Roadside Soils Research Articles

Evaluation of the potential of Erodium glaucophyllum L. for phytoremediation of metal-polluted arid soils.

The present work aimed at studying pollution of traffic-related heavy metals (HMs) in roadside soils and their uptake by the Mediterranean native species Erodium glaucophyllum L., growing along Gabès-El Hamma highway, Gabès (Tunisia). Here, heavy metals were analyzed in soils and in plant roots and shoots along different distances from the highway edge. High levels of all the investigated soil trace elements were found in samples collected at 15m distance from the highway. Overall, HM concentrations in the below- and aboveground part of E. glaucophyllum showed significant decreases with increasing distance from the highway. The lowest values were recorded at 150m. Biological concentration factor (BCF) and mobility ratio (MR) of all investigated heavy metals were > 1 at all distances from the highway, except for Mn and Cu. High values of BCF and MR for Zn indicate that E. glaucophyllum has an excellent potential for the assimilation of this element from the soil. In addition, the higher translocation factors (TF) of Pb, Cd, Zn, and Fe in E. glaucophyllum shoots make it suitable for their phytoextraction from soil, while the lower TF for Mn and Cu make this plant convenient for their phytostabilization. Moreover, the significant positive correlations of Mn, Pb, Cu, and Zn in soil and Erodium organs may suggest its potential use as biomonitor of these trace elements. According to these results, E. glaucophyllum seems to be valued as an efficient native species for in situ phytoremediation program on traffic metal-polluted soils.

Mucilaginibacter formosus sp. nov., a bacterium isolated from road-side soil.

A Gram-stain negative, aerobic, non-motile and rod-shaped novel bacterial strain, designated as MAH-5T, was isolated from a road-side soil sample and was characterised by using a polyphasic taxonomic approach. The colonies were observed to be yellowish orange in colour, smooth, circular and 0.3-0.7mm in diameter when grown on nutrient agar for 2days. Strain MAH-5T was found to be able to grow at 15-35°C and at pH 4.0-8.0. The strain was observed to be positive for both the catalase and oxidase tests. Cells were found to be able to hydrolyse aesculin, gelatin and starch. By 16S rRNA gene sequence comparisons, the isolate was identified as a member of the genus Mucilaginibacter and to be closely related to Mucilaginibacter panaciglaebae BXN5-31T (98.35%), Mucilaginibacter soyangensis HME6664T (97.82%), Mucilaginibacter antarcticus S14-88T (97.49%) and Mucilaginibacter ximonensis XM-003T (97.06%). In DNA-DNA hybridization tests, the DNA relatedness values between strain MAH-5T and its close phylogenetic neighbors were below 45.0%. The genomic DNA G + C content of strain MAH-5T was determined to be 41.5mol% and the predominant isoprenoid quinine was identified as MK-7. The major fatty acids were identified as C15:0 iso and summed feature 3 (comprising C16:1ω7c and/or C16:1ω6c). The genetic characteristics, in combination with chemotaxonomic and physiological data, demonstrated that the isolated strain MAH-5T represents a novel species within the genus Mucilaginibacter, for which the name Mucilaginibacter formosus sp. nov. is proposed, with MAH-5T as the type strain (= KACC 19291T = CGMCC1.16489T).

Potential ecological risks of metal(loid)s in riverine floodplain soils

The quality of soils under different land uses is getting deteriorated throughout the world due to various anthropogenic activities. This deterioration is highly complex in riverine floodplain areas due to contamination by multiple point and non-point sources and change in seasons. Therefore, a study was conducted to analyze seasonal (pre and post-monsoon) variations in physico-chemical characteristics, contents of metal(loid)s (Al, As, Cd, Cr, Co, Cu, Fe, Mn, Mo, Ni, Pb, Sb and Zn) in riverine floodplain soils under three land uses (agricultural, riverbank and roadside) from areas around the rivers Beas and Sutlej in Punjab, India. Further, analysis was done to assess the ecological and genotoxic risks (Allium cepa genotoxicity assay) posed by metal(loid)s in these soils. It was observed that soil samples under the three land uses were slightly alkaline (pre-monsoon) to acidic (post-monsoon) in nature with sandy texture and low soil organic matter. The levels of most metal(loid)s increased in post-monsoon soil samples under the three land uses, which was attributed to increase in soil organic matter, silt and clay contents in post-monsoon samples due to precipitation, flooding and sedimentation. The ecological Risk Index (58.3–104.5) and Modified Risk Index (145.2–178.9) calculated to analyze the level of ecological risks of metal(loid)s revealed that As, Cd and Sb posed moderate to considerable ecological risks in the agricultural and roadside soils in both seasons. Allium cepa genotoxicity assay indicated that the metal(loid)s in studied soils can cause genotoxic effects in biological systems. Therefore, various steps such as reduction in use of agrochemicals, promotion of organic agricultural methods and decontamination of soils using techniques such as phytoremediation etc must be taken to ensure reduction and containment of metal(loid)s in such riverine floodplain areas.

