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931.
Bhattarai HD Paudel B Park NS Lee KS Shin HW 《Journal of environmental biology / Academy of Environmental Biology, India》2007,28(4):857-863
Environmental impacts caused by tin and copper based commercial antifouling (AF) paints were proved to be detrimental to aquatic ecosystems. Therefore, a search of environmental friendly AF compounds to be used in marine paint to protect the surface of maritime developmental structures from the unwanted biofouling is a burning issue of the present time. Commercially available eight organic chemicals--allyl isothiocyanate, beta-myrecene, cis-3-hexenyl acetate, citral, ethyl heptanoate, eugenol, methyl caproate, and octyl alcohol were evaluated forAF activities using both laboratory and field assays. The test chemicals were found to repel the target motile marine bacteria--Alteromonas marina, Bacillus atrophaeus, Roseobactergallaeciensis and Shewanella oneidensis and motile spores of the green alga, Ulva pertusa. The bacterial and Ulva spore repulsion activities of the test chemicals were measured by chemotaxis and agar diffusion methods respectively interestingly these test chemicals were less toxic to the test fouling species. The toxicity of the test chemicals was measured by using antibiotic assay disks against the bacteria and motility test against Ulva spores. Moreover, in field assay, all test chemicals showed a perfect performance ofAF activity showing no fouling during the experimental period of one year Such results and commercial as well as technical feasibility of the test chemicals firmly showed the possibility of using as alternatives of the existing toxic AF agents. 相似文献
932.
Batch scale reactions were conducted to evaluate the efficacy of modified low-grade kaolin for the treatment of petroleum
contaminants. Low-grade kaolin, which has been unvalued as material in the mining process because of its low quality for commercial
products, was modified with HDTMA (hexadecyl-trimethylammonium), and its efficiency was compared with that of HDTMA-modified
bentonite, which is used as a secondary containment barrier for underground storage tanks. The sorption capacity and hydraulic
conductivity of both the HDTMA-modified bentonite and low-grade kaolin were investigated and showed distribution coefficients
in the sorption of benzene, toluene, ethylbenzene and xylene ranging between 45.7 and 583.7 and 57.0 and 525.1, respectively.
The hydraulic conductivities were 2.53 × 10−8 and 5.62 × 10−8 cm/s for the HDTMA-modified bentonite and low-grade kaolin, respectively. These results suggest that HDTMA-modified low-grade
kaolin could be used as a hydraulic barrier against advection migration of petroleum contaminants. Simulation of the one-dimensional
transport of benzene through a liner made of either one of the compounds was also performed. These results also showed that
HDTMA-modified kaolin more effectively retards the transport of benzene. 相似文献
933.
Bioleaching from soil artificially contaminated with analogues of radionuclides, Co and Sr, was carried out using a Fe-oxidizing
bacterium, Acidithiobacillus ferrooxidans. Due to bacterial metabolism, the pH and dissolved Fe3+ concentration in a biotic slurry decreased and increased respectively, over time, but the concentrations of Co and Sr extracted
from the soil showed no significant enhancement compared with those under abiotic control. In both cases, Co and Sr were leached
from the soil during the initial period of the experiment, due to the initially low solution pH of 2.0, and the dissolved
concentrations remained almost constant for the duration of the experiment (300 h). Since oxidation of Fe2+ by A. ferrooxidans led to the production of Fe precipitates and colloidal suspensions, the Co and Sr extracted into solution were most likely
re-adsorbed onto the Fe solids. Also, A. ferrooxidans, without an external supply of Fe2+, extracted almost equal or greater amounts of Co and Sr from the soil than when Fe2+ was supplied. Under the same leaching conditions, the extent of Sr removal was much lower than that of Co. On the contrary
to the high efficiency of microbial metal leaching in biohydrometallurgy for low-graded sulfide ores, which has been widely
documented, conventional bioleaching techniques with A. ferrooxidans supplied with enough Fe2+ showed low efficiency for the removal of radionuclides loosely bound onto soil particle surfaces. 相似文献
934.
935.
