Sand-Sized Limestone Treatment of Streams Impacted by Acid Mine Drainage

Direct single point, instreamapplications of limestone sand were made in twostreams severely acidified by acid mine drainage. After high flows distributed the sand downstream,dissolution of the limestone significantly reduced theacid loads in both streams. Data from the treatedstream sections and laboratory experiments showed thatthe efficiency of treatment was more dependent onlimestone particle size than CaCO₃ content. Results from the stream treated with a narrow range oflimestone sand-sized particles showed a highutilization efficiency with nearly completedissolution of the limestone. The data indicated thatmonthly addition of limestone sand may be sufficientfor complete treatment of the streams studied. Ananalysis of such a treatment scheme indicated it to behighly cost efficient when compared to other activeand passive treatment systems.     

Treatment of Acid Mine Drainage Using Fly Ash Zeolite

In this paper, two Indian fly ashes (from Talcher and Ramagundam) were converted into zeolites and both the raw fly ash and zeolite were used to treat two British acidic mine waters. The results demonstrate that fly ash zeolites are more effective than raw fly ash for treatment of acid mine drainage. Fly ash has been found effective for removal of Pb, but with increased dosing, caused release of Ba, Cr, Sr (both fly ashes) plus Zn, Ni (Talcher), or Fe (Ramagundam) into mine water. In contrast, increased dosing with fly ash zeolite removed 100% Pb, 98.9% Cd, 98.8% Zn, 85.6% Cu, 82.8% Fe, 48.3% Ni, and 44.8% Ba from mine water. Fly ash is amorphous in nature and many metals attached on the surface of the ash particles are easily leached off when ash comes in contact with acidic mine water. However, fly ash zeolite is crystalline in nature and due to its high cation exchange properties, most of the metals present in acid mine water are retained in surface sites.     

Treatment of Acid Mine Drainage by Sulphate-reducing Bacteria Using Low Cost Matrices

This paper reports a laboratory-scale investigation concerning the use of sulphate-reducing bacteria (SRB) in a semi-continuous process, where column packed-bed type bioreactors were used for the treatment of acid mine drainage (AMD). The use of different materials as solid matrices was tested and the performance of the bioremediation processes was discussed in terms of sulphate and metals removal and acid neutralization. The behaviour of a reactor filled with acidic soil from a mining area and organic wastes was compared with other three reactors where coarse sand, glass spheres and cereal straw were used as packaging materials. Batch experiments showed the presence and growth of SRB from the acidic soil in different pH conditions and the effect of the absence or presence of several added carbon sources: lactate, ethanol and lactose. The data showed that it is possible to grow SRB using the acidic soil as source of inocula, in the absence and in the presence of the carbon sources tested, since the pH of the media was previously increased to values of 5 or higher. When acidic soil from the mining area and organic wastes were utilised as column matrices, it is possible to remove the metals and to neutralise the acidity of AMD, although an inefficient sulphate removal was observed. When coarse sand or glass spheres were utilised, efficient metals sulphate removal were achieved. However, the incapacity of both systems to generate enough alkalinity does not allow maintaining their good performances in terms of iron removal and sulphate reduction. As a result, the incorporation of materials with neutralizing and buffer capacity to the matrix is recommended. Due to its low density, cereal straw was not suitable to obtain an anaerobic environment inside the column for SRB activity.     

腐植酸对水溶液中丁草胺光化学降解的影响

采用紫外光照射的方法研究了腐植酸对丁草胺光降解特性的影响。结果表明,潮土腐植酸对丁草胺的光降解具有明显的抑制。潮土腐植酸浓度较低（〈10mg·L^-1）时,随腐植酸浓度的增加,对丁草胺光降解的抑制作用越强,丁草胺光降解速率越低;当潮土腐植酸的浓度≥10mg·L^-1时,腐植酸浓度的变化对丁草胺光降解的抑制作用影响不大,20mg·L^-1腐植酸与10mg·L^-1腐植酸对丁草胺光降解的影响相近。不同腐植酸对丁草胺光降解的抑制作用不同,商品腐植酸对丁草胺光降解抑制作用较强,潮土腐植酸和黑土腐植酸对丁草胺光降解的抑制作用则相对较弱。这种现象可能是由腐植酸的纯度和腐植酸本身结构特性的差异造成的。     

