Construction of Dry Cover System for Prevention of Acid Mine Drainage at Mine Waste Dump in Open Cast Coal Mines, Indonesia

Acid Mine Drainage (AMD) which occurs when sulfide minerals are exposed to water and oxygen with an excavation is one of the serious environmental problems in the world. A dry cover system is generally constructed in waste dump for the prevention of AMD in Indonesia by virtue of low cost and availability of waste rocks for a cover layer. However, the failure of the system caused by the lack of information related to the construction of cover system in mines, which leads to AMD, has been reported recently in Indonesia. In this study, the field investigation was conducted in pit and waste dump in open cast coal mine in Indonesia with the aim of obtaining the information on the construction of a cover layer and backfilling conditions of waste rocks in the waste dump. The rock samples taken in two areas of the mine were analyzed by geochemical analysis and sequential extraction with acids. The results indicated that Net Acid Producing Potential (NAPP) of the rocks in the waste dump down to 100 cm depth in both areas was from 10 to 30 kg H2SO4/ton, suggesting that Potentially Acid Forming (PAF) was backfilled in a cover layer. The backfill of PAF was contrary to the concept of cover system, which caused the failure of constructing a cover layer. The cause of the failure was likely attributed to the shortage of cover rocks which are classified as Non Acid Forming (NAF) or the failure of proper placement of them by an operational problem in the areas. Moreover, the results of the extraction with acids suggested that the form of iron and sulfur has to be taken into account to discuss the occurrence of AMD.

Application of Fly Ash and Organic Material as Dry Cover System in Prevention of Acid Mine Drainage Generation

The common practice in AMD prevention is a dry cover technique. In this technique, rock that is potential in producing acidity (PAF) will be placed below non-acid producing rock (NAF). Depends on NAF availability in the mine site situation, organic covers can be used to prevent diffusion of oxygen into reactive sulphide wastes and subsequently to eliminate sulphide compounds oxidation and generation of acidic waters. The utilization of additional material cover layer is proposed, by using fly ash and organic material combination. To investigate the possibility of using these materials, a column leaching test in the laboratory scale was conducted with several scenarios of simulation. By comparing between column with different thickness of fly ash and organic material, the leachate water behavior is observed in the experiment, including the measurement of water quality (pH and EC), major cations-anions. The result suggests the possible thickness of fly ash (FA) and organic material (OM) as cover layer material, especially in the case of mine with domination of PAF rock material.

Vegetation cover density and disturbance affected arbuscular mycorrhiza fungi spore density and root colonization in a dry Afromontane forest, northern Ethiopia

Arbuscular mycorrhiza fungi(AMF) are vital in the regeneration of vegetation in disturbed ecosystems due to their numerous ecological advantages and therefore are good indicators of soil and ecosystem health at large. This study was aimed at determining how the seasonal, vegetation cover density, edaphic and anthropogenic factors affect AMF root colonization(RC) and spore density(SD)in Desa’a dry Afromontane forest. AMF RC and SD in the rhizosphere of five dominant woody species, Juniperus procera, Olea europaea, Maytenus arbutifolia, Carissa spinarum and Dodonaea angustifolia growing in Desa’a forest were studied during the rainy and the dry seasons in three permanent study vegetation cover density plots(dense, medium, and poor). Each plot(160 x40 m2) has two management practices(fenced and unfenced plots) of area. A 100 g sample of rhizosphere soil from moisturefree composite soil was used to determine spore density.Spore density ranged from 50 to 4467 spores/100 g soil,and all species were colonized by AMF within a range of 4–95%. Glomus was the dominant genus in the rhizosphere of all species. Vegetation cover density strongly affected SD and RC. The SD was significantly higher(p < 0.05) in the poor vegetation cover density than in the other two and lowest in the dense cover; root colonization showed the reverse trend. Management practices significantly(p <0.05) influenced AMF SD and RC, with the fenced plots being more favoured. Seasons significantly(p < 0.05) affected RC and SD. More RC and SD were observed in the wet period than the dry period. Correlating AMF SD and RC with soil physical and chemical properties showed no significant difference(p> 0.05) except for total nitrogen. Disturbance, vegetation cover density, season and total nitrogen are significant factors that control the dynamics and management interventions to maintain the forest health of dry Afromontane forests.

