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371.
The toxicity of naphthalene to a freshwater microalga, Chlorella pyrenoidosa, and the subsequent recovery of algae from the damage
were investigated under two nutrient conditions, either enriched with nitrogen (N) and phosphorus (P), or starved of N and P. Results
showed that C. pyrenoidosa was more sensitive to naphthalene under N,P-enriched condition, and the inhibitory rate generally increased
at first and then decreased gradually with the evaporation of naphthalene under both nutrient conditions. Enriched N, P reduced the
inhibitory rate at initial naphthalene concentration of 5 and 10 mg/L, but enhanced it at 100 mg/L, at which more severe ultrastructure
damages were found than those under N,P-starved condition. Observed damages included partly or totally disappearance of nucleolus,
nuclear, and plasma membranes. According to the chlorophyll content and cell density measurements, C. pyrenoidosa could recover
from naphthalene damage with initial concentrations 6 50 mg/L in 7 days under both nutrient conditions, while they could not recover
if the initial concentration of naphthalene was at 100 mg/L. Under the N,P-starved condition, the inability of C. pyrenoidosa to recover
from the naphthalene damage was consistent with the results of high inhibitory rate, low value of specific growth rate (SGR, 0.05
day??1), and the severe destruction of cell structure. However, under the N,P-enriched conditions, the observed lower inhibitory rate,
higher value of SGR (0.55 day??1), and the intact cell structure of most cells suggested that algae could potentially recover from the
naphthalene damage. 相似文献
372.
研究了分别以葡萄糖和乙酸钠为碳源时多点交替进水阶式A2/O(CMICAO)工艺氮磷的去除效果,以及在不同进水C/N比时各进水量分配对脱氮除磷效果的影响。结果表明,在相同的进水COD浓度下,乙酸钠比葡萄糖更适合作为碳源,更能提高脱氮除磷效率。以葡萄糖为碳源时,COD为200mg/L、C/N比为5、缺氧池与厌氧池进水配比为1:2时,出水COD、TN、氨氮和TP浓度分别为28.5、10.8、2.1和0.5mg/L,均达到国家一级A排放标准。若采用葡萄糖作为碳源,投加量以使进水C/N比为5~7.5为宜,外加碳源时缺氧池与厌氧池进水分配比可统一采用1:1。 相似文献
373.
北京地区蜉蝣目(Ephemeroptera)稚虫的分布及与水质关系的研究 总被引:3,自引:0,他引:3
报道了北京地区几条主要河流蜉蝣稚虫的种类分布,探讨了其群落结构特征及其与水体环境质量之间的关系。运用种类多样性指数和聚类分析方法对各水体质量状况进行分类评价,结果表明白河和拒马河质量为最好,其余依次为永定河,清水河上游,潮河和清水河。 相似文献
374.
The measurements of atmospheric carbonyls concentrations in Beijing were conducted from 12 July to 8 October, 2008, covering the periods of the 2008 Olympic Games and Paralympic Games. Six carbonyls, including formaldehyde, acetaldehyde, acetone, butyraldehyde, valeraldehyde, and hexaldehyde, were identified in all air samples. The total average concentrations of these carbonyls before, during, and after traffic restriction were (48.1 ± 15.2), (36.6 ± 14.5) and (23.4 ± 12.3) μg/m3, respectively. Compared with the period after traffic restriction, the distinct high concentrations of the carbonyls before and during traffic restriction were primarily ascribed to the remarkable contribution of photochemical reactions. With respect to our previous investigation in the summer of 2005, the reductions of formaldehyde, acetaldehyde and acetone during traffic restriction period were about 64%, 47% and 27%, respectively, indicating that the air cleaning actions adopted by the Chinese government for the two games were efficient. The lowest levels of atmospheric carbonyls and the extremely high composition proportion of acetone after the traffic restriction were mainly attributed to the long-term effect of the control measures for the two games. 相似文献
375.
376.
农村环境连片整治工作自2010年开展以来,连云港市取得了显著的成效,但对农村环境连片整治工作的监控工作仍停留在《全国农村环境监测工作指导意见》(环办[2009]150号)和《江苏省农村地表水环境质量监测实施方案》(苏环然[2007]25号)的要求上,即对连片整治示范区内的农村地表水环境、乡镇和村庄生活污水处理设施进行例行监测,对连片整治示范工程进行验收监测和例行监测工作的层面上。为了加强农村环境连片整治工作的监控,保护农村生态环境,从农村环境连片整治系统架构入手,深入细致地研究了基于WEBGIS的数字监控系统,提出系统所要达到的功能要求。 相似文献
377.
