粉煤灰的农业利用及其环境放射性污染评价

对北京、内蒙、宁夏、河北、广东和天津等地大型火力发电厂粉煤灰的采样分析表明：粉煤灰中主要放射性成分为２３８ Ｕ 、２３２ Ｔｈ 衰变系和４０ Ｋ ,比活度范围分别为９３２ ～２８３８ Ｂｑ／ｋｇ ,８０３ ～２３８８ Ｂｑ／ｋｇ 和１１５６ ～４４７４ Ｂｑ／ｋｇ 。试样模拟研究表明, 当粉煤灰施用量达６７５ Ｔ／ｈ ｍ ２ 时,土壤中天然放射性核素２２６ Ｒａ 和２２８ Ｒａ 的比活度分别是对照的３５６ 倍和２６０ 倍。土壤中天然放射性核素的比活度和地面１ ｍ 高处空气吸收剂量及地面γ辐射所致人均年有效剂量当量随粉煤灰的施用量增加呈现增加的趋势。土壤中２２８ Ｒａ 的比活度与粉煤灰施用量的相关性可表示为ｙ ＝ ２２０４ｘ ＋ １７２５ ,（ｒ２ ＝ ０９９０９） ;对于２２６ Ｒａ ,ｙ ＝ ２１３８ｘ ＋ ２４５ ,（ｒ２ ＝ ０９９６６） 。地面１ ｍ 高处空气吸收剂量率（ Ｄ） 与粉煤灰施用量的相关性可表示为：ｙ ＝ １８９６ｘ ＋ ３８７５ ,（ｒ２ ＝ ０９８９１ ） 。有效剂量当量（ Ｈ） 的变化与施用粉煤灰的量之间的相关性可表示为：ｙ ＝ ２３２４５ｘ ＋４７５０５ ,（ｒ２ ＝ ０９８９１） 。当粉煤灰施用     

华东地区粉煤灰农田模拟试验和放射性分析

对浙江、福建、山东、江西、安徽和江苏 6省部分大型热电厂粉煤灰的采样分析表明 :粉煤灰中主要放射性成分为2 38U、2 32 Th衰变系和4 0 K ,比活度范围分别为 75～2 84Bq kg、60～ 1 64Bq kg和 1 2 0～ 73 8Bq kg。粉煤灰农田施用模拟试验表明 :当施用量达到 52 5t hm2 时 ,土壤中天然放射性核素2 2 6 Ra和2 2 8Ra的比活度分别是对照的 1 88倍和 1 3 9倍 ;生产的食品 (稻谷、玉米籽和麦粒 )中 2种核素的比活度与对照没有明显差异 ,对作物的食用安全性影响不明显     

农用稀土天然放射性及其对土壤和作物污染的评价

１９８１－１９９３年对我国农用硝酸稀土样品的天然放射性进行了监测，查明农用稀土化合物中主要的天然放射性成分是＾２３２Ｔｈ，平均含量为５４．９Ｂｑ．ｋｇ＾－１。通过１０年定位试验和两年喷施不同放射性活度稀土的田间试验，均未检测出土壤中天然放性活度的变化，也测不出作物体中α、Ｕ和＾４０Ｋ活度增加的趋势，仅作物茎叶＾２３２Ｔｈ活度有增加。     

成都经济区放射性环境评价分析研究

运用区域1/25万土壤化探数据中铀、钍、钾的含量数据,对成都经济区的放射性水平进行了评价。介绍了放射性核素含量分布情况和环境放射性水平,通过成都经济区地质情况和成都经济区放射性环境分布情况,分析了地质条件对成都经济区环境放射性的影响,并初步研究了地质条件影响放射性水平的原因。最后总结了成都经济区地质环境对天然放射性水平分布情况的影响规律:除龙门山褶皱带和峨眉山-瓦山断块少部分地区外,绝大部分地区γ射线内外照射指数都在国家建筑材料放射性核素限量标准控制式的范围内;地质构造、地表出露岩层和地表水对放射性水平有较大的影响。     

粉煤灰对土壤性质改善及肥力提升的作用研究进展

我国粉煤灰生产量巨大,农业生产中合理利用粉煤灰是提高粉煤灰综合利用水平的重要途径之一。本文综述了近年来粉煤灰在土壤结构改良、促进作物生长发育以及粉煤灰衍生肥对农业生产的作用等方面的研究进展。最后,对粉煤灰农业化资源利用风险进行了分析,并根据当前粉煤灰研究中存在的主要问题,指出了今后粉煤灰农用研究的重点。     

微波消解-分光光度法测定农用粉煤灰中的硼

研究了分光光度法测定农用粉煤灰中硼时样品的微波消解方法,建立了合理的分析步骤.试验结果表明:微波完全消解粉煤灰仅需25 min,相对标准偏差5.8% ～ 7.3%,其方法的加标回收率为94% ～ 109%.结果表明,微波消解-分光光度法是测定粉煤灰中硼的一种快速、准确且低环境污染的方法.     

