Modeling of single and competitive metal adsorption onto a natural polysaccharide

Sugar beet pulp, a common agricultural waste, was studied in the removal of metal ions from aqueous solutions. Potentiometric titrations were used to characterize the surface acidity of the polysaccharide. The acid properties of the material can be described by invoking three distinct types of surface functional groups with the intrinsic acidity constants (pKa(int)) values 3.43+/-0.1, 6.05+/-0.05, and 7.89+/-0.1, respectively. The contents of each functional group (i.e., the carboxyl and phenol moieties) were also determined. Then, a simple surface complexation model with the diffuse layer model successfully described the sorption of several metal ions (Cu2+, Zn2+, Cd2+, and Ni2+) onto the polysaccharide under various experimental conditions: pH ranging from 2 to 5.5, ionic strength from 0.01 to 0.1 M, metal concentration between 10(-4) and 10(-3) M, for a constant sorbent concentration equal to 2.5 g x L(-1). It was observed experimentally that the affinity of the polysaccharide was in the sequence of Cu2+ > Zn2+ > Cd2+ > Ni2+. Predictions of sorption in binary-metal systems based on single-metal data fits represented competitive sorption data reasonably well.     

植物乳杆菌X7021吸附重金属和降解亚硝酸盐能力的研究

目的 为了发掘植物乳杆菌X7021在食品发酵剂和益生菌方面的应用潜力, 本文研究了该菌株吸附重金属与降解亚硝酸盐的能力 。方法 采用分光光度法检测Cu2+和亚硝酸盐含量, 采用石墨炉原子吸收分光光度法检测Cd2+和Pb2+含量。探讨pH、温度、吸附时间和离子浓度等因素对植物乳杆菌X7021吸附重金属能力的影响, 以及亚硝酸盐浓度对其生长和降解能力的影响。结果 植物乳杆菌X7021对重金属的吸附率和吸附量均受到吸附条件的影响。首先，吸附量随着金属离子浓度的增加而增加, 而吸附率呈现出先快速下降后趋于平缓的趋势。其次, 吸附率和吸附量均随吸附时间增加而增加, 且植物乳杆菌X7021对Pb2+的吸附量明显优于Cu2+、和Cd2+。第三, Cu2+、Cd2+和Pb2+的最大吸附率分别在pH=7、7和6；且温度为37 °C时, 三种重金属离子的吸附率和吸附量均达到最大。除此之外, 植物乳杆菌X7021在24 h内几乎完全降解100 mg/L NaNO2, 且可耐受浓度高达700 mg/L的亚硝酸盐。结论 植物乳杆菌X7021能够有效吸附Cu2+、Cd2+、Pd2+等重金属离子, 且对亚硝酸盐有较强的降解和耐受能力, 在发酵食品及益生菌领域具有潜在的应用前景。     

Chemical speciation of Zn,Cd, Cu,and Pb in pore waters of agricultural and contaminated soils using Donnan dialysis

Knowledge of trace metal speciation in soil pore waters is important in addressing metal bioavailability and risk assessment of contaminated soils. Numerous analytical methods have been utilized for determining trace metal speciation in aqueous environmental matrixes; however, most of these methods suffer from significant interferences. The Donnan dialysis membrane technique minimizes these interferences and has been used in this study to determine free Zn2+, Cd2+, Cu2+, and Pb2+ activities in pore waters from 15 agricultural and 12 long-term contaminated soils. The soils vary widely in their origin, pH, organic carbon content, and total metal concentrations. Pore water pM2+ activities also covered a wide range and were controlled by soil pH and total metal concentrations. For the agricultural soils, most of the free metal activities were below detection limit, apart from Zn2+ for which the fraction of free Zn2+ in soluble Zn ranged from 2.3 to 87% (mean 43%). Five of the agricultural soils had detectable free Cd2+ with fractions of free metal ranging from 59 to 102% (mean 75%). For the contaminated soils with detectable free metal concentrations, the fraction of free metal as a percentage of soluble metal varied from 9.9 to 97% (mean 50%) for Zn2+, from 22 to 86% (mean 49%) for Cd2+, from 0.4 to 32.1% (mean 5%) for Cu2+, and from 2.9 to 48.8% (mean 20.1%) for Pb2+. For the contaminated soils, the equilibrium speciation programs GEOCHEM and WHAM Model VI provided reasonable estimates of free Zn2+ fractions in comparison to the measured fractions (R2 approximately 0.7), while estimates of free Cd2+ fractions were less agreeable (R2 approximately 0.5). The models generally predicted stronger binding of Cu2+ to DOC and hence lower fractions of free Cu2+ as compared with the observed fractions. The binding of Cu2+ and Pb2+ to DOC predicted by WHAM Model VI was much strongerthan that predicted by GEOCHEM.     

