氨水土壤混合物脱除CO2温室气体的实验研究

为了脱除CO2温室气体,提出了利用氨水土壤混合物去除CO2的新方法.分别考察了土壤颗粒粒径、CO2初始流量、氨水浓度(质量比)和温度对CO2脱除量和脱除率的影响.实验结果表明,该方法去除CO2的量较土壤物理吸附量和氨水化学吸收量的总和提高了大约15%;随着氨水浓度的增大,CO2的脱除率和脱除量都增大;随着土壤颗粒粒径和CO2初始流量的增大,CO2的脱除率和脱除量都减小;当温度由22℃升高到31℃,CO2的脱除率随着温度的升高而增大,但是继续升高温度到40 ℃,CO2的脱除率反而下降.     

氨水土壤混合物脱除CO2温室气体的实验研究

为了脱除CO2温室气体,提出了利用氨水土壤混合物去除CO2的新方法。分别考察了土壤颗粒粒径、CO2初始流量、氨水浓度（质量比）和温度对CO2脱除量和脱除率的影响。实验结果表明,该方法去除CO2的量较土壤物理吸附量和氨水化学吸收量的总和提高了大约15%;随着氨水浓度的增大,CO2的脱除率和脱除量都增大;随着土壤颗粒粒径和CO2初始流量的增大,CO2的脱除率和脱除量都减小;当温度由22℃升高到31℃,CO2的脱除率随着温度的升高而增大,但是继续升高温度到40℃,CO2的脱除率反而下降。     

不同利用方式土壤中磷的吸附与解吸特性

研究不同利用方式土壤对磷的吸附解吸特性及其影响因素。采用室内恒温培养法研究了湖南典型土壤(红壤、潮土和紫色土)的不同利用方式(旱地、水田)土壤对P的吸附和解吸过程。土壤对磷的吸附解吸过程是分阶段进行的,用Langmuir方程拟合程度比Freundlich方程高,相关系数均在0.90(P<0.05)以上;从最大吸附量(Qm)、吸附反应常数(K)和最大缓冲容量(MBC)3项吸附参数综合考虑,旱地对P的吸附无论在强度还是容量方面均大于同母质的水田土壤;解吸率随着吸附量的增加而增大,其大小为旱地<水田。Qm与<0.002 mm粘粒及无定形铁含量呈正相关,相关系数分别为0.95和0.94(P<0.05)。不同利用方式土壤P吸附解吸特性差别较大,针对不同土壤应采取不同的磷素管理措施以实现作物增产和保护环境的双重效益。     

施用高炉渣对土壤磷吸附-解吸特性的影响

采用振荡平衡法,研究了施用高炉渣对土壤磷的吸附解吸特征的影响。结果表明:Langmuir、Freundlich和Temkin方程都能较好地描述高炉渣对土壤磷的吸附特征,但以Langmuir模型为最优。与对照处理相比,施用高炉渣的土壤吸附平衡常数k值增大,自由能ΔG降低,最大吸附量Xm和最大缓冲容量MBC提高;磷的解吸量增加,总解吸量和总解吸率分别是对照处理的1.05～1.25倍和1.02～1.36倍;施用高炉渣还能减弱吸附-解吸过程中的滞后效应。上述结果说明施用高炉渣可以改善土壤保蓄和供应磷的能力。     

汞矿区周边土壤和溪流底泥对汞的吸附解吸特征

为充分认识汞在土壤和底泥中的吸附解吸特征,采取恒温水平振荡法对汞矿区周边未污染土壤和溪流底泥进行了Hg~(2+)的吸附解吸实验并用吸附等温方程和动力学方程对吸附过程进行了拟合对比。结果表明,土壤和底泥对Hg~(2+)的吸附过程类似,在中性条件下,其饱和吸附量分别为1 848.77 mg·kg~(-1)、941.25 mg·kg~(-1)在过酸或者过碱的条件下,均不利于土壤和底泥对Hg(Ⅱ)的吸附;在初始5 min内,土壤和底泥对Hg~(2+)的吸附量分别达到了饱和吸附量的72.64%、62.68%,200 min内基本达到吸附饱和;Hg~(2+)在土壤和底泥中的吸附量越大,其解吸量也越大,土壤对Hg~(2+)的吸附量及量成正比例关系,且Hg~(2+)一旦进入土壤或底泥,则很难再被解吸出来,土壤和底泥的最大解吸率分别为0.92%、1.32%。Langmuir、Freundlich和TemKin 3种曲线均能较好地拟合土壤和底泥二者对Hg~(2+)的等温吸附过程,但Langmuir的拟合度更高,显著水平分别达到了0.997 6,0.995 9;Elovich、双常数方程均能较好地拟合土壤和底泥对Hg~(2+)的吸附动力学过程,Eovich方程更适合拟合土壤对Hg~(2+)的吸附动力学,双常数方程更适合底泥的动力学拟合,显著水平分别达到0.935 0、0.919 9。     

