Modeling 4-Chlorophenol Removal from Aqueous Solutions by Granular Activated Carbon

Since phenols and phenolic compounds in many industrial wastewaters are toxic organic contaminants for humans and aquatic life, to remove these compounds via the most efficient way is very important for environmental remediation treatment. In this context, almost all of the isotherm models (Freundlich, Langmuir, Temkin, Redlich–Peterson, Sips, and Khan) for adsorption in the literature were applied to explain the adsorption mechanism of 4-chlorophenol on activated carbon in this study. Also theoretical modeling data were obtained using model equations; interpolation and analysis of variance were made to compare data by using statistics software. In addition, the thermodynamic and kinetic studies for adsorption mechanism were included in the article. The adsorption of 4-chlorophenol on activated carbon fits well to the pseudo-first-order kinetic model than the pseudo-second-order, intraparticular diffusion and Bangham models. It is also indicated that 4-chlorophenol adsorption by granular activated carbon would be attributed to a type of transition between physical and chemical adsorption rather than a pure physical or chemical adsorption process. As a result, an environmental remediation problem and the adsorption mechanism on activated carbon that can be regarded as a solution to this problem are described and explained using the mathematical models and calculations in this study.     

Atrazine Transport Within a Coastal Zone in Southeastern Puerto Rico: a Sensitivity Analysis of an Agricultural Field Model and Riparian Zone Management Model

Agrichemical runoff from farmland may adversely impact coastal water quality. Two models, the Agricultural Policy/Environmental eXtender (APEX) and the Riparian Ecosystem Management Model (REMM), were used to evaluate the movement of the herbicide atrazine to the Jobos Bay National Estuarine Research Reserve from adjacent fields. The reserve is located on Puerto Rico’s southeast coast. Edge-of-field atrazine outputs simulated with the APEX were routed through a grass-forest buffer using the REMM. Atrazine DT₅₀ (half-life) values measured in both field and buffer soils indicated that accelerated degradation conditions had developed in the field soil due to repeated atrazine application. APEX simulations examined both the measured field and buffer soil atrazine DT₅₀ and the model’s default value. The use of the measured field soil atrazine degradation rate in the APEX resulted in 33 % lower atrazine transport from the field. REMM simulations indicated that the buffer system had the potential to reduce dissolved atrazine transport in surface runoff by 77 % during non-tropical storm events by increasing infiltration, slowing transport, and increasing time for pesticide degradation. During a large runoff event due to a tropical storm that occurred close to the time of an atrazine application, the REMM simulated only a 37 % reduction in atrazine transport. The results indicate that large storm events soon after herbicide application likely dominate herbicide transport to coastal waters in the region. These results agree with water quality measurements in the reserve. This study demonstrated the sensitivity of these models to variations in DT₅₀ values in evaluating atrazine fate and transport in the region and emphasizes that the use of measured DT₅₀ values can improve model accuracy.     

Assessment of Pesticide Residues in Two Arable Soils from the Semi-Arid and Subtropical Regions of China

The residues of 31 chlorinated hydrocarbons (CHCs), 25 chlorophenols (CPs), 30 organophosphorus (OP) and pyrethroid (PRT) in two arable soils from the semi-arid and subtropical regions of China were assessed. Data obtained indicate that the main compounds of CHC pesticide residues in the semi-arid soil were 4,4′-DDE (25.3 ng/g) and β-HCH (14.1 ng/g), which totally accounted to about 90% of total CHC residues detected. The total content of CHC residues detected in the subtropical soil was only 3.1 ng/g, of which approximately 50% was β-HCH. However, the total content of CP residues in both of the soils was about 11 ng/g. In the semi-arid soil, only parathion-methyl amongst the 30 compounds of OP and PRT residues was detected (32.5 ng/g), whilst malathion and parathion-methyl (8.7 and 17.7 ng/g, respectively) detected in the subtropical soil. Based on these results, it was suggested the environmental risk of pesticide residues ranked in an order as CHCs (mainly as 4,4′-DDE, β-HCH) > OP (parathion-methyl) > CPs for the semi-arid soil, and as OPs (parathion-methyl and malathion) > CPs > CHCs (β-HCH) for the subtropical soil.     