Characterizing export of land-based microplastics to the estuary - Part II: Sensitivity analysis of an integrated geospatial microplastic transport modeling assessment of tire and road wear particles

Integrated models addressing microplastic (MP) generation, terrestrial distribution, and freshwater transport are useful tools characterizing the export of MP to marine waters. In Part I of this study, a baseline watershed-scale MP mass balance model was developed for tire and road wear particles (TRWP) in the Seine watershed. In Part II, uncertainty and sensitivity analysis (SA) methods were used to identify the parameters that determine the transport of these particles to the estuary. Local differential, local range and global first-order variance-based SA identified similar key parameters. The global SA (1000 Monte Carlo simulations) indicated that most of the variance in TRWP exported to the estuary can be apportioned to TRWP diameter (76%), TRWP density (5.6%), the fraction of TRWP directed to combined sewers with treatment (3.9%), and the fraction of TRWP distributed to runoff (versus roadside soil; 2.2%). The export fraction was relatively insensitive to heteroaggregation processes and the rainfall intensity threshold for road surface washoff. The fraction of TRWP exported to estuary in the probabilistic assessment was centered on the baseline estimate of 2%. This fraction ranged from 1.4 to 4.9% (central tendency defined as 25th to 75th percentile) and 0.97% to 13% (plausible upper bound defined as 10th to 90th percentiles). This study emphasizes the importance of in situ characterization of TRWP diameter and density, and confirms the baseline mass balance presented in Part I, which indicated an appreciable potential for capture of TRWP in freshwater sediment.

Winter road management effects on roadside soil and vegetation along a mountain pass in the Adirondack Park, New York, USA

In 2003–2005, we resurveyed and expanded plots surveyed in 1985 to examine the cumulative impact of road salt (sodium chloride) and sand along a two-lane highway in the Adirondack State Park in New York State (USA). Annual salt applications in the period 1985–2005 ranged from 50 tonnes per centerline-km (1985) to 140 tonnes (2005) and sand applications ranged from nearly zero tonnes (2005) to 325 tonnes (1985). Roadside soils and vegetation were significantly impacted by salt deposition compared to soils and vegetation 30 m and 150 m from the road. Roadside soil contained more sand, less organic matter, had a lower cation exchange capacity, was denser, and retained less water than soils 30 m and 150 m from the road. The concentration of sodium in roadside soils was elevated (103 vs. 44 ppm in soil 150 m from the roadside), and roadside concentrations of plant-nutritive cations were lower than 150 m from the road (roadside Mg, Ca and K concentrations were 0.2, 5, and 1 ppm respectively vs. 23,168, and 30 ppm at 150 m from the road). Along the roadside, paper birch trees (Betula papyrifera) and other woody vegetation present in 1980 were absent in 2004, suggesting that survival and recruitment of paper birch trees was impacted by degradation of soil fertility, deposition of road salt and aerosolization of salt from the roadway. Roadside environmental degradation caused by winter road management has worsened since 1980; revegetation with native salt-tolerant plants may provide some mitigation of the most severe effects. Overall, we conclude that the full extent of roadside environmental degradation caused by winter road management can take decades to manifest, and this may be the case more generally along cold-climate montane roadways.

Long-Term Land Use Affects Phosphorus Speciation and the Composition of Phosphorus Cycling Genes in Agricultural Soils.

