Urban Soil Contamination Research Articles

Spatial characteristics of heavy metal contamination and potential human health risk assessment of urban soils: A case study from an urban region of South India.

Due to the rapid development of urbanization, the contamination of heavy metals in urban soils has become one of the major concerns of environmental and risk to humans. The main objective was to determine the contamination of six heavy metals in 25 urban soils and also to evaluate the associated health risk via diverse indices for adults and children. The mean concentration of Pb (47.48mg/kg), Cr (43.24mg/kg), Cu (40.64mg/kg), Zn (34.68mg/kg), Co (16.54mg/kg), and Ni (7.55mg/kg) exceeded the geochemical background values. Pb and Zn were closely attributed to traffic sources. Geo-accumulation index (Igeo) showed that Pb and Co in the soils were at the moderately pollution level, while 4% of soil samples were moderately polluted to heavily pollution levels by Cu. Enrichment factor (EF) showed that soils presented minor to severe anthropogenic pollution levels in the investigated region. The heavy metals to the non-carcinogenic risk of humans in the investigated region are absolutely from Cr and Pb, while the carcinogenic risk is controlled by Cr, and the remaining metals pose no possible risk to the local people. Specially, children had larger health risks in terms of non-carcinogenic risks than adults which may be related to their behavioral and physiological characteristics.

Urban soil contamination in Salerno (Italy): Concentrations and patterns of major, minor, trace and ultra-trace elements in soils

This work discusses the results of a geochemical survey conducted in the Salerno urban area to determine the sources patterns of major, minor, trace and ultra-trace elements in soils. In particular, the study focused on elements that are potentially toxic and listed in the environmental Italian legislation (D.L. 152/06), in order to effectively monitoring an important aspect of environment health. A total of 151 topsoil samples were collected, air-dried and sieved (<2 mm). After aqua regia digestion the samples were analyzed for 42 elements by ICP-MS and ICP-AES. Geostatistical analyses were carried out in order to show the single element spatial distribution and the distribution of factor scores elemental associations from R-mode factor analysis. In performing factor analysis, the additive logratio (alr) transformation was applied to the whole dataset in order to deal with the closure effects of the investigated geochemical data, avoiding artefacts and spurious correlation. The use of alr-transformed data instead of the normal data in the factor analysis allowed for a better interpretation of the distribution patterns, since this produced four factor models which, once mapped, were easier to interpret.The study revealed that major and minor elements (Al, Ca, Fe, K, Mg, Na, P, S and Ti) have a perfectly natural distribution with no discernible association to any human activity or presence. In contrast, many trace and ultra-trace elements (Ag, As, Au, Ba, Be, Cd, Co, Cr, Cu, Hg, Mn, Mo, Ni, Pb, Pd, Pt, Rh, Sb, Sn, Tl, V and Zn) show anomalous concentration values located almost exclusively in highly inhabited areas, industrial sites and along high traffic roads. Other trace and ultra-trace elements (B, Bi, Ga, La, Sc, Se, Sr, Te, Th, Tl, U and W) show concentrations compatible with the natural background levels. Some potentially toxic elements (e.g. Pb and Zn) reach concentration levels tens of times higher than the legal limits in the busiest areas of the city. Exposure to high concentrations of these contaminants may cause health problems to people living in these zones.

The role of urbanization in soil and groundwater contamination by heavy metals and pathogenic bacteria: A case study from Oman

This study assessed the perception of urban residents of A'Seeb city, Oman, about the impact of their activities on environment. A sociological survey using questionnaire was used to know the residents' perceptions about urban gardening, municipal-waste disposal, and soil and water contamination. Viable pathogenic bacteria, water soluble metals, basic cations, salinity, and texture were quantified and identified in soil and groundwater in proximity of urban gardens and municipal-waste disposal sites. The majority of surveyed residents are not paying attention to the negative consequences of their activities on soil and environment. Although the measured heavy metals concentrations in some of the contaminated sites were significant but still below the international standards. Fecal contaminants reported in in some samples from gardens, garbage-disposal sites and groundwater. Human pathogens belonging to risk group-2 including Klebsiella pneumonia, Shigella spp and E. Coil were identified. More socio-environmental studies required to correlate the behavior of urban residents and pollution and to delineate the sources of the detected pathogenic bacteria. Our results set a foundation for future studies on urban soils and associated residence behaviors and practices in Oman and the neighboring Gulf countries.

