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971.
972.
Nitrate and phosphate leaching in a Phaeozem soil treated with biosolids,composted biosolids and inorganic fertilizers 总被引:2,自引:0,他引:2
M.V. Esteller H. Martínez-Valdés S. Garrido Q. Uribe 《Waste management (New York, N.Y.)》2009,29(6):1936-1944
The use of organic wastes in agriculture may increase the production of crops by incorporating organic matter and nutrients into the soil, and by improving its physical characteristics; however, this use may cause environmental problems such as the leaching of certain ions. The objective of this study was to establish possible nitrogen and phosphorus leaching under real field conditions in Phaeozem soils. The experimental work was performed in a corn (Zea mays L.) field where three plots were conditioned with inorganic fertilizer, three plots with 4.5 Mg ha?1 of biosolids on dry basis, and three plots with the same amount of composted biosolids. The quality of biosolids and composted biosolids complied with the Mexican Official Standards. Soil water samples were collected with suction cups during two agricultural cycles and were analysed. Soil samples were also taken and analysed.The N–NO3 concentrations in soil water fluctuated between 0.9 and 98 mg L?1 in the composted biosolid treatment, between 0.7 and 64 mg L?1 in the biosolid treatment, and between 1 and 61 mg L?1 in the inorganic fertilizer treatment. The maximum concentration of N–NO2 and N–NH3 in soil water was 1.02 and 2.65 mg L?1, respectively. The greatest percentage of nitrogen leached is produced when inorganic fertilizer is used (37.4% and 24.0% N leached in the first and second years, respectively), followed by composted biosolids (17.1% and 13.5% N leached in the first and second years, respectively) and last by biosolids (11% for both years). This difference could be related to the form in which nitrogen is present in the fertilizers, while commercial fertilizer is as inorganic nitrogen, organic wastes are basically presented as organic nitrogen. The maximum concentration in soil water was 1.9 mg L?1 in the composted biosolid treatment, 1.7 mg L?1 in the biosolid treatment and 0.9 mg L?1 in the inorganic fertilizer treatment. The estimated percentage of leached phosphorus was less than 1% for all treatments. The minimum leaching that occurred seemed to be due to a sorption–precipitation process. 相似文献
973.
Immobilisation of heavy metal in cement-based solidification/stabilisation: a review 总被引:2,自引:0,他引:2
Heavy metal-bearing waste usually needs solidification/stabilization (s/s) prior to landfill to lower the leaching rate. Cement is the most adaptable binder currently available for the immobilisation of heavy metals. The selection of cements and operating parameters depends upon an understanding of chemistry of the system. This paper discusses interactions of heavy metals and cement phases in the solidification/stabilisation process. It provides a clarification of heavy metal effects on cement hydration. According to the decomposition rate of minerals, heavy metals accelerate the hydration of tricalcium silicate (C3S) and Portland cement, although they retard the precipitation of portlandite due to the reduction of pH resulted from hydrolyses of heavy metal ions. The chemical mechanism relevant to the accelerating effect of heavy metals is considered to be H+ attacks on cement phases and the precipitation of calcium heavy metal double hydroxides, which consumes calcium ions and then promotes the decomposition of C3S. In this work, molecular models of calcium silicate hydrate gel are presented based on the examination of 29Si solid-state magic angle spinning/nuclear magnetic resonance (MAS/NMR). This paper also reviews immobilisation mechanisms of heavy metals in hydrated cement matrices, focusing on the sorption, precipitation and chemical incorporation of cement hydration products. It is concluded that further research on the phase development during cement hydration in the presence of heavy metals and thermodynamic modelling is needed to improve effectiveness of cement-based s/s and extend this waste management technique. 相似文献
974.
975.
976.
Tofael Ahamed M. I. N. Khan Tomohiro Takigawa Masayuki Koike Farhat Tasnim J. M. Q. Zaman 《Environment, Development and Sustainability》2009,11(5):933-954
A combined approach utilizing GIS, Participatory Rural Appraisal (PRA) and Focus Group Discussion (FGD) has been developed
for resource mapping in a rural poverty-prone area of Bangladesh. This model integrated GIS and participatory tools to include
the voices of the stakeholders in assessing available resources and needs. The resource mapping framework, developed using
PRA with local community people and community gatekeepers, was aimed at sustainable resource management, and ArcView GIS was
used to digitize the resource maps as a Decision Support System (DSS). A detailed assessment and analysis of the quality,
quantity and physical status of resources was first mapped in the field and then digitized using GIS. FGD-based interaction
with community people at each union in a subdistrict of Bangladesh revealed stakeholders’ opinions on land and water body
management. The present paper demonstrates the power of this model as a policy-making tool for sustainable development and
poverty eradication. It also recognized the need for collaboration between interdisciplinary policy planners and researchers
to develop and implement a policy on agricultural resource management for poverty-prone areas. 相似文献
977.