Source Treatment of Acid Mine Drainage at a Backfilled Coal Mine Using Remote Sensing and Biogeochemistry

A biological source treatment (BST) technique using remote sensing and biogeochemistry has been developed to address acid mine drainage (AMD) at its source. The BST technique utilizes down-hole injections of microbial inoculum and substrate amendments to establish a biofilm on the surface of metal sulfides (AMD source material). The treatment results in an elevated groundwater pH (from acidic to circum-neutral levels) and prevents further oxidation of AMD source material. The first 2 years of an ongoing field study of the BST technique at a reclaimed coal mine in central Tennessee (USA) has produced successful results. For instance, the water chemistry in a monitoring well down-gradient from injection wells has improved substantially as follows: the pH increased 1.3 units from 5.7 to 7.3, the dissolved (0.45 µm-filtered) iron concentration decreased by 84% from 93 to 15 mg/l, the conductivity decreased by 379 µS/cm, and sulfate decreased by 78 mg/l. Electromagnetic induction surveys were conducted to identify AMD source material and monitor BST performance by measuring changes in subsurface resistivity throughout the site. These surveys revealed a treatment zone created between injection wells where the resistance of contaminated groundwater from up-gradient AMD sources increased as it flowed past injection wells, thus, suggesting this technique could be used to treat AMD sources directly or to intercept and neutralize sub-surface AMD.     

Phosphorus Removal by Sediment in Streams Contaminated with Acid Mine Drainage

Acid mine drainage (AMD) affects thousands of stream miles in the Appalachian region of the USA and results in elevated concentrations of iron and aluminum in the stream water and sediments and wide ranging pH values. It was hypothesized that these conditions would lead to increased P buffering capacity of the sediments which in turn would cause a decrease in dissolved reactive phosphorus (DRP) in the water column. In the lab fresh Fe, Al, and Mn oxide precipitates all adsorbed DRP strongly but over different pH ranges. Sulfate and calcium ions inhibited adsorption of DRP with Fe oxides but the effect was less apparent with Al oxides. In the field DRP concentration was reduced 54–90% just downstream of an AMD input compared to upstream of the input. In addition the sediment buffering capacity increased and equilibrium phosphate concentration decreased dramatically downstream of the AMD inputs. The strength of the effect and the widespread occurrence of AMD suggest that AMD could be altering the P dynamics of streams and rivers throughout the Appalachian region.     

Nitrogen Forms in Humic Substances

In this paper,the nitrogen forms in newly-formed humic substances,including humic acid (HA),fulvic acid (FA) and humic acid in humin (HAI),were studied by using the ^15N CP-MAS NMR technique in combination with chemical approaches.Results show that the majority of nitrogen in HA,FA and HAI was in the amide form with some presented as aliphatic and/ or aromatic amines and some as pyrrole type nitrogen,although the contents of nonhydrolyzable nitrogen in them differed greatly from each other (15-55%).     

Characteristics of Humic Substances in Paddy Soils

In the present paper,the composition of humus and the charateristics of humic acid from seven paddy soils were compared with those of upland (and/or natural) soils.Results show that:(1) in each group of the soil samples for comparison the HA/FA ratio of the humus of a paddy soil,in most cases,was appreciable higher than that of adjacent upland(and/or natural) soil derived from the same parent material;(2) the humic acid extracted from the paddy soils was characterized by a higher C/O ratio,a higher content of methoxyl groups,and a lower content of carboxyl groups than those from the corresponding upland (and/or natural) flooded soils,implying that the humic acid formed under rice cultivation is in a lower degree of humification than that formed under upland(and/or natural) conditions;and (3) the humic acid of paddy soils,however,was not always characterized by a lower aromaticity than that of the corresponding upland(and/or natural) soils.     

