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991.
I. H. Choi J. H. Choi S. H. Ko P. A. Moore Jr 《Journal of environmental science and health. Part. B》2013,48(5):432-435
This study was a pen trial in which the effects of adding different rates of liquid aluminum chloride (AlCl3) on litter pH, total volatile fatty acids (VFAs), and ammonia (NH3) fluxes was evaluated. Liquid AlCl3 treatments used in this study were sprayed on the rice hull surface at rates of 100 g, 200 g, and 300 g liquid AlCl3/kg rice hulls; untreated rice hulls served as controls. Litter pH, total VFAs, and NH3 fluxes were all lowered (P< 0.05) by all of the liquid AlCl3 treatments compared with controls during certain times of the 5 week study. However, there were no significant differences among treatments on litter pH at the end of the study (from 3 to 5 weeks) or NH3 fluxes at beginning of the study (0 to 3 weeks). Total VFAs were reduced 16 %, 29 %, and 53 % by 100 g liquid AlCl3/kg rice hulls, 200 g liquid AlCl3/kg rice hulls, and 300 g liquid AlCl3/kg rice hulls, respectively. Liquid AlCl3additions reduced NH3 fluxes by 35 %, 57 % and 67 %, respectively, at the low, medium and high rates. In summary, these results indicate that adding liquid aluminum chloride to rice hulls would be a useful tool in reducing the negative environmental impact of poultry litter. It should be noted that the decreased VFA production and NH3 volatilization was chiefly associated with reduction in litter pH. 相似文献
992.
993.
Mexico's vast human and environmental diversity offers an initial framework for comprehending some of the prevailing great disparities between rich and poor. Its socio-economic constructed vulnerability to climatic events serves to expand this understanding. Based on a spatial econometric model, this paper tests the contribution of natural disasters to stimulating the emigration process in vulnerable regions of Mexico. Besides coping and adaptive capacity, it assesses the effects of economic losses due to disasters as well as the adverse production and trade conditions of the 1990s on emigration rates in 2000 at the municipality level. Weather-related disasters were responsible for approximately 80 per cent of economic losses in Mexico between 1980 and 2005, mostly in the agricultural sector, which continues to dominate many parts of the country. It is dramatic that this sector generates around only four per cent of gross domestic product but provides a livelihood to about one-quarter of the national population. It is no wonder, therefore, that most emigration from this country arises in vulnerable rural areas. 相似文献
994.
995.
996.
Myung-Chan Ahn Thomas M. Holsen Young-Ji Han 《Environmental pollution (Barking, Essex : 1987)》2010,158(2):347-355
The effects of various factors including turbidity, pH, DOC, temperature, and solar radiation on the concentrations of total mercury (TM) and dissolved gaseous mercury (DGM) were investigated in an artificial reservoir in Korea. Episodic total mercury accumulation events occurred during the rainy season as turbidity increased, indicating that the TM concentration was not controlled by direct atmospheric deposition. The DGM concentration in surface water ranged from 3.6 to 160 pg/L, having a maximum in summer and minimum in winter. While in most previous studies DGM was controlled primarily by a photo-reduction process, DGM concentrations tracked the amount of solar radiation only in winter when the water temperature was fairly low in this study. During the other seasons microbial transformation seemed to play an important role in reducing Hg(II) to Hg(0). DGM increased as dissolved organic carbon (DOC) concentration increased (p-value < 0.01) while it increased with a decrease of pH (p-value < 0.01). 相似文献
997.
Carly J. Stevens Cecilia Duprè Cassandre Gaudnik Albert Bleeker Didier Alard David Fowler J. Owen Mountford Per Arild Aarrestad Nancy B. Dise 《Environmental pollution (Barking, Essex : 1987)》2010,158(9):2940-2945
Evidence from an international survey in the Atlantic biogeographic region of Europe indicates that chronic nitrogen deposition is reducing plant species richness in acid grasslands. Across the deposition gradient in this region (2-44 kg N ha−1 yr−1) species richness showed a curvilinear response, with greatest reductions in species richness when deposition increased from low levels. This has important implications for conservation policies, suggesting that to protect the most sensitive grasslands resources should be focussed where deposition is currently low. Soil pH is also an important driver of species richness indicating that the acidifying effect of nitrogen deposition may be contributing to species richness reductions. The results of this survey suggest that the impacts of nitrogen deposition can be observed over a large geographical range. 相似文献
998.
S.P. McGrath C. Micó F.J. Zhao 《Environmental pollution (Barking, Essex : 1987)》2010,158(10):3095-3102
The effect of soil properties on the toxicity of molybdenum (Mo) to four plant species was investigated. Soil organic carbon or ammonium-oxalate extractable Fe oxides were found to be the best predictors of the 50% effective dose (ED50) of Mo in different soils, explaining > 65% of the variance in ED50 for four species except for ryegrass (26-38%). Molybdenum concentrations in soil solution and consequently plant uptake were increased when soil pH was artificially raised because sorption of Mo to amorphous oxides is greatly reduced at high pH. The addition of sulphate significantly decreased Mo uptake by oilseed rape. For risk assessment, we suggest that Mo toxicity values for plants should be normalised using soil amorphous iron oxide concentrations. 相似文献
999.
对不同浓度KCL和不同pH下,3种可变电荷土壤和4种恒电荷土壤CI-吸附量进行了测定。结果表明,土壤CI-吸附量随平衡 CI-浓度 C(e)增加而增大,恒电荷土壤呈线性,可变电荷土壤在添加 CI- 0.5-5.0 mmol/L.下,符合 Langmuir吸附等温式。同一浓度下的CI-吸附量及其随浓度增加的速率均为砖红壤>红壤>赤红壤>黄棕壤>棕壤、暗棕壤和黑土,与这些土壤所带正电荷量顺序相一致。Langmuir方程K值较小且几种土壤差异不大。恒电荷土壤对CI-的吸附量很小,在浓度较低时常出现负吸附,其吸附机理可能更多的是与K+吸附时的同时吸附。7种土壤CI-吸附量均随pH增加而降低,但降低强度可变电荷土壤远大于恒电荷土壤。 相似文献
1000.
Acid rain is a problem of increasing agricultural, environmental, and ecological concerns worldwide. This study investigated impacts of simulated acid rain (SAR) on cation leaching from the Latosol in south China. Latosol is an acidic red soil and occurs in the tropical rainforest biome. Laboratory experiments were performed by leaching the soil columns with the SAR at a pH range from 2.5 to 7.0 over a 21-day period. A linear increase in effluent K+ concentration was found at the SAR pH 3.0, whereas an exponential decrease in effluent Na+ concentration was observed at all levels of the SAR pH. In general, leaching of Ca2+ and Mg2+ from the Latosol increased as the SAR pH decreased. There was a very good nonlinear correlation between the removal of soil K+ and the SAR pH (R2 = 0.91), a good nonlinear correlation between the removal of soil Mg+2 and the SAR pH (R2 = 0.83), a fairly good nonlinear correlation between the removal of soil Ca+2 and the SAR pH (R2 = 0.56), and no correlation between the removal of soil Na+ and the SAR pH (R2 = 0.06). Our study further revealed that the removal of soil cations such as K+, Ca+2, and Mg+2 can be quantified by the quadratic polynomial equations. In addition, impacts of the SAR on cation leaching depended not only on the SAR pH but also on the original soil pH. 相似文献