成都市区酸雨变化及降雨化学组成分析

依据成都市1995～2003年城区酸雨监测统计资料,本文对成都市城区酸雨的变化特征、离子化学组成进行了分析。结果表明:城区降水酸度变化呈现出一定的波动性,酸雨频变化表现出较大的波动性;1999年和2000年酸雨年均酸度及频率情况都较好,之后出现反弹;降水中离子含量高,雨水污染严重;降水中CSO2-的比值正在逐步缩小,酸雨状况转变为硫/CNO-34酸型和硝酸型并重的局面,大气污染物中NOx的贡献率正在升高。灰色关联分析表明:降水pH值与雨水中碱性阳离子的关联序为NH+4>Ca2+>Mg2+>K+>Na+;降水pH′值与雨水中酸性阴离子的关联序为Cl->F->SO2-3。4>NO-     

大气中SO2的液相氧化研究

大气中ＳＯ２液相氧化是形成酸雨的重要途径，降雨中含有各种无机离子和有机物质，它们可能催化或抑制液相氧化反应的进行。本文根据四川酸雨样品组成，进行了ＳＯ２在模拟雨水及实际雨水中的氧化实验，考查了Ｖ，Ｆｅ，Ｍｎ等离子对ＳＯ２氧化的催化作用，Ｈ２Ｏ２对ＳＯ２的氧化以及降水中有机物质甲醛对各反应的影响。实验结果为了解酸雨的成固，研究酸雨控制对策提供了科学依据。     

酸雨条件下城市农业土壤镉的释放研究

本文选取成都市典型农业土壤为研究对象，根据成都市降雨特征，模拟一定范围pH及主要阴、阳离子浓度配制成母液开展酸雨淋滤实验，以确定酸雨中影响土壤重金属元素镉溶解度的关键因素，探明其对镉释放的影响程度。研究结果表明，总体上酸雨加速了土壤镉的释放。不同类型土壤在同一酸雨条件下，镉的释放速度和最大释放量也不同。酸雨pH值和主要阴、阳离子浓度对镉释放的影响有明显的规律。     

四川省酸雨污染现状及趋势分析

本文从酸雨成因入手,根据全省降水监测数据等资料,对四川省酸雨污染现状及变化趋势进行分析,结果表明：我省酸雨法污染面积广、频率高;酸度强,近五年,酸雨频率有下降趋势,但降水酸度无明显减弱,酸雨污染形势依然严峻;降水组份中,硫酸根离子和硝酸根离子比值逐年下降,说明大气污染特征已由煤烟型转为煤烟型与机动车尾气混合型。     

2011～2020年昆山市酸雨变化特征及成因分析

酸雨，对人类生活和生产造成了巨大的影响。为了解昆山市酸雨污染状况及其变化特征，根据昆山市2011～2020年降水监测数据，对酸雨的变化特征、变化趋势、离子化学组成、各离子间的相关性及酸雨成因进行了分析。结果表明：2011～2020年昆山市降水的pH年均值总体呈升高趋势，酸雨频率总体呈下降趋势；酸雨呈季节性变化，冬季酸雨频率最高，夏季酸雨频率最低；大气降水中主要阳离子为NH⁺₄和Ca²⁺,主要阴离子为SO₄^2-和NO^-₃;降水中的SO₄^2-和NO^-₃的比值在逐年缩小，从2014年的3.80逐步下降到2020年的0.97,硝酸根离子浓度呈波动变化，但变化不显著，酸雨的特征由硫酸型转化为硫酸-硝酸复合型。因此，加快产业结构调整、优化能源结构、加强工业废气和机动车尾气等的综合治理，从而减少SO₂和NO_X的排放，是...     

污泥土地利用中重金属铜污染地下水的潜在风险研究

本研究旨在通过土柱淋溶实验来研究堆肥污泥土地利用后重金属铜的溶出性,以及对地下水的影响。结果表明:与去离子水相比,模拟酸雨(pH=4.5)会使土壤中Cu的淋溶强度增加,并更能促使其向下迁移。经长期淋溶后发现,淋出液中铜的浓度呈现有起伏的递减趋势,最高峰浓度达到0.0702mg/L,远低于地下水Ⅲ类标准(1.0mg/L),污泥土地利用后Cu对地下水的污染风险较小。     

模拟酸雨对油菜生长影响的试验研究

酸雨对陆生生态环境及农作物的影响已引起人们的关注。国外有关这方面的研究已有不少报道,国内有过模拟酸雨对蔬菜、水稻、小麦生长影响的研究报道,但对油菜影响的研究报道尚未见到。为了正确估价酸雨对成都平原油菜生长可能产生的影响,本试验设计了采用盆栽与田间试验相结合的方法,进行模拟酸雨对油菜生长影响的试验研究,现将模拟酸雨对油菜的伤害症状、产量及品质的影响报道于下。     

