煤矸石中氧化铝溶出的实验研究

煤矸石是主要的煤系固废,其中氧化铝的含量占到25%左右,又是一种可以利用的资源.本实验以山西潞安煤矿的煤矸石为原料,采用正交试验的方法,研究了盐酸作为酸浸介质浸取煤矸石中氧化铝.主要影响因素为煅烧温度、酸量、固液比及酸浸时间,最佳工艺条件为:煅烧温度为650℃,酸量为225mL(按照煤矸石中氧化铝和盐酸反应的摩尔比为1:6计)、固液比为1:3、酸浸时间为3 h,单因素重复试验结果和正交实验的结果相符,在最佳条件下,氧化铝的溶出实验验证结果表明,三氧化二铝溶出率为71.49%.本研究对实现煤矸石的资源化综合利用具有重要的意义.     

卫生填埋场伊-灰复合土防渗层抗渗性能现场模拟试验研究

以伊（伊利土）－灰（粉煤灰）复合土和普通粘土作为对比进行了卫生填埋场防渗层抗渗性能现场模拟试验,防渗层密度１．８ｇ／ｃｍ＾３,模拟降水强度１．７－２．１ｍｍ／ｍｉｎ,试验结果表明：伊－灰复合土防渗层在抗渗性能上明显优于普通粘土防渗层;模拟降水发生后,卫生填埋场的渗滤液发生期可长达２５ｄ左右,８０５的渗滤液发生于前２／５时段。     

南方土壤酸沉降敏感性研究Ⅶ——盐基淋溶与缓冲机理

研究了模拟酸雨对我国南方主要土壤类型盐基离子淋溶的影响,结果表明,ＰＨ低于３．０或３．５时,盐基离子淋溶总量明显增加,但ＰＨ高于３．５时,则影响不明显。     

模拟实验研究煤矿酸性水中Co、Ni、Zn、Cd、Al、Cr、As、Pb可溶性金属迁移行为

通过模拟煤矿酸性水环境,对来自2个不同产地的煤系非均质黄铁矿样品进行了不同固液比的淋滤实验,对反应体系物理化学状态以及其中的Co、Ni、Zn、Cd、Al、Cr、As、Pb8种元素的释放行为进行了长达312h跟踪检测和对比.结果显示,在2种不同来源的煤系黄铁矿样品反应体系中,Co、Ni、Zn、Cd的释放行为均为持续升高,说明这些元素的释放受体系中物理化学状态的影响相对较小,在液相中具有较高的迁移行为;Al、Cr、As、Pb在不同样品体系中的释放行为差异较大,受到体系pH值、吸附及共沉淀作用等因素的影响,是相对不易迁移的元素.煤矿酸性水环境中元素释放和迁移行为主要受到黄铁矿的氧化还原反应速率、反应体系介质pH值和围岩矿物学性质3个宏观因素控制.     

Using Multiple Chemical Criteria for Critical Loads of Acidity in Maritime Regions

Critical loads have become a well-establishedpart of the work programme of the UnitedNations Economic Commission for Europe (UNECE) Conventionon Long-Range Transboundary Air Pollution (CLRTAP). Thelinking of ecosystem response to deposition level is thecentral principal of the critical loads approach. Foreach ecosystem, a biological indicator is chosen, asuitable chemical criterion selected and a criticalchemical limit assigned. The Bc:Al ratio is the mostwidely used chemical criterion for setting criticalloads. However, critical loads based on this criterionare very sensitive to marine deposition. In regions whichreceive high depositions of marine-derived base cations,such as the Republic of Ireland (ROI) and the UnitedKingdom (UK), critical loads based on the Bc:Al criterionwill inevitably be high. Therefore, it is proposed thatcritical loads are estimated using multiple chemicalcriteria with appropriate critical limits to protect thechosen biological indicators. The range of publishedchemical criteria have been applied to the ROI and theUK. The chemical criterion corresponding to the mostsensitive critical load have been mapped and thecontribution of each to the final maps investigated. Thesimulations indicate that the most sensitive criteria forsetting critical loads are based on specifying critical Hor Al concentrations. However, the choice of critical limits andmodel parameters will ultimately effect the criticalloads. Therefore, it is important that appropriate criticallimits are chosen to protect the biological indicator andreceptor ecosystem from long-term damage.     

TRANSPORT AND FATE OF ATRAZINE IN MIDWESTERN RIPARIAN BUFFER STRIPS1

ABSTRACT: The fate of pesticides entering the Riparian Buffer Strips (RBS) has not been well documented. This study compared the transport and fate of atrazine in soil of three‐, five‐, and nine‐year‐old switchgrass (Panicum virgatum L.) RBS to that in adjacent soils cropped to a corn‐soybean rotation or a grass‐alfalfa pasture. Undisturbed soil columns were collected from the RBS and cropped areas within the Bear Creek watershed, near Roland, Iowa. Atrazine and bromide breakthrough curves obtained using intact soil columns under saturated conditions were described by a two‐region, mobile‐immobile transport model. Preferential flow of bromide and atrazine was evident in five‐and nine‐year‐old RBS soil, but there was little difference in transport characteristics between these two RBS soils and the adjacent cropped soils. There was a trend towards an increase in dispersion coefficients between the five‐and nine‐year‐old RBS sites, which suggests an increased degree of preferential flow with increasing RBS age. Despite similar texture and organic C contents, atrazine sorption was significantly greater in RBS soil than the adjacent cropped soil. Cropped soil degraded atrazine faster than the RBS soil. The rapid degradation of atrazine in the corn‐soybean soil adjacent to the five‐year‐old RBS (atrazine half‐life of 19 days) appeared to be due to a larger population of atrazine‐degrading microorganisms. Atrazine‐degrading microorganisms in the corn‐soybean soil were 50,940 cells g^‐1 soil compared with 2,970 cells g^‐4 soil in 5‐year‐old RBS soil which resulted in 60 percent mineralization of [¹⁴C‐UL‐atrazine] in the corn‐soybean soil.     