Adsorption–desorption of metolachlor and atrazine in Indian soils: effect of fly ash amendment

The effect of two fly ashes as soil amendment on the adsorption–desorption of metolachlor [2-chloro-N-(2-ethyl-6-methylphenyl)-N-(2-methoxy-1-methylphenyl)] and atrazine (2-chloro-4-ethylamino-6-isopropylamino-1,3,5-triazine) was studied in alluvial and laterite soils. The adsorption data for both the herbicides fitted well the Freundlich equation, and Freundlich adsorption coefficient (K _f) increased with an increase of fly ash amount. Both the fly ashes differed in their extent to increase herbicide sorption, and the effect was different in different soils. Atrazine was sorbed more in the soils/soils?+?fly ash mixtures than the metolachlor. The K _f values showed significant correlation with the amount of fly ash amendment (correlation coefficient, R?>?0.982). The desorption isotherms also fitted the Freundlich equation, and desorption showed hysteresis which increased with an increase in the content of fly ash amendment. The free energy change (ΔG) indicated that the sorption process is exothermic, spontaneous, and physical in nature. The study has shown that fly ash as soil amendment significantly increased the sorption of metolachlor and atrazine, but the effect is soil- and fly ash-specific.     

Adsorption of the antiepileptic carbamazepine onto agricultural soils

Carbamazepine is an antiepileptic pharmaceutical which is commonly found in environmental matrices. It passes through wastewater treatment plants (WWTPs) almost completely unaffected and has been found to be highly persistent in the environment. The application of sludge in agricultural fields and the use of WWTP effluents for irrigation constitute a potential source of soil contamination. Consequently, the assessment of the interaction between carbamazepine and soils is of crucial importance to understand its fate in the environment. To monitor the sorption behavior of carbamazepine onto agricultural soils, batch equilibrium experiments were performed using soils subjected to distinct long-term fertilizations. In order to follow the adsorption experiments, an UV spectral deconvolution methodology was applied and the results compared with those from micellar electrokinetic chromatography. The results obtained by both methods did not present significant statistical differences at 95% confidence level. Therefore, it was proven that, in the context of adsorption studies, UV spectral deconvolution is a valid alternative to common chromatographic methods, with the major advantage of being a simple and fast procedure. The adsorption of carbamazepine onto the selected soils was satisfactorily described by the Freundlich model. The obtained Freundlich parameters (K(F)) (between 1.79 ± 0.07 and 4.8 ± 0.2 mg kg(-1) (mg L(-1))(-N)) indicate that the adsorption behavior of carbamazepine is dependent on the soil fertilization. Also, it is not extensively sorbed, indicating that carbamazepine present in soils can be a potential source of contamination of surface and ground waters through run-off and infiltration.     

Characterizing agrochemical patterns and effective BMPs for surface waters using mechanistic modeling and GIS

Monitoring programs in the agriculturally intense San Joaquin River Valley of California have periodically found organophosphate (OP) insecticide concentrations, predominantly chlorpyrifos, diazinon and methidathion, at levels high enough to cause mortality for the aquatic invertebrate Ceriodaphnia dubia. These detections are likely the result of off-site movement from treated fields. However, the relative significance and magnitude of off-site transport pathways cannot be readily deduced from monitoring data alone. Therefore, a comprehensive modeling system has been constructed to estimate temporal and spatial pesticide source magnitudes and to follow the pesticide dissipation pathways once in surface water. The USEPA models HSPF and PRZM3 were used for the hydrology and non-point source predictions, respectively. Spray drift was accounted for using the mechanistic model AgDrift. The Orestimba Creek Watershed in the San Joaquin Valley was characterized and used as a typical watershed for this region. Representative transport pathways were ranked and quantified, and numerical implementation of best management practices (BMPs) determined which practice may have the highest likelihood for reducing pesticide loadings. Approximately 85% of the predicted chlorpyrifos mass detected between May 1, 1996, and April 30, 1997 resulted from drift, with the largest contributions coming from walnut orchards immediately adjacent to Orestimba Creek. Various simulated drift mitigation measures suggest chlorpyrifos mass loadings can be decreased by over 90% depending upon the type of mitigation chosen. Imposed drift BMPs should be effective in reducing chlorpyrifos levels found in surface waters of the San Joaquin valley if the Orestimba creek watershed is considered representative of watersheds found in this area of California.     

