black effluent was reseanable in technique and technology. 2. The second experiment plan-anaerobic digestion was used after the chemical method was used to deplate lignin in the black effluent. The result of dynamic experiment of II-UASB reactor showed: (1)High effect mesophilic (35℃±1℃)UASB reactor having soft slaffing in was used. When influent COD was about 7000-13000mg/l, HRT was shortened from 6 days to 1 day and organic loading rate was increased from 0.90 to 11g COD /l·d, average COD removal efficiency remained stable on 70-77%. BOD, removal efficiency was between 87.3-93.1%. Biogass production rate was 0.2-2.6l/l ·d .Biogass converted efficiency from a gram of COD was 0.39-0.481/gCOD·d with the high value of 0.53l/gCOD·d. Methane content was 63-70%. (2)The way that using physical, chemical Pre-treatment-anaerobic digestion to treat alkaline black effluent is feasible and can be used in some factories when the condition exists. 3. Counting of several class of microoganisms in anaerobic digestion stage showed: (1)As the disgestion was in stable motion, the compositon of microorganic colony could get relative stable. Dynamic balance was remaining among different kinds of microorganism such as methanogenic bacteria, Acidogenic bacteria, sulfate reducing bacteria, and heterotrophic bacteria. (2)Under stable motion, the pre-treatment of black effluent produced favourable eco-enviroment for methanegenic digestion. Good treatment effect and high biogass convertent efficiency from COD(0.39-0.48l/g·COD· d)were gotten. Some stable and high quantity(10-100times more than sewage sludge)microorganism colony were formed in the reactor. This result provided theoretical basis for anaerobic digestion of black effluent.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

畜禽废水是农村水环境污染的主要来源之一,其处理的难点在于脱氮。传统生物脱氮法具有能耗高、需大量外加碳源等缺点,开发低成本、高效率的新型生物脱氮技术具有重要意义。 本研究将短程硝化反硝化和厌氧氨氧化两种脱氮新技术结合,让前者为后者创造去除可降解COD、降低总氮负荷、调整pH、调整氨氮和亚硝酸盐氮浓度比例等进水条件,而后者可在无需外加碳源的条件下进一步脱氮,二者结合可成为高氨氮、低C/N废水脱氮的新途径。 试验以低碳氮比猪场废水为研究对象,首先进行了短程硝化反硝化预处理研究,同时启动并运行调控厌氧氨氧化反应器,最后以经过短程硝化反硝化预处理的猪场废水为进水,进行厌氧氨氧化脱氮考察。实验表明:(1)短程硝化反硝化作为厌氧氨氧化的预处理工序是可行的。猪场废水通过短程硝化反硝化,可以达到基本去除可生化COD、部分脱氮、控制出水氨氮和亚硝酸盐氮浓度之比在1︰1左右、pH在7.5~8.0的目的, COD和总氮平均去除率分别为64.3%、49.1%,出水可达到厌氧氨氧化反应的进水要求。(2)采用模拟废水启动厌氧氨氧化反应器,经过5个月左右的运行调控,反应器启动成功并稳定运行,最高总氮去除率为87.1%,总氮容积去除率最高达到0.14kg/m3.d;整个稳定阶段,氨氮、亚硝酸盐氮、硝酸盐氮的变化量之比为1︰1.21︰0.33。(3)经过短程硝化反硝化预处理的猪场废水厌氧氨氧化脱氮效果稳定,氨氮、亚硝酸盐氮、总氮、COD的平均去除率分别为93.0%、99.4%、84.6%、18.1%,处理效果与模拟废水处理系统相比无明显变化。(4)经过短程硝化反硝化预处理后,猪场废水中残留有机物成分在厌氧氨氧化反应过程中无显著变化,主要为酯类和烷烃类物质;残留有机物对厌氧氨氧化效果无明显影响。(5)采用PCR技术进行特殊功能菌种检测,结果表明模拟废水处理系统和猪场废水处理系统的菌群中均含有厌氧氨氧化菌和好氧硝化菌;通过blast比对,厌氧氨氧化菌扩增序列与未培养的Planctomycetales菌和Candidatus Brocadia fulgida菌16S rRNA部分序列相似性分别为95%、90%。(6)MPN法菌种计数结果显示,模拟废水处理系统和猪场废水处理系统的菌群中均含有硝化细菌、亚硝化细菌和少量反硝化菌,实验条件下的微生物系统是一个厌氧氨氧化菌与好氧硝化菌、反硝化菌共存的系统。 Poultry wastewater is one of the main source of water pollution in rural areas,and nitrogen removal is the most difficult part in treating poultry wastewater. There are some disadvantages in traditional nitrogen removal, such as high energy consumption and more additional organic carbon. It is important to develop ecolomical and efficient technologyies. Shortcut nitricfication/denitrification, as a pretreatment process, was combined with Anammox in this research, so that part of total nitrogen and most degradable COD could be removed by the former, and further nitrogen removal could be implemented by the latter. The combination of the two technologies was a new approach to treat wastewater with high ammonium and low C/N. Piggery wastewater with low C/N was treated in lab-scale experiment. Firstly, shortcut nitrification/denitrification was investigated, and Anammox reactor was started up successfully at the same time. Then piggery wastewater after pretreatment was treated by Anammox. The results showed :(1) It was feasible to take nitrification/denitrification as the pretreatment process of Anammox. By using this process, part of total nitrogen and COD were removed, the ratio of ammonium and nitrite reached around 1︰1 and the pH was about 7.8, which were favorable for Anammox. The average removal percentage of COD and total nitrogen were about 64.3% and 49.1%, respectively. (2) Simulated wastewater was used to start up Anammox reactor. The reactor was started up successfully within 5 months and stable performance was achieved. The highest nitrogen removal reached 87.1% and the biggest volumetric total nitrogen removal rate reached 0.14kg/m3.d. The average ratio of ammonium, nitrite and nitrate was 1:1.21:0.33. (3)Taking the effluent of shortcut nitrification/denitrification as the influent, the nitrogen removal efficiency of Anammox was stable, and the the average removal percentage of ammonium, nitrite, total nitrogen and COD were 93.0%, 99.4% , 84.6% and 18.1%, respectively, which had little difference with that by using simulated wastewater..(4) After pretreatment, the residual organic carbon in piggery wastewater showed no obvious change during the Anammox process, and the main organic compounds were saturated hydrocarbon and ester, which had no obvious negative effect on Anammox process.(5) By PCR technology, the existence of Anammox bacteria was confirmed and the aerobic nitrifying bacteria was found to coexist as well. The result of blast showed that the identities of Anammox bacterium to part of 16S rRNA sequence of uncultured Planctomycetales bacterium and Candidatus Brocadia fulgida bacterium were 95% and 90%, respectively.(6)By MPN method, nitrite oxidizer, ammonium oxidizer and denitrification bacteria were detected in both simulated and piggery wastewater treatment system of Anammox, and the microorganism system was composed of Anammox bacteria,aerobic bacteria and denitrification bacteria together.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