Organic Matter Dynamics,Aggregation, and Carbon Sequestration in Mine Tailings Amended with Humic Substances

Mechanisms of macroaggregation, carbon dynamics, and carbon sequestration were investigated in degraded mine tailings. Humic substances (HSs), wheat straw, lime, and their various combinations were added to the mine tailings and then incubated at 20 °C for 24 weeks. A significant increase (up to 79%) of water‐stable macroaggregates was observed in the HS‐amended tailings after the incubation. During the macroaggregation, 20–33% sand of the mine tailings was bound by HS‐derived active carbon pool. The organic carbon concentration of the macroaggregates significantly increased in the HS‐amended mine tailings compared to the control. Mineral‐associated organic matter carbon derived from the HSs was mainly responsible for the increased concentration of macroaggregate carbon and the increased amount of macroaggregates as well. This active pool of added organic matter was sequestered in aggregates during the process of macroaggregation and thus improved the structure of the mine tailings.     

Controlling Acid Drainage in a Pyritic Mine Waste Rock. Part II: Geochemistry of Drainage

Mine waste rock can produce acid rock drainage (ARD) when constituent sulphide minerals (for example, pyrite) oxidize upon exposure to the atmosphere. Outdoor experiments were performed to test techniques for preventing and controlling ARD in a pyritic mine waste rock. The experiments involved lysimeter (plastic drum) experiments in which the crushed (25–50 mm particle sizes), amended and unamended waste rock was exposed to natural weather conditions (rain, drying, freezing and thawing) for 125 weeks. The amendments consisted of separately covering the waste rock with compacted soil, wood bark and water and mixing with limestone and phosphate rock at 1 and 3%. Waters draining the various rocks were collected and analyzed for acidity, pH, sulphate and metals. In general, concentrations of SO₄ ^2-, Fe, As, Cu, Al and Mg in the drainage from the control rock increased gradually in the first year, peaked in the second year and increased further in the third year, reflecting increasing acid generation with time. SO₄ ^2- displayed strong positive correlation (0.91 to 0.98) with Al, As, Cu, Fe and Mg.Concentrations of Zn, Mn and Cd reached their maximumin the second year. Geochemical analysis of thecomplete water quality data using the equilibriumspeciation model WATEQ4F suggested waste rockoxidation was most likely controlled by Fe³⁺. Al, SO₄ ^2- and Fe concentrations in thecontrol rock appeared to be controlled by alunite(KAl₃(SO₄)₂(OH)₆), jarosite(KFe₃(SO₄)₂(OH)₆) and amorphousferric hydroxide [(am)Fe(OH)₃] during the firstyear. Ion activity product data (log IAP) forFe³⁺ and OH^- generally ranged between –37and –34 in the first two years but decreased to –39and –40 in the third year, suggesting that amorphousferric hydroxides were beginning to crystallize intomore stable forms such as ferrihydrite (Fe[OH]₃)and goethite (FeOOH) in the third year. The addedlimestone lost its effectiveness after a while,probably because of precipitation of secondaryminerals on the limestone particles. The phosphaterock could not sustain the drainage pH above 6 andlost its effectiveness before the limestone did. Underthe conditions of the experiments, the soil cover didnot work as expected, probably because of sidewallpassage of oxygen and water. The water cover was themost effective control method, reducing the acidproduction rate data from 41 to only 0.08 mgCaCO₃ week^-1 kg^-1 waste rock. The wood bark was theworst performer and accelerated acid production by 170%.     

Humic Substances on Soybeans Grown Under Water Stress

Hypothetically, humic substances (HSs) can improve the response of plants in sandy soils. The objective was to assess the effect of applying an organomineral fertilizer enriched with HSs on soybean plants grown with and without water stress. The experimental design was entirely randomized, in a greenhouse, in a 2 × 5 factorial setup (two moisture levels and five fertilizer doses: 0, 1, 2, 4, and 8 mL dm^?3), for a total of 10 treatments, with eight repetitions, using as substrate a Psamment. The organomineral fertilizer was applied in the soil 21 days after plant emergence, and the water regimes were established 1 week thereafter. Plant height, shoot and root dry mass, mineral nutrition, and grain yield were evaluated. There was a positive response to the doses, with the most efficient one under water stress being 6.5 mL dm^?3 and HSs favored the uptake of micronutrients.     