Monitoring and risk assessment of pesticides in a tropical river of an agricultural watershed in northern Thailand

The increasing application of pesticides in the uplands of northern Thailand has increased the transfer of pesticides to surface water. To assess the risk of pesticide use for stream water quality, we monitored the concentrations of seven pesticides (atrazine, dichlorvos, chlorpyrifos, dimethoate, chlorothalonil, (α-, β-) endosulfan, cypermethrin) frequently used in the Mae Sa watershed (77 km²) in water and sediment samples over a period of one and a half years (2007–2008). All investigated pesticides were recorded in the river. Chlorpyrifos was detected most often in water samples (75 % at the headwater station), while cypermethrin was most often found in riverbed (86 %) and in all suspended sediment samples. The highest concentrations of the pesticides were detected during the rainy season. About 0.002 to 4.1 % by mass of the applied pesticides was lost to surface water. The risk assessment was based on the risk characterization ratio (RCR). The RCRs of dichlorvos in water, (α-, β-) endosulfan, and cypermethrin in water and sediments were higher than unity indicating that they are likely to pose a threat to aquatic ecosystem. Finally, we discuss the role of sampling design on ecotoxicological risk assessment. Our study shows that pesticide contamination of surface waters is an environmental issue in the Mae Sa watershed and that measures need to be undertaken to reduce the loss of pesticides from soil to surface waters.     

Adsorption of domoic acid to marine sediments and clays

Conditional solid-water distribution coefficients (K(d)) for the adsorption of domoic acid (DA) to a series of complex sediments and clays were determined in artificial seawater. K(d) ranged from 5.11 L g(-1) to 0.97 L g(-1), with a corresponding ranking of: kaolinite > Gulf of Mexico sediment > Santa Barbara Basin sediment > Bread and Butter Creek sediment > poorly crystallized kaolin > Ca-montmorillonite > Na-montmorillonite > well crystallized kaolin > diatomaceous earth. Adsorption correlated with the anion exchange capacity of the clays tested (R(2) = 0.98), but not the more structurally complex sediments. The effect of added transition metals (Fe(iii), Cu(ii), Al(iii)) and terrestrially derived dissolved organic matter (Suwannee River DOM, SRDOM) on DA adsorption to Na-montmorillonite, well crystallized kaolin, and Gulf of Mexico sediment, was also tested. The addition of transition metals led to increased adsorption to all surfaces by a factor of 2-7, presumably by enabling the adsorption of DA-metal complexes. SRDOM enhanced DA adsorption by a factor of approximately 2.5. The release of adsorbed DA from sediments was also examined. Under our conditions, adsorbed DA equilibrated with the overlying aqueous phase within minutes with approximately 50% release.     

Contamination from historic metal mines and the need for non-invasive remediation techniques: a case study from Southwest England

The UK is legally required by the EU Water Framework Directive (WFD) to improve the environmental quality of inland and coastal waters in the coming years. Historic metal mine sites are recognised as an important source of some of the elements on the WFD priority chemicals list. Despite their contamination potential, such sites are valued for their heritage and for other cultural and scientific reasons. Remediating historic mining areas to control the contamination of stream waters, whilst also preserving the integrity of the mine site, is a challenge but might be achieved by novel forms of remediation. In this study, we have carried out environmental monitoring at a historic, and culturally-sensitive, lead-silver mine site in southwest England and have undertaken a pilot experiment to investigate the potential for a novel, non-invasive remediation method at the site. Concentrations of Pb and Zn in mine spoil were clearly elevated with geometric mean concentrations of 6,888 and 710 microg g(-1), respectively. Mean concentrations of Pb in stream waters were between 21 and 54 microg l(-1), in exceedance of the WFD environmental quality standard (EQS) of 7.2 microg l(-1) (annual average). Mean Zn concentrations in water were between 30 and 97 microg l(-1), compared to the UK EQS of 66.5 microg l(-1) (average). Stream sediments within, and downstream from, the mining site were similarly elevated, indicating transport of mine waste particles into and within the stream. We undertook a simple trial to investigate the potential of hydroxyapatite, in the form of bonemeal, to passively remove the Pb and Zn, from the stream waters. After percolating through bonemeal in a leaching column, 96-99% of the dissolved Pb and Zn in stream water samples was removed.     