为探究镉(Cd)对海洋动物的毒性效应,考察了不同质量浓度(0.005、0.05和0.5 mg·L~(-1)) Cd处理对单环刺螠相关免疫生理指标及主要组织中Cd蓄积量的影响。结果表明:Cd胁迫下,血细胞密度(density of hemocyte, DHC)先升后降再升,酚氧化酶(phenoloxidase, PO)活力先升后降,溶菌酶(lysozyme, LSZ)活力先降后升再降,至处理96 h,处理组DHC均显著高于对照组(P0.05),总蛋白含量变化不显著;除低浓度胁迫组(0.005 mg·L~(-1))PO活力与对照组相近外,其他处理组的PO和LSZ活力均显著低于对照组(P0.05)。超氧化物歧化酶(superoxide dismutase, SOD)活力和丙二醛(malondialdehyde, MDA)含量总体呈上升趋势,过氧化氢(H_2O_2)含量先升后降再升,至胁迫96 h,各处理组SOD活力、MDA和H_2O_2含量均显著高于对照组(P0.05)。总之,Cd胁迫对单环刺螠非特异性免疫影响显著,Cd的短期胁迫可刺激DHC、PO和LSZ升高,免疫力增强,而高浓度Cd的胁迫时间较长会造成机体解毒能力下降,持续刺激机体产生过氧化反应,MDA含量升高,可作为单环刺螠在Cd长期胁迫下的免疫检测指标。不同胁迫浓度组单环刺螠肌肉和消化道中的Cd含量随胁迫时间均呈上升趋势,且存在显著的时间-剂量-效应关系(P0.05),其蓄积量水平为:消化道肌肉,具有组织特异性。 相似文献
378.
The relationship between oxygen consumption rate and temperature during coal spontaneous combustion 总被引:1,自引:0,他引:1
Spontaneous combustion is a major natural disaster in coal production. In the process of exploring coal self-ignition, a series of hypotheses have been put forward, most scholars agree that the current coal-oxygen compound theory. Oxygen consumption rate reflects the status of coal spontaneous combustion, and it is also one of the parameters necessary for numerical simulation of coal spontaneous combustion. In this paper, a coal heating and oxidation experiment was designed, Experimental device consists of heating and oxidation furnace, gas chromatograph, temperature control and data acquisition systems and other equipment components. Three coal samples whose weight each is 5 g were selected for the study. By experiment, oxygen concentration at the inlet and outlet of temperature oxidation furnace was measured. Oxygen consumption rate is calculated in the heating process of coal according to air flow. In the Cartesian coordinate system, the temperature as abscissa and the oxygen consumption rate for the longitudinal coordinates, drawing the relationship between oxygen consumption rate and temperature plot. And then regression analysis was used to analyze the relationship between oxygen consumption rate and coal temperature during the heating and oxidation process of coal. The results show that the oxygen consumption rate and temperature of coal were linear relationships both before and after the critical temperature when the coal temperature is less than 180 °C. Before the critical temperature oxygen consumption rate is low, however it increases rapidly when coal temperature reaches a critical temperature. The result is important for the prevention and treatment of spontaneous combustion of coal. 相似文献
379.
Hua Zhang Zhiliang Zhu Noboru Yoshikawa 《Frontiers of Environmental Science & Engineering in China》2011,5(2):205-211
Microwave processing was used to stabilize copper ions in soil samples. Its effects on the stabilization efficiency were studied
as a function of additive, microwave power, process time, and reaction atmosphere. The stabilization efficiency of the microwave
process was evaluated based on the results of the toxicity characteristic leaching procedure (TCLP) test. The results showed
that the optimal experimental condition contained a 700W microwave power, 20 min process time and 3 iron wires as the additive,
and that the highest stabilization efficiency level was more than 70%. In addition, the different reaction atmospheres showed
no apparent effect on the stabilization efficiency of copper in the artificially contaminated soil. According to the result
of the Tessier sequential extraction, the partial species of copper in the contaminated soil was deduced to transform from
unstable species to stable states after the microwave process. 相似文献
380.