Complexation with dissolved organic matter and solubility control of heavy metals in a sandy soil

The complexation of heavy metals with dissolved organic matter (DOM) in the environment influences the solubility and mobility of these metals. In this paper, we measured the complexation of Cu, Cd, Zn, Ni, and Pb with DOM in the soil solution at pH 3.7-6.1 using a Donnan membrane technique. The results show that the DOM-complexed species is generally more significant for Cu and Pb than for Cd, Zn, and Ni. The ability of two advanced models for ion binding to humic substances, e.g., model VI and NICA-Donnan, in the simulation of metal binding to natural DOM was assessed by comparing the model predictions with the measurements. Using the default parameters of fulvic and humic acid, the predicted concentrations of free metal ions from the solution speciation calculation using the two models are mostly within 1 order of magnitude difference from the measured concentrations, except for Ni and Pb in a few samples. Furthermore, the solid-solution partitioning of the metals was simulated using a multisurface model, in which metal binding to soil organic matter, dissolved organic matter, clay, and iron hydroxides was accounted for using adsorption and cation exchange models (NICA-Donnan, Donnan, DDL, CD-MUSIC). The model estimation of the dissolved concentration of the metals is mostly within 1 order of magnitude difference from those measured except for Ni in some samples and Pb. The solubility of the metals depends mainly on the metal loading over soil sorbents, pH, and the concentration of inorganic ligands and DOM in the soil solution.     

Effective recovery of harmful metal ions from squid wastes using subcritical and supercritical water treatments

The Japanese common squid wastes contained high concentration of metal ions such as 31.7 ppm Cd(II), 264.0 ppm Cu(II), and 140.0 ppm Zn(II). The use of sub- and supercritical water treatment has been investigated as a new method of recovering heavy metals from squid wastes. The reactions were carried out in the temperature range of 443-653 K, a pressure range of 0.792-30 MPa, and reaction times of 1-40 min. The wastes were decomposed into soluble proteins, organic acids, amino acids, and so on in the aqueous phase, and the fat and oil were extracted by sub- and supercritical water. The maximum yields on concentration of Cd(II), Cu(II), and Zn(II) in the solid, fat, and oil phases were found at 653, 573, and 513-573 K, respectively. The aqueous phase showed the lowest concentration of the metal ions (0.05-0.5 ppm). The distribution coefficient of metal ions in the fat, solid, and oil phases to aqueous phase were examined and found highest in the fat phase (max. 48 000). The solid phase (max. 39,000) and oil phase (max. 245) showed the second and third highest. Moreover, the fat and oil phases produced during this method act as chelating agents to catch metal ions with an order of recovery of Cu2+ > Zn2+ > Cd2+ and Zn2+ > Cu2+ > Cd2+, respectively.     

Sorption and desorption of Cd2+ and Zn2+ ions in apatite-aqueous systems

As a low-soluble phosphate mineral capable of binding various metal ions, apatite can be used to immobilize toxic metals in soils and waters. In the present research the factors affecting sorption and desorption of Cd2+ and Zn2+ ions on/from apatites are investigated. Batch experiments were carried out using synthetic hydroxy-, fluoride-, and carbonate-substituted apatites having various specific surface area (SSA). Apatite sorption capacity was found to depend mainly on its SSA, ranging from 16 to 78 and from 11 to 79 mmol per 100 g of apatite for Cd2+ and Zn2+, respectively. The solution composition (pH, and presence of Cl- and NO3- ions) had no essential impact on sorption. Desorption of bound cations depended both on the sorption level and solution composition. The amount of desorbed Cd2+ and Zn2+ increased proportionally to the amount of sorbed cations. However, apatites having higher sorption capacity release relatively less sorbed cations. Desorption increases with increasing Ca2+ concentration in the solution, reaching 8-20% of sorbed Cd2+ in 0.002 M, 10-35% in 0.01 M, and 33-45% in 0.05 M Ca(NO3)2 solution. Compared to nitrate solutions, the presence of Cl- ions in the solution promotes the release of bound cations. Desorption of Zn2+ is slightly higher than that of Cd2+. The desorption mechanism was assumed to include both ion-exchange and adsorption of Ca2+ ions on apatite surface.     