针对密云水库上游承德"21世纪水资源可持续利用项目"中水土流失治理后来水减少,加剧下游城市(北京)水资源供需矛盾的问题,探讨集水区减少水土保持用水,增加流域产水量,从而水资源在下游(首都圈)发挥最大效益的思路。在将流域分成3种类型区的基础上,提出了流域分区治理方案及其标准:1)生态产水功能区,以增加产水供给下游为主要目的,提出以需水量最低的低覆盖度草地配置为主的水土流失坡面治理模式和减少蓄水、增大拦沙的弱化与强化相结合的沟道治理模式;2)生产生活功能区,以满足流域基本粮食生产为主要目的,提出以黄土丘陵区坝地为主的水土流失治理模式及其标准;3)生态产水与生产生活复合功能区,兼顾二者功能,提出以需水量中等的灌木林和疏林配置为主的水土流失治理模式及标准。

Relevância:

100.00% 100.00%

Publicador:

Resumo:

分析国内外水资源的现状、中国水资源危机及走向 2 1世纪存在的主要水问题 .说明中国属于世界上贫水的国家之一 ,人均拥有量只占世界平均水平的 2 5% ,在 6 6 8座城市中有 4 0 0余座缺水 .进入 2 1世纪 ,中国的水资源矛盾将进一步加剧 ,洪灾、干旱、断流、水污染、水土流失等问题将继续存在 .中国必须进行大规模国土整治 ,逆转恶化的水生态环境 ,合理开发、利用、保护水资源 .