Accumulation of cadmium (Cd) in T1 transgenic tobacco seedlings expressing metallothionein gene from Eleusine indica

Cadmium (Cd) contamination of urban and agricultural soils is toxic to humans, animals and may cause negative effects on plant growth and crop production. The existing conventional methods are found to be not efficient to remove Cd from contaminated soil. The present experiment reports the analysis of nine T1 lines of transgenic tobacco carrying metallothionein gene (eiMT1) from Eleusine indica, with potential for high efficiency to remediate Cd in contaminated soils. Thirty-days old tobacco plants were treated with different concentrations of CdNO3 (0, 50, 100 and, 150 µmol) for seven days and the accumulation of Cd in the whole seedling was quantitatively determined by using atomic absorption spectrometer (AAS). All transgenic tobacco lines showed greater tolerance and accumulated higher level of Cd than the wild type with lines 18D, 20D1 and, 18C were among the highest (678.7, 623.0 and 611.9 mgkg-1 Cd, respectively). Meanwhile, transgenic tobacco lines 18B1 and 20D1 showed higher expression of eiMT1 gene. These results suggest that the cadmium accumulation in transgenic tobacco did not strictly associate with the expression level of eiMT1 gene. However, expression of eiMT1 greatly required for higher accumulation of Cd in transgenic tobacco seedling.

Human impacts recorded in chemical and isotopic fingerprints of soils from Dunedin City, New Zealand

We present results from the first urban chemical and isotopic soil baseline survey to be completed for a New Zealand city. The major, minor, trace and isotopic composition of soils from different depths across the city of Dunedin are shown to be spatially variable due to geogenic and anthropogenic influences. Based on Principal component analysis (PCA) for the shallow soil depth, at least 40% (PC1 and PC3) of the dataset variance is attributed to a geogenic source. Soils enriched in Al, Cr, Fe, Hf, Mo, Ni, Th, Ti, U, V and Zr (PC1) are spatially associated with mapped units of the basaltic Dunedin Volcanic Group, indicating a geogenic source. An anthropogenic influence is attributed to at least 23% (PC2 and PC5) of the dataset variance. The chemical elements As, B, Bi, Cd, Cu, P, Pb, Sb, Sn and Zn (PC2) are strongly spatially associated with soils sampled above high-density urban residential, commercial and industrial sites, and are interpreted to reflect heavy metal contamination from human activities. In conjunction with historical vehicle emissions from leaded petrol, we suggest that legacy leaded paint from residential, commercial and industrial buildings flaking into Dunedin City soils is a significant contributor to Pb in the Dunedin urban environment. Median heavy metal contents for shallow soils (0–2 cm) from a variety of land-uses throughout Dunedin City are shown to be almost an order of magnitude greater than median heavy metal concentrations in soils from regional baselines. Significantly, urban anthropogenic sources of heavy metals, and C, N and S isotopes are shown to exert a stronger influence on soil composition than rural anthropogenic sources. Results from this study provide an important case-study for urban soil contamination for a relatively young city from the Southern Hemisphere, for which there are currently few examples.

Heavy metals contamination in urban surface soils of Medak province, India, and its risk assessment and spatial distribution.

