排序方式: 共有38条查询结果,搜索用时 36 毫秒
1.
Physico-chemical characteristics of some river and hand-dug well waters used for drinking and domestic purposes in the oil
rich Niger Delta area of Nigeria were assessed using standard methods. The concentrations of the parameters in the river water
samples ranged in the following order: pH (5.6–6.9), temperature (26.90–28.60°C), turbidity (23–63 NTU), electrical conductivity
(52–184 μs/cm), DO (5.4–7.2 mg/l), BOD (21–57 mg/l), TDS (6.0–217 mg/l), PO4
3− (0.19–1.72 mg/l), SO4
2− (25–36.8 mg/l), NO3
− (20.3–28 mg/l), Fe (6.07–15.71 mg/l), Zn (0.04–0.24 mg/l), Pb (0.01–0.17 mg/l), Ni (0.01–0.13 mg/l), Vn (0.01–0.20 mg/l)
and Hg (0.001–0.002 mg/l). The concentrations of these parameters in the hand-dug well water ranged in the following order:
pH (5.7–6.8) temperature (26–30°C), turbidity (134–171 NTU), electrical conductivity (160–340 μs/cm), DO (5.4–6.4 mg/l), BOD
(13–34 mg/l), TDS (110–190 mg/l), PO4
3− (0.84–1.84 mg/l), SO4
2− (10.6–28.1 mg/l), NO3
− (11.3–23 mg/l), Fe (13.17–16.31 mg/l), Ni (0.01–0.02 mg/l), Vn (0.01–0.04 mg/l) and Hg (0.001–0.004 mg/l). The concentrations
of BOD, turbidity, NO3
− and Fe in the water samples were above WHO and FMENV permissible limits for safe drinking water. The results suggest that
the use of such waters for drinking and domestic purposes pose a serious threat to the health of the users and calls for the
intervention of government agencies. 相似文献
2.
A larval medaka (Oryzias latipes) assay was proposed to evaluate the fish safety level of river waters and wastewaters. Organic toxicants were 10-100 times concentrated with adsorption cartridges from 4 l of river water or 1-10 times concentrated from 400 ml of wastewater. Toxicity of these concentrated solutions was determined by exposing 48-72 h post-hatch age larvae for 48 h. The method effectively revealed a variation of the median lethal concentration ratio (LCR50) from 13 to >100 in 125 river water samples, and from <1 to >10 in five typical wastewater samples. Ayase River, which takes water mostly from agricultural or household discharge, showed significantly (P<0.001) lower LCR50 than Sagami River that takes natural water as the source. Safety Levels in both Sagami River and Ayase River were influenced by the irrigation activity, LCR50 at some sites showing a seasonal-specific decrease in winter. Pollution from pulp and paper industries contributed to the low LCR50 in several tributaries of Ayase River. Required little manpower in sampling, pretreatment and testing, the proposed larval medaka assay was proved as an efficient tool for screening those high risk sites for priority management. 相似文献
3.
Arpita Bhowmik Koji Ishimura Kohei Nakamura Kazuhiro Takamizawa 《Journal of Material Cycles and Waste Management》2012,14(3):212-219
We showed the cis-1,2-dichloroethylene (cis-1,2-DCE) dechlorination ability of Clostridium species DC-1 in association with other bacteria. Result of denaturing gradient gel electrophoresis showed the dominant band pattern of DC-1 during the degradation time of cis-1,2-DCE and dominance of some other Clostridium species. Experiment with addition of Escherichia coli (E. coli) showed that dechlorinating activity of DC-1 was not inhibited by the presence of E. coli. Pour plate experiment with DC-1 and E. coli revealed that the dominance of Clostridium species caused the decrease of E. coli growth in a bioremediation state. This result suggested the possibility of Clostridium species DC-1 as a degrader of cis-1,2-DCE, in a cis-1,2-DCE contaminated site where an indigenous microbial community is present. Experiment conducting with E. coli suggested that the strain in the contaminated site did not inhibit the degradation of cis-1,2-DCE and during the degradation period, rather some other Clostridium species became dominant and the growth of E. coli would be decreased. This finding could be a very positive approach for implementing the dechlorinating bacteria at aliphatic chlorinated component contaminated sites. 相似文献
4.
5.
6.
It is necessary to develop technical systems for controlling and monitoring dioxins in stack gas from waste incineration facilities. However, it required much labor, high technical skill and extreme cost to measure dioxins for obtaining the toxic equivalent quantity (TEQ) values. In this study, the positive correlations of the WHO-TEQ values of PCDDs/PCDFs/Co-PCBs or PCDDs/PCDFs with the conventional I-TEQ values of PCDDs/PCDFs were confirmed beforehand for a large number of incineration facilities in a wide concentration range of a hundred thousand times. The relationships between the TEQ values and the concentrations of total PCDDs/PCDFs, each toxic isomer of PCDDs/PCDFs, total Cl4-6BZs, or each homologue of Cl4-6BZs were investigated for various incineration facilities. And it was found that positive correlations of the TEQ values with the concentrations of total PCDDs/PCDFs, 2,3,4,7,8-P5CDF, or Cl5BZ for a large number of different incineration facilities and in a wide concentration range. Consequently, the concentrations of total PCDDs/PCDFs, 2,3,4,7,8-P5CDF and Cl5BZ, whose measuring methods are much easier than that of obtaining the TEQ values, could be used as convenient substitute indices to the TEQ values for controlling and monitoring dioxins in stack gas from various waste incineration facilities. 相似文献
7.