中药提取物中重金属离子的去除方法研究

采用001×7强酸性阳离子交换树脂,对中药提取物中有害重金属离子pb2+、Cd2+、Cu2+进行吸附去除试验,并检测离子交换处理对其黄酮含量回收率的影响.结果表明:001×7强酸性阳离子交换树脂对于中药提取物所含重金属离子pb2+、Cd2+、Cu2+去除效果显著,黄酮回收率为95.3～97.9％.001×7强酸性阳离子...     

北京市售大米重金属含量监测及膳食风险评估

监测市售大米重金属含量,为北京市食品安全风险评估提供参考和数据支撑,采集了市售大米样品537件,分析其9种重金属(Cd、Cr、Cu、Fe、Mn、Ni、Pb、Sr和Zn)含量。采用内梅罗综合污染指数法评价市售大米的重金属污染水平,采用健康风险评价模型进行食用安全评估。结果如下:大米Cd、Cr、Cu、Fe、Mn、Ni、Pb、Sr和Zn含量平均值分别为0.02、0.02、2.27、2.63、9.10、0.15、0.07、0.17和14.27 mg/kg。大米重金属污染程度依次为:PbZnNiCuCdCr,其风险等级依次为:CuZnCdPbCrNi。结果表明,大米重金属的内梅罗综合污染指数较低,表明当前北京市售大米整体状况较好、处于安全水平;大米重金属对儿童的THQ贡献率高于成人,相关部门应加强有毒重金属监督与相应膳食指导。     

Stability of metal-glutathione complexes during oxidation by hydrogen peroxide and Cu(II)-catalysis

Thiol-containing ligands such as glutathione (GSH) are expected to degrade in the presence of oxygen; however, complexation by Hg, Ag, and other trace metals may protect free thiol functional groups (R-S-) from oxidation, leading to persistence in surface water environments. In this study, the stability of GSH complexes with Hg2+, Ag+, and other metals including Cd2+, Zn2+, and Pb2+ was assessed during exposure to two potential environmental oxidants: H202 and Cu2+. The results indicated that Hg-(GSH)2 and Ag(GSH) complexes were completely stable for at least 2 days in the presence of either H202 or Cu2+. In contrast, free GSH oxidized within minutes to hours. Complexation by Cd, Zn, and Pb slightly decreased or did not significantly affect the oxidation rate of GSH, depending upon the pH (tested between pH 6 and 9). Thermodynamic modeling of GSH speciation demonstrated that the observed oxidation rates were not consistent with predicted free GSH3- concentration. These results indicated that Cd-, Zn-, and Pb-GSH complexes were susceptible to oxidation by a mechanism that differs from GSH3- oxidation. In contrast, Hg- and Ag-GSH complexes were inert for days, suggesting that they are stable for relatively long periods in the oxic water column. These results demonstrate that coordination of Hg(II) and Ag(I) to thiol-containing ligands can potentially increase persistence and transport in surface waters.     

Substrate specificity of a tripeptidase as a metalloenzyme purified from Lactococcus lactis subsp. lactis biovar. diacetylactis ATCC 13675

The peptidase purified to homogeneity from Lactococcus lactis subsp. lactis biovar. diacetylactis ATCC 13675 was considered to be an aminotripeptidase (EC 3.4.11.4) from the results of substrate specificity. The K(m) value showed a tendency to decrease with the number of alanine residues, but to increase with the number of glycine residues in the substrate tripeptide. The effects of divalent metal ions on enzyme activity were considerably different depending on the tripepride used as a substrate. In the case of Mn2+, Co2+, Ni2+, Cu2+, Zn2+ and Cd2+, there was apparent correlation between enzyme activities observed in the presence of metal ions and following metal ion replacement. The Zn2+-replaced enzyme showed almost the same K(m) and k(cat) values as the native enzyme, suggesting the enzyme to be a zinc metallopeptidase. The K(m) of the divalent metal-replaced enzyme increased in the order of Co2+, Zn2+, and Mn2+. As a result of replacement with Co2+ an enzyme having 2.3-fold higher activity compared to the native enzyme for GGF as a substrate was obtained. Thus, the change in substrate specificity observed following metal replacement may suggest a highly specific interaction between the enzyme, metal and substrate, leading to the activity expression and stability of the tripeptidase.     