Agriculturally-driven land transformation is increasing globally. Improving phosphorus (P) use efficiency to sustain optimum productivity in diverse ecosystems, based on knowledge of soil P dynamics, is also globally important in light of potential shortages of rock phosphate to manufacture P fertilizer. We investigated P chemical speciation and P cycling with solution 31P nuclear magnetic resonance, P K-edge X-ray absorption near-edge structure spectroscopy, phosphatase activity assays, and shotgun metagenomics in soil samples from long-term agricultural fields containing four different land-use types (native and tame grasslands, annual croplands, and roadside ditches). Across these land use types, native and tame grasslands showed high accumulation of organic P, principally orthophosphate monoesters, and high acid phosphomonoesterase activity but the lowest abundance of P cycling genes. The proportion of inositol hexaphosphates (IHP), especially the neo-IHP stereoisomer that likely originates from microbes rather than plants, was significantly increased in native grasslands than croplands. Annual croplands had the largest variances of soil P composition, and the highest potential capacity for P cycling processes based on the abundance of genes coding for P cycling processes. In contrast, roadside soils had the highest soil Olsen-P concentrations, lowest organic P, and highest tricalcium phosphate concentrations, which were likely facilitated by the neutral pH and high exchangeable Ca of these soils. Redundancy analysis demonstrated that IHP by NMR, potential phosphatase activity, Olsen-P, and pH were important P chemistry predictors of the P cycling bacterial community and functional gene composition. Combining chemical and metagenomics results provides important insights into soil P processes and dynamics in different land-use ecosystems.

Ecological risk assessment of some heavy metals in roadside soils at traffic circles in Gombe, northern Nigeria

The study evaluated the levels of some heavy metals in the roadside soils at different traffic circles using geo-accumulation index, ecological risk and Hakanson method to assess the overall ecological risk and identify ecological potential risk of heavy metals pollution. The top soil samples were collected at three different traffic circles from edge and at 50 m distance from the roadside, and analysed for heavy metal (Pb, Cd, Cu and Zn) using atomic absorption spectrophotometer. The mean concentrations of heavy metals (mg/kg) ranged from (15.0 - 45.07) Pb, (0.35 - 2.60) Cd, (19.05 - 38.0) Cu and (58.10 - 101.0) Zn. The abundance of metals was found in declining order: Zn > Pb > Cu > Cd. The metals concentrations were found to be higher in the soil samples from edge due to high traffic volume and human activities, and there was significantly decrease in concentration with increase in roadside distance. The Geoaccumulation index (I geo ) examined in this study revealed that soil samples from edge and 50 m distance from the roadside were polluted with cadmium. Ecological risk assessment carried out showed that the metals posed low ecological risk and cadmium contributed 66.63 - 94.21% of the total potentially ecological risk. Keywords: Assessment, Ecological risk, Heavy metals, Roadside soil

Applied Research in Heavy Metals Pollution in Expressway Roadside Soil in China

With the rapid development of expressway in China, soil pollution with heavy metal along expressways has become increasingly serious in the environmental system. The pollution will not only affect directly the quality and safety of agricultural products, but also endanger indirectly human health through food chain. Therefore, the environmental effect of expressway is a very worthwhile concern. A brief review concerning the occurrence, influencing factors and plant barriers of heavy metals pollution in expressway roadside soil in China is presented.

Porosity of roadside soil as indicator of edaphic quality for tree planting

Roadside tree pits commonly suffer from small size, poor soil, and heavy compaction. Their three soil types with different properties, respectively site soil, backfill and rootball, could constrain tree establishment and long-term growth. Sixty-nine soil samples were taken from 19 tree pits, with multiple artificial layers sampled separately, at roadside sites in Hong Kong. They were analyzed for profile characteristics, pH, bulk density and particle-size distributions. Pores were divided by into three classes: (1) unavailable moisture UM at <0.2 μm (also known as micro-pores); (2) available water AW at 0.2–60 μm (meso-pores); and (3) and air capacity AC at >60 μm (macro-pores). Critical pore-volume thresholds, namely extreme, marginal and optimal, assessed soil-porosity quality. Site soils were heavily compacted with <40% and <30% total porosity, denoting respectively marginal and extreme thresholds, equivalent to bulk density exceeding 1.6 and 1.9 Mg/m3. The upper soil zone was more compacted than middle and lower zones to generate undesirable surface sealing. Backfill and rootball soils had less stressful porosity and bulk-density limitations. Long-term root growth into site soil would be hampered to suppress tree health and stability. The excessively sandy texture, upon compaction to a certain degree, generated a continuous coarse matrix. It established inter-granular contacts and high load-bearing capacity to arrest further compaction. Some AW pores could be sustained for available-water storage to support tree growth. The findings could inform porosity specification in urban soil management to foster roadside tree performance.