Improvement of Iron Uptake in Table Grape by Addition of Humic Substances

Two experiments in consecutive years were conducted at a table grape plantation located in southeastern Spain. The objective was to test whether the addition of commercial organic compounds could improve the uptake of iron (Fe) by plants. A commercial humic substance and two mixtures of amino acids were used as organic compounds in the first experiment and FeEDDHA was the source of Fe. The joint addition of FeEDDHA and organic compounds improved Fe nutrition. The humic substance was more effective than the amino acids in increasing Fe uptake. In the following year, a similar experiment was conducted by progressively replacing part of the chelate with the humic substance. An increase in foliar Fe and phosphorus (P) and a decrease in sodium (Na) levels were observed. The best results with respect to nutrient foliar content and nutrient relationships were obtained for a range of substitutions for the chelate by the humic substance of from 30% to 50% with no loss in yield or fruit quality.     

纯培养条件下蓝细菌形成腐殖物质的可能性研究

采用红外光谱和元素分析,初步研究了纯培养条件下水华鱼腥藻(一种常见蓝细菌)不同生长期的菌体和胞外代谢物以及作为唯一基质形成的菌体混合物的结构特征。结果表明:蓝细菌样品的红外光谱图中均没有1 720 cm-1峰。2 926/1 650比值显示,水华鱼腥藻对数生长期与衰亡后期的菌体芳香物质含量高,复杂度与土壤富里酸接近,但低于土壤胡敏酸;微生物处理能使菌体混合物具有更多芳香族物质,但1 530 cm-1峰消失,表明部分C=C及氨基酸类物质被分解。相对于土壤腐殖物质,水华鱼腥藻菌体的H/C比值及(O+S)/C比值均较大,即缩合度较低而氧化度较高;经微生物处理后,其缩合度进一步降低,氧化度升高。总之,本实验条件下蓝细菌自发形成腐殖物质的可能性较低,且其作为唯一基质在其他微生物作用下形成的菌体混合物与土壤腐殖物质在结构上存在差距,但从蓝细菌的组成与结构上看,其可为腐殖物质的形成提供物质条件。该结果为土壤腐殖物质的形成研究与起源探索提供了一定的科学依据。     

Field Investigation of Controlling Acid Mine Drainage Using Alkaline Paper Mill Waste

To verify in situ laboratory test results for the control of acid mine drainage using alkaline paper mill waste, five demonstration cells were built on the Ascot mine site in Sherbrooke (Québec, Canada). A monitoring program was set up to record temperature, leached water quality, oxygen concentration and electrical conductivity.Monitoring results showed that mixing mine residueswith alkaline paper mill waste and covering mine residues with paper mill waste allows an efficient control of acid mine drainage. The paper mill waste cover generates an alkaline front which results in metal precipitation as hydroxides. Also, an increase in pH results in an inhibitionof bacterial catalytic activity. Chemical analyses conducted on the collecting water shows a high reduction of leachingmetals to under ground water. Moreover, a significant reduction of diffusion of oxygen to the mine residue is observed.     

Controlling Acid Drainage in a Pyritic Mine Waste Rock. Part I: Statistical Analysis of Drainage Data

Field experiments were conducted to evaluate the relativeeffectiveness of several covers and amendment techniques forpreventing or controlling acid generation in a pyritic minewaste rock. The covers and techniques consisted of water cover,soil cover, wood bark cover, limestone addition and phosphaterock addition. Water quality data (pH, sulphate, zinc and ironconcentrations) obtained from the experiments were analyzedusing two-way ANOVA (analysis of variance) with repeatedmeasurements. A 5% test of significance (p-value of 0.05) wasused in the analysis. The results suggested that the covers andamendments should be either compared on a time-by-time basis orgrouped into four, based on their performance: (i) water cover, (ii)1% and 3% limestone, (iii) clay, 1% and 3%PO₄, andcontrol (no cover), and (iv) wood bark. The results did not showany significant difference between the drainage quality from1% and 3% limestone-amended rocks. The drainage quality from the 1%and 3% phosphate and clay-covered rocks did not significantlydiffer from the control (unamended) rock. Water cover was foundto be the most effective, while the wood bark cover proved to bean ineffective method for controlling acid drainage in the wasterock. The statistical analysis also showed good replication inthe experiments, as no significant difference in the quality ofthe drainage from the replicates was observed.     