粉煤灰资源农业利用的现状与展望

本文综述了粉煤灰资源农业利用的现状与问题。粉煤灰资源农业利用的主要途径有填坑造地、纯灰种植农作物、用作土壤改良剂和肥源等。运输与施用成本高以及大量施用引起的污染物质在土壤、植物中积累是限制粉煤灰资源农业利用的主要因素,发展磁化粉煤灰和用粉煤灰制造高效肥料是粉煤灰农业利用的发展方向。     

粉煤灰的特性及其农业利用

参阅有关文献,本文在对粉煤灰的物理、化学特性剖析的基础上,综合论述了粉煤灰资源农业利用的现状,包括粉煤灰的改土培肥效应、粉煤灰的增产效果、粉煤灰对土壤中重金属含量及生物有效性的影响、磁化粉煤灰及粉煤灰复混肥的应用前景、粉煤灰资源农业利用的环境效应评价等,同时也指出了粉煤灰农用的潜在问题     

真菌是环境保护的好助手

<正> 科学家发现,早为人类熟悉和利用的真菌,能帮助人类防止环境污染,维护生态平衡。在环境放射性污染物和包括二恶英在内的有毒物质天然解毒过程中,真菌起着十分重要的作用。在“天然吸尘器”的功能中,真菌的意义比植物更大。可以预料,培育真菌的技术将会成为人类保护土地,防止生态灾难的一项重要工艺。     

采煤沉陷地粉煤灰充填复垦土壤元素淋溶特性实验研究

以采煤沉陷地粉煤灰充填复垦土壤的污染问题为研究背景，从措施的实地可操作性出发进行实验设计，采取了灰土，灰矸不同比例混合和隔层排列处理措施，对淋溶液中各检测元素的含量进行了分析和比较。结果表明，粉煤灰中大部分元素在淋溶液中含量高，淋溶作用强烈，在各种元素中，大多数污染重金属元素在淋溶液中的含量极低，只有铬的含量略高。不同处理设施对粉煤灰的淋溶特性有显著影响。     

煤矸充填复垦土壤可溶性镉的分布特征与运移模拟

在现场调查研究煤矸石充填复垦地上覆土壤可溶性镉含量的基础上,应用田间小区试验,模拟土壤可溶性镉的迁移特征。结果表明,土壤可溶性镉在时间和空间维度上都具有明显的分布特征：可溶性镉浓度沿剖面深度逐渐递增,即离煤矸石层越近,浓度越高;随时间推移,土壤下部接近煤矸石处,可溶性镉浓度的富集现象存在。模型模拟结果显示,由于土壤毛管力作用,接近煤矸石层的土壤可溶性镉浓度每年可增加10%左右,但表层土壤（0~40cm）增加速度缓慢或反而有所下降。尽管如此,由于植物根系活动,煤矸石中镉析出具有一定的生态环境风险。     

鸡西矿区矸石山基质改良研究

以黑龙江省鸡西煤矿区为研究区,利用鸡西本地河道清淤土和电厂粉煤灰两种固体废弃物作为改良剂进行矸石山基质改良研究。结果表明:改良后基质的pH值平均由对照的8.26下降到6.90;饱和含水率平均比对照提高了59.84%,持水时间比对照延长了11.5 d;速效氮含量达到316.05 mg/kg,比对照提高了4.38倍;速效磷含量达到24.224 mg/kg,比对照提高了43.53倍;对家榆、紫穗槐、紫花苜蓿的高生长、地径生长和冠幅增长等都有显著的促进作用。利用河道清淤土和电厂粉煤灰联合配施具有良好的基质改良效果,为东北地区矸石山基质改良提供了一条有效途径,也为固体废弃物合理再利用提出新的途径。     

Studies on the Phase Mineralogy and Leaching Characteristics of Coal Fly Ash

The phase mineralogy and leaching characteristics of some Indian coal fly ashes were studied to assess their safe disposal in abandoned coal mines. Since, fly ash contains a number of toxic trace elements, the leaching of fly ash was tested using strong acid/alkali solutions and distilled water under different conditions (solid-liquid ratio, leaching time, pH) in the temperature range of 30-100 °C. It was found that the concentration of various metals in leachates depends on their chemical nature, association with mineral phases of ash and follows the almost similar concentration profile to that of iron, especially in acidic medium. The distribution of toxic trace elements in fly ash and their leachability were found to depend on the amount of unburnt carbon and iron in fly ash. In alkaline medium, leaching of iron and toxic trace elements (except As) from fly ash was very negligible. Hence, alkali treatment of coal fly ash is desirable for its safe use in refilling of coal mines.     