Occurrence, distribution and risk of organophosphate esters in urban road dust in Beijing, China

As a major group of plasticizers and flame-retardants, organophosphate esters (OPEs) have attracted particular attention due to their wide occurrence and potential impacts on human health and ecosystems. In the present study, the occurrence and distribution of 14 OPEs, including seven Alkyl-OPEs, three Cl-OPEs, and four Aryl-OPEs, were investigated in 65 road dust samples collected from November to December 2014 in Beijing, China. Cl-OPEs were the predominant compounds in the road dust samples, with the median concentration of 646 μg/kg, followed by the Alkyl-OPEs (median 135 μg/kg) and Aryl-OPEs (median 129 μg/kg). Tris(2-chloro-1-methylethyl) phosphate (TCPP) was the most abundant OPE with the median concentration of 384 μg/kg. In addition, OPEs levels showed significant difference (p < 0.05) in the spatial distribution. Markedly higher levels of OPEs were observed in 2nd and 3rd ring road with heavy traffic and high population density, indicating that the traffic and population were important factors for this distribution pattern. It was further supported by the analysis of OPEs in roadside soil and indoor dust in the vicinity of road dust sample sites. Finally, the average daily dose (ADD) for OPEs via inhalation, dermal absorption, and ingestion was calculated to evaluate the carcinogenic and non-carcinogenic risks to residents exposed to OPEs in the road dust. Risk assessment revealed that the risk originating from exposure to OPEs of road dust is currently low in Beijing, China.

Accumulation of Heavy Metals in Roadside Soil in Urban Area and the Related Impacting Factors.

Heavy metal contamination in roadside soil due to traffic emission has been recognized for a long time. However, seldom has been reported regarding identification of critical factors influencing the accumulation of heavy metals in urban roadside soils due to the frequent disturbances such as the repair of damaged roads and green belt maintanance. Heavy metals in the roadside soils of 45 roads in Xihu district, Hangzhou city were investigated. Results suggested the accumulation of Cu, Pb, Cd, Cr, and Zn in roadside soil was affected by human activity. However, only two sites had Pb and Zn excessing the standards for residential areas, respectively, according to Chinese Environmental Quality Standards for soils. The concentrations of Cu, Pb, Cd, and Zn were significantly and positively correlated to soil pH and organic matter. An insignificant correlation between the age of the roads or vegetation cover types and the concentration of heavy metals was found although they were reported closely relating to the accumulation of heavy metals in roadside soils of highways. The highest Pb, Cd, and Cr taking place in sites with heavy traffic and significant differences in the concentrations of Cu, Pb, Cd, and Zn among the different categories of roads suggested the contribution of traffic intensity. However, it was difficult to establish a quantitative relationship between traffic intensity and the concentrations of heavy metals in the roadside soil. It could be concluded that impaction of traffic emission on the accumulation of heavy metals in roadside soils in urban area was slight and soil properties such as pH and organic matters were critical factors influencing the retention of heavy metals in soils.

Vehicular stress a cause for heavy metal accumulation and change in physico-chemical characteristics of road side soils in Pahalgam.

