Background Soil Samples Research Articles

Biodynamic compost effects on soil parameters in a 27-year long-term field experiment

BackgroundSoil samples were taken after 27 years from a long-term field experiment to study the effects of composted pure cattle farmyard manure (FYM) and two FYM treatments with biodynamic preparations on soil chemical and microbiological properties.MethodsSoil organic carbon (SOC), total nitrogen, basal respiration, fungal ergosterol, microbial biomass C (MBC) and nitrogen (MBN) were analyzed in a 6-field crop rotation system, conducted as a randomized block design with six replicates. The multi-substrate-induced respiration (multi-SIR) approach was used to assess microbial functional diversity by the respiratory response of 17 low molecular weight organic substances.ResultsAll composted FYM treatments revealed generally positive effects on SOC, total N, basal respiration, MBC, and MBN in contrast to control without FYM. Only fungal ergosterol was not increased by FYM application. After 27 experimental years, discriminant function analysis of multi-SIR data not only revealed significant general effects of biodynamic preparations, but was also able to differentiate between the sole application of the Achillea millefolium preparation and the standard application of all 6 biodynamic compost preparations.ConclusionsThe Achillea preparation was specifically able to improve the N status of the microbial community as indicated by the higher catabolic use of D-glucosamine as well as the amino acids γ-aminobutyric acid, L-cysteine, and L-leucine. The reason for different effects of the sole Achillea preparation and all 6 preparations cannot be explained by the current study.Graphical

Preliminary Investigation of Soil and Sediments Using Magnetic Susceptibility Method in Kogi State, Nigeria

Over the years, there has been significant increase in population and urbanization in Kogi State as a result of rural - urban migration. This has become a major threat to soil sustainability which is a natural non-renewable resource. The aim of this research is to carry out magnetic susceptibility mapping on the surface and subsurface soil of Kogi State using environmental magnetism techniques and geochemical analysis. The susceptibility test on rock samples and background soil samples within the study area shows an average of about 112.0 × 10^-5 SI. The magnetic susceptibility measurement on soil from Kogi State shows magnetic susceptibility enhancement of about (450.0 - 700.0) × 10^-5 SI. These values were dominant along the major towns, road pavements and commercial areas at the surface to a depth of about 50.0 cm in soil profiles. The 2D spatial distribution of magnetic susceptibility with depth reveals that these magnetic grains are distributed in the subsurface as a result of anthropogenic loading. The frequency-dependence of magnetic susceptibility (χfd%) values are very low (2 - 10.0 %) in most of the areas on the surface soil. These values indicate that the magnetic properties are predominantly contributed by the coarse multi-domain (MD) and stable single-domain (SSD) grains of anthropogenic origin. Atomic Absorbtion Spectrometer (AAS) analysis of these soil samples indicates the presence of Lead (300.0 - 900.0) mg/l and Cadmium (20.0 - 60.0) mg/l in large concentration at the surface soil in most part of the Kogi State. While Chromium show relatively low concentration on the surface soil. From the statistical correlation analysis, Lead and Cadmium show high positive correlation with magnetic susceptibility. These results suggests that the high enhancement of magnetic susceptibility on the surface and sub-surface soil in most part of Kogi State arise from anthropogenic activities rather than lithological and pedogenic processes and most likely cause by high concentration of Lead and Cadmium.

Characteristics and sources of Pb exposure via household dust from the urban area of Shanghai, China

Household dust has been considered as an important pathway for children's environmental Pb exposure. Shanghai was one of the first cities in China that removed Pb from petrol and has been shown in our previous study to have the lowest childhood blood Pb levels in China. This study therefore examines household dust Pb (PbHD) in Shanghai in order to determine the extent and exposure risks of PbHD. Household vacuum cleaner dust samples (n = 40) were collected and analyzed for total Pb concentration, bio-accessible Pb concentration and Pb isotopic compositions (PbIC). The mean concentration of PbHD was 195 mg/kg, which is between 7 and 10 times the Pb concentration of background soil samples from Shanghai. Among the investigated homes, those living in neighborhoods with lower average estate prices have higher dust Pb exposure risks for children. Bio-accessibility of Pb in household dust ranged between 53 and 91%, with a mean value of 71%. Analysis of PbIC of household dust samples (208Pb/206Pb: 2.1096 ± 0.0054; 207Pb/206Pb: 0.8648 ± 0.0025) are a close match to PbIC of coal combustion and solid waste incineration and fit well with those of outdoor air PbIC and urban surface soil PbIC of Shanghai. The study shows that children living in Shanghai are subject to PbHD exposure, with children living in the homes with lower average price having increased susceptibility to PbHD exposure. The data indicate that PbHD is derived primarily from contemporary coal combustion and solid waste incineration rather than common legacy Pb sources (e.g., Pb petrol and paint). Practices including closing doors and windows on days with poor air quality or high wind and preventing shoe wearing inside homes will aid in minimizing outdoor surface soil and ambient particulate intrusion indoors.