The main purpose of the current study is to assess the contamination status, human health risk, and spatial distribution of heavy metals in the urban soils from the Medak province in India. For this purposes, a total of 40 urban surface soil samples were collected and analyzed seven heavy metals including chromium (Cr), copper (Cu), cadmium (Cd), arsenic (As), nickel (Ni), lead (Pb), and zinc (Zn). The results of the study showed that the concentration of Cr (81-751mg/kg), Cu (2-180mg/kg), Zn (25-108mg/kg), Pb (5-77mg/kg), Ni (1-50mg/kg), As (0.4-14mg/kg), and Cd (0.1-4.2mg/kg), respectively, was found above their natural background values. The geo-accumulation index analysis indicated that except Zn, all other tested heavy metals had a range of moderately to heavily polluted/contaminated in the study region. Spatial distribution pattern analysis inferred that the soil heavy metal (Cu, Cr, Zn, and Ni) pollutions in western regions of Medak were relatively larger than that in central and eastern regions. The hazard index (HI) values for Cu, Cd, Zn, As, Pb, and Ni were below 1, implying that there is no non-carcinogenic risks exposure from these heavy metals in soil for children and adults in the study region. However, HI value for Cr ranged from 3.08E-01 to 2.86E+00 for children, implying that children were relatively vulnerable population than adults in the current study region. Comparatively speaking, 67.5% and 100% total carcinogenic risks for Cr values for adults and children were larger than the acceptable threshold value of 1.0E-04, indicating chromium poses the greatest carcinogenic risk in the study region.

Metal Release under Anaerobic Conditions of Urban Soils of Four European Cities

Urban soil contamination may represent an environmental threat in view of their proximity to humans. The ecological homogenization of urban areas has been postulated, and as the sources of pollution are the same in most European cities, it is possible that soil contamination is another factor of convergence. The current climate change with consequent increase of extreme rain events may affect the mobility of potentially toxic elements (PTE) thus increasing the risks. If the soil is submerged, Eh decreases and causes the solubilization of Fe and Mn oxides, which are important carriers of PTE. We compared the release of Cu, Pb, and Zn from 48 soils of four cities (namely Glasgow, Ljubljana, Sevilla, and Torino) when submerged for up to 30 days. A decrease of the redox potential was observed in all soils after a few days and an increase of Mn and then Fe in solution. Cu, Pb, and Zn were consequently released to the solution according to the general soil contamination. Despite the marked differences in soil properties, the reaction to anaerobiosis appeared to be similar in all samples indicating that waterlogging of urban soil contaminated with PTE may pose a serious environmental risk and substantiating the hypothesis of ecological convergence.

Assessment of potentially toxic trace element contamination in urban allotment soils and their uptake by onions: A preliminary case study from Sheffield, England

Toxic trace element (TTE) contamination in urban soils may pose potential health risks, especially in cities with previous industrial activities. This study aimed to investigate soil contamination in urban allotments in Sheffield, the uptake of TTEs in autumn and spring sown onions (Allium cepa), and their potential risks on human health via consumption of the crops. Paired soil and plant samples were taken in triplicates from four private allotments to assess potentially elevated levels of lead (Pb), zinc (Zn), copper (Cu), arsenic (As), and chromium (Cr). These elements in soils exceeded the ambient background levels for England. Both Pb and As exceeded some UK and EU soil tolerable limits. Concentration factors (CF) were calculated as the ratio of trace element in the plant as compared to that in the soil, and uptake rates were in the order Zn>Cu>Cr>Pb>As. Concentrations were higher for most TTEs in spring sown onions (SSO), and had significantly higher CF (p < 0.05) for Pb and Cr than autumn sown onions (ASO), whereas the opposite was true for As. Toxic elements in plants did not exceed FAO/WHO intake limits when considering TTE content per plant and consumption rates. Human health risk assessment calculations using target hazard quotients (THQ) and hazard indexes (HI) indicated that consuming onions alone did not pose an immediate health risk.

