A Seasonal Assessment of the Impact of Coal Fly Ash Disposal on the River Yamuna,Delhi, II. Biology

The impact of fly ash on the biology of the Yamuna River, Delhi, was studied. Effluents come from a 200 MW capacity I.P. thermal power station. Seasonal variations in the biological features in the non-impacted (Y-1) and the impacted (Y-2) segments of the river receiving fly ash effluents were studied. 60 genera of phytoplankton including 29 Chlorophyceae, 19 Bacillariophyceae, 8 Cyanobacteria, and 4 Euglenophyceae were recorded. Phytoplankton diversity was reduced at the impacted site in comparison to the non-impacted site of the river and substantial changes in the composition of various groups inhabiting these areas were observed. Zooplankton were also reduced at Y-2 compared to Y-1, especially rotifers and protozoans, while copepods and nauplii larvae were not affected to the same degree. Species diversity was not significantly different at Y-2 and Y-1 but similarity index varied from low to high between the two stations. Thus, not only was the density, number of genera and diversity reduced, even the generic composition of the plankton was markedly affected in the impacted waters. The observed perturbations could be due to sedimentation of ash particles, pH or elevated metal or salt concentration. A change in the concentration of one or more constituents disturbs the relationship between biota and could be the possible cause of reduced densities in the impacted waters.     

Solubility and Fractionation of Different Metals in Fly Ash of Powder River Basin Coal

Coal is one of the major sources of fuel for electricity production and will continue to be used for many more decades. Thus, it is important to study the effects of disposal of coal burning byproducts including fly ash into the environment. In this study, the solubility of cations and anions from the fly ash in water is discussed. Also, the fractionation of different metals from fly ash in water is studied to understand which fraction of the metals would likely be mobilized. The results from these studies suggested that the metals in the fly ash are bound mostly to carbonate, organic, and residual fractions. Also, when water solubility data are modeled with a geochemical model (Visual MINTEQ), the saturation index predictions suggested that brucite (Mg(OH)₂) and calcite (CaCO₃) could potentially precipitate and mineralize the atmospheric CO₂. Such mineralization process could potentially reduce the leaching of toxic metals from fly ash. Results from this study will be helpful in understanding the fate of different metals from fly ash land disposal environments.     

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.     

Effects of High Rates of Coal Fly Ash on Soil,Turfgrass, and Groundwater Quality

A field study (1993–1996) assessed the effects of applying unusually high rates of coal fly ash as a soil additive forthe turf culture of centipedegrass (Eremochloa ophiroides).In addition, the quality of the soil and the underlying groundwater was evaluated. A Latin Square plot design was employed to include 0 (control, no ash applied), 280, 560, and 1120 Mg ha^-1 (mega gram ha^-1, i.e., tonne ha^-1)application rates of unweathered precipitator fly ash. The onceapplied fly ash was rototilled and allowed to weather for 8 months before seeding. Ash application significantly increasedthe concentrations in plant tissue of B, Mo, As, Be, Se, and Bawhile also significantly reducing the concentrations of Mg, Mn,and Zn. The other elements measured (i.e., N, K, Ca, Cu, Fe, Ag,Cd, Cr, Hg, Ni, Pb, Sb, Tl, Na, and Al) were not affected. Of these elements Mg, Cu, and Mo concentrations in plant tissue increased with time while B and Se decreased temporally. The diminution of B and Na appears to be related to the leaching ofsoluble salts from ash-treated soils. Of all the elements measured, only Mn produced significant correlation (p = 0.0001) between the tissue and soil extractable concentrations. Ash treatment elevated the soil pH to as high as 6.45 with theenhanced effect occurring primarily in the 0–15 cm depth. Soilsalinity increased with the application rate with the largestincreases occurring in the initial year of application. However,by the second year, most of the soluble salts had already leachedfrom the treatment zone into deeper depths, and by the fourthyear, these salts had completely disappeared from the profile.The chemical composition of the underlying groundwater was notadversely impacted by the ash application. Plant tissue and groundwater data however, indicate that much higher rates of fly ash can be used on this type of land use where the plant species is tolerant of soil salinity and does not appear tobioaccumulate potentially toxic trace elements.     

