滚石灾害研究现状及发展趋势

滚石是我国西部山区常见的一种地质灾害,它分布范围极广,发生突然,频率高,严重威胁其周围的人类以及各种构筑物.目前,国内外有关滚石的理论研究比较薄弱,以致滚石灾害的防治工作受到严重的影响.基于对国内外大量滚石灾害研究资料的分析,将其研究现状概化为滚石风险分析、滚石运动轨迹、滚石冲击力以及滚石防护等4个方面.据此对滚石研究的发展趋势进行了探讨,以便为滚石灾害的机理研究和治理提供参考依据.     

Biohydrogen production through fermentation using liquid swine manure as substrate

In this paper, continuous production of hydrogen through fermentation with liquid swine manure as substrate was researched using a semi-continuously fed fermenter (8 L in total volume and 4 L in working volume). The pH and temperature for the fermenter were controlled at 5.3 +/- 0.1 and 35 +/- 1 degrees C, respectively, throughout the experiment. Three hydraulic retention times (16, 20, and 24 h) were investigated for their impact on the efficiency and performance of the fermenter in terms of hydrogen yields. The results indicate that hydraulic retention time (HRT) has a strong influence on the fermenter performance. An increasing HRT would increase the variation in hydrogen concentration in the offgas. To produce hydrogen with a fairly consistent concentration, the HRT of the fermenter should not exceed 16 h, which, however, did not appear to be short enough to control methanogenesis because the offgas still contained about 5% methane. When methane content in the offgas exceeded 2%, an inverse linear relationship between hydrogen and methane was observed with a correlation coefficient of 0.9699. To increase hydrogen content in the offgas, methane production has to be limited to below 2%. Also, keeping oxygen content in the fermenter below 1.5% would increase the hydrogen concentration to over 15%. The product to substrate ratio was found to be around 50% for the fermenter system studied, evidenced by the observation that for every 6 liters of manure fermented, 3 liters of pure hydrogen were produced, which was significant and encouraging.     

In situ studies on the distribution patterns and dynamics of microcystins in a biomanipulation fish--bighead carp (Aristichthys nobilis)

The distribution and dynamics of microcystins in various organs of the phytoplanktivorous bighead carp were studied monthly in Lake Taihu, which is dominated by toxic cyanobacteria. There was a good agreement between LC-MS and HPLC-UV determinations. Average recoveries of spiked fish samples were 63% for MC-RR and 71% for MC-LR. The highest MC contents in intestine, liver, kidney and spleen were 85.67, 2.83, 1.70 and 1.57 microg g-1 DW, respectively. MCs were much higher in mid-gut walls (1.22 microg g-1 DW) than in hind- and fore-gut walls (0.31 and 0.18 microg g-1 DW, respectively), suggesting the importance of mid-gut wall as major site for MC absorption. A cysteine conjugate of MC-LR was detected frequently in kidney. Among the muscle samples analyzed, 25% were above the provisional tolerable daily intake level by WHO. Bighead is strongly resistant to microcystins and can be used as biomanipulation fish to counteract cyanotoxin contamination in eutrophic waters.     

Monitoring of organochlorine pesticides using PFU systems in Yunnan lakes and rivers, China

Polyurethane foam unit (PFU) systems were collected from 11 lakes and three rivers in the Yunnan Plateau, China and, the PFU extrusion liquids were analyzed for organochlorine pesticides (OCPs) by gas chromatography with electron capture detection (GC-ECD). The concentrations of pp'-DDE, HCB and HCHs were undetectable to 1.86 microgl-1 (mean 0.27 microgl-1), undetectable to 0.72 microgl-1 (mean 0.11 microgl-1), and 0.24-21.95 microgl-1 (mean 7.39 microgl-1) respectively in lakes; and those in rivers were undetectable to 0.23 microgl-1 (mean 0.08 microgl-1), 0.68-2.93 microgl-1 (mean 1.70 microgl-1), and 2.71-37.56 microgl-1 (mean 17.01 microgl-1) respectively. Notably, some residue levels of OCPs exceeded the US National Recommended Water Quality Criteria, implying Yunnan has levels of OCPs potentially harmful to human health. Further, the contamination by OCPs showed an obvious spatial distribution pattern. Amongst the lakes, Dianchi, Xingyun, Lugu and Yangzonghai had the highest OCP levels dominated by beta-HCH, whereas among rivers, Nujiang and Lancang Rivers had the highest contents of OCPs dominated by alpha-HCH. This demonstrates that HCHs are the predominant contaminants and some point sources of HCHs may still exist in Yunnan. The pollution levels in Yunnan were compared with other studies, suggesting the PFU method is suitable for long-term on-line monitoring of trace OCPs in aquatic ecosystems. Therefore, continuous studies monitoring OCPs in lakes and rivers are needed to further understand the future trend of contamination.     