温度和表面活性剂对菲在土壤中吸附的影响

通过静态吸附实验,研究了北京地区土壤对菲的吸附行为,考察了温度和表面活性剂对菲吸附的影响.结果表明,6种土样对菲的吸附等温线均较好地符合Freundlich吸附模式,其吸附能力的大小顺序为:轻壤土>轻粘土>砂壤土>中壤土>重壤土>紧砂土;温度升高不利于菲在土壤中的吸附;十二烷基苯磺酸钠(LAS)和十六烷基三甲基澳化铵(CTAB)均利于菲在土壤表面的解吸,LAS和CTAB对菲的解吸率最高可达66.2%和31.8%,且LAS的解吸效果更好.     

热解吸对土壤中POPs农药的去除及土壤理化性质的影响

为探索土壤热解吸修复技术对POPs污染土壤的修复效果及修复后土壤可耕作性,选择北京某农药厂旧址的POPs农药污染土壤,研究了不同温度下热解吸处理后土壤中滴滴涕(DDTs)和六六六(HCHs)各组分的去除率以及土壤理化性质的变化。结果表明,热解吸修复技术可有效去除土壤中POPs农药,其中,p,p’-DDE与α-HCH组分去除率受热解吸温度的影响比其他组分更为明显。∑HCH与∑DDT在310℃、340℃时分别达到97%、99%的去除率,且此时土壤中的污染物含量低于我国《展览会用地土壤环境质量评价标准》,此后去除率受温度的影响不明显。热解吸温度对修复后土壤的理化性质有一定的影响,不同温度影响的程度各不相同,其中,有机质含量与全氮含量分别由0.78%、0.0352%降至0.14%、0.0107%;pH波动幅度较小,由7.80变至8.25;阳离子交换量变化存在波动,但呈整体下降趋势,由7.87 mg/kg降至5.00mg/kg;土壤中速效磷显著增加,由7.59 mg/kg升至21.8 mg/kg。而在最优温度条件下,土壤理化性质受热解吸温度的影响较小。由此可以说明,热解吸技术可以用于POPs污染土壤的修复,选择适当的热解吸温度对土壤的可耕作性影响有限,因而是一种潜在的绿色修复技术。     

海河沉积物对邻苯二甲酸二甲酯吸附行为研究

邻苯二甲酸二甲酯(DMP)是一种广泛使用的化工原料,也是一种环境内分泌干扰物.研究了海河沉积物和土壤对DMP的吸附解吸作用,以及颗粒物粒径、浓度和离子浓度对DMP在颗粒物上吸附的影响.研究发现DMP在土壤上的吸附符合Langmuir等温式,在海河沉积物上的吸附符合线性等温式,单位吸附量随着颗粒物浓度的增大而减小,离子浓度的增大而增大,粒径对DMP的吸附影响不明显.用DMP将海河沉积物污染并于室温老化1个月后进行解吸实验,被吸附DMP解吸速率前20 h较快,以后逐渐达到吸附平衡,解吸量较小.     

苯并三唑在土壤中的吸附特性

为了解苯并三唑(BTA)在水-土系统中的迁移转化,通过批实验方法研究了BTA在华北平原土样(GSS13)中的吸附,考察了平衡时间、土壤投加量、溶液初始p H以及共存阳离子对吸附的影响。结果表明,在初始阶段,土壤对BTA的吸附速率较快,之后随着吸附点位的减少,吸附逐渐变慢;吸附过程符合准二级反应动力学方程。土壤对BTA的平衡吸附为非线性吸附,吸附等温线为Freundlich型;随着土壤投加量的增大,单位质量土壤吸附BTA的量减少,可能原因是所选土壤对BTA的吸附存在"固体浓度效应"。溶液的p H通过改变BTA的存在形式和土壤表面的带电性而影响吸附,当溶液p H在BTA的p Ka2(8.6)附近时,土壤对BTA的吸附效果最好。此外,溶液中共存阳离子对土壤吸附BTA有不同的影响,Na+对吸附影响不明显,而不同浓度Ca2+对BTA的吸附有不同程度的促进作用。     