酸雨胁迫对白兰花(Michelia alba DC．)抗氧化酶活性及丙二醛(MDA)含量的影响

本文以长势良好且树龄相同的木兰科植物白兰花(Michelia alba.DC)为实验材料,采用盆栽方式,用模拟酸雨的处理方法,研究了其在模拟酸雨胁迫下的抗氧化酶系统和丙二醛(MDA)的变化规律。结果表明,pH2.0酸雨比pH3.0和pH4.0对白兰花的影响更大,到第六次喷施酸雨时,SOD、POD、CAT酶活性均低于对照;各处理MDA含量在第六次处理时达到最高值,且均与对照呈显著性差异(P0.05)。说明酸雨胁迫对白兰花的影响较大,白兰花在酸雨胁迫下抗逆性和耐受性较弱,其结果为酸雨控制区选择城市绿化植物提供重要的现实意义。     

南充市近十年酸雨变化特征及降水化学组成研究

依据南充市2003~2012年城区降水环境监测统计资料,分析了酸雨变化特征及降水离子化学组成。研究表明:这十年,酸雨频率平均为50.4%,2007年降雨量为最高,呈波动递减趋势变化,降水年平均pH值为4.88,呈现"低—高—低"的变化特征,城区酸雨频率和降水pH值月均值变化呈现高低交替的波动趋势。城区降水中主要阳离子成分是Ca2+,主要阴离子成分是SO2-4和NO-3。(SO2-4/NO-3)比值逐年下降,平均比值为7.82,酸雨污染类型仍以硫酸型为主;降水(NH+4+Ca2+)/(SO2-4+NO-3)和Ca2+/NH+4比值呈波动性变化,2007年分别达到最高值为6.71和50.27,除2010年比值均较低小于1外,近年来均有增加趋势,表明碱性离子缓冲能力增强了,降水酸度降低,pH值增加,但2007年pH值较低,主要与降雨量有关。综合分析,降水酸度不仅是酸性离子和碱性离子中和作用,也受其他离子浓度和降雨量、风向等气候条件、距离传输以及地形等影响。     

宜宾市酸雨pH值预测的偏最小二乘回归分析

酸雨pH值受酸性离子(有机酸、无机酸)和碱性离子的影响。这些影响因素之间存在多重相关性。用一般最小二乘回归法建模预测pH值,估计参数存在着很大的误差,而且物理意义明显不足。本文以宜宾市区2002-2003年的27组降雨监测数据作为样本数据,应用偏最小二乘回归技术建立pH值预测模型,克服了自变量之间的多重相关性的问题。与最小二乘回归法相比更具有先进性,计算结果更为可靠;在确定了模型可行性后,分析比较了影响宜宾市区酸雨pH值的离子的重要性和离子来源。     

Leaching from organic matter-rich soils by rain of different qualities: I. Concentrations

Soil monoliths from an area exposed to acid precipitation and from an unpolluted area were used in a lysimeter experiment to study effects of different rain qualities on the chemical composition of the leachate from shallow soils rich in organic matter. The vegetation was either dominated by moorgrass [Molinia caerulea (L.) Moench] or heather [Calluna vulgaris (L.) Hull]. The lysimeters received either "acid rain" (pH 4.3) or "normal rain" (pH 5.3). High concentrations of dissolved organic carbon (DOC) were characteristic of the leachate. The different "rain" qualities had no significant influence on the DOC concentration. More DOC was, however, leached from lysimeters with heather vegetation. Roughly 50% of the aluminum (Al) was in complex with organic material and the Al charge was calculated to be between +1.4 and +2.0. Sulfate (SO4(2-)) was the only component that was significantly influenced by the treatment, as more was leached from lysimeters receiving "acid rain." Sulfate was poorly correlated with pH, suggesting that reduced SO4(2-) input would not necessarily lead to reduced acidity. Differences in the pH of the leachate due to the treatments were less than 0.15 pH units. Nitrate (NO3-) was only leached in very low concentrations and of little consequence for the leachate acidity. Some observations do, however, suggest that NO3- may contribute to acidification in episodes with high precipitation. High concentrations of Cl- in the leachate and a significant positive correlation between Cl-, H+, and base cations indicate that sea salt episodes may be important for soil acidification and acidity of the leachate.     