15N-Urea Efficiency in Maize as Influenced by Humic Substances and Urease Inhibitors Treatments

Urea treated with urease inhibitors (UI) in association with humic substances (HS) is expected to improve urea efficiency by reducing ammonia losses and also provide the benefits of HS such as improve nitrogen (N) recovery by plants. Ammonia volatilization (AV), ¹⁵N recovery efficiency in the soil (NRE) and ¹⁵N use efficiency (NUE) were evaluated in maize (Zea mays L.) in a greenhouse pot trial. Treatments consisted of ¹⁵N-urea treated with UI (0, 0.4% boron (B) +0.15% copper (Cu), 0.64% B, and NBPT (N-(n-butyl) thiophosphoric triamide)) and three levels of HS (0%, 0.6%, and 1.2%). A control treatment (without N) was also included. N treatments were applied at V4 (vegetative leaf stage 4) on soil surface. HS was not efficient on AV reduction, NBPT had the greatest reduction in AV, and B had higher efficiency on AV reduction than Cu. At V8 (vegetative leaf stage 8), NBPT had the greatest NUE followed by B. At VT (tassel fully emerged), NUE from urea treated with NBPT reduced when increased levels of HS, and NBPT had the greatest NRE. UI in association with HS treated-urea does not reduce AV and it does not improve NUE by maize in vegetative stages.     

生物腐植酸对露天矿排土场黑麦草生长的影响

[目的]研究生物腐植酸对露天矿排土场土壤改良效果的影响,为进一步提高露天矿排土场的土壤质量提供科学参考。[方法]通过盆栽试验,研究不同生物腐植酸含量(0~400kg/hm2)对露天矿排土场不同土地利用类型〔(刺槐(Robinia pseudoacacia)林、榆树(Ulmus pumila)林、荆条(Vitex negundo)林、农田、未复垦土地〕下黑麦草(Lolium multiflorum)生长状况的影响。[结果]刺槐土、榆树土、荆条土、农田土、未复垦土出苗率最大值分别出现在加入生物腐植酸量为200,200,300,300,200kg/hm2的试验盆;5种土壤黑麦草幼苗株高所需生物腐植酸最大量值分别为200,200,200,300,300kg/hm2;5种土壤黑麦草根系长度最大值分别出现在300,100,300,300,300kg/hm2的试验盆;而生物量最大值分别出现在加入生物腐植酸量为200,100,200,300,300kg/hm2的试验盆。随着生物腐植酸量的增加,各土地利用类型条件下种植的黑麦草出苗率、株高、根系长度、生物量均表现出先增加后减小的趋势。[结论]生物腐植酸对露天矿排土场不同土壤植物更新与生长具有剂量效应,表现为"单峰型"变化规律,体现出适量的生物腐植酸对露天矿排土场植被恢复具有促进作用。     

Agronomic Evaluation of Liquid Humus Derived From Earthworm Humic Substances

Carbon (C), commonly expressed as organic matter (OM), is of vital importance in soil productivity. Liquid humus is an alkaline suspension containing humic and fulvic acids, which can facilitate C addition to the soil through the irrigation system to increase OM and soil fertility levels. Two liquid humus products were formulated from earthworm humic substances and the effects of these and other commercial products derived from leonardite, on soil and ryegrass were evaluated in a pot experiment under greenhouse conditions. On average, C application, regardless of source, increased the aerial and root dry matter, plant greenness, nitrogen (N), phosphorus (P), and potassium (K) uptake, and nutrient use efficiency. Carbon effects on plant production were larger when added over fertilized plants. Residual soil N was lowered by the application of liquid humus. No significant effect of C rate was observed on soil pH or electrical conductivity (EC) at the end of the experiment. Optimal C rates found in this study were higher than the recommended commercial ones. No major differences among earthworm liquid humus and leonardite-based products were observed; therefore the former would constitute a more sustainable alternative for organic matter additions as they are made from a renewable resource.