Human Health Risks Associated with Potentially Harmful Elements from Urban Soils of Hamedan City, Iran

Previous studies have shown that certain urban elements and arsenic are significantly concentrated in the surface soils of Hamedan, the largest city in western Iran. This study was carried out to assess the non-cancer and cancer risks ‎from exposure to these potentially harmful elements (As, Cd, Cr, Cu, Ni, Pb, and Zn) for Hamedan residence. In so doing, thirty-one urban and three background soil samples were analyzed by ICP-MS and the Risk Assessment Model established by the USEPA was applied to assess the health risk. It was found that the hazard index values for all the concerned ‎elements are below 1, which indicates negligible to low non-carcinogenic risk for the exposed population. Nevertheless, some close to threshold values were recognized for As, Cr, and Pb implying that these elements have the potential to cause non-cancer risk for Hamedan citizens in case of long-term overexposure. The contribution of HQ-ingestion to total HI was the highest while the health effect associated with the inhalation exposure was trivial. Children were found to be more susceptible to potentially harmful elements than adults. ‎The cancer risk calculation revealed that both children and adults are at increasing risk of developing ‎cancer over a lifetime through ingestion, inhalation, and skin contact. All of the verified elements exceeded the ‎tolerable level (1×10-6) of cancer risk however arsenic and chromium were found to be the most carcinogenic ‎elements followed by Pb, Ni, and Cd. The carcinogenic risks were moderate for adults and high for ‎children. This study indicates the necessity of designing effective strategies to reduce elemental ‎pollution and to mitigate adverse human health effects of PHEs in Hamedan.‎

Heavy metals and related properties in farming soils adjacent to a future copper mine, interpretation using GIS, and statistical methods

Exploitation of mines can lead to the entrance of heavy metals into the environment. There is a possibility of water, soil, and plant pollution in Darreh Zereshk area in the near future. To assess the soil contamination and determine the origin of selected heavy metals, enrichment factor (EF) and geoaccumulation index (Igeo) accompanied with principle factor analysis (PCA) and map of spatial distribution of the elements were conducted. A total of 30 agricultural soil samples and 12 background soil samples were collected from Darreh Zereshk area in central Iran which is going to be one of the richest copper mines in Iran and the Middle East. Total and soluble concentration of heavy metals (Cu, Pb, Zn, Mn, As, Fe, Ni, and Cr) and some physico-chemical properties of soils were determined. The results showed that contamination of the agricultural soils is more severe for Pb, Cu, and Zn and less severe for As. The origin of Ni and Cr did not seem to be anthropogenic. The average concentration of Cu, Pb, Zn, Mn, As, Fe, Ni, and Cr in agricultural soils of the area were 36.87 mg/kg, 190.78 mg/kg, 170.33 mg/kg, 367.41 mg/kg, 69.42 mg/kg, 15494.1 mg/kg, 29.25 mg/kg, and 25.01 mg/kg, respectively. Since the Fe and Mn with geogenic origin were located in the same component with Cu, Zn, Pb, and As; it can be inferred that the source of these elements is controlled by both parent material of soil and anthropic activity.

Effect of Deadwood Decomposition on the Restoration of Soil Cover in Landslide Areas of the Karpaty Mountains, Poland

Disturbances play an essential role in the shaping of temporal and spatial heterogeneity in natural community structures. The aim of this study was to provide an assessment of the deadwood influence on the chemical and biochemical properties of soils in a landslide area. The samples used to determine soil properties were collected from the entire landslide area, with locations distributed on a regular grid (50 × 50 m). The soil samples were collected from directly under the logs, and background soil samples were taken 1 m from the deadwood logs. The effect of the deadwood decomposition process was visible in the total organic carbon (C) and nitrogen (N) content and microbial activity of the soil. An increase in the enzyme activity and microbial biomass of the soil from directly beneath the deadwood was noted. In this study, it was found that a greater stock of deadwood was present in the accumulation zone, which resulted in a stronger effect of the released components on the soil cover. In order to restore landslide soils, microbial activity can be effectively stimulated by leaving deadwood on the landslide surface.