Atrazine and Alachlor Inputs to Surface and Ground Waters in Irrigated Corn Cultivation Areas of Castilla-Leon Region, Spain

The inputs of atrazine and alachlor herbicides to surface and ground waters from irrigated areas dedicated to corn cultivation in the Castilla-León (C-L) region (Spain) as related to the application of both herbicides were studied. Enzyme-linked immunosorbent assays (ELISA) were used for monitoring the atrazine and alachlor concentrations in 98 water samples taken from these areas. Seventy-nine of the samples were of ground waters and 19 were of surface waters. The concentration ranges of the herbicides detected in the study period (October 1997–October 1998) were 0.04–25.3 g L^–1 in the surface waters and 0.04–3.45 g L^–1 in the ground waters for atrazine, and 0.06–31.9 g L^–1 in the surface waters and 0.05–4.85 g L^–1 in the ground waters in the case of alachlor. The highly significant correlation observed between the concentrations of both herbicides in the surface waters (r = 0.89, p < 0.001) pointed to a parallel transport of atrazine and alachlor to these waters. A study was made of the temporal evolution of the concentrations of both herbicides, and it was found a maximum recharge of atrazine in the ground waters for April 1998 and of alachlor in October 1997 and October 1998. The temporal evolution of the concentrations of both herbicides in surface waters was parallel. The highly significant correlations observed between atrazine concentrations determined by ELISA and by HPLC (r = 0.92, p < 0.001) and between alachlor concentrations also determined by both methods (r = 0.96, p < 0.001) confirmed the usefulness of ELISA for monitoring both herbicides in an elevated number of samples. Using HPLC, the presence in some waters of the alachlor ethanesulfonate (ESA) metabolite was found at a concentration range of 0.52–4.01 g L^–1. However the interference of ESA in the determination of alachlor by ELISA was negligible. The inputs of atrazine and alachlor to waters found in this study, especially the inputs to ground waters, could pose a risk for human health considering that some waters, though sporadically, are even used for human consumption.     

Treatment of wastewater containing arsenic using Rhazya stricta as a new adsorbent

The effective removal of heavy metals from aqueous wastes is among the most important issues for many industrialized countries. Removal of arsenic (As) from aqueous solutions was studied using Rhazia stricta biomass. The batch experiments are carried out to investigate the effect of the significant process parameters such as pH, contact time, solute concentration and adsorbent dose. The optimum pH required for maximum adsorption was found to be 5. The equilibrium data for the adsorption of As(V) on R. stricta are tested with various adsorption isotherm models such as Langmuir, Freundlich, Tempkin and Generalized equation. Results indicate the following order to fit the isotherm: Langmuir (1 and 2)?>?Tempkin?>?Generalized form?>?Freundlich. A comparison of two kinetic models showed that our data fitted well to the Elovich model.     

Estimation of chlorpyriphos and cypermethrin residues in chilli (Capsicum annuum L.) by gas–liquid chromatography

Dissipation of chlorpyriphos and cypermethrin in chilli was studied following three applications of a combination formulation of Nurelle-D 505 (chlorpyriphos 50 %?+?cypermethrin 5 %) at 1 and 2 L?ha^?1 at an interval of 15 days. Residues of chlorpyriphos and cypermethrin in chilli were estimated by gas–liquid chromatography and confirmed by gas chromatography–mass spectrometry. Half-life periods for chlorpyriphos were found to be 4.43 and 2.01 days, whereas for cypermethrin these values were observed to be 2.51 and 2.64 days at single and double the application rates, respectively. Residues of chlorpyriphos dissipated to more than 80 % after 10 days at both the dosages. However, residues of cypermethrin dissipated to the extent of more than 70 % in 7 days. Soil samples collected after 15 days of the last application did not show the presence of chlorpyriphos and cypermethrin at their respective determination limit of 0.01 mg?kg^?1. The use of chlorpyriphos and cypermethrin mixture at the recommended dosage does not seem to pose any hazards to the consumers, and a waiting period of 1 day is suggested to reduce the risk before consumption of green chilli.     