Partial purification and characterization of an extracellular proteinase from Aeromonas hydrophila strain A4

An extracellular metalloproteinase from Aeromonas hydrophila strain A4, isolated from milk, was purified by a factor of 300 by chromatography on DEAE-cellulose and Sephadex G-150. The enzyme had a mol. wt of 43,000 and contained 2 g atom Ca/mol. It was active over a pH range 4.8-9.5 and had optimum activity on casein at pH 7.0 with Km = 0.17 mM. It was strongly inactivated by metal chelators and the apoenzyme was fully reactivated with Ca2+, Mn2+ or Co2+. Heavy metal ions such as Ag+, Hg2+, Fe2+, Zn2+, Cd2+, Ni2+ and Cu2+ totally or partly inactivated the enzymic activity at 5 mM concentration. The enzyme was not inactivated by diisopropylfluorophosphate, soyabean trypsin inhibitor or sulphydryl group reagents. It was optimally active at 45 degrees C; above 50 degrees C activity declined rapidly, but significant activity persisted at 4 degrees C. It was heat labile in phosphate or Tris-maleate buffer but exogenous Ca2+ afforded protection.     

A terrestrial biotic ligand model. 1. Development and application to Cu and Ni toxicities to barley root elongation in soils

A Terrestrial Biotic Ligand Model (TBLM) was developed using noncalcareous soils from Europe based on Cu and Ni speciation and barley (Hordeum vulgare cv. Regina) root elongation bioassays. Free metal ion (M2+) activity was computed by the WHAM VI model using inputs of soil metal, soil organic matter, and alkali and alkaline earth metals concentrations, and pH in soil solution. The TBLM assumes that metal in soil and in the solution are in equilibrium. Metal ions react with the biotic ligand, the receptor site, and inhibit root elongation. Other ions, principally H+, Ca2+ and Mg2+, compete with M2+ and, therefore, affect its toxicity. Toxicity is correlated only to the fraction of the total biotic ligand sites occupied by M2+. Compared to other models using either the soil metal concentration or M2+ activity as the toxic dose, the TBLM provides a more consistent method to normalize and compare Cu and Ni toxicities to root elongation among different soils. The TBLM was able to predictthe EC50 soil Cu and Ni concentrations generally within a factor of 2 of the observed values, a level of precision similar to that for the aquatic Biotic Ligand Model, indicating its potential utility in metals risk assessment in soils.     

皮芯复合离子交换纤维的吸附性能

测定自制皮芯复合离子交换纤维对Zn2+、Cu2+的静态吸附量,研究纤维对Zn2+、Cu2+吸附动力学以及影响吸附性能的主要因素,探讨该纤维材料的化学稳定性和使用再生性能,结果表明：该离子交换纤维对Cu2+、Zn2+吸附的主控步骤为液膜扩散,在实验的浓度范围内(0.005～0.2 mol/L),纤维对这2种金属离子的吸附均属单分子层吸附,其等温吸附可以用Langmuir和Freundlich方程来描述,该纤维对Cu2+、Zn2+吸附速率快,最大吸附量均超过2mmol/g,最佳pH值为8.0～9.0左右,有良好的吸附性能和使用稳定性。     

Analysis of trace metal humic acid interactions using counterion condensation theory

Recent extensions of counterion condensation theory, originally developed for well-defined linear polyelectrolytes, enable us to analyze the interaction of trace metals with humic acid. In the present model, the heterogeneity of the macromolecule is taken into account as well as the chemical binding of the considered metal ions to the humic material. Experimentally, potentiometric titrations have been performed for humic acid in solution in the presence of different environmentally important (heavy) metals (Ca, Cd, Cu, Ni, and Pb) at various metal concentrations by titrating with potassium hydroxide without additional salt. From proton release data obtained for the initial point in the titration, it was estimated that the interaction of the different metals with the humic acid in terms of binding strength increased in the order Ca < Cd approximately = Ni < Pb approximately = Cu. These results were confirmed by model analysis. Experimentally obtained apparent dissociation constants were in good agreement for the humic acid systems containing Ca, Cd, and Ni at concentrations ranging from 0 up to 0.75 x 10(-3) mol L(-1) and polymer dissociation degree from about 0.1 up to approximately 0.8. Also for the Cu/humic acid and Pb/humic acid systems, the agreement between experimental data and calculated data was satisfactory atthe lowest metal concentrations over the complete titration curve. For elevated levels of Cu and Pb, the agreement between experimental data and theoretical calculations becomes less satisfactory at low degrees of dissociation of the humic acid. This distortion of the potentiometric curves is probably due to changes in the intrinsic pK of the functional groups due to metal binding. This complex process is not included in present polyelectrolytic models.     