西苕溪流域沉积物及土壤对磷吸附/解吸特性研究

以赋石水库和其上游河道沉积物以及流域内代表性水稻土为对象,通过分析其理化性质,改变上覆水磷浓度和pH的方法探讨沉积物和土壤对磷吸附/解吸的影响。结果表明:(1)沉积物内较高的磷含量,导致吸附/解吸平衡浓度较高,因此在水库和水体中起着磷"源"的作用;(2)土壤最大磷吸附量为566.45mg/kg,远大于沉积物的吸附量,同时吸附/解吸平衡浓度较低,因此在治理湖泊富营养化时,要加大水土保持的力度,尽量减少作为最主要污染源的农田土壤磷素流入水体;(3)无论上覆水中磷浓度升高还是降低,在未达到吸附/解吸平衡浓度前,土壤和沉积物会持续释放磷,故应把水体治理的重点放在降低土壤和沉积物的磷含量上;(4)上覆水的pH对样品的磷吸附和释放都有显著的影响。在酸性(pH3)或碱性(pH9)环境下,样品的磷吸附量均急剧下降,而水体酸化更易导致平衡后上覆水磷浓度的降低。     

Adsorption-desorption and leaching of pyraclostrobin in Indian soils

Pyraclostrobin is a new broad-spectrum foliar applied and seed protectant fungicide of the strobilurin group. In this paper, adsorption-desorption of pyraclostrobin has been investigated in three different soils viz. Inceptisol (sandy loam, Delhi), Vertisol (sandy clay, Hyderabad) and Ultisol (sandy clay loam, Thrissur). Effect of organic matter and clay content on sorption was also studied in Inceptisol of Delhi. Leaching potential of pyraclostrobin as influenced by rainfall was studied in intact soil columns to confirm the results of adsorption-desorption studies. The adsorption studies were carried out at initial concentrations of 0.05, 0.1, 0.5, 1 and 1.5 μg mL^?1. The distribution coefficient (K_d) values in three test soils ranged from 4.91 to 18.26 indicating moderate to high adsorption. Among the three test soils, adsorption was the highest in Ultisol (K_d 18.26), followed by Vertisol (K_d 9.87) and Inceptisol (K_d 4.91). K_F value was also highest for Ultisol soil (66.21), followed by Vertisol (40.88) and Inceptisol (8.59). S-type adsorption isotherms were observed in all the three test soils. K_d values in organic carbon-removed soil and clay-removed soil were 3.57 and 2.83 respectively, indicating lower adsorption than normal Inceptisol. Desorption studies were carried out at initial concentrations of 0.5, 1 and 1.5 μg mL^?1. Desorption was the greatest in Inceptisol, followed by Vertisol and Ultisol. Amounts of pyraclostrobin desorbed in three desorption cycles for different concentrations were 23.1–25.3%, 9.4–20.7% and 8.1–13.6% in Inceptisol, Vertisol and Ultisol respectively. Desorption was higher in clay fraction-removed and organic carbonremoved soils than normal Inceptisol. Desorption was slower than adsorption in all the test soils, indicating hysteresis effect (with hysteresis coefficient values varying from 0.05 to 0.20). Low values of hysteresis coefficient suggest high hysteresis effect indicating easy and strong adsorption, and slow desorption, of pyraclostrobin in soils. Higher hysteresis coefficient values in organic carbon removed soil (0.25–0.30) and clay fraction removed soil (0.28–0.36) as compared to normal Inceptisol soil suggest relatively weak adsorption and easy desorption of pyraclostrobin. Results of regression analysis suggest that the organic matter and pH of the soil play a major role in adsorption of pyraclostrobin. Leaching studies were carried out in intact soil columns in Inceptisol. The columns were leached with different amounts of water simulating different amounts of rainfall. The results suggest that most of the pyraclostrobin residues will remain present in the top soil layers even under high rainfall conditions and chances of pyraclostrobin moving to lower soil depth are almost negligible.     