紫花苜蓿种植模式对干热河谷咖啡园土壤质量的影响

为改善干热河谷地区咖啡园脆弱的生态环境,探讨不同的覆盖作物种植模式对咖啡园土壤质量的影响,本研究通过设置紫花苜蓿单播(A1),紫花苜蓿×光叶紫花苕混播(A2)两个处理,以休闲处理(CK)为对照,分析了覆盖作物盛花期时对土壤酶活、理化性质、细菌群落结构和多样性的影响。结果表明:A1、A2处理都能显著提高咖啡园土壤有机质和氮素含量(P<0.05),促进土壤pH从弱碱性恢复到中性,更利于咖啡树的生长;与CK相比,A1的土壤脲酶显著提高(P<0.05),A1、A2、CK的土壤过氧化氢酶活性无显著差异(P>0.05);A1的Sobs指数、Chao1指数显著低于A2、CK处理(P<0.05),A1、A2的Shannon指数显著低于CK(P<0.05),与休闲处理相比,单播/混播覆盖作物种植降低了土壤细菌多样性,但紫花苜蓿×光叶紫花苕混播的土壤细菌多样性比紫花苜蓿单播更丰富;酸杆菌门是A1的优势菌门,放线菌门是A2、CK组的优势菌门,酸杆菌门的RB41是3个处理的优势菌属;pH值对土壤细菌种群分布的影响最大;细菌群落的主要功能是碳水化合物代谢和氨基酸代谢。覆盖作物种植可以显著增加干热河谷地区咖啡园土壤营养,调整土壤酸碱度,影响土壤细菌群落结构和功能,土壤改良效果显著,紫花苜蓿和光叶紫花苕混播是干热河谷地区咖啡园覆盖作物种植的较优模式。

预制装配式盖梁施工轻型化工艺对比及工程应用研究

为解决超重、大体积盖梁施工过程中场地条件、运输和吊装条件受限的问题,逐渐形成了以整体预制盖梁、节段干接盖梁、节段湿接盖梁以及干湿接组合式盖梁为体系的城市高架桥梁盖梁轻型化结构体系。简要介绍了国内外相关预制盖梁施工的研究成果,总结了干湿接盖梁设计施工工艺。通过在S3公路新建工程项目上盖梁轻型化的实践应用,从适用盖梁长度、预制速度及便捷性、运输难度、吊装难度及施工周期等多方面分析了各自的优缺点,不同类型预制盖梁施工工艺的成功应用,拓展和丰富了市政桥梁工程的预制装配体系。

干式松散覆岩充填体下残留矿柱回采综合技术

为保证干式松散覆岩充填体下的残留矿柱的安全回采,采用超前注浆技术固结充填体,形成具有一定强度的人工假顶,通过回采工艺、技术安全经济指标的对比,优选出合适的采矿方法,保障作业的顶板安全.现场工业试验结果证明,采用超前注浆固结技术能很好地维护采场顶板安全,对类似矿山残留矿柱的回采可以提供借鉴作用,具有较好的工程实际意义.

Effects of a Remotely Sensed Land Cover Dataset with High Spatial Resolution on the Simulation of Secondary Air Pollutants over China Using the Nested-grid GEOS-Chem Chemical Transport Model