Antacid and sorption properties of mushroom powder made of dried solids (Pleurotus ostreatus)

It was established in the experiments determining the influence of the mushroom powder on acidity of the HCl solution by means of ionometrical method that in 15 minutes after introduction 3 gram of the powder pH of the solution increases from 1.62 up to 2.64. The stable meaning of the solution pH (without fall) can be (held) the same in the presence of the powder more than 23 hours. The mushroom powder reduces the high content of the ions Pb2+ and Cu2+ in the solution from 8.8 x 10(-6) up to 3.3 x 10(-6) and from 11.8 x 10(-6) up to 8.6 x 10(-6) mole/ml correspondingly. The trustworthy reduction (fall) of the concentration of the ions Zn2+ and Cd2+ in the filtrate was not discovered (found out). To determine the content of metal in the solution the method of flaming atomic adsorption.     

江西抚州烟区土壤及烟叶重金属污染状况评价

为了弄清江西抚州烟区土壤和烟叶中As、Cd、Cr、Cu、Ni、Pb、Zn和Hg等重金属含量和污染状况,运用内梅罗指数和相关分析法,对这些重金属元素在土壤和烟叶中的含量进行了测定。结果表明,该烟区土壤中重金属含量总体上低于我国土壤二级标准（GB15618-1995）,但其污染程度已处于警戒线水平,Cd和Hg为烟区土壤主要风险因子。土壤和烟叶中重金属含量顺序分别为Zn> Pb> Cr> Cu> Ni> As> Cd> Hg和Zn> Cu> Pb> Cd> Cr> Ni> As> Hg,土壤中Hg、Cd、As和烟叶中Ni、Cr变异系数均较大。烟叶中重金属富集系数顺序为Cd> Zn> Cu> Hg> Ni> Cr> Pb> As,烟叶Cd富集系数高达11.67,表明烟草属于Cd强烈富集作物。     

Slow formation and dissolution of Zn precipitates in soil: a combined column-transport and XAFS study

Recent spectroscopic studies have demonstrated the formation of layered double hydroxides (LDH) and phyllosilicates upon sorption of Zn2+, Ni2+, and Co2+ to clay minerals and aluminum oxides at neutral to alkaline pH and at relatively high initial metal concentrations (>1 mM). The intention of the present study was to investigate whether such phases also form in soil under slightly acidic conditions and at lower metal concentrations. Columns packed with a loamy soil were percolated with aqueous solutions containing 0.1 or 0.2 mM Zn, Ni, Co, and Cd in a 10 mM CaCl2 background at pH 6.5. Metal breakthrough curves indicated a rapid initial sorption step, resulting in retarded breakthrough fronts, followed by further slow metal retention during the entire loading period of 42 days (7000 pore volumes). Total metal sorption and the contribution of slow sorption processes decreased in the order Zn > Ni > Co > Cd. Leaching the reacted soil with 10 mM CaCl2 at pH 6.5 remobilized 8% of the total retained Zn, 15% of Ni, 21% of Co, and 77% of Cd. Subsequent leaching with acidified influent (pH 3.0) remobilized most of the remaining metals. X-ray absorption fine-structure (XAFS) spectroscopy revealed that slow Zn sorption was due to the formation of a Zn-Al LDH precipitate. Although Ni, Co, and Cd concentrations were too low for XAFS analysis, their leaching patterns suggest that part of Ni and Co were also incorporated in solid phases, while most sorbed Cd was still present as exchangeable sorption complex after 42 days. A small but significant percentage of the sorbed metals (2-5%) remained in the soil, even after leaching with more than 3000 pore volumes at pH 3.0, which may suggest micropore diffusion or incorporation into more stable mineral phases.     