Assessing Trace Element Uptake by Vegetation on a Coal Fly Ash Landfill

Improved methods are required to assess the risks posed by the uptake of potentially toxic elements such as selenium (Se), boron (B), and molybdenum (Mo) by vegetation on contaminated sites. In order to develop such methods and assess risk, vegetation was collected from two sites on a soil-capped coal fly ash landfill near Dunkirk, New York, during June of 1991 and June and August of 1992. The mean concentrations (μg g-1 dry weight) of Se and Mo in the shoots did not exceed, respectively, 0.12 and 18.7 in bird's-foot trefoil (Lotus corniculatus L.), 0.06 and 12.1 in red clover (Trifolium pratense L.), 0.07 and 5.3 in timothy (Phleum pratense L.), and 0.09 and 2.2 in a mixture of grasses. These concentrations were greater than those in the same species harvested concurrently from a non-landfill site. The mean concentrations of B at the landfill ranged from 29 to 53 μg g-1 in the legumes and from 2 to 11 μg g-1 in the grasses, less than those at one non-landfill site but greater than those at another. Within the landfill, the concentration of Se in grasses was not correlated with the concentration of Se in soil and fly ash. The concentration of Se in grasses on both landfill sites was double that of grasses on the non-landfill site despite higher mean concentrations of Se in the upper soil (0–15 cm) on the non-landfill site. Therefore grass roots seem to be accessing Se from the ash by means of mass flow or other mechanisms. Based on our findings of significant variation in trace element uptake among species, harvests, and locations within sites, we recommend that contemporaneous transect sampling of at least two species be used to assess uptake of potentially toxic trace elements on landfills or other sites where contamination may occur.     

Pilot Study of Coal Ash Compost

? Washington State University, in Pullman, Washington, has recently begun plans to compost approximately 16,500 tons of the waste generated annually on campus. Animal manure from the university dairy and from Veterinary Sciences will contribute 10,000 tons. A food pulper has been installed in one of the dining halls and will contribute approximately 440 tons. Mixed waste paper that does not have a market, landscape trimmings and used potting soil will also be composted. In addition, Washington State University power plant generates approximately 1,000 tons of coal ash annually. This paper discuss a pilot project to determine the feasibility of including coal ash in the compost mixture.     

Analysis of Coal Ash for Trace Elements and their Geo-environmental Implications

This study determined the content of trace elements in coal ash collected from a coal-fired thermal power plant using local coal from Sawarak, Malaysia. This is crucial for the potential impact on the geoenvironment from its disposal and utilization; as coal ash has recently been produced locally in substantial amounts and very limited data is available. The trace elements concentrations presents in coal ashes are compared with the reported coal ash concentrations and the risk for the local wet tropical geoenvironment from the perspective of its vulnerability to these is studied for an indication of potential environmental implications on the wet tropics. The trace elements were found to be in concentrations that, if applied or inadvertently released into the environmental media, present a potential hazard and further necessary research in this regard is indicated.     

Coal sorbent system for the extraction and disposal of heavy metals and organic compounds

The Coal Sorbent System (CSS) utilizes a newly developed coal-based sorbent, which has the combined characteristics of an activated carbon and ion exchange resin. The low cost and excellent combustion characteristics (including very low sulfur and ash) of the coal sorbent enabled the development of a system to extract metals and organics from aqueous streams, concentrate them on the sorbent and encapsulate the metals (destroy organics) utilizing developed incineration or vitrification processes. Coal Sorbent is produced by the chemical leaching of ordinary coal using the TRW Molten Caustic Leaching (MCL) process. The coal sorbent produced from the MCL process is much like activated carbon with a large internal surface area (up to 1000 m²/g). In addition to its high surface area, the coal sorbent, unlike activated carbon, has inherent carboxyl groups much like ion exchange resins that can remove heavy metals from wastewater. Heavy metal capacities up to 70 mg/g (7%) of coal sorbent have been demonstrated. The coal sorbent has both a high surface area and a large concentration of carboxyl groups on the surface. These two features enable the Coal Sorbent to be used as a wastewater treating medium to remove both organics (high carbonaceous surface area) and heavy metals (carboxyl ion exchange groups). Once the heavy metals and organics are adsorbed on the virtually sulfur and ash-free coal sorbent, the spent coal sorbent can be processed by commercially available combustion/vitrification processes to encapsulate the metals and destroy the organics. Waste volume reductions as high as 420,000:1 have been demonstrated for uranium groundwater applications at an estimated costthrough disposal of < $0.001/gallon water treated.     

煤矿区矸石山周边土壤重金属污染特征与规律

以山东某矿区为例,通过淋溶模拟实验,研究了煤矸石中重金属的淋溶规律,并探讨了煤矸石山周边土壤重金属污染特征.结果表明:风化矸石淋滤液中的Zn、Pb、Cr和Cu浓度较高,并很快稳定;新鲜矸石在淋溶初期检出Zn,其它重金属元素没有检出;风化矸石淋滤液中重金属的含量要高于未风化矸石.矸石山周边表层土壤中的Zn、pb、Cr和Cu较高,且浓度高出矸石淋溶液许多倍,表明煤矸石中重金属淋滤具有长期性,矿区土壤对重金属具有迁移性和富集性.表层土壤重金属含量随着距煤矸石堆的距离增加而呈明显的下降趋势,充分表明矸石山对周边土壤造成了严重的重金属污染,而且在土壤剖面上,重金属含量表现出随土壤深度的增加而降低的趋势.