Release dynamic process identification for a cement based material in various leaching conditions. Part II. Modelling the release dynamics for different leaching conditions

This paper deals with process identification and model development for the case of a porous reference material leaching under certain hydrodynamic conditions. Four different dynamic leaching tests have been applied in order to take into account different types of solid/liquid contact conditions corresponding to various real leaching scenarios: monolithic and granular material with sequential eluate renewal, and granular material and continuously renewed eluate with different hydrodynamic conditions (dispersion, residence time). A coupled chemical-mass transfer model has been developed to describe the leaching behaviour under all experimental conditions. Diffusion has been considered as the mass transport mechanism inside the saturated porous material and dispersive convection as that in the leachate. Two specific phenomena have been identified and considered in the model: (i) the early surface dissolution of the material which results in high Ca concentration and (ii) the late weak dissolution of Na and K giving rise to a long-term residual release. The intrinsic material parameters such as the initial concentrations in the pore water and solid phases were determined by applying equilibrium leaching tests and geochemical modelling. Diffusion coefficients for different elements and the late solubility of alkalines have been found to reach the same values in the four tests. The estimated values of the surface dissolution kinetic constant have shown a dependence on leachate hydrodynamics when the thickness of the degraded layer is nearly the same in the four tests (intrinsic parameter of the material). The competition between the four main dynamic processes, i.e. diffusion, convection, late dissolution, and surface dissolution, has been emphasized and compared in the four leaching tests: the hydrodynamic dispersion and the residence time had no effect on the leaching behaviour of alkalines, which is controlled by diffusion, whereas the behaviour of calcium (a major element of the material) was strongly influenced. This has significant effects on eluate pH values and on the concentration of Pb (the monitored pollutant). The model was then applied to simulate a landfill scenario in the case of a stabilized/solidified incinerator residue containing heavy metals and chloride. A high rain infiltration level and the use of small blocs are favourable conditions for enhanced pollutant release.     

Accelerated weathering of biosolid-amended copper mine tailings

Application of municipal biosolids to mine tailings can enhance revegetation success, but may cause adverse environmental impacts, such as increased leaching of NO3- and metals to ground water. Kinetic weathering cells were used to simulate geochemical weathering to determine the effects of biosolid amendment on (i) pH of leachate and tailings, (ii) leaching of NO3- and SO4(2-), (iii) leaching and bioavailability (DTPA-extractable) of selected metals, and (iv) changes in tailing mineralogy. Four Cu mine tailings from southern Arizona differing in initial pH (3.3-7.3) and degree of weathering were packed into triplicate weathering cells and were unamended and amended with two rates (equivalent to 134 and 200 Mg dry matter ha(-1)) of biosolids. Biosolid application to acid (pH 3.3) tailings resulted in pH values as high as 6.3 and leachate pH as high as 5.7, and biosolids applied to circumneutral tailings resulted in no change in tailing or leachate pH. Concentrations of NO3--N of up to 23 mg L(-1) occurred in leachates from circumneutral tailings. The low pH of the acidic tailing apparently inhibited nitrification, resulting in leachate NO3--N of <5 mg L(-1). Less SO4(2-)-S was leached in biosolid-amended versus unamended acid tailings (final rate of 0.04 compared with 0.11 g SO4(2-)-S wk(-1)). Copper concentrations in leachates from acidic tailings were reduced from 53 to 27 mg L(-1) with biosolid amendment. Copper and As concentrations increased slightly in leachates from biosolid-amended circumneutral tailings. Small increases in DTPA-extractable Cu, Ni, and Zn occurred in all tailings with increased biosolid rate. Overall, there was little evidence of potential for adverse environmental impacts resulting from biosolid application to these Cu mine tailings.     

Temperature and microbial activity effects on trace element leaching from metalliferous peats

Due to geochemical processes, peat soils often have elevated concentrations of trace elements, which are gradually released following drainage for agriculture. Our objectives were to use incubation temperatures to vary microbial activity in two metalliferous peats (M7 acidic peat and M3 neutral peat) from the Elba, New York region, and to use periodic leaching to assess the extent of trace element release from these soils. Dried soils were mixed with glass beads to maintain aeration, moistened, and incubated at 4, 16, 28, and 37 degrees C in 10-cm-diameter x 8-cm-tall columns. Five incubation-leaching cycles were performed, each consisting of 7.3 d of incubation (28 d for the final cycle) followed by 16 h of leaching with synthetic acid rain at 2.5 mm h(-1). Microbial activity was determined initially and after the final leaching by measuring C mineralization following glucose stimulation. Cumulative respiration results were ranked 28 > 16 > 4 > 37 degrees C, with M7 acidic peat respiration values greater than M3 neutral peat at each temperature. Initial leachate pH levels were between 2 and 4, with acidification less pronounced and shorter-lived for the M3 peat. Leachate S, dissolved organic carbon (DOC), NO3-N, and trace elements declined with successive leachings (rebounding slightly in the final M3 leachate), with concentrations typically greater in the M7 leachate. Elemental losses followed the same general ranking (28 > 16 > 4 > 37 degrees C); losses at 28 degrees C were 15 to 22% for As, Cd, Ni, and Zn from the M7 peat; losses from M3 were comparable only for Cu (1%) and Ni (19%). The correlation of respiration with S, DOC, and trace elements losses indicates that microbial processes mediated the release of trace elements in both peat soils. Neutral M3 peat pH levels limited losses of most analytes.     