Investigation of a new approach to decompose two potent greenhouse gases: photoreduction of SF(6) and SF(5)CF(3) in the presence of acetone

In this paper, we addressed the utilization of photochemical method as an innovative technology for the destruction and removal of two potent greenhouse gases, SF(6) and SF(5)CF(3). The destruction and removal efficiency (DRE) of the process was determined as a function of excitation wavelength, irradiation time, initial ratio of acetone to SF(5)X (X represented F or CF(3)), initial SF(5)X concentration, additive oxygen and water vapor concentration. A complete removal was achieved by a radiation period of 55min and 120min for SF(6)-CH(3)COCH(3) system and SF(5)CF(3)-CH(3)COCH(3) system respectively under 184.9nm irradiation. Extra addition of water vapor can enhance DRE by approximately 6% points in both systems. Further studies with GC/MS and FT-IR proved that no hazardous products such as S(2)F(10), SO(2)F(2), SOF(2), SOF(4) were generated in this process.     

旱地长期定位施肥对土壤剖面硝态氮分布与累积的影响

在 １５ ａ长期定位试验基础上研究了黄土高原旱地长期施用不同用量和配比的氮、磷肥对土壤剖面中硝态氮分布和累积的影响。结果表明：长期大量施用氮肥,在土壤剖面 １００～１８０ ｃｍ之间形成硝态氮累积层,峰值出现在 １４０ ｃｍ处,最大值为 ６７．９２ｍｇ／ｋｇ（单施 Ｎ １８０ ｋｇ／ｈｍ~２）; 配合施用磷肥可以降低土壤剖面硝态氮质量分数,根据试验,提出了旱地合理施肥的氮磷肥用量。     

湖北农村降水中SO_4~(2-)浓度变化研究

在湖北农村 10个地点 ,利用澳大利亚集雨器自 1996年 1月至 1998年 6月 ,按季度采集大气降水样品测定SO2 - 4浓度 ,并对数据进行统计分析。研究结果表明 ,各地 1997年降水中SO2 - 4浓度年均值比 1996年显著升高 ;大多数地点 1996、1997、1998年 1季度和 2季度降水中SO2 - 4浓度呈逐年升高趋势 ;大多数地点每年 1、4季度降水中SO2 - 4浓度高 ,2、3季度降水中SO2 - 4浓度低 ,说明湖北农村降水中的硫对秋冬作物影响比对春夏作物影响大 ;湖北农村降水中SO2 - 4浓度近两年不仅有时间变化规律 ,而且同一季度内的地区差异也很明显 ,在 1996年和 1997年 8个季度 10个点的降水SO2 - 4浓度最大值中 ,有 4个最大值出现在襄樊 ,它是目前湖北继宜昌市区、恩施市区之后又一个酸雨发展较快的地区     

Sb release characteristics of the solid waste produced in antimony mining smelting process

Sb release characteristics of blast furnace slag, mining waste rock and tailing sand were investigated in static immersion and dynamic leaching test. These three kinds of waste samples were collected from the antimony mine in Lengshuijiang, China, produced in mining smelting process. Effects of solid/liquid ratio, sample size and pH of leaching solution on Sb release characteristics were inspected based on the analysis of scanning electron microscope, pH and EC of leachate. The optimal parameters for Sb leaching of each sample were analyzed. For blast furnace slag and mining waste rock, Sb release contents increased along with the decline of solid/liquid ratio. The maximum accumulative release contents were 42.13, 34.26 mg/kg at the solid/liquid ratio of 1:20. While Sb release content for tailing sand decreased first and then increased with the reduction of solid/liquid ratio. When the solid/liquid ratio was 1:5, the accumulative Sb release content reached the most (24.30 mg/kg). Sb release content of mining waste rock increased with the drop of leaching solution pH, with the highest accumulative release content of 26.01 mg/kg at pH 2.0. Sb release contents of blast furnace slag and tailing sand showed positive correlation with the variation of leaching solution pH. The maximum accumulative release contents of these two samples were 215.91 and 147.83 mg/kg, respectively, when leaching solution pH was 7.0. In summary, Sb release capacity of the three samples in descending order was tailing sand, blast furnace slag and mining waste rock. pH and EC of the leachate in dynamic test varied independently with the initial pH of leaching solution while showing close relationship with mineral hydrolysis in the waste.     

太湖流域水环境保护目标责任考核机制研究

建立科学规范的环境保护目标责任考核机制是实现我国环境保护目标的重要手段之一。作为一个自上而下的制度典范,基层环境保护管理部门是环境管理目标的落实者也是被考核的对象。本研究以太湖流域水环境保护基层管理部门面临的水环境保护目标责任考核机制为研究对象,从水环境保护考核指标的设定、考核评价的实施以及考核结果的应用三个方面分析太湖流域水环境保护目标考核机制的实施现状。结果表明,现阶段的考核体系存在考核指标设置不合理、考核过程实施过程成本较高,以及考核结果缺乏对管理部门的激励性等问题。最后,本文从提高现阶段太湖流域水环境保护考核指标设定的科学性、协调不同部门之间的关系以及加强考核结果的公开与合理应用方面对太湖流域水环境保护目标责任考核机制提出了政策建议。