降雨因子对粉煤灰产流产渣的影响

为研究降雨因子对粉煤灰产流产渣的影响,揭示粉煤灰产流产渣的规律,采用径流小区定位观测试验,研究雨季期粉煤灰径流小区在自然降雨条件下的产流产渣特征。结果表明:(1)观测期内总降雨量为1 160.0mm,侵蚀降雨量为720.7mm,7月份降雨、侵蚀降雨均最多,分别为409.6mm和217.1mm,暴雨的侵蚀降雨量最大,为280.1mm;(2)7月份产流产渣最多,3个小区的产流产渣量分别为0.72,1.06,0.67m~3和0.30,0.90,0.21kg,暴雨的产流产渣量最大,分别为0.62,1.02,0.73m~3和0.16,0.57,0.15kg,降雨量大于50mm的降雨产流产渣量最多,分别为0.79,0.98,0.53m~3和0.17,0.72,0.15kg,雨强大于40mm/h的降雨产流产渣量最多,分别为0.82,1.06,0.76m3~和0.21,0.87,0.19kg;(3)降雨量、I30、降雨侵蚀力与产流产渣显著相关,径流量受降雨量影响最大,产渣受降雨侵蚀力影响最大,受降雨历时的影响都最小。产流产渣与降雨量、I_(30)、降雨侵蚀力均呈多项式关系,产流与降雨历时呈线性关系,产渣与降雨历时线性关系不明显。随着降雨的持续,粉煤灰产流产渣也随之增加,侵蚀降雨量、降雨侵蚀力对其影响尤为明显。研究成果利于贮灰场粉煤灰流失的预防和治理,为贮灰场的生态恢复提供参考。     

Effect of Flue Gas Treatment on the Solubility and Fractionation of Different Metals in Fly Ash of Powder River Basin Coal

Studies were conducted to examine the effect of flue gas carbon dioxide (CO₂) on solubility and availability of different metals in fly ash of Powder River Basin (PRB) coal, Wyoming, USA. Initial fly ash (control) was alkaline and contains large amounts of water-soluble and exchangeable metals. Reaction of flue gas CO₂ with alkaline fly ash resulted in the formation of carbonates which minimized the solubility of metals. Results for metal fractionation studies also supported this fact. The present study also suggested that most of the water-soluble and exchangeable metals present in the control (untreated) fly ash samples decreased in the flue gas-treated samples. This may be due to the transfer of the above two forms to more resistant forms like carbonate bound (CBD), oxide bound (OXD), and residual (RS). Geochemical modeling (Visual MINTEQ) of water solubility data suggested that the saturation index (SI) values of dolomite (CaMg(CO₃)₂) and calcite (CaCO₃) were oversaturated, which has potential to mineralize atmospheric CO₂ and thereby reduce leaching of toxic metals from fly ash. Results from this study also showed that the reaction of flue gas CO₂ with alkaline fly ash not only control the solubility of toxic metals but also form carbonate minerals which have the potential to fix CO₂.     

Reducing Bioavailability and Leachability of Copper in Soils using Coal Fly Ash,Apatite, and Bentonite

Soils treated with two concentrations of copper (Cu; 200 and 400 mg kg^?1) were amended with three amendments (coal fly ash, apatite, and bentonite) at the rates of 1.5% and 2.5%, respectively. The effects of amendment application on the bioavailability and leachability of Cu in the soil were evaluated using the wheat uptake, single extraction, and sequential extraction tests. The addition of coal fly ash, apatite, and bentonite at the rate of 2.5% increased wheat biomass by 50.5%, 41.1%, and 61.7%, respectively. The application of amendments significantly (P < 0.01) reduced the Cu contents extract that will buy DW (deionized water), TCLP (toxicity characteristics leaching procedure), and DTPA (diethylenetriaminepentaacetic acid) in the soil. The amendments also reduced the water-soluble/exchangeable, carbonate, iron (Fe)–manganese (Mn) oxide, and organically bound fraction contents of Cu but increased the amounts of residual Cu in soil. Our results demonstrated that these amendments were effective in reducing the bioavailability and leachability of Cu in soil.     