A measuring method of chlorobenzenes as a convenient substitute index of dioxins in stack gas from waste incineration facilities 总被引:3,自引:0,他引:3
Much labor, high technical skill and extreme cost are required to measure dioxins for obtaining the toxic equivalent quantity (TEQ) values. On one side, it was found that there were high amounts of chlorobenzenes (CBZs) in the flue gas from waste incineration facilities, and they are also thought to be one of the principal precursors for dioxins. The concentrations of CBZs could be used as a convenient substitute index to the TEQ values for controlling and monitoring dioxins in stack gas from waste incineration facilities as shown in another report. In this study, collection efficiencies in the sampling performed by a convenient train which was composed of two bottles containing water and diethylene glycol in a cooling box, recoveries in the evaporation of the extract by an evaporator, proper procedure of the concentration by nitrogen purge were investigated for measuring CBZs. It was found that tetra-, penta-, and hexa-chlorobenzenes (Cl4-6BZs) whose boiling points are higher than ca. 240 degrees C could be sufficiently collected and recovered in the sampling and the evaporation. For sufficient recoveries of Cl4-6BZs in the concentration by the nitrogen purge, the final volume should be larger than 200 microliters with a proper receiver of the K-D concentrator at 35 degrees C. However, Cl1-3BZs were lost in each of the procedures. 相似文献
8.
Kazuhiro Takamizawa Eri Ishikawa Kohei Nakamura Takafumi Futamura 《Journal of Material Cycles and Waste Management》2013,15(1):16-24
The utilization of bioethanol is being focused on as a fuel alternative to oil and or natural gas. Bioethanol production from cellulosic plant residues is one of the solutions proposed for the problems caused by usage of food crops that are also vital for human consumption, such as sugar cane and corn, as a source of bioethanol. However, to utilize these new sources for bioethanol production, conditions for saccharification in each different material have not been optimized. In this study, we reported some optimum conditions for the saccharification of Korean lawn grass (KL) and bent grass (BG) using acremonium cellulase and endoglucanase as saccharifying enzymes for ethanol fermentation. With respect to saccharification of KL and BG, 0.19 and 0.18 g of d-glucose per g-substrate at maximum were produced, respectively. Comminution with a ball mill was found to be effective in the saccharification of KL, while ball-milled BG showed no significant improvement in saccharification. Being incorporated with 99 % of d-glucose consumption, saccharified KL was incubated for 3 days with Saccharomyces cerevisiae and Zymomonas mobilis, respectively, and each mixture fermented to ethanol yielding approximately 100 % of theoretical values from d-glucose consumption, respectively. 相似文献
9.
Bacterial endophytes were found from 6 plant leaves among 35 plant leaves screened. Two of the isolated bacteria showed antagonistic activity against fungal plant pathogens. An isolate named KL1 showed the clear inihibition against plant pathogens, Fusarium oxysporum and Rhizoctonia solani, on PDA as well as TSA plate. Supernatant of the bacterial culture also showed the clear inhibition against the fungal growth on the plate and the antibiotic substance was identified as iturin A by HPLC analysis. KL1 was identified as Bacillus sp. from the 16S rRNA gene analysis. Very thin hyphae of R. solani was miccroscopically observed when the fungus was co-cultivated with KL1. 相似文献
10.
Sex mosaics in a male dimorphic ant Cardiocondyla kagutsuchi 总被引:1,自引:1,他引:0
Gynandromorphy, or the development of organisms with a combination of male and female morphological features, is common in
Hymenoptera. The underlying mechanism is likely associated with the sex-determination system, and studying this phenomenon
should lead to a deeper understanding of both embryonic development and sex determination. The reproductive capabilities of
gynandromorphs (hereafter, sex mosaics) remain unclear. We studied gynandromorphy in the Malaysian ant Cardiocondyla kagutsuchi, which has sex mosaics of queens (gynandromorphs; mosaic of queens and winged male) and workers (ergatandromorphs; mosaic
of worker and wingless ergatoid male). These sex mosaics were classified into seven morphological categories. Most individuals
had more male than female body areas. Behavioral observations revealed that sex mosaics behave more in accordance with the
“sex” of their brain than that of the reproductive organs (gaster). Relative DNA quantities showed that both female and male
regions contained haploid and diploid nuclei, irrespective of their phenotypic appearance, indicating that external appearance
did not reflect internal tissues. Nearly one third of the adults were sex mosaics and they were not infected with Wolbachia. Our results suggest that the production of sex mosaics in this species does not pose a substantial cost to colonies and
that the underlying causes are therefore not strongly selected against. 相似文献