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761.
762.
实验以吉林石化污水处理厂初沉池出水为原水在SBR中培养好氧颗粒污泥。实验初期,依次以比例为40%、60%的含石化废水的培养液进行培养,于第15天SBR中出现颗粒污泥,此后直接采用石化废水培养,同时逐步缩短沉降时间,第27天起反应器出水稳定,COD去除率达到89%,TN、NH3-N和TP去除率分别达到56%、86%和90%。采用此方法培养的颗粒污泥平均粒径约为1.3 mm,外表棕黄色,颗粒表面粗糙,在扫描电子显微镜(SEM)下观察到好氧颗粒污泥主要由杆状菌和丝状菌组成,颗粒内部存在若干孔隙。研究结果表明,在SBR中通过逐步增加石化废水进水比例,缩短沉降时间可以快速培养出好氧颗粒污泥,好氧颗粒污泥处理石化废水效果良好。 相似文献
763.
Freshwater scarcity is a global issue of environmental concern that threatens agricultural production and human health.In this study,we established freshwater stress indices(WSIs) for the nine water basins of Tanzania by using the quantity of freshwater available and various water uses.The relationship between water availability and different water uses,including environmental water requirements,was analyzed,with uncertainty and sensitivity analysis performed by a Monte Carlo simulation technique.Extreme WSI values close to 1.00 were obtained in the Rufiji,Pangani,and Wami-ruvu basins,Internal drainage,and Lake Rukwa,while low and moderate WSI values ranging from 0.03 to 0.84 were found in Lake Victoria and the Ruvuma,Tanganyika,and Nyasa basins.This study adds further knowledge on the level of freshwater scarcity,relationships between water availability and different water uses,and suggests policy options to reduce freshwater scarcity at the basin level for sustainable water supply. 相似文献
764.
Gongliang Yu Yongguang Jiang Gaofei Song Wenhua Tan Mengling Zhu Renhui Li 《Environmental science and pollution research international》2014,21(16):9887-9898
Lake Erhai is the second largest lake of Southwest China and an important drinking water source. The lake is currently defined as the preliminary stage of eutrophic states, but facing a serious threat with transfer into intensive eutrophication. The present study examined the dynamics of Microcystis blooms and toxic Microcystis in Lake Erhai during 2010, based on quantitative real-time PCR method using 16S rRNA gene specific for Microcystis and microcystin systhesis gene (mcy), and chemical analysis on microcystin (MC) concentrations. Total Microcystis cell abundance at 16 sampling sites were shown as an average of 1.7?×?107 cells l?1 (1.3?×?102–3.8?×?109 cells l?1). Microcystin LR (MC-LR) and microcystin RR (MC-RR) were the main variants. The strong southwesterly winds, anticlockwise circular flows and geographical characteristics of lake and phytoplankton community succession impacted the distribution patterns of Chl a and MC in the lake. The concentration of Chl a and MC and abundances of total Microsytis and MC-producing Microsystis (MCM) were shown to be positively correlated with pH, DO and TP, negatively correlated with SD, NO3-N, TN/Chl a and TN/TP, and not correlated with NH4-N, TN, dissolved total nitrogen (DTN) and water temperatures. When TN/TP decrease, Microcystis tended to dominate and MC concentrations tended to increase, suggesting that the “TN/TP rule” can be partially applied to explain the correlation between the cyanobacterial blooms and nutrients N and P only within a certain nutrient level. It is speculated that N and P nutrients and the associated genes (e.g., mcy) may jointly drive MC concentration and toxigenicity of Microcystis in Lake Erhai. 相似文献
765.
Fragrance materials are widely present in the environment, such as air, water, and soil. Concerns have been raised due to the increasing utilization and suspected impact on human health. The bioaccumulating property is considered as one of the causes of the toxicity to human beings. The removal of fragrance materials from environmental sinks has not been paid enough attention due to the lack of regulation and research on their toxicity. This paper provides systematic information on how fragrance materials are transferred to the environment, how do they affect human lives, and what is their fate in water, wastewater, wastewater sludge, and soil. 相似文献
766.
767.