Evaluation of Cocomposted Coal Fly Ash on Dynamics of Microbial Populations and Heavy Metal Uptake

Vicia faba, in a pot experiment with sandy and clayey soils under greenhouse conditions, was checked for growth response to different amendments with coal alkaline fly ash or cocomposted fly ash mixed with lignocellulosic residues. Soil microbial populations, pH and electrical conductivity as well as heavy metal uptake by plants were monitored. At rates of five and ten percent (on a dry matter basis) in both soils, neither fly ash alone nor cocomposted fly ash exerted any negative effect. Plant biomass production was not influenced in either clayey or sandy soil. Alkaline fly ash did not promote microbial growth when applied alone to the soils. However, cocomposted fly ash generally increased bacterial and actinomycetes counts in both soils. Fungi were not affected by ash. Due to the increase of soil pH by alkaline fly ash or cocomposted fly ash, plant uptake of heavy metals was depressed in the sandy soil. Heavy metal mobility did not cause change in the clayey soil where a high buffering capacity mitigated the effects of fly ash amendments.     

Impact of Fly Ash Amendment and Incorporation Method on Hydraulic Properties of a Sandy Soil

Coal fly ash has physical and chemical characteristics that makeit useful as a soil amendment, one of the more important beingthe potential to permanently improve the soil water relations ofsandy, drought-prone soils. We axemined changes in theinfiltration rate and water holding capacity of a sandy soilafter application of high rates (up to 950 Mg ha^-1) of aClass F fly ash. Fly ash was applied to large field plots byeither conventional tillage (CT; moldboard plow-disk) orintensive tillage (IT; chisel plow-rotovate-disk), and tomicroplots using a rototiller. Infiltration rate (i) wasmeasured in both studies with a disk permeameter on threeoccasions over a 12-month period. Ash effects on gravimetric water content (θ_g) at the 0–40 cm soil depth were measuredduring a 168 hr period following a 2.5 cm rainfall event andwater release curves (33 to 500 kPa) were constructed in thelaboratory using soils from the large plots. In both studiesi was decreased by ～80% one year after additionof fly ash and θ_gin ash-amended soil was higher than unamended soil throughoutthe 168 hr monitoring period. Soil water distribution variedwith tillage; the IT treatment had the highest θ_g increasesin the 0–20 cm depth while the CT treatment had θ_gincreases throughout the 0–40 cm depth. Soil water content anddistribution in ash-amended microplots were similar to ITtreatments. Fly ash amendment not only increased water holdingcapacity but also increased plant available water by 7–13% inthe 100–300 kPa range. These results suggest fly ash amendmentmay have the potential to improve crop production in excessivelydrained soils by decreasing i and increasing the amountof plant available water in the root zone.     

粉煤灰、砒砂岩对煤矿排土场土壤水分特性改良的研究

露天煤矿排土场土壤理化特性差直接影响复垦效果,改善土壤水分特性对排土场的复垦具有重要的理论与实践意义。本试验以内蒙古自治区的黑岱沟露天煤矿为对象进行土壤改良试验,将粉煤灰（F）、砒砂岩（S）作为添加物,对排土场土壤（L）进行3种组合处理（LF、LS、LFS）并设置不同的质量比例梯度,试验共设（L3F1、L4F1、L5F1、L1S1、L2S1、L3S1、L4S1、L5S1、L1F1S1、L2F1S1、L3F1S1、L4F1S1、L5F1S1）13种不同质量比的混合处理和（L、F、S）3种对照处理,采用离心机法测定各复配土壤在不同水吸力下的含水量,利用Gardner模型拟合并绘制其水分特征曲线,计算各复配土壤的比水容量、田间持水量、萎蔫系数、有效水含量。结果表明：（1）Gardner模型能够很好地拟合13种复配土壤的水分特征曲线,粉煤灰的添加使排土场土壤中的细土粒含量（黏粒、粉粒）增加了24.11%～37.19%,提高了土壤的持水性和供水性,添加砒砂岩能够改良土壤的持水性但不能改良供水性能。（2）排土场土壤、粉煤灰、砒砂岩质量比为1︰1︰1(L1F1S1)时持水性能最好,较排土场土壤提高了...     

Effects of Fly Ash pH on the Uptake of Heavy Metals by Chicory

Chicory was cultivated in a pot experiment using two soils of different pH. Treatments were NPK, fly ash (pH 8) + NP and fly ash (pH 12) + NP, respectively. Another series of pots received heavy metals in soluble form additionally to the described treatments. It was observed that fly ash causes generally a decrease in Zn, Cd, Ni and Cu concentrations of chicory. The reduction occurs both for the metals naturally present in the soil and, to a greater extent, for those added as salts. This effect is more evident when fly ash at pH 12, rather than that at pH 8, was used. The increase of soil-pH through the fly ash addition is the major factor decreasing heavy metal availability. It was observed that potassium originating from fly ash is not available for crop uptake.     