A number of remotely sensed land cover datasets with spatial resolutions ~〈 1 km have recently become available or are in the process of being mapped. The application of these higher resolution and more up-to-date land cover datasets in chemical transport models （CTMs） is expected to improve the simulation of dry deposition and biogenic emissions of non-methane volatile organic compounds （NMVOCs）, which affect ozone and other secondary air pollutants. In the present study, we updated the land cover dataset in the nested-grid GEOS-Chem CTM with the 1 km resolution GLC2000 land cover map and examined the resulting changes in the simulation of surface ozone and sulfate over China in July 2007. Through affecting the dry deposition velocities of ozone and its precursors, using GLC2000 in the dry deposition module can decrease the simulated surface ozone by 3% （up to 6 ppb） over China. Simulated surface sulfate shows an increase of 3% in northwestern China and a decrease of 1% in northern China. Applying GLC2000 in the biogenic emissions of the NMVOC module can lead to a 0.5--4.5 ppb increase in simulated surface ozone over East China, mainly driven by the larger cove~：age of broadleaf trees in East China in the GLC2000 dataset. Our study quantifies the large sensitivity to land cover dataset~ with different spatial resolutions and time periods of simulated secondary air pollutants over China, supporting ongoing research efforts to produce high resolution and dynamically updated land cover datasets over China, as well as for the globe.

Effects of Land Use Change on the Ecosystem Services Value in the Dry-Hot Valley

The objective of the study reported here was to determine whether LANDSAT TM images could be used to quantify changes in land-use and ecosystem services in Yuanmou County. The sizes of six land use/land cover （LUCC） categories were estimated in Yuanmou County according to the LANDSAT TM images in the summer of 1986 and 2005. Coefficients published by Xie Gaodi and co-workers in 2003 were used to value changes in ecosystem services delivered by each land use/land cover category, and the ecosystem services sensitivity analysis was conducted to determine the effect of manipulating these coefficients on the estimated values. The important results are summarized as followings. （1） The estimated size of cultivated land, pasture land, water area and unused land decreased by 6.39%, 1.35%, 2.25% and 10.67% respectively between 1986 and 2005. By contrast, the estimated size of forest land and construction land increased by about 2.23% and 71.15% respectively between 1986 and 2005. （2） The total ecosystem services value （EVS） of the study area increased from 2 142 132 609.46 yuan to 2 146 416 621.00 yuan, with the net increase of 4 284 011.54 yuan during the 20-year time period. （3） The coefficient sensitivity （CS） of the study are less than unity in all cases （CS 〈 1）. This indicates that the total ecosystem values estimated for the study area are relatively inelastic with respect to the ecosystem service coefficients. While this implies that our estimates are robust and the coefficient is reasonable, highly under or over valued coefficients can substantially affect the veracity of estimated changes in ecosystem service values overtime even when the CS are less than unity（CS 〈 1）.

干枯植被覆盖对公路沿线地表风沙流结构的影响

[目的]以内蒙古S105草原公路沿线地表为研究对象,探讨挟沙风作用下干枯植被覆盖度对风沙流结构的影响,旨在为防治公路两侧土壤风蚀提供理论参考依据。[方法]采用风洞模拟试验,在0%,20%,40%和50%覆盖度水平下测定输沙率。[结果]在挟沙风作用下,输沙率随干枯植被覆盖度的增大而递减,最大输沙率点的高度层不断上升。覆盖度为0%时,输沙率随高度的增加呈指数函数规律降低;覆盖度为20%,40%和50%时,输沙率随高度的增加呈递减→递增→递减→趋于平缓的变化规律;在85 mm高度以下符合多项式函数关系,85 mm高度以上符合指数函数关系。随覆盖度的增大总输沙量递减,最大抗风蚀效率达65.73%。[结论]干枯植被覆盖显著影响地表风沙流结构,可削弱挟沙风侵蚀力,是抑制公路沿线地表土壤风蚀沙化的有效措施。