In an effort to determine vehicular impact on soil quality, soil samples were collected from three different zones (Pahalgam, Batakote, and Chandanwari) in Pahalgam forest ecosystem. Results showed that a significant decrease in moisture content, organic carbon, available nitrogen, and potassium was observed in nearby road side soils. However, pH was observed to be on neutral side and available phosphorus recorded high concentration. The concentration of heavy metals Pb2+, Cu2+, Zn2+, Ni2+, and Cd2+ estimated was also significantly high. Furthermore, concentration of Pb2+ at high vehicular load subzones was observed to be highest (1.168mg/Kg) followed by Zn2+ (0.896mg/Kg), Ni2+ (0.649mg/Kg), Cu2+ (0.415mg/Kg), and Cd2+ (0.079mg/Kg). An inter-zone analysis revealed that the concentration of the heavy metals (Pb2+ > Ni2+ > Cd2+) was observed to follow the trend, Z-I > Z-II > Z-III. Variation along the temporal gradient and the impact on soil qualities were notably higher in summer. Vehicular pollution to a great extent impacts physico-chemical characteristics and more interestingly adds substantial concentration of heavy metals in soils.

Microbial Activity and Decomposition of Soil Organic Matter in Roadside Soils Contaminated With Petroleum Hydrocarbons

Petroleum hydrocarbons (PHs) are the most widespread organic pollutants of roadside soils, the reclamation of which is costly due to large areas affected, and natural PHs biodegradation is the only way of mitigating negative ecological consequences. This study aimed to investigate the microbial response to PHs in roadside soils and to identify soil organic matter (SOM) and PHs involved in biodegradation processes. To address this aim, soil respiration is related to light (chain‐length ≤C14) medium (C15–C27), and heavy fractions (≥C28) of total PHs, and to SOM components: carbohydrates, proteins, lignin, aliphates, carbonyl/carboxyl, and char amounts of soils sampled at distances of up to 100 m from three roads in Kharkiv, Ukraine. A close relation between soil respiration and ratio of the light fraction to the sum of medium and heavy alkane fractions indicate the preferential mineralization of more biodegradable light PHs fractions. A positive relation between soil respiration and carbohydrate C, as well as negative correlation with aliphatic C, indicate preferred degradation of carbohydrates compared to more recalcitrant aliphates. Carbohydrate content increased and aliphatic C decreased with distance from the roads, and carbohydrates decreased with PHs concentration, indicating increased degradation of carbohydrates at high PHs concentrations (positive priming). It is concluded that microorganisms generate the energy required for PHs degradation by enhanced oxidation of native SOM where carbohydrates were of paramount importance.

Determining Heavy Metal Contents of Hollyhock (Alcea rosea L.) in Roadside Soils of a Turkish Lake Basin

Determining Heavy Metal Contents of Hollyhock (Alcea rosea L.) in Roadside Soils of a Turkish Lake Basin

Vegetation and Soil Responses to Concrete Grinding Residue Application on Highway Roadsides of Eastern Nebraska.

As a precautionary principle, the National Pollutant Discharge Elimination System (NPDES) permit establishes that the primary pollutant in concrete grinding residue (CGR) is its alkalinity and restricts CGR roadside discharge to 11 Mg ha or the agronomic liming rate, whichever is lower. We evaluated the effect of CGR application on roadside soil chemical properties, existing vegetation, and rainfall runoff. Five CGR rates (0, 11, 22, 45, and 90 dry Mg ha) were tested on roadsides slopes at two different locations in eastern Nebraska. Vegetation, soil, and runoff characteristics were evaluated before CGR application and 30 d and 1 yr after CGR application. Soil pH of control plots averaged 8.3 and 8.5 for each site respectively, across depths and slope positions, thus not requiring any liming for agronomic purposes. Soil electrical conductivity (EC, 1:1) averages of control plots were 0.79 and 1.24 dS m across depths and slope positions. In the short term (30 d) the highest CGR application affected the 0- to 7.5-cm soil depth by increasing soil extractable Ca (21 and 25% for each site, respectively), soil pH (0.2, south site), and soil EC (0.2 dS m) compared with the control. However, these changes in soil did not persist 1 yr after CGR application. The pH buffering capacity of soil prevented post-CGR-application pH from exceeding 8.9, even at the highest application rate. Application of CGR did not produce any differences in biomass production, botanical composition, and runoff characteristics at either site. From our study, CGR up to ?90 dry Mg ha-about the amount produced during diamond grinding operations-can be one-time applied to roadside soils of similar characteristics on already established vegetation.

Polychlorinated Biphenyls in Surface Soil from North-East India: Implication for Sources Apportionment and Health-Risk Assessment.