污泥添加粉煤灰堆肥化对Cu、Zn、Pb形态的影响

污泥中重金属的危害是影响污泥土地利用的重要因素;污泥重金属危害不仅取决于总量,其形态分布更能反映重金属的迁移性以及生物有效性。实验以木屑为调节剂,粉煤灰作为钝化剂,研究污泥堆肥前后重金属Cu、Zn与Pb的形态分布变化。结果表明,堆肥对Cu有活化作用,而添加粉煤灰堆肥化能有效抑制这种活化,起到钝化作用,堆肥化使Pb向更稳定形态转化,添加粉煤灰堆肥化对Zn的钝化效果较好,当粉煤灰添加量为35%时,对Cu、Zn、Pb 3种重金属的易迁移态均具明显的钝化效果。     

Assessment of Seasonal and Site-Specific Variations in Soil Physical, Chemical and Biological Properties Around Opencast Coal Mines

Coal mining adversely affects soil quality around opencast mines. Therefore, a study was conducted in 2010 and 2011 to assess seasonal and site-specific variations in physical, chemical, and biological properties of soil collected at different distances from mining areas in the Jharia coalfield, India. Throughout the year, the soil in sites near coal mines had a significantly higher bulk density, temperature, electrical conductivity, and sulfate and heavy metal contents and a significantly lower water-holding capacity, porosity, moisture content, pH, and total nitrogen and available phosphorus contents, compared with the soil collected far from the mines. However, biological properties were site-specific and seasonal. Soil microbial biomass carbon (MBC) and nitrogen (MBN), MBC/MBN, and soil respiration were the highest during the rainy season and the lowest in summer, with the minimum values in the soil near coal mines. A soil quality index revealed a significant effect of heavy metal content on soil biological properties in the coal mining areas.     

Immobilization of Boron and Arsenic in Alkaline Coal Fly Ash through an Aging Process with Water and Elucidation of the Immobilization Mechanism

We previously reported that a simple treatment—addition of only small amounts of water to coal fly ash (CFA) to form CFA paste followed by aging for 1–4 weeks—is advantageous for the immobilization of highly soluble B, F, Cr, and As. In this study, we investigated the leachability of Ca, SO₄, B, and As over time from non-aged and aged CFA samples to elucidate a possible immobilization mechanism. For this purpose, two types of CFA samples, one showing effective immobilization of B and As by water addition and aging (sample A) and the other showing less or no immobilization (sample B), were examined. Calcium and SO₄, B, and As in non-aged sample A dissolved immediately after the start of the leaching test, indicating that these elements existed in highly soluble particles. After the rapid dissolution, their concentrations in the leachate gradually increased, possibly due to the dissolution of glassy phases. During the 1-week leaching test, the B and As concentrations in the leachate finally decreased. The addition of only small amounts of water to CFA (Sample A) for aging produce both alkaline and supersaturation conditions for the formation of several types of Ca-bearing secondary minerals such as calcite and ettringite, which are formed under alkaline conditions. Boron and As originally existing as highly soluble particles in CFA are expected to be incorporated into and/or sorbed on these secondary minerals as water-insoluble phases. Compared to non-aged CFA, their leachability from the aged sample A remained lower throughout the entire leaching test. Possibly due to these secondary minerals being formed on the CFA surface, B and As dissolutions associated with glassy phases are also prevented. In contrast, the pH of the leachate from CFA (sample B) at the beginning of the leaching test was acidic and then abruptly became alkaline. This means that water-soluble particles that can produce acidic conditions are also contained in these alkaline CFAs. Dissolution of these substances during aging makes it difficult to generate alkaline conditions in the CFA paste. Consequently, the formation of secondary minerals and the concomitant immobilization of toxic elements are prevented.     