Relevância:

100.00% 100.00%

Publicador:

Resumo:

通过回顾已有的成果 ,分析评价了我国土壤可蚀性研究的进展及存在的问题 ,提出我国土壤可蚀性研究中的标准小区定义。运用野外观测资料 ,研究计算了黄土高原地区土壤可蚀性指标值。结果表明 ,陕北和晋西北一带黄土可蚀性 K值变化于 0 .3~ 0 .7之间 ,并且有以陕西子洲、绥德一带为最大 ,以此为中心 ,向南、向北和向东都减少的变化趋势。

Relevância:

60.00% 60.00%

Publicador:

Resumo:

Lake of the Woods (LOW) is an international waterbody spanning the Canadian provinces of Ontario and Manitoba, and the U.S. state of Minnesota. In recent years, there has been a perception that water quality has deteriorated in northern regions of the lake, with all increase in the frequency and intensity of toxin-producing cyanobacterial blooms. However, given the lack of long-term data these trends are difficult to verify. As a first step, we examine spatial and seasonal patterns in water quality in this highly complex lake on the Canadian Shield. Further, we examine surface sediment diatom assemblages across multiple sites to determine if they track within-take differences in environmental conditions. Our results show that there are significant spatial patterns in water quality in LOW. Principal Component Analysis divides the lake into three geographic zones based primarily on algal nutrients (i.e., total phosphorus, TP), with the highest concentrations at sites proximal to Rainy River. This variation is closely tracked by sedimentary diatom assemblages, with [TP] explaining 43% of the variation in diatom assemblages across sites. The close correlation between water quality and the surface sediment diatom record indicate that paleoecological models could be used to provide data on the relative importance of natural and anthropogenic sources of nutrients to the lake.

Relevância:

50.00% 50.00%

Publicador:

Resumo:

There is increasing recognition that protozoa is very useful in monitoring and evaluating water ecological healthy and quality. In order to study the relationship between structure and function of protozoan communities and water qualities, six sampling stations were set on Lake Donghu, a hypereutrophic subtropical Chinese lake. Microbial communities and protists sampling from the six stations was conducted by PFU (Polyurethane foam unit) method. Species number (S), diversity index (DI), percentage of phytomastigophra, community pollution value (CPV), community similarity and heterophy index (HI) were mensurated. The measured indicators of water quality included total phosphorus (TP), dissolved oxygen (DO), Chemical oxygen demand (COD), NH4 (+), NO2 (-) and NO3-. Every month water samples from stations I, II, III, IV were chemically analyzed for a whole year, Among the chemically analyzed stations, station I was the most heavily polluted, station II was the next, stations III and IV had similar pollution degrees. The variable tendencies of COD, TP, NH3, NO2-, NO3-, and DO during the year was approximately coincident among the six stations. Analysis from the community parameters showed that the pollution of station 0 was much more serious than others, and station V was the most slight. Of the community parameters, CPV and HI were sensitive in reflecting the variables of the water quality. Community similarity index was also sensitive in dividing water qualities and the water quality status of different stations could be correctly classified by the cluster analysis. DI could reflect the tendency of water quality gradient, species number and percentage of Phytomastigophora was not obvious in indicating the water quality gradient.

Relevância:

50.00% 50.00%

Publicador:

Resumo:

Urbanization can exert a profound influence on land covers and landscape characteristics. In this study, we characterize the impact of urbanization on land cover and lacustrine landscape and their consequences in a large urban lake watershed, Donghu Lake watershed (the largest urban lake in China), Central China, by using Landsat TM satellite images of three periods of 1987, 1993 and 1999 and ground-based information. We grouped the land covers into six categories: water body, vegetable land, forested land, shrub-grass land, open area and urban land, and calculated patch-related landscape indices to analyze the effects of urbanization on landscape features. We overlaid the land cover maps of the three periods to track the land cover change processes. The results indicated that urban land continuously expanded from 9.1% of the total watershed area in 1987, to 19.4% in 1993, and to 29.6% in 1999. The vegetable land increased from 7.0% in 1987, 11.9% in 1993, to 13.9% in 1999 to sustain the demands of vegetable for increased urban population. Concurrently, continuous reduction of other land cover types occurred between 1987 and 1999: water body decreased from 30.4% to 23.8%, and forested land from 33.6% to 24.3%. We found that the expansion of urban land has at least in part caused a decrease in relatively wild habitats, such as urban forest and lake water area. These alterations had resulted in significant negative environmental consequences, including decline of lakes, deterioration of water and air quality, and loss of biodiversity.