推进规划环境影响评价,既是贯彻落实<中华人民共和国环境影响评价法>、促进生态文明建设的需要.也是环境保护行政主管部门加强污染源头控制、参与宏观决策的有效途径.在对江苏、云南、重庆等地进行实地调研的基础上,分析了中国当前规划环境影响评价工作所面临的形势,重点研究了浙江省在推进规划环境影响评价工作中需要重点关注的问题,并提出了浙江省推进规划环境影响评价的相关建议. 相似文献
978.
炭管膜曝气生物膜反应器SNAD脱氮研究 总被引:1,自引:0,他引:1
以包裹无纺布的微孔炭管作为膜曝气生物膜反应器(MABR)的膜组件,进行了短程硝化,厌氧氨氧化和反硝化耦合脱氮(SNAD)研究。实验中,控制温度34±1℃,pH 7.5~8.5, HRT 8 h,通过逐步降低膜内压力使反应器中的溶解氧由8 mg/L逐步降低到0.5 mg/L以下。实验采用亚硝酸细菌挂膜,然后接种厌氧氨氧化细菌,实现在单一反应器中同时发生短程硝化、厌氧氨氧化和反硝化耦合脱氮功能。结果表明,经过180 d的连续稳定运行,氨氮去除率达到了93.4%,总氮去除率达到了92.5%,COD去除率达到97.2%, 氨氮去除负荷0.6 kg N/(m3 ·d)。适合SNAD工艺的最佳C/N比为0.2~0.6,当COD浓度过高时,会抑制厌氧氨氧化细菌,使SNAD工艺的处理效果明显下降。 相似文献
979.
累托石/腐殖酸微球的制备及其对Cr(Ⅵ)的吸附研究 总被引:1,自引:0,他引:1
采用累托石(REC)、腐殖酸(HA)等材料制备微球状吸附剂,考察了累托石、腐殖酸、聚乙烯醇(PVA)、海藻酸钠(SA)、氯化钙等材料的用量对制得的微球吸附性能的影响,通过正交试验确定了微球的最佳制备条件,还考察了微球用量、振荡时间和溶液pH值等因素对微球吸附去除水中Cr(VI)效果的影响。结果表明,采用累托石、腐殖酸、聚乙烯醇等材料可制得高效去除水中六价铬离子的微球状吸附剂,微球的最佳制备条件为:REC 1%,HA 4%,PVA 7%,SA 0.1%,CaCl2 0.5%。制得的累托石/腐殖酸微球孔系发达,吸附性能良好。在温度30℃,微球用量0.02 g/mL,振荡时间为2.5 h,pH值为1的条件下,微球对Cr(VI)的吸附效率可达98%以上。 相似文献
980.
Robert Gifford Leila Scannell Christine Kormos Lidia Smolova Anders Biel Stefan Boncu Victor Corral Hartmut Güntherf Kazunori Hanyu Donald Hine Florian G. Kaiser Kalevi Korpela Luisa Marie Lima Angela G. Mertig Ricardo Garcia Mira Gabriel Moser Paola Passafaro José Q. Pinheiro Sunil Saini Toshihiko Sako Elena Sautkina Yannick Savina Peter Schmuck Wesley Schultz Karin Sobeck Eva-Lotta Sundblad David Uzzell 《Journal of environmental psychology》2009
The personal assessments of the current and expected future state of the environment by 3232 community respondents in 18 nations were investigated at the local, national, and global spatial levels. These assessments were compared to a ranking of each country's environmental quality by an expert panel. Temporal pessimism (“things will get worse”) was found in the assessments at all three spatial levels. Spatial optimism bias (“things are better here than there”) was found in the assessments of current environmental conditions in 15 of 18 countries, but not in the assessments of the future. All countries except one exhibited temporal pessimism, but significant differences between them were common. Evaluations of current environmental conditions also differed by country. Citizens' assessments of current conditions, and the degree of comparative optimism, were strongly correlated with the expert panel's assessments of national environmental quality. Aside from the value of understanding global trends in environmental assessments, the results have important implications for environmental policy and risk management strategies. 相似文献