Air Pollution and its Impact on Lung Function of Children in Delhi, the Capital City of India

Air pollution is a major contributor to several respiratory problems, it affects the whole population in general but children are more susceptible. Exposure to automobile exhaust is associated with increased respiratory symptoms and may impair lung function in children. In view of this, the study was conducted among the children of Delhi, the capital city of India, where ambient air quality was much above the National Ambient Air Quality Standards. The study was conducted in children aged 9–17 years. Pulmonary function test was carried out following the guideline of American Thoracic Society using a portable, electronic spirometer. Air quality data was collected from Central and State Pollution Control Boards. In addition, the level of particulate matter in indoor air was measured by portable laser photometer. Lung function was reduced in 43.5% schoolchildren of the urban area compared with 25.7% of control group. The urban children had increased prevalence of restrictive, obstructive, as well as combined type of lung functions deficits. Besides higher prevalence, the magnitude of lung function deficits was also much more in them. After controlling potential confounders like season, socioeconomic conditions and ETS, PM10 level in ambient air was found to be associated with restrictive (OR?=?1.35, 95% CI 1.07–1.58), obstructive (OR?=?1.45, 95% CI 1.16–1.82), and combined type of lung function deficits (OR?=?1.74, 95% CI 1.37–2.71) in children. Spearman's rank correlation test reaffirmed the association. The study confirms that the level of air pollution is affecting the children.     

Influence of nitrogen,phosphorus, and potassium fertilization on the mineral concentrations in Medicago sativa L. I. Seasonal changes

Abstract

An established stand of Ranger alfalfa was topdressed with equal rates, but different combinations, of N, P, and K. Five harvests were taken and the material analyzed for cation concentrations.

Phosphorus application significantly increased P concentrations in alfalfa, but had little influence on concentration of other ions. Potassium applications showed striking effects by significantly increasing K levels of the forage while decreasing Ca, Mg, Cu, Zn, Al, and Mo levels.

Significant differences occurred among harvest dates for 14 of the 16 cations analyzed. Seasonal trends were evident for SiO₂, Zn, Al, Co, and Na.

Applied N, P, and K and available soil P and K were associated with cation concentration of alfalfa and these interrelationships are discussed.     

黄河源区气候温暖化及其对植被生产力影响评价

在分析黄河源区气温、降水变化的基础上，用Turc经验模式计算黄河源区的蒸散量，同时分析了近十几年来土壤湿度、植被地上净初级生产力的变化特征。结果表明，1959—2005年，黄河源区年平均气温按0．0284℃／a的变率升高，降水变化态势平稳，但蒸散量增加趋势明显，上升倾向率达0．7315mm／a，气温上升趋势与年代增加具有明显的相关性。从1987年以来土壤湿度的监测结果分析得知，黄河源区下垫面蒸散量的加大使土壤向干暖化发展。这种气候因素的影响，导致近十几年来植被地上净初级生产力按9．506g／（m^2a）的倾向率下降。     

Fog- and Rainwater Chemistry in the Tropical Seasonal Rain Forest of Xishuangbanna, Southwest China

Fogwater, fog drip and rainwater chemistry were examined at a tropical seasonal rain forest in Xishuangbanna, southwest China between November 2001 and October 2002. During the period of observation, 204 days with the occurrence of radiation fog were observed and the total duration of fog was 1949 h, of which 1618 h occurred in the dry season (November to April), accounting for 37.0% of the time during the season. The mean pH of fogwater, fog drip and rainwater were 6.78, 7.30, and 6.13, respectively. The ion with the highest concentration for fog- and rainwater was HCO₃ ^?, which amounted to 85.2 and 37.3 μeq l^?1, followed by Ca²⁺, Mg²⁺ and NH₄ ⁺. Concentrations of NO₃ ^?, HCO₃ ^?, NH₄ ⁺, Ca²⁺, and K⁺ in fogwater samples collected in the dry season were significantly greater when compared to those collected in the rainy season. It was found that the ionic concentrations in fog drip were higher than those in fogwater, except for NH₄ ⁺ and H⁺, which was attributed to the washout of the soil- and ash-oriented ions deposited on the leaves and the alkaline ionic emissions by the leaves, since biomass burns are very common in the region and nearby road was widening.     

劣质型煤着火燃尽性能的试验研究

煤矸石和粉煤灰都存在着灰分高、热值低、燃烧性能差、飞灰污染严重等特点,其型煤的燃用技术难度较大。通过对比试验,研究了煤矸石和粉煤灰等劣质型煤的着火燃尽性能,测算出不同燃烧工况下劣质型煤的挥发物产率、燃尽率及其关联式,并分析探讨了CR助燃剂在劣质型煤燃烧过程中的助燃作用。