Connections between Soil and Human Health

Connections between Soil and Human Health

Vegetation reflectance spectroscopy for biomonitoring of heavy metal pollution in urban soils

Heavy metals in urban soils may impose a threat to public health and may negatively affect urban tree viability. Vegetation spectroscopy techniques applied to bio-indicators bring new opportunities to characterize heavy metal contamination, without being constrained by laborious soil sampling and lab-based sample processing. Here we used Tilia tomentosa trees, sampled across three European cities, as bio-indicators i) to investigate the impacts of elevated concentrations of cadmium (Cd) and lead (Pb) on leaf mass per area (LMA), total chlorophyll content (Chl), chlorophyll a to b ratio (Chla:Chlb) and the maximal PSII photochemical efficiency (Fv/Fm); and ii) to evaluate the feasibility of detecting Cd and Pb contamination using leaf reflectance spectra. For the latter, we used a partial-least-squares discriminant analysis (PLS-DA) to train spectral-based models for the classification of Cd and/or Pb contamination. We show that elevated soil Pb concentrations induced a significant decrease in the LMA and Chla:Chlb, with no decrease in Chl. We did not observe pronounced reductions of Fv/Fm due to Cd and Pb contamination. Elevated Cd and Pb concentrations induced contrasting spectral changes in the red-edge (690–740 nm) region, which might be associated with the proportional changes in leaf pigments. PLS-DA models allowed for the classifications of Cd and Pb contamination, with a classification accuracy of 86% (Kappa = 0.48) and 83% (Kappa = 0.66), respectively. PLS-DA models also allowed for the detection of a collective elevation of soil Cd and Pb, with an accuracy of 66% (Kappa = 0.49). This study demonstrates the potential of using reflectance spectroscopy for biomonitoring of heavy metal contamination in urban soils.

Methodological approaches to the assessment of heavy metal contamination in urban ecosystems soils

The paper presents the assessment of heavy metal pollution of Abakan soils, the main source of which is motor transport. The pollution assessment of the upper horizons soils located near four main highways of the city was conducted under established standards. The maximum concentration of elements was recorded in the area with very high traffic, which confirms the importance of the role of motor transport as the main source of pollutants. When calculating the total pollution index (Zc) all highways were in a dangerous category. A similar indicator calculated on the basis of the data content in the soil-forming rock, allowed us to determine the degree of pollution as moderately hazardous. Analysis of heavy metals content in soil profiles has allowed to establish in the upper soil horizons, a significant excess of gross and mobile forms of all elements at sites with very high and high degree of traffic load, which indicates intense аerogenic intake of pollutants. Determined the proportion of elements of anthropogenic origin and the fact of the uneven distribution of heavy metals in the soil profile and their concentration in different geochemical barriers. When determining causal relationships between heavy metal content and separate soil characteristics we have found a direct dependence on the following parameters: pH, humus, cation exchange capacity, carbon dioxide, carbonates, particle size distribution, and in some cases we can talk about complex influence of soil properties on the concentration of elements. Assessment of heavy metal contamination in urban ecosystems soils, using the data content of elements in soil-forming rock with the use of the profile approach is the most objective.

Magnetite contamination of urban soils in European Russia

Abstract Urban soils are enriched in magnetite (Fe3O4), thanks to aerial emissions of industry, energy and cars emission. Magnetite contamination of urban soils in Russia has both common features of the world and its specificity. The magnetite content through the magnetic susceptibility is used as an indirect indicator of the contamination degree of urban soils with some heavy metals. In the cities of Russia: Moscow, Cherepovets, Perm and Chusovoy, magnetite soil pollution is in agreement with some of the heavy metals pollution. The correlation coefficients between magnetic susceptibility and mobile forms contents are higher than coefficients with a total contents of heavy metals. The volume magnetic susceptibility, measured in the field conditions, is less correlated with the pollution of urban soils with heavy metals than an express specific magnetic susceptibility, which is determined in the laboratory. In Moscow and Chusovoy, magnetic susceptibility of soils is high in the territory of the old town and it is the lowest in the field of new buildings. Soil magnetic susceptibility is indicator of Cu, Zn and Pb in Moscow. Soil magnetic susceptibility is indicator of Pb, Zn and Cr in Cherepovets. In Chusovoy, the oxidation degree of the magnetite is low, and a stoichiometric index of magnetite is high; soil magnetic susceptibility is indicator of Mn, Zn and Cr. In Perm, the magnetic susceptibility of magnetite in the soils is low, but it is highly variable; soil magnetic susceptibility is indicator of Ni, Zn and Cr.