Rural sociologists and geographers have conceptualised different rural development trajectories including “the agri-industrial model”, “the post-productivist model” and “the rural development model”. Alternative food networks (AFNs) are increasingly recognised as a “forerunner” and a critical component of the emerging “rural development model” in the West. Meanwhile, Marsden and Franklin [2013. Replacing neoliberalism: theoretical implications of the rise of local food movements. Local Environment, 18 (5), 636–641] pointed out that there is a “local trap” in the current conceptualisation of AFNs that overemphasises their local embeddedness and heterogeneity. This “local trap” marginalises AFNs and, therefore, hinders their potential for transforming the industrialised conventional food system. The convergence and scaling-up of fragmented AFNs have been recognised as important ways to address this marginalisation issue and thus have attracted considerable attention. However, current studies of the convergence of AFNs focus mainly on the role of food-centred organisations without recognising the role of the emerging “rural development” initiatives in the convergence of AFNs. Based on in-depth interviews with key stakeholders and analysis of secondary data, this paper uses the New Rural Reconstruction Movement (NRRM), an emerging alternative rural development movement in China, as an example to illustrate how the NRRM opens up a novel space for the convergence of AFNs. We argue that the interrelationship between AFNs and rural development is indeed reciprocal. The NRRM, following the “rural development” trajectory, functions as a hub for the convergence and scaling-up of various alternative food initiatives. Strategies for achieving convergence include constructing a “common ground” for these initiatives, establishing national alliances and organisations, sharing knowledge and exchanging personnel among them. 相似文献
936.
937.
Wonkyeong Kang Ik-hyeon Kim Tae-jin Lee Ki-yeon Kim Daekeun Kim 《Waste management (New York, N.Y.)》2014,34(6):1006-1011
Swine manure was subjected to laboratory scale composting in order to quantify bioaerosols, i.e., airborne culturable bacteria and endotoxin, in the exhaust gas, which provided details on the effect of temperature on bacterial emissions. The concentration of airborne bacteria reached 31,250 colony-forming units (CFU)/m3 during the thermophilic stage of composting, and positively correlated with the temperature profile of the compost pile. Initially, the endotoxin concentration was 1820 endotoxin units (EU)/m3, but it decreased exponentially as the composting process proceeded. The temperature can be an excellent indicator of bacterial emissions during the composting process, indicating that the composting process requires a consistently high temperature to ensure sanitization of both compost and bacterial emissions. The cumulative emission data showed that emission factors was 11.2?13.5 CFU/g dry swine manure and that of endotoxin was 0.5?0.9 EU/g dry swine manure. The bacterial diversity in the bioaerosol was analyzed by polymerase chain reaction-denaturing gradient gel electrophoresis, revealing the presence of various gram-negative bacterial consortia. 相似文献
938.
939.
以西南丘陵区村镇典型供水水源原水及其净化水为研究对象,分析了水质净化常规工艺前后其有机污染物分布特征及对饮水水质的影响.结果表明:该区域村镇供水水源属微污染水源水体,有机污染物以溶解性中小分子有机物为主,占有机物总量的50%~80%.共检测到53种共14类有机物,主要为烷烃、酯、酚、苯类物质,占有机物总量的80%~90%左右,有机酸、烯烃、醇和醛含量较小.有机物中二氯甲烷、苯酚、邻苯二甲酸二丁酯含量较高,并且出现了除草剂、食品添加剂、抗生素等污染物,如特丁津、2,6-二叔丁基对甲酚、萘啶酸等.水质净化常规工艺主要去除相对分子质量10×10~3的有机物,小分子量有机物中有机酸类去除效果较好,但烷烃、酯、酚、苯类有机物去除效果较差. 相似文献
940.
Absolute dominance of hydrogenotrophic methanogens in full-scale anaerobic sewage sludge digesters 总被引:1,自引:0,他引:1
Anaerobic digestion (AD) is gaining increasing attention due to the ability to covert organic pollutants into energy-rich biogas and, accordingly, growing interest is paid to the microbial ecology of AD systems. Despite extensive efforts, AD microbial ecology is still limitedly understood, especially due to the lack of quantitative information on the structures and dynamics of AD microbial communities. Such knowledge gap is particularly pronounced in sewage sludge AD processes although treating sewage sludge is among the major practical applications of AD. Therefore, we examined the microbial communities in three full-scale sewage sludge digesters using qualitative and quantitative molecular techniques in combination: denaturing gradient gel electrophoresis (DGGE) and real-time polymerase chain reaction (PCR). Eight out of eleven bacterial sequences retrieved from the DGGE analysis were not affiliated to any known species while all eleven archaeal sequences were assigned to known methanogen species. Quantitative real-time PCR analysis revealed that, based on the 16S rRNA gene abundance, the hydrogenotrophic order Methanomicrobiales is the most dominant methanogen group (〉 94% of the total methanogen population) in all digesters. This corresponds well to the prevailing occurrence of the DGGE bands related to Methanolinea and Methanospirillum, both belonging to the order Methanomicrobiales, in all sludge samples. It is therefore suggested that hydrogenotrophic methanogens, especially Methanomicrobiales strains, are likely the major players responsible for biogas production in the digesters studied. Our observation is contrary to the conventional understanding that aceticlastic methanogens generally dominate methanogen communities in stable AD environments, suggesting the need for further studies on the dominance relationship in various AD systems. 相似文献