Donghwan Shim Sangwoo Kim Young-Im Choi Won-Yong Song Jiyoung Park Eun Soo Youk Soon-Chun Jeong Enrico Martinoia Eun-Woon Noh Youngsook Lee 《Chemosphere》2013,90(4):1478-1486
Genetic engineering of plants for phytoremediation is thought to be possible based on results using model plants expressing genes involved in heavy metal resistance, which improve the plant’s tolerance of heavy metals and accumulation capacity. The next step of progress in this technology requires the genetic engineering of plants that produce large amounts of biomass and the testing of these transgenic plants in contaminated soils. Thus, we transformed a sterile line of poplar Populus alba X P. tremula var. glandulosa with a heavy metal resistance gene, ScYCF1 (yeast cadmium factor 1), which encodes a transporter that sequesters toxic metal(loid)s into the vacuoles of budding yeast, and tested these transgenic plants in soil taken from a closed mine site contaminated with multiple toxic metal(loid)s under greenhouse and field conditions. The YCF1-expressing transgenic poplar plants exhibited enhanced growth, reduced toxicity symptoms, and increased Cd content in the aerial tissue compared to the non-transgenic plants. Furthermore, the plants accumulated increased amounts of Cd, Zn, and Pb in the root, because they could establish an extensive root system in mine tailing soil. These results suggest that the generation of YCF1-expressing transgenic poplar represents the first step towards producing plants for phytoremediation. The YCF1-expressing poplar may be useful for phytostabilization and phytoattenuation, especially in highly contaminated regions, where wild-type plants cannot survive. 相似文献
768.
769.
Huang DJ Zhang YM Song G Long J Liu JH Ji WH 《Environmental monitoring and assessment》2007,128(1-3):483-488
The Yellow River, the second largest river in China, is the most important resource of water supply in North China. In the
last 40 years, even in the upper Yellow River, with the development of industry and agriculture, more and more contaminants
have been discharged into this river and greatly polluted the water. Although a routine chemical component analysis has been
performed, little is known about the real toxic effects of the polluted water on organisms at environmental level. To explore
whether the pollutants induced oxidative stress and damage to aquatic organisms, malondialdehyde (MDA) level and activities
of superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx) and glutathione S-transferase (GST) in hepatopancreas,
kidney and intestine of the field-collected carp Cyprinus carpio from a mixed polluted (Lanzhou Region, LZR) and a relatively unpolluted (Liujiaxia Region, LJXR) sites of the upper Yellow
River were measured. The results showed that when the values of LZR compared with those of LJXR, SOD and GST activities increased
and GPx activity decreased significantly in all the three organs (P < 0.05–0.01); CAT activity decreased but MDA level increased significantly (P < 0.05–0.01) only in kidney and intestine. In conclusion, the results of this study suggest that the pollutants can induce
obvious oxidative damage in the carp, and the SOD, GST and GPx might be better indicators for the oxidative damage in aquatic
organisms. 相似文献
770.
The Natural Vegetation Responses to the Groundwater Change Resulting from Ecological Water Conveyances to the Lower Tarim River 总被引:4,自引:0,他引:4
This paper takes the ecological water conveyance project (EWCP) that transfers water from the Bosten Lake, to Daxihaizi Reservoir, and finally to the Taitema Lake as a case study to analyze
the dynamic change of the groundwater depth, the vegetation responses to the elevation of the groundwater depth as well as
the relationship between the groundwater depth and the natural vegetation. The results from many years’ monitoring in field
indicate: (1) the groundwater depth has been elevating gradually with the increase in the times of watering and the elevation
range has been expanding continuously in the lower reaches of Tarim River. Correspondingly, the natural vegetation has a favorable
response to the elevation of the groundwater depth. The change of the natural vegetation has accordance with that of the groundwater
depth. Such facts not only show that groundwater is a key factor to the growth of the native vegetation but also prove it
is feasible that the degraded ecosystem can be restored and protected by the EWCP; (2) the results of analysis of the spatial-temporal response of the natural vegetation to watering reveals that the beneficial
influence of the EWCP on the ecosystem in the lower Tarim River is a long-term process; (3) in terms of the function and structure of ecosystem
after watering in the lower reaches of Tarim River, the EWCP does not still reach the goal of ecological restoration at a large spatial scale at present. Based on such monitoring results,
some countermeasures and suggestions for the future restoration strategy are proposed so as to provide a theoretical basis
for restoring and protecting the ecosystem in Tarim River, and meanwhile it can also provide some scientific references for
implementing the similar ecological projects in other areas. 相似文献