Case studies and evidence-based approaches to addressing urban soil lead contamination

Urban soils in many communities in the United States and internationally have been contaminated by lead (Pb) from past use of lead additives in gasoline, deterioration of exterior paint, emissions from Pb smelters and battery recycling and other industries. Exposure to Pb in soil and related dust is widespread in many inner city areas. Up to 20–40% of urban children in some neighborhoods have blood lead levels (BLLs) equal to or above 5 μg per decilitre, the reference level of health concern by the U.S. Centers for Disease Control. Given the widespread nature of Pb contamination in urban soils it has proven a challenge to reduce exposure. In order to prevent this exposure, an evidence-based approach is required to isolate or remediate the soils and prevent children and adult's ongoing exposure. To date, the majority of community soil Pb remediation efforts have been focused in mining towns or in discrete neighborhoods where Pb smelters have impacted communities. These efforts have usually entailed very expensive dig and dump soil Pb remediation techniques, funded by the point source polluters. Remediating widespread non-point source urban soil contamination using this approach is neither economical nor feasible from a practical standpoint. Despite the need to remediate/isolate urban soils in inner city areas, no deliberate, large scale, cost effective Pb remediation schemes have been implemented to isolate inner city soils impacted from sources other than mines and smelters. However, a city-wide natural experiment of flooding in New Orleans by Hurricane Katrina demonstrated that declines in soil Pb resulted in major BLL reductions. Also a growing body of literature of smaller scale pilot studies and programs does exist regarding low cost efforts to isolate Pb contaminated urban soils. This paper reviews the literature regarding the effectiveness of soil Pb remediation for reducing Pb exposure and BLL in children, and suggests best practices for addressing the epidemics of low-level Pb poisoning occurring in many inner city areas.

Phytoremediation of urban soils contaminated with trace metals using Noccaea caerulescens: comparing non-metallicolous populations to the metallicolous 'Ganges' in field trials.

Urban soil contamination with trace metals is a major obstacle to the development of urban agriculture as crops grown in urban gardens are prone to accumulate trace metals up to toxic levels for human consumption. Phytoextraction is considered as a potentially cost-effective alternative to conventional methods such as excavation. Field trials of phytoextraction with Noccaea caerulescens were conducted on urban soils contaminated with Cd, Cu, Pb, and Zn (respectively around 2, 150-200, 400-500, and 400-700μgg-1 of dry soil). Metallicolous (Ganges population) and non-metallicolous (NMET) populations were compared for biomass production and trace metal uptake. Moreover, we tested the effect of compost and fertilizer addition. Maximal biomass of 5tha-1 was obtained with NMET populations on some plots. Compared to Ganges- the high Cd-accumulating ecotype from South of France often used in phytoextraction trials- NMET populations have an advantage for biomass production and for Zn accumulation, with an average Zn uptake of 2.5 times higher. The addition of compost seems detrimental due to metal immobilization in the soil with little or no effect on plant growth. In addition to differences between populations, variations of growth and metal accumulation were mostly explained by soil Cd and Zn concentrations and texture. Our field trials confirm the potential of using N. caerulescens for both Cd and Zn remediation of moderately contaminated soils-with uptake values of up to 200gCdha-1 and 47kgZnha-1-and show the interest of selecting the adequate population according to the targeted metal.