PESTICIDE OCCURRENCE IN GROUNDWATER IN TULARE COUNTY, CALIFORNIA

Geographic Information Systems (GIS) and statistical methodswere used to identify the major factors affecting pesticideleaching in groundwater from agricultural fields in TulareCounty, California. Residues of bromacil, diuron, and simazineincreased in groundwater during the 1980s. Bromacil, diuron,and simazine contamination were positively correlated to cropdiversity and water demand. Diuron and simazine were positively correlated to groundwater depth and negatively correlatedto soil water-holding capacity. DBCP concentration in groundwater was related to the crop coverage. The Goss model wasused to examine soil-pesticide interactions and a PesticideContamination Index (PCI) was developed. Areas having highleaching potentials were mainly associated with citrus andorchards and coarse-textured sandy soils along the SierraNevada foothills, while areas having low leaching potentialswere associated with field crops and clay soils of the southwest region. The PCI was largest for DBCP during the 1980s,suggesting that it was the most significant contaminant before1977 when it was widely used; however, wells were not testedfor this pesticide during that period. Twelve years after DBCPwas banned, it was still the most significant health riskcontaminant. Spatial maps showing the distribution of leachingpotentials and soil interactions for these pesticides canprovide useful information to regulatory and planning agenciesfor land use planning and pesticide management.     

Impact of Post-Methanation Distillery Effluent Irrigation on Groundwater Quality

Molasses-based distilleries generate large quantities of effluent, which is used for irrigation in many countries including India. The effluent is rich in organic and inorganic ions, which may leach down and pollute the groundwater. An on-farm experiment was conducted to assess the impact of long-term irrigation with post-methanation distillery effluent (PMDE) on nitrate, sulphate, chloride, sodium, potassium, and magnesium contents in the groundwater of two sites in northwest India. Electrical conductivity (EC), pH, total dissolved solids (TDS), sodium adsorption ratio (SAR) and colour were also determined to assess the chemical load in the groundwater. Nitrate content in the groundwater samples ranged from 16.95 mg L⁻¹ in the unamended fields to 59.81 mg L⁻¹ in the PMDE-amended fields during the 2-year study (2001–2002). Concentrations of TDS in water samples from tubewell of the amended field was higher by 40.4% over the tubewell water of the unamended field. Colour of the water samples of the amended fields was also darker than that of the unamended fields. The study indicated that the organic and inorganic ions added through the effluent could pose a serious threat to the groundwater quality if applied without proper monitoring.     

Evaluation of Lead Availability in Amended Soils Monitored Over a Long-Term Time Period

Two different soil amendment processes were evaluated for reducing lead availability from a contaminated soil at a demonstration study site, to reduce potential public health and environmental concerns. A limited variety of in vitro laboratory “availability” tests (relative bioaccessible and environmental mobility) were performed to determine if the available lead in the contaminated soil would be less available after in situ soil amendment (chemical treatment). The relative bioaccessibility results were evaluated in both a short-term period (within 24 h after treatment) and over a long-term time period (quarterly basis for 5 years). Reduction in relative bioaccessibility was noted for one of the treatments immediately after treatment; however, both treatments indicated a significant upward trend in bioaccessibility values over a 5-year time period after treatment. The comparison between the treated units and the control units indicated that the long-term effectiveness of the treatment processes could not be demonstrated.     

危险废物焚烧飞灰玻璃化产物危险特性

《国家危险废物名录》中HW18焚烧处置残渣明确规定,"危险废物等离子体、高温熔融等处置过程产生的非玻璃态物质和飞灰"判定为危险废物.为降低危险废物焚烧飞灰的生态环境危害,并期望对其进行更好的资源化利用,采用国际前沿的玻璃化技术对危险废物焚烧飞灰进行处置,制备得到玻璃态物质,即玻璃体.结果表明:①焚烧飞灰掺杂不同比例的高岭土、SiO₂、CaO后,可形成符合玻璃体烧制条件的CaO-Al₂O₃-SiO₂系统,经过2 h 1 400℃高温熔融,几种不同配料比的玻璃体均可形成无定型的、微观表面平滑的结构.②玻璃体对Zn、Cr、Pb、Cd和As等重金属均有不同程度的固化作用,采用HJ/T 300-2007《固体废物浸出毒性浸出方法醋酸缓冲溶液法》测得的重金属浸出浓度均低于焚烧飞灰.③采用Hakanson公式中潜在生态危害模型对焚烧飞灰及玻璃体进行风险评价显示,几种玻璃体的RI（潜在生态危害风险指数）均在50~100范围内,呈中等风险,低于焚烧飞灰（299.34）.④效果最优的玻璃体的碱度（CaO/SiO₂,质量分数）为0.3,呈现浅绿色且质地透明的外观形貌,它对Zn、Cr的浸出浓度分别为0.12、0.05 mg/L,但均未检出Pb、Cd、As,远低于焚烧飞灰浸出浓度及GB 16889-2008《生活垃圾填埋场控制标准》中生活垃圾焚烧飞灰和医疗废物焚烧残渣浸出限值（Zn、Cr、Pb、Cd、As浸出浓度限值依次为100、4.5、0.25、0.15、0.3 mg/L）,该玻璃体的RI为60.05,远低于焚烧飞灰的299.34.研究显示,采用玻璃化技术对焚烧飞灰进行处置后,焚烧飞灰可形成无定型的玻璃态结构,碱度为0.3时,玻璃体的重金属浸出浓度最低,且潜在生态风险最低,为最适用于焚烧飞灰玻璃化技术的调控比例.