BFRP筋增强生态高延性混凝土的干燥收缩性能

生态高延性混凝土(ecological high ductility concrete, Eco-HDC)具有优异的抗拉性能,可用来浇筑桥面无缝连接板。为避免Eco-HDC收缩引发的开裂问题,采用BFRP筋作为抗裂筋。为结构设计优选BFRP筋保护层厚度,从BFRP筋对Eco-HDC收缩的影响角度,研究保护层厚度对试件干燥收缩的影响,对比分析配BFRP筋与不配筋对Eco-HDC收缩性能的影响。试验结果表明:随着龄期的增加,素Eco-HDC和BFRP筋增强Eco-HDC的干燥收缩均逐渐增加,BFRP筋压应变呈增加趋势,养护1~7 d时增加趋势较为明显,之后增加趋势逐渐变缓;随着保护层厚度的减小,BFRP筋增强Eco-HDC的收缩逐渐增加,BFRP筋压应变也逐渐增大,BFRP筋的约束效果更加明显,但经历45 d后BFRP筋压应变数值差别不大。在桥面无缝连接板施工养护时应注意早龄期7 d内保湿以减少收缩;在结构设计中,优选BFRP筋保护层厚度为25 mm.

双膜条件下不同干播湿出水分处理对棉花生理、生长特性的影响

【目的】研究不同灌水定额及滴灌频次对棉花生理、生长特性及产量的影响规律。【方法】在新疆阿克苏地区沙雅县开展大田试验。试验共设计5个不同灌水定额及滴灌频次处理(S_(1):675 m^(3)/hm^(2),S 2:900 m^(3)/hm^(2),S_(3):1125 m^(3)/hm^(2),S 4:675 m^(3)/hm^(2)+450 m^(3)/hm^(2),S_(5):675 m^(3)/hm^(2)+300 m^(3)/hm^(2)+150 m^(3)/hm^(2)),1个冬灌对照处理(CK:2700 m^(3)/hm^(2)),分析不同水分处理对棉花生理、生长状况及产量的影响。【结果】(1)在株高及干物质量表现上,随灌溉定额增加,在苗期至吐絮期呈先减小后升高的趋势,其中CK与S_(1)处理在苗期无显著差异,与S_(3)处理在蕾期至吐絮期差异性较小。随滴水频次增加,在苗期至吐絮期呈显著升高趋势,其中CK与S_(5)处理差异性较小。(2)在叶绿素荧光表现上,随灌溉定额增加叶绿素荧光参数呈显著降低趋势,其中CK显著大于各灌水定额处理。随滴水频次增加叶绿素荧光参数逐渐增加,其中CK与S_(5)处理荧光参数差异性较小。叶绿素荧光参数Fm′值与棉花群体叶面积指数呈良好线性关系,Fo′值与干物质累积量建立的相关性模型决定系数较高。(3)在群体生理指标及产量表现上,随灌溉定额及滴水频次增加棉花群体生理指标呈逐渐升高的趋势,其中CK与S_(5)处理差异性较小。各干播湿出处理中S_(5)处理棉花产量及灌溉水分生产效率显著较高,与CK处理相比,产量大小无显著差异,灌溉水分生产效率升高26.7%。【结论】低出苗水量、高滴水频次处理(S_(5))对于棉花生长促进作用更强,作物产量更高,且有着较高的灌溉水分生产效率,能够达到节水增产的目的。

不同覆盖材料和灌溉量对机采棉产量形成及有效积温生产效率的影响

【目的】研究不同覆盖材料和灌溉量对机采棉产量形成及有效积温生产效率的影响。【方法】采用裂区试验设计,以地膜覆盖材料(裸地(A_(1))、高堡膜覆盖(A_(2))、普通PE地膜覆盖(A_(3))为主区),灌溉量(3150 m^(3)/hm^(2)(W 1)、4050m^(3)/hm^(2)(W_(2))、4950m^(3)/hm^(2)(W_(3)))为副区3个灌溉量,分析不同覆盖材料和灌溉量对机采棉产量形成及有效积温生产效率的影响。【结果】随着灌溉量的增加,干物质积累速率加快,但棉田土壤温度逐渐降低。在不同覆盖材料条件下,A_(2)处理较A_(1)和A_(3)处理可提高苗期棉田土壤温度,分别提高2.39、0.20℃,A_(2)处理的全生育期有效积温较A_(1)和A_(3)分别提高6.96%、0.77%。二者互作条件下,W 1A_(2)处理的棉田有效积温最高为1476.98℃·d,单株干物质生长速率最快,达到1.61 g/d,生殖器官占比最高为47.00%,产量最高为6431.10 kg/hm^(2),有效积温生产效率达到4.58 kg/(hm^(2)·℃·d)。【结论】高堡膜覆盖条件下,采用3150 m^(3)/hm^(2)的灌溉量时,有助于提高棉田土壤温度,增加有效积温,提高生殖器官的分配比例,促进棉花籽棉产量和有效积温生产效率的提高。