Spatial distribution of potentially harmful elements in urban soils, city of Talcahuano, Chile

The objective of this study is to ascertain the spatial distribution of Cu, Pb and Zn in order to determine the degree of contamination in urban soils from Talcahuano (Chile) and to identify the influence of possible contamination sources. A total of 420 samples were collected from the study area based on the following criteria: 140 topsoil samples (TS) (0–10cm), 140 subsoil samples (SS) (10–20cm) and 140 deep soil samples (DS) (150cm). The soils were characterized for their physical characteristics such as grain size distribution, pH, organic matter content etc. and the concentrations of Cu, Pb and Zn were analyzed by Atomic Absorption Photospectrometry following Aqua Regia digestion. Correlations combined with spatial analysis were implemented in order to distinguish the sources of the trace metals and whether they are geogenic or anthropogenic of origin. Several simple and robust statistical methods were applied to the data sets in order to evaluate useful and robust background values. The degree of contamination along with the geoaccumulation index, enrichment factors and contamination factors were also evaluated. The median concentrations obtained for the studied trace metals includes: Cu 23.1mgkg−1, Pb 10.2mgkg−1 and Zn 56.7mgkg−1. In general, the concentrations of Cu, Pb and Zn decrease with depth however, in certain sites the subsoil samples (SS) levels show higher concentrations than topsoil samples (TS). A possible explanation could be related to the uncontrolled clandestine landfill sites using both construction material debris and/or industrial solid wastes. Correlation analysis suggests that Cu, Pb and Zn are contributed by external sources. The spatial distribution of Cu, Pb and Zn in topsoil samples (TS) displays a spatial pattern extending along major roadway environments and emission sources. Estimated background values determined with the iterative 2σ-technique yields 43.7mgkg−1 for Cu, 17.5mgkg−1 for Pb and 91.7mgkg−1 for Zn respectively. The geochemical index, enrichment factor and the contamination factor all register a moderate to high contamination level in some of the soil samples.

Community based bioremediation: grassroots responses to urban soil contamination

The past 150 years of industrial processes have left a legacy of toxicity in the soils of today’s urban environments. Exposure to soil based pollutants disproportionately affects low-income communities who are frequently located within formerly industrialized zones. Both gardeners, who come into direct contact with soil, as well as those who eat the products grown in the soil, are at risk to exposure from industrial contaminants. Options for low-income communities for remediating contaminated soils are limited, with most remediation work being carried out by costly engineering firms. Even more problematic is the overall lack of awareness and available information regarding safety and best practices with soils. In response to these challenges, a grassroots movement has emerged that seeks to empower urban residents with the tools and information necessary to address residual industrial toxicity in their ecosystems. Focusing on methods that are simple and affordable, this movement wishes to remove the barriers of cost and technical expertise that may be otherwise prohibitive. This paper will give an overview of this exemplar of generative justice, looking at case studies of organizations that have been successful in implementing these strategies.

A comparative study of metals in roadside soils and urban parks from Hamedan metropolis, Iran

A total of 25 roadside and 25 park soils have been sampled from six major streets and seven urban parks of the city of Hamedan (Iran) and analyzed for Pb and Cd. Metal pollution and spatial distribution maps were carried out using the pollution index(PI), integrated pollution index(IPI) and ordinary kriging with Geographic Information Systems. High levels of Cd and Pb were observed with average concentrations of Cd and Pb in the urban roadside soils being 1.57±0.53, and 164.04±50.08mg/kg, respectively. However, the concentrations in urban park soils (1.16±0.62, and 105.4±46.47mg/kg, respectively), were significantly lower. Vehicle traffic has resulted in a significant enrichment of Cd and Pb in the roadside soils with the highest concentrations found in the city center. The spatial distribution pattern of Cd and Pb in urban soils of Hamedan indicated that the concentration of metals in the central and northern parts of Hamedan is high, due to the human activities. Findings of metals in soils of major streets and urban parks indicated that metal contamination in urban roadside soils was higher than urban parks showing suitability of these soils than urban parks as indicators of metal contamination in urban areas.