Partitioning of mercury onto suspended sediments in estuaries

Radiochemical partitioning experiments using 203Hg have been undertaken with mixtures of river, seawater and sediment samples taken from three geochemically contrasting UK estuaries: the Plym, Beaulieu and Mersey. Species of dissolved Hg were determined using reversed-phase C18 chelating columns and particulate species were determined by sequential leaching with 1 M NH4OAc and 1 M HCl. Mercury had a high particle reactivity with partition coefficients, KDs, ranging from 10(4) to 5 x 10(5) ml g(-1), depending on salinity, the chemical composition of the end-member waters, and on the physico-chemical characteristics of the sediment. Dissolved organic matter present in the waters (humic substances and/or anthropogenic compounds) was found to be the main factor governing the forms of dissolved Hg and their reactivity. From the spiked 203Hg, up to 95% of the dissolved metal was retained on the C18 columns for the Mersey waters, whereas this fraction was < 60% in the Plym and Beaulieu waters. Quasi-irreversible adsorption of Hg onto particles from each estuary was observed over a time-scale of a few hours and < 20% of total particulate Hg was released by the sequential leach. In this paper, physico-chemical processes are proposed to explain the estuarine behaviour of Hg and the results are discussed in terms of Hg availability in estuarine systems.     

A study on the behaviour of pesticides and their transformation products in the Scheldt estuary using liquid chromatography-electrospray tandem mass spectrometry

Off-line solid-phase extraction (SPE) combined with liquid chromatography-electrospray tandem mass spectrometry (LC-ESI-MS-MS) was used to study the estuarine behaviour of the polar pesticides, atrazine, chloridazon, diuron and metolachlor, and their transformation products (TPs), hydroxyatrazine (HA), desisopropylatrazine (DIA), desethylatrazine (DEA), 3,4-dichlorophenylmethylurea (DPMU) and monuron. The compounds were identified by comparing their LC retention times and product-ion spectra with those of standard solutions. In all but one case the detection limits of the method were sufficient to determine the compounds of interest over the entire salinity range in the estuary. The concentrations of the dissolved pesticides ranged from 70 ng l-1 for chloridazon to 1350 ng l-1 for diuron. The levels of TPs were 3-8% of the levels of their parent pesticide. The mixing plots of polar pesticides and their TPs indicated that TPs, which are present in fresh river water, are conservatively transported to the sea and that no additional amounts of TPs are formed during their transport through the estuary. The one exception was HA, of which approximately 10% of the amount transported to the North Sea is formed in the lower part of the estuary by photochemical oxidation of atrazine. The latter was concluded from the ratios of each analyte over the sum total of the parent pesticide and all TPs along the salinity gradient, which proved to be a useful tool for identifying such estuarine transformations.     

Fruit Stones from Industrial Waste for the Removal of Lead Ions from Polluted Water

Lead, one of the earliest metals recognized and used by humans, has a long history of beneficial use. However, it is now recognized as toxic and as posing a widespread threat to humans and wildlife. Treatment of lead from polluted water and wastewater has received a great deal of attention. Adsorption is one of the most common technologies for the treatment of lead-polluted water. This technique was evaluated here, with the goal of identifying innovative, low-cost adsorbent. This study presents experiments undertaken to determine the suitable conditions for the use of peach and apricot stones, produced from food industries as solid waste, as adsorbents for the removal of lead from aqueous solution. Chemical stability of adsorbents, effect of pH, adsorbents dose, adsorption time and equilibrium concentration were studied. The results reveal that adsorption of lead ions onto peach stone was stronger than onto apricot stone up to 3.36% at 3 h adsorption time. Suitable equilibrium time for the adsorption was 3–5 h (% Pb adsorption 93% for apricot and 97.64% for peach). The effective adsorption range for pH in the range was 7–8. Application of Langmuir and Freundlich isotherm models show high adsorption maximum and binding energies for using these adsorbents for the removal of lead ions from contaminated water and wastewater.     

Risk assessment and remediation suggestion of impacted soil by produced water associated with oil production

Produced water is water trapped in underground formations that is brought to the surface along with oil or gas production. Oilfield impacted soil is the most common environmental problem associated with oil production. The produced water associated with oil-production contaminates the soil and causes the outright death of plants, and the subsequent erosion of topsoil. Also, impacted soil serves to contaminate surface waters and shallow aquifers. This paper is intended to provide an approach for full characterization of contaminated soil by produced water, by means of analysis of both the produced water and the impacted soil using several recommended analytical techniques and then identify and assay the main constituents that cause contamination of the soil. Gialo-59 oilfield (29N, 21E), Libya, has been chosen as the case study of this work. The field has a long history of petroleum production since 1959, where about 300,000 bbl of produced water be discharged into open pit. Test samples of contaminated soil were collected from one of the disposal pits. Samples of produced water were collected from different points throughout the oil production process, and the analyses were carried out at the labs of Libyan Petroleum Institute, Tripoli, Libya. The results are compared with the local environmental limiting constituents in order to prepare for a plan of soil remediation. The results showed that the main constituents (pollutants) that impact the soil are salts and hydrocarbon compounds. Accordingly; an action of soil remediation has been proposed to remove the salts and degradation of hydrocarbons.     