Role of organic matter in microbial transport during irrigation with sewage effluent

Reduction of migration of fecal coliforms (FC) and streptococci (FS) by limiting the leaching in effluent-irrigated soil was tested in lysimeters packed with quartz sand without or with added biosolids compost or with one of two clayey soils. The 200-L, 70-cm-deep lysimeters were either planted with a Eucalyptus camaldulensis or an Oroblanco citrus tree (in the sand only), or not planted. The Eucalyptus was irrigated with oxidation pond effluent (OPE) and the Oroblanco with mechanical-biological treatment plant effluent (MBTPE). The leaching fraction (LF) ranged from 0.2 to about 1.0, and the residence time (RT) from under 1 to 40 d. The Eucalyptus was also tested under intermittent leaching (RT 11-20 d) and deficit irrigation (without leaching for about 6 mo) regimes. Under MBTPE irrigation there was little or no leaching of FC and FS. Under OPE irrigation at LF 1 without a Eucalyptus there was little or no bacterial leaching at irrigation rates below 40 L d(-1) per lysimeter (RT > or = 0.8 d). Bacterial counts in the leachate were substantial in the presence of a Eucalyptus tree under LF 0.2 and intermittent leaching regimes, and when sand-packed unplanted lysimeters received OPE effluent at >45 L d(-1). Bacterial recovery peaked at LF 0.2, at up to 45% of the input level. At LF 1 (RT 0.6-2.8 d) and with intermittent leaching the recoveries were minute. Bacterial counts in the washout from the deficit-irrigated lysimeters were typical of nonpolluted soils. The bacterial concentration and recovery patterns in the leachate mostly matched the organic carbon (OC) load in the irrigation water, and its concentration and bioavailablity in the leachate. We related the leaching patterns of the fecal bacteria to their relative reproduction and die-off rates, and to the dependence of their regrowth on available carbon sources.     

Rainfall timing and frequency influence on leaching of Escherichia coli RS2G through soil following manure application

The time between swine (Sus scrofa) manure application to soil as a crop fertilizer, the first rainfall event, and the frequency of rainfall events should influence leaching potential of fecal pathogens. Soil microcosms were inoculated in the lab with a swine manure isolate of Escherichia coli, strain RS2G, expressing green fluorescent protein, to examine how timing and frequency of rainfall events influences RS2G leaching and survival in soil. Liquid swine manure inoculated with RS2G was applied to intact soil cores (20 cm in diameter x 30 cm long) 4, 8, or 16 d before the first rainfall event (50.8 mm over a 4-h period), and each core received one to three rainfall events. Manure application methods (no-till surface-broadcast, broadcast and incorporated, and tilled before broadcast) had no affect on leaching, although there was greater survival in soils when the manure had been incorporated. Most of the RS2G in the leachate appeared following the first rainfall event and RS2G leaching decreased with increasing time between manure application and the first rainfall, although leachates contained as much as 3.4 to 4.5 log colony forming units (CFU) 100 mL(-1) of RS2G when the first rainfall occurred 16 d after manure application. With increasing frequency of rainfalls there was a decrease in subsequent concentrations of RS2G in the leachate. There was no correlation between leachate RS2G and total coliforms or fecal streptococci concentrations. Soil RS2G numbers were 1 to 10% of the inoculum regardless of the length of time between manure application and the first rainfall. RS2G leaching was mostly influenced by the time between manure application and first rainfall event, and significant leaching and survival in soil was possible even if the first rain occurred 16 d after manure application.     

Characterisation of sequential leachate discharges of mining waste rock dumps in the Tinto and Odiel rivers

Mining waste rock dumps (WRDs) are potential sources of pollution, which after rainfall produce leachate discharges, loaded with acid mining drainage (AMD). The discharges generally occur in two phases: initial rapid leaching over a period of 1-7 days, followed by a period of variable duration during which leaching decelerates. The relative preponderance of each phase depends on the characteristics of the WRD, including its antecedent hydrological condition, and the temporal pattern and amount of rainfall.