Heavy metals (HMs) and polycyclic aromatic hydrocarbons (PAHs) in soils of different land uses in Erbil metropolis, Kurdistan Region, Iraq.

Urban soil contamination is a growing concern for the potential health impact on the increasing number of people living in these areas. In this study, the concentration, the distribution, the contamination levels, and the role of land use were investigated in Erbil metropolis, the capital of Iraqi Kurdistan. A total of 74 soil samples were collected, treated, and analyzed for their physicochemical properties, and for 7 heavy metals (As, Cd, Cr, Cu, Fe, Pb, and Zn) and 16 PAH contents. High concentrations, especially of Cd, Cu Pb, and Zn, were found. The Geoaccumulation index (Igeo), along with correlation coefficients and principal component analysis (PCA) showed that Cd, Cu, Pb, and Zn have similar behaviors and spatial distribution patterns. Heavy traffic density mainly contributed to the high concentrations of these metals. The total concentration of ∑PAHs ranged from 24.26 to 6129.14ng/g with a mean of 2296.1ng/g. The PAH pattern was dominated by 4- and 5-ring PAHs, while diagnostic ratios and PCA indicated that the main sources of PAHs were pyrogenic. The toxic equivalent (TEQ) values ranged from 3.26 to 362.84ng/g, with higher values in central parts of the city. A statistically significant difference in As, Cd, Cu, Pb, Zn, and ∑PAH concentrations between different land uses was observed. The highest As concentrations were found in agricultural areas while roadside, commercial, and industrial areas had the highest Cd, Cu, Pb, Zn, and ∑PAH contents.

An assessment of the potentially hazardous element contamination in urban soils of Arica, Chile

As a common component of urban ecosystems, urban soils generally have elevated concentrations of potentially hazardous elements originating from both point and diffuse sources of pollution in cities. This study focuses on the port city of Arica in northern Chile, where anthropogenic activities may have led to contamination of the uppermost topsoil layer. The purpose of this study is to (1) establish background content levels of potentially hazardous elements in topsoils of different land uses using different statistical approaches and (2) assess the degree of topsoil pollution and identify the local sources of pollution using multivariate statistical and geostatistical methods. Data from a Chilean Government CONAMA report were analyzed. Geostatistical methods such as kriging were applied to identify the spatial distribution of potential hazards elements. Potentially hazardous elements' background values were determined by median+2MAD, inflection points within cumulative frequency plots and upper whisker of a Tukey's boxplot. Multivariate statistical methods were applied in the identification of trace metal sources (anthropogenic vs natural origin). Soil pollution assessment was performed using the geoaccumulation index (Igeo), enrichment factor (EF), contamination factor (Cf) and integrated pollution index (IPI). The maps obtained show high baseline values for some elements (As, Cu, Pb and Zn), which denote a clear anthropogenic contribution due to the long period of constant human activities in the study area. Therefore, background values are estimated with the median+2×MAD procedure and yielded As (17.4mgkg−1), Ba (23.3mgkg−1), Cr (13.6mgkg−1), Cu (37.4mgkg−1), Ni (8.3mgkg−1), Pb (313mgkg−1), V (101mgkg−1) and Zn (235mgkg−1). The calculated soil pollution indexes Igeo, EF, Cf and IPI revealed significant ecological impacts. Copper and As are the two trace elements with the highest contaminated soil values; however, Cu, Pb and Zn have greater numbers of soil sample sites in the moderately to heavily contaminated range. The IPI showed extremely high pollution index in ten soil sites in Arica. Moreover, significant differences were observed with different land uses, where soils along the railway line and industrial area are the most polluted.

Biological contamination of urban soils in Leicester, UK, with Cryptosporidium spp.: A pilot study

Biological contamination of urban soils in Leicester, UK, with Cryptosporidium spp.: A pilot study