Although India never manufactured polychlorinated biphenyls (PCBs), evidence suggests the prevalence of PCBs in multi-environmental matrices. Despite the high level of PCBs that has been detailed in the major urban areas of India, little is known about the fate and sources of PCBs in Northeast India (NEI). This motivated us to investigate the contamination level and sources of PCBs in the surface soil. In this study, the environmental concentration and sources of 25 PCBs were investigated in surface soil (n = 60) from three states of NEI (lower Assam, Manipur, and Tripura). Additionally, the relationship between soil organic carbon (SOC) and PCBs was studied to investigate the role of SOC in the distribution of PCBs. Overall, the concentration of ∑25PCBs ranged from 2950 to 16,700pg/g dw (median 7080pg/g dw), 3580-21,100pg/g dw (median 11,500pg/g dw), and 2040-11,000pg/g dw (median 4270pg/g dw) in Assam, Manipur, and Tripura, respectively. Low-chlorinated PCBs were more prevalent than highly chlorinated PCBs. PCB-49 was identified as the most abundant in soil, followed by PCB-52, and accounted for 13% and 12.9% of ∑25PCBs, respectively. With respect to land use categories, high ∑25PCBs were related to grassland areas and proximity to the roadside soil. The principal component analysis indicated emissions from technical PCB mixtures, combustion of municipal wastes/residential wood, incineration of hospital wastes, and e-waste recycling/disposal sites are the real sources of PCBs. Marginally, a moderate-to-weak correlation of SOC with ∑25PCBs (R2 = 0.144, p < 0.05) and their homologs (R2 = 0.280-0.365, p < 0.05) indicated the little role of SOC in the dispersion of PCBs. The estimated toxic equivalency of dioxin-like PCBs suggested that PCB-126 is the most toxic contaminant to endanger the human population.

Assessment of Heavy Metal Pollution and Ecological Risk of Roadside Soils in Tlemcen (Algeria) Using Flame-Atomic Absorption Spectrometry

ABSTRACTIn Algeria, few studies have been conducted on the evaluation of roadside soil pollution. A total of 34 soil samples (28 roadside and 6 off-road) was obtained at 0–20 cm depth along the RN 35 national road. Heavy metal (Cd, Cr, Cu, Fe, Ni, Pb, and Zn) contents were extracted using aqua regia digestion and determined using atomic absorption spectrometry. Background values of heavy metal contents were determined using the robust statistical method of median plus two times the median absolute deviation. Single- and multi-element pollution and ecological risk indices were calculated. The results showed that background values were 2.5 ± 0.3, 64.9 ± 8.1, 28.0 ± 4.1, 29371.5 ± 4403.0, 32.9 ± 4.4, 72.2 ± 12.8, and 445.1 ± 62.9 mg/kg for Cd, Cr, Cu, Fe, Ni, Pb, and Zn, respectively. The results were all higher than their corresponding median values. Single-element pollution indices (enrichment factor and geoaccumulation index) showed that the pollution is primarily due to Pb and Zn. Multi-element pollution index (Nemerow index) indicated that only 3% of the soil samples are strongly contaminated, whereas 23% are seriously contaminated. The potential ecological risk index showed that Cd is the most harmful element, followed by Pb and Zn. 65% of the soil samples had moderate potential ecological risk, while only 3% had considerable potential ecological risk. This study may be used as a baseline for future monitoring and as a tool for decision-making regarding environmental protection policies and sustainability of this semiarid agroecosystem.

Effect of Organic Matter Amendment on Lead Contamination in Roadside Soil and Plant