Removal of organic contaminants in bioretention medium amended with activated carbon from sewage sludge

Bioretention, also known as rain garden, allows stormwater to soak into the ground through a soil-based medium, leading to removal of particulate and dissolved pollutants and reduced peak flows. Although soil organic matter (SOM) is efficient at sorbing many pollutants, amending the bioretention medium with highly effective adsorbents has been proposed to optimize pollutant removal and extend bioretention lifetime. The aim of this research was to investigate whether soil amended with activated carbon produced from sewage sludge increases the efficiency to remove hydrophobic organic compounds frequently detected in stormwater, compared to non-amended soil. Three lab-scale columns (520 cm³) were packed with soil (bulk density 1.22 g/cm³); activated carbon (0.5% w/w) was added to two of the columns. During 28 days, synthetic stormwater—ultrapure water spiked with seven hydrophobic organic pollutants and dissolved organic matter in the form of humic acids—was passed through the column beds using upward flow (45 mm/h). Pollutant concentrations in effluent water (collected every 12 h) and polluted soils, as well as desorbed amounts of pollutants from soils were determined using GC-MS. Compared to SOM, the activated carbon exhibited a significantly higher adsorption capacity for tested pollutants. The amended soil was most efficient for removing moderately hydrophobic compounds (log K _ow 4.0–4.4): as little as 0.5% (w/w), carbon addition may extend bioretention medium lifetime by approximately 10–20 years before saturation of these pollutants occurs. The column tests also indicated that released SOM sorb onto activated carbon, which may lead to early saturation of sorption sites on the carbon surface. The desorption test revealed that the pollutants are generally strongly sorbed to the soil particles, indicating low bioavailability and limited biodegradation.

     

Sorption, desorption, and degradation of (4-chloro-2-methylphenoxy)acetic acid in representative soils of the Danubian Lowland, Slovakia

Herbicide leaching through soil into groundwater greatly depends upon sorption-desorption and degradation phenomena. Batch adsorption, desorption and degradation experiments were performed with acidic herbicide MCPA and three soil types collected from their respective soil horizons. MCPA was found to be weakly sorbed by the soils with Freundlich coefficient values ranging from 0.37 to 1.03 mg^1−1/n kg⁻¹ L^1/n. It was shown that MCPA sorption positively correlated with soil organic carbon content, humic and fulvic acid carbon contents, and negatively with soil pH. The importance of soil organic matter in MCPA sorption by soils was also confirmed by performing sorption experiments after soil organic matter removal. MCPA sorption in these treated soils decreased by 37-100% compared to the original soils. A relatively large part of the sorbed MCPA was released from soils into aqueous solution after four successive desorption steps, although some hysteresis occurred during desorption of MCPA from all soils. Both sorption and desorption were depth-dependent, the A soil horizons exhibited higher retention capacity of the herbicide than B or C soil horizons. Generally, MCPA sorption decreased in the presence of phosphate and low molecular weight organic acids. Degradation of MCPA was faster in the A soil horizons than the corresponding B or C soil horizons with half-life values ranging from 4.9 to 9.6 d in topsoils and from 11.6 to 23.4 d in subsoils.     

人工湿地基质对 NH+4-N 吸附性能简

为研究建筑废物红砖和工业废物煤渣用作人工湿地脱氮基质的可行性,分别通过静态吸附实验和动态NH₄⁺-N去除效果实验进行考察。结果表明,红砖和煤渣对NH₄⁺-N最大静态吸附量分别为0.2533 mg/g和0.0533 mg/g,其吸附等温曲线均符合Freundlich型吸附方程,吸附常数分别为0.0419和0.0091;红砖煤渣组合对污水中NH₄⁺-N平均动态脱除率达到41.18%,高于红砖的37.63%和煤渣的30.92%。     

Adsorption,Desorption, and Mobility of Permethrin in Malaysian Soils

Abstract

The adsorption, desorption, and mobility of permethrin in six tropical soils was determined under laboratory and greenhouse conditions. The six soils were selected from vegetable growing areas in Malaysia. Soil organic matter (OM) was positively correlated (r ² = 0.97) with the adsorption of permethrin. The two soils, namely, Teringkap 1 and Lating series with the highest OM (3.2 and 2.9%) released 32.5 and 30.8% of the adsorbed permethrin after four consecutive repetitions of the desorption process, respectively, compared to approximately 75.4% of the Gunung Berinchang soil with the lowest OM (1.0%) under the same conditions. The mobility of permethrin down the soil column was inversely correlated to the organic matter content of the soil. Permethrin residue penetrated only to the 10–15 cm zone in the Teringkap 1 soil with 3.2% OM but penetrated to a depth of more than 20 cm in the other soils. The Berinchang series soil with the lowest OM (1.0%) yielded leachate with 14.8% permethrin, the highest level in leachates from all the soils tested. Therefore, the possibility for permethrin to contaminate underground water may be greater in the presence of low organic matter content, which subsequently allows a higher percentage of permethrin to move downwards through the soil column.     