非连续干湿循环对混凝土表层氯离子迁移的影响规律

为探究滨海环境中干湿循环的不规律性对混凝土表层氯离子传输的影响,设计了连续、非连续干湿循环对比试验,研究了不同干湿循环下水灰比和干湿循环制度对混凝土表层氯离子含量分布规律及对流区氯离子含量变化规律的影响.结果表明:当自然风干时间/湿润时间(t_(d)/t_(w))较大时,由于双向对流与扩散的传输现象,使得氯离子含量在对流区存在1个拐点;对流区深度基本随水灰比减小而减小;连续干湿循环下氯离子峰值含量随着t_(d)/t_(w)的减小而增大;相较于连续干湿循环而言,非连续干湿循环对表层氯离子含量随深度的变化规律和氯离子峰值含量的影响较大.

不同水分处理干播湿出水热盐效应对棉花出苗率的影响

【目的】研究适合双膜覆盖条件下棉花干播湿出的灌溉方案。【方法】在新疆阿克苏市沙雅县设置大田试验,设计3个灌水定额处理(S_(1):675 m^(3)/hm(2),S_(2):900 m^(3)/hm(2),S_(3):1125 m^(3)/hm(2))、2个滴水频次处理(S_(4):675 m^(3)/hm(2)+450 m^(3)/hm(2),S 5:675 m^(3)/hm(2)+300 m^(3)/hm(2)+150 m^(3)/hm(2))和1个冬灌对照处理(CK:2700 m^(3)/hm(2)),共6个处理。分析不同灌溉定额及滴水频次对土壤水盐运移、水热效应及出苗率的影响。【结果】(1)在0~40 cm土层,滴水频次相同,随灌水定额增加土壤平均含水率逐渐增加,表现为S_(1)<S_(2)<S_(3);灌水定额相同,随滴水频次增加土壤平均含水率逐渐增加,表现为S 5>S_(4)>S_(3);CK处理土壤平均含水率显著小于各干播湿出处理。(2)0~40 cm土层,滴水频次相同,灌水定额越大灌后土壤脱盐率越高;灌水定额相同,滴水频次越少,土壤脱盐率越高;CK处理脱盐率显著大于各干播湿出处理。(3)0~40 cm土层,滴水频次相同,随灌水定额增加土壤日均温度逐渐减小,表现为S_(1)>S_(2)>S_(3);灌水定额相同,随滴水频次增加土壤日均温度逐渐降低,表现为S_(3)>S_(4)>S 5;CK处理土壤日均温度与S_(1)处理无明显差异,且显著大于其余各干播湿出处理。(4)出苗率随灌水定额的减少而升高,随滴水频次的减少而降低。各处理出苗率表现为CK≈S_(1)>S_(2)≈S 5>S_(4)>S_(3)。【结论】综合各处理土壤水盐、地温及出苗情况,S_(1)(675 m^(3)/hm(2))为最佳出苗水处理。

三合一氯气干燥塔运行总结

将氯气干燥工艺由原来的一级填料干燥塔、二级填料干燥塔和泡罩干燥塔的三塔流程改为一塔干燥,简化了流程,稳定了生产,提高了企业的市场竞争力。工艺改造后,每年可节省费用360000元。

分段预制盖梁干接拼装施工关键技术

以上海S3项目施工1标段为背景工程,介绍分段预制干接拼装盖梁施工在项目中的应用情况。从预制、运输、现场分段安装、预应力施工及固定措施拆除等环节出发,重点阐述分段预制盖梁干接拼装施工工艺和关键技术,可为类似项目提供一定的参考。

云南西双版纳2021年一次冬季暴雨天气浅析

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