茶多酚金属络合物的制备及其抑菌活性

以茶多酚镉(TP-Cd)络合物的制备工艺为例,对反应温度、时间、pH和TP/Cd2+摩尔比等茶多酚金属络合物的制备工艺进行了研究,在此基础上制备了TP-Cd、TP-Cu、TP-Zn、TP-Fe(Ⅲ)、TP-Al、TP-Mn、TP-K、TP-Ca、TP-Se、TP-Cr、TP-W、TP-Pb 12种金属离子络合物,并比较了这些络合物对金黄色葡萄球菌和软腐病菌的抑菌活性。结果表明,制备TP-Cd络合物的最佳工艺参数为:TP/Cd2+摩尔比1:1,pH6.5,30 ℃下反应30 min;在此条件下,茶多酚沉淀率最高为93.91%。除Se4+、K+外,TP与大多数金属离子络合后,对金黄色葡萄球菌的抑菌活性均增强,其抑菌能力大小为TP-Cu>TP-Cd>TP-Zn>TP-Pb>TP-Mn>TP-W≈TP-Al>TP-Fe(Ⅲ)>TP-Cr≈TP-Ca>TP;TP仅与Cu2+、Cd2+、Zn2+、Se4+、Mn2+络合后对软腐病菌的抑菌活性显著增强,其抑菌能力大小为TP-Cu≈TP-Cd>TP-Zn>TP-Se>TP-Mn>TP,TP与Pb2+、Cr2+络合后其抗真菌活性完全丧失。可见,金属离子与TP络合后影响了TP的抑菌活性,其中以TP-Cu、TP-Cd和TP-Zn的抑菌活性最强。Cu2+、Cd2+和Zn2+等离子与TP络合后,不仅能显著增强TP的抑菌活性,还能有效减轻它们的毒副作用,为开发、利用安全高效的新型抑菌药物提供理论依据,也为茶资源的综合利用提供了新的思路。     

Reaction-based model describing competitive sorption and transport of Cd, Zn, and Ni in an acidic soil

Predicting the mobility of heavy metals in soils requires models that accurately describe metal adsorption in the presence of competing cations. They should also be easily adjustable to specific soil materials and applicable in reactive transport codes. In this study, Cd adsorption to an acidic soil material was investigated over a wide concentration range (10(-8) to 10(-2) M CdCl2) in the presence of different background electrolytes (10(-4) to 10(-2) M CaCl2 or MgCl2 or 0.05 to 0.5 M NaCl). The adsorption experiments were conducted at pH values between 4.6 and 6.5 A reaction-based sorption model was developed using a combination of nonspecific cation exchange reactions and competitive sorption reactions to sites with high affinity for heavy metals. This combined cation exchange/specific sorption (CESS) model accurately described the entire Cd sorption data set. Coupled to a solute transport code, the model accurately predicted Cd breakthrough curves obtained in column transport experiments. The model was further extended to describe competitive sorption and transport of Cd, Zn, and Ni. At pH 4.6, both Zn and Ni exhibited similar sorption and transport behavior as observed for Cd. In all transport experiments conducted under acidic conditions, heavy metal adsorption was shown to be reversible and kinetic effects were negligible within time periods ranging from hours up to four weeks.     

Impacts of traffic and rainfall characteristics on heavy metals build-up and wash-off from urban roads

An investigation into the effects of changes in urban traffic characteristics due to rapid urbanisation and the predicted changes in rainfall characteristics due to climate change on the build-up and wash-off of heavy metals was carried out in Gold Coast, Australia. The study sites encompassed three different urban land uses. Nine heavy metals commonly associated with traffic emissions were selected. The results were interpreted using multivariate data analysis and decision making tools, such as principal component analysis (PCA), fuzzy clustering (FC), PROMETHEE, and GAIA. Initial analyses established high, low, and moderate traffic scenarios as well as low, low to moderate, moderate, high, and extreme rainfall scenarios for build-up and wash-off investigations. GAIA analyses established that moderate to high traffic scenarios could affect the build-up, while moderate to high rainfall scenarios could affect the wash-off of heavy metals under changed conditions. However, in wash-off, metal concentrations in 1-75 μm fraction were found to be independent of the changes to rainfall characteristics. In build-up, high traffic activities in commercial and industrial areas influenced the accumulation of heavy metal concentrations in particulate size range from 75 - >300 μm, whereas metal concentrations in finer size range of <1-75 μm were not affected. As practical implications, solids <1 μm and organic matter from 1 - >300 μm can be targeted for removal of Ni, Cu, Pb, Cd, Cr, and Zn from build-up, while organic matter from <1 - >300 μm can be targeted for removal of Cd, Cr, Pb, and Ni from wash-off. Cu and Zn need to be removed as free ions from most fractions in wash-off.