Sorption and transport of trichloroethylene in caliche soil

Sorption of TCE to the caliche soil exhibited linear isotherm at the high TCE concentrations (Co = 122-1300 mg L⁻¹) but Freundlich isotherm at the low concentration range (1-122 mg L⁻¹). Sorption strength of the carbonate fraction of the soil was about 100-fold lower than the sorption strength of soil organic matter (SOM) in the caliche soil, indicating weak affinity of TCE for the carbonate fraction of the soil. Desorption of TCE from the caliche soil was initially rapid (7.6 × 10⁻⁴ s⁻¹), then continued at a 100-fold slower rate (7.7 × 10⁻⁶ s⁻¹). Predominant calcium carbonate fraction of the soil (96%) was responsible for the fast desorption of TCE while the SOM fraction (0.97%) controlled the rate-limited desorption of TCE. Transport of TCE in the caliche soil was moderately retarded with respect to the water (R = 1.75-2.95). Flow interruption tests in the column experiments indicated that the rate-limited desorption of TCE controlled the non-ideal transport of TCE in the soil. Modeling studies showed that both linear and non-linear nonequilibrium transport models provided reasonably good match to the TCE breakthrough curves (r² = 0.95-0.98). Non-linear sorption had a negligible impact on both the breakthrough curve shape and the values of sorption kinetics parameters at the high TCE concentration (Co = 1300 mg L⁻¹). However, rate-limited sorption/desorption processes dominated at this concentration. For the low TCE concentration case (110 mg L⁻¹), in addition to the rate-limited sorption/desorption, contribution of the non-linear sorption to the values of sorption kinetics became fairly noticeable.     

Adsorption studies of the herbicide simazine in agricultural soils of the Aconcagua valley, central Chile

Simazine is a s-triazine herbicide that has been applied worldwide for agriculture. This herbicide is the second most commonly detected pesticide in surface and groundwater in the United States, Europe and Australia. In this study, simazine adsorption behaviour was studied in two agricultural soils of the Aconcagua valley, central Chile. The two studied soils were soil A (loam, 8.5% organic matter content) and soil B (clay-loam, 3.5% organic matter content). Three times higher simazine adsorption capacity was observed in soil A (68.03 mg kg⁻¹) compared to soil B (22.03 mg kg⁻¹). The simazine adsorption distribution coefficients (K_d) were 9.32 L kg⁻¹ for soil A and 7.74 L kg⁻¹ for soil B. The simazine adsorption enthalpy in soil A was −21.0 kJ mol⁻¹ while in soil B the adsorption enthalpy value was −11.5 kJ mol⁻¹. These results indicate that simazine adsorption process in these soils is exothermic, governing H bonds the adsorption process of simazine in both the loam and clay-loam soils. These results and the potentiometric profiles of both soils, suggest that simazine adsorption in soil A is mainly governed by simazine–organic matter interactions and in soil B by simazine–clay interactions. The understanding of simazine sorption–desorption processes is essential to determine the pesticide fate and availability in soil for pest control, biodegradation, runoff and leaching.     

Adsorption and desorption of 2,4,6-trichlorophenol onto and from ash as affected by Ag+, Zn2+, and Al3+

Metal cations and organic pollutants mostly co-exist in the natural environment. However, their interactions in adsorption processes have yet to be adequately addressed. In the current study, the effect of inorganic cations with different charges (Ag⁺, Zn²⁺, and Al³⁺) on the adsorption and desorption of 2,4,6-trichlorophenol (TCP) onto and from processed ash derived from wheat (Triticum aestivum L.) straw was investigated. The adsorption and desorption of TCP were both nonlinear; the isotherm and kinetics curves fitted well using the Freundlich equation and a pseudo-second-order model, respectively. The presence of Ag⁺ promoted TCP adsorption, while Zn²⁺ and Al³⁺ reduced TCP adsorption onto ash. The desorption of TCP from ash showed obvious hysteresis, and the presence of Ag⁺, Zn²⁺, and Al³⁺ caused the desorption to be less hysteretic. The suppression of TCP adsorption by Zn²⁺ and Al³⁺ was ascribed to the partial overlapping of adsorption groups between TCP and metal ions. Al³⁺ had a stronger inhibition effect than that of Zn²⁺ due to its higher binding capacity and larger hydrated ionic radius than those of Zn²⁺. Enhanced adsorption of TCP onto ash by Ag⁺ was ascribed to its ability to reduce the competitive adsorption of water molecules on ash surface by replacing the original ions, such as Na⁺ and Ca²⁺, and compressing the hydrated ionic radius of these metal ions. In addition, Ag⁺ was able to bind with the aromatic organic compounds containing π-electrons, which resulted in a further increase of TCP adsorption by ash.