New procedures for simultaneous determination of mesotrione and atrazine in water and soil. Comparison of the degradation processes of mesotrione and atrazine

A method for the determination of residues of mesotrione, atrazine and its degradation products: deethylatrazine, hydroxyatrazine, deisopropylatrazine, desethyldesisopropylatrazine in a variety of water and soil matrices has been developed. Mesotrione is a new selective herbicide for use in corn, which has been substituted for atrazine, which has been banned in European Union countries since 2007. Although atrazine has not been used for three vegetative periods, it is still detected in the environment. The analysis was conducted by means of ultra-high-pressure liquid chromatography with ultraviolet detection and liquid chromatography with diode array detection. The procedures for analyte separation from water and soil matrices were also established. The optimal conditions for solid-phase extraction (SPE) were determined. The recoveries were compared with that obtained by means of SPE. Method fortification recoveries from water samples averaged 78–97% and for soil 80–97% depending on the analyte and type of sample. The limits of detection were 0.04–0.61 μg/L for water samples and for soil samples 0.02–0.88 μg/g. The soil samples were collected in spring 2009 from three different fields with water samples being made from effluents from these fields. Samples collection was conducted in the day of mesotrione (Callisto 100SC) application and then done weekly, until the mesotrione concentration was below the limit of quantification. The results enabled the monitoring of mesotrione degradation in soil and its permeability into surface waters; simultaneously, the same studies were conducted for atrazine.     

Morphological abnormalities in frogs from a rice-growing region in NSW, Australia, with investigations into pesticide exposure

Three frog species (Limnodynastes tasmaniensis, Limnodynastes fletcheri and Litoria raniformis) were surveyed in rice bays of the Coleambally Irrigation Area (CIA), NSW, Australia, during the rice-growing seasons of 2005/2006 and 2006/2007. A total external morphological abnormality index of 7.0% was observed in frogs of the CIA (n?=?1,209). The types and frequencies of abnormalities were typical of reports from agricultural areas with ectrodactyly being the most common aberration. A relatively low abnormality index of 1.2% was observed in L. raniformis (n?=?87) compared to indices of 7.1% and 8.2% observed in L. fletcheri (n?=?694) and L. tasmaniensis (n?=?428), respectively. No conclusive evidence was found of unnaturally high rates of intersex, gonadal maldevelopment or unbalanced sex ratios in any species. Rice bay surface waters differed significantly in mean pesticide concentrations of atrazine and metolachlor on farms growing rice and corn compared to farms with rice as the sole crop. However, the similar abnormality indices observed in recent metamorphs emerging from these two farm types provided no evidence to suggest a link between larval exposure to the measured pesticides and developmental malformations.     

固相微萃取-气相色谱-质谱法测定水中痕量有机磷和阿特拉津农药

采用PA萃取纤维吸附水中敌敌畏、乐果、内吸磷、甲基对硫磷、对硫磷、马拉硫磷等6种有机磷和阿特拉津农药,在气相色谱-质谱仪进样口热解吸后进行检测.筛选比较了几种萃取纤维,优化了萃取方式、萃取时间、离子强度、pH、解吸温度和解吸时间等萃取条件.方法适用于多类型水体中6种有机磷和阿特拉津农药的分析.     

土壤中铁氧化物对铅吸附-解吸的影响

选择上海地区广泛分布的水稻土,通过静态吸附平衡试验,比较土壤去除非晶质氧化铁和去除游离氧化铁后对Pb2+的吸附-解吸行为,采用数学模型拟合,探讨3种土壤的最佳拟合方程、最大吸附的理论值和亲和能力,进而研究非晶质氧化铁和游离氧化铁对Pb2+吸附-解吸的影响。结果表明,去除氧化铁后吸附能力和亲和能力均减弱,原土的最大吸附量为29.21 g/kg,非晶质氧化铁的贡献值为3.52 g/kg,游离氧化铁的贡献值为8.32 g/kg。