Lad Contamination in Roadside Soil and Plant and Effect of Organic Matter Amendment (Sabaruddin, D Budianta and Mardia): Roadside soils and plants may be the most important sink of lead (Pb). It has been widely known that soil organic matter (SOM) plays important roles in determining concentrations of metals in soil solution and their extractability from the soil. To investigate Pb contamination in the roadside soils and plants, as well as the effect of organic matter (OM) on the soluble Pb in the roadside soils, surface soils (0 to 20 cm) were collected from a busy road. The soils were incubated for 4 weeks under room temperature after being treated with 0, 30, 60 and 90 Mg ha-1 of OM. Leaves of oil palms (Elaeis guineensis) planted on the roadside were also analyzed for Pb content. Current study revealed that Pb content in roadside soils and leaves of oil palm was 1.5 and 5.5 times higher than the safe level of Pb in soil and plant. It confirms that both soil and plant at the study site were contaminated by Pb. Current study also showed that SOM amendment significantly (P&lt;0.01) affected soluble Pb content in the soils. Adding OM to the soil at 30 Mg ha-1 to correct the level of SOC from very low to low was sufficient to significantly reduce soluble Pb in the soils. However, the application of 60 Mg ha-1 of OM triggered the increases in soluble Pb in the soils. Further increases in OM application to 90 Mg ha-1 resulted in significant increases in soluble Pb as compared with that in the soil receiving 30 Mg ha-1 of OM. In spite of the increases, the level of soluble Pb in the soils receiving 60 and 90 Mg ha-1 of OM was still much below the safe level of Pb in soil.

Chemometric evaluation of heavy metal pollutions in Patna region of the Ganges alluvial plain, India: implication for source apportionment and health risk assessment.

While metal pollution and distribution in soil are well documented for many countries, the situation is more serious in developing countries because of the rapid increase in industrialization and urbanization during last decades. Although it is well documented in developed countries, data about substantial metal pollution in Indian soil, especially in eastern Ganges alluvial plain (GAP), are limited. In this study, eight different blocks of Patna district located in eastern GAP were selected to investigate the contamination, accumulation, and sources of metals in surface soil considering different land use types. Additionally, human health risk assessment was estimated to mark the potential carcinogenic and non-carcinogenic effect of metals in soil. The concentration of all metals (except Pb) in soil was below the Indian standard limit of the potential toxic element for agricultural soil. Pb was the most abundant in soil, followed by Zn and Cu, and accounted for 52, 33 and 8% of the total metal. In terms of land use types, roadside soil detected higher concentrations of all metals, followed by park/grassland soil. Principal component analysis results indicated traffic pollution and industrial emissions are the major sources of heavy metals in soil. This was further confirmed by strong inter-correlation of heavy metals (Cd, Cr, Ni, Cu and Pb). Human health risk assessment results indicated ingestion via soil as the primary pathway of heavy metal exposure to both adults and children population. The estimated hazard index was highest for Pb, suggesting significant non-carcinogenic effect to both adults and children population. The children were more prone to the non-carcinogenic effect of Pb than adults. However, relatively low cancer risk value estimated for all metals suggested non-significant carcinogenic risk in the soil.

Distribution of heavy metals and associated human health risk in mine, agricultural and roadside soils at the largest chromite mine of India.

This study accessed the levels of Cd, Cr, Fe, Mn, Ni, Pb and Zn concentration in soils of different locations (mine, roadside, agricultural and control sites) of Sukinda chromite mine (the India's largest Chromite mine and listed among the world's ten most polluted regions). Geo-accumulation (Igeo) index indicates that the mine, agricultural and roadside soils are 'heavily to extremely contaminated' due to Cr, Ni, Pb and Cd, hence human residing/working in this region can have health hazards due to contaminated soil via different exposure pathways. The concentration of heavy metals (mg/kg) in mine site vary between 52.35 and 244.8 (Cr6+), 12,030.2 and 31,818.6 (Cr3+), 5460.4 and 8866.0 (Ni), 70.02 and 208.6 (Pb), 0.95 and 5.3 (Cd), 209.1 and 360.4 (Mn), 21,531.8 and 28,847 (Fe) and 221 and 349.3 (Zn). Fe, Cr6+, Cr3+ and Ni concentration in soil follows an order of mine site > road sites > agricultural lands > control forest sites. Principal component analysis and hierarchical cluster analysis indicate Cd, Cr, Fe, Ni and Pb as major pollutants in the region. Cancer Risk is 'high' in both adult (5.38E-04) and children (4.45E-04) in mining sites and 'low' to 'very low' in agricultural and road side soils. The hazard index for all the heavy metals in a mining areas is varied from 2.9 to 5.2 in adult and 2.8-5.1 in children, indicating 'high' to 'very high' non-cancer risk due to significant contribution of Ni, Pb and Cr6+ concentration (73, 11 and 10%, respectively).