Distribution Characteristics of Heavy Metals and Pb Isotope in Profile Soils from a Mining and Smelting Area in Northwestern China

The distribution characteristics of typical heavy metals (HMs) and Pb isotopic compositions in profile soils from different areas were investigated in Baiyin district, northwest China. The soil samples from the ore district and the sewage irrigation area showed an obvious enrichment of HMs in different depths, and the difference in the longitudinal migration depth of Pb, Cu, Zn, and Cd was insignificant, which might be due to the migration behavior of HMs mainly controlled by carbonate in alkaline soil. With the sewage irrigation activities, the content of soil organic matter was no longer the main controlling factor for the migration behavior of HMs. In ore district and sewage irrigation area, the HMs contents of nonresidual fractions in topsoil were much higher than that in the corresponding deep soil, which indicated that HMs activities in topsoil were significantly high. The Pb isotopic compositions of profile soils indicated that the long-term mining and smelting activities remained the main source of vertical enrichment of HMs in Baiyin district. Moreover, the Pb isotope ratios 206Pb/207Pb of nonresidual fractions (1.1359-1.1916) were all lower than that in the corresponding residual fractions (1.1641-1.2010), showing the characteristics that HMs input from anthropogenic source were in different degrees. The Pb isotopic compositions of residual fractions in the topsoil of ore district and sewage irrigation area (1.1641 and 1.1703) were between the two end-members composed of background soil and local mineral samples, which suggested that some anthropogenic HMs might enter into the residual components in the soil that was greatly affected by the input of HMs.

MOBILE FORMS OF METALS IN SOILS IN THE NADYM-PUR INTERFLUVE (WESTERN SIBERIA)

The total concentrations of metals (Fe, Mn, Cu, Ni, Cr, Sr) and their mobile forms extracted by an ammonium acetate buffer (pH = 4,8) were studied in soils samples collected from Nadym-Pur interfluve (West Siberia), near the northern limit of the taiga zone. The heavy metal content was determined in 55 background soil samples and in 25 pyrogenic ones. Gross content was determined on a spectrometer "SPECTROSCAN MAX-GV" using x-ray fluorescence analysis. Mobile forms of metals were determined on a ContrAA 700 atomic absorption spectrometer by flame and electrothermal methods. The statistics are calculated using the Excel software package. The study confirmed the weak accumulation of metals in the soils of the northern regions of Western Siberia. The total content below the soil world average for Fe is 5 times, Mn - 3 times, Sr - 2 times, Cr - 1,4 times. The content of mobile forms varies widely depending on the amount of organic matter. The percentage of mobile forms of metals from the total content was: Cr - 0.84%, Fe - 1,2%, Sr - 3,8%, Mn - 8,7%, Ni - 15%. In the profile of podzols, the distribution of mobile forms of metals has an eluvial-illuvial character. Mn and Sr accumulate intensively in the surface organogenic horizons, and the Fe content increases in the BF horizon. Minimum values are marked in horizon E. In pyrogenic soils, there is an increase in the content of mobile forms of metals due to the intake of ash. Metal content usually not exceeded the maximal permissible concentrations for soils.

Magnetic Pollution of Soil Samples at Some Industrial Sites in Jos Metropolis, Plateau State, Nigeria

Magnetic susceptibility of polluted material can give a general view of the degree of heavy metal pollution, prior to a more expensive and time- consuming chemical analyses. In this study, magnetic susceptibility measurements of 40 soil samples collected from some industrial sites of Jos Metropolis, were made using MS2G Sensor connected to Bartington MS 2 susceptibility meter. Volume magnetic susceptibility values ranged from 0.00026 x 10-5 SI to 0.0650 x 10-5 SI while low frequency mass specific susceptibility values ranged from 0.1181 x 10-6 m3kg-1 to 20.3 x 10- 6 m3kg-1. In both cases least and highest values are recorded at Zuma Steel and Dilimi respectively. Comparing low frequency mass specific susceptibility values obtained from industrial sites to that obtained from non-industrial sites, it was observed that samples 11 and 12 from JIB and all samples collected from Dilimi recorded values higher than the background soil samples thus indicating magnetic enhancement of soil at these locations by anthropogenic sources. The relationship between the volume magnetic susceptibility and mass specific susceptibility showed correlation of 0.983 implying that volume magnetic susceptibility results can be accepted in the absence of low frequency mass specific susceptibility measurement to assess magnetic pollution. The study also revealed that the magnetic behaviour of the dried soil samples collected from the industrial sites are controlled by concentration of ferrimagnetic minerals. 
 Keywords: Magnetic, Pollution, Ferrimagnetic, Susceptibility, Anthropogenic, Dilimi

Levels and enantiomeric signatures of organochlorine pesticides in Chinese forest soils: Implications for sources and environmental behavior

We investigated the levels and distributions of organochlorine pesticides (OCPs) in 159 background soil samples collected from 30 forested mountain sites across China. The sum of DDT was the most abundant OCP, with the concentrations of 0.197–207 ng/g and 0.033–122 ng/g in the O-horizon and A-horizon, respectively. High concentrations of OCPs usually occur near agricultural regions or high consumption areas. The spatial distribution was mainly influenced by the emission sources and soil total organic contents (TOC). The chiral compounds were generally nonracemic in the soils and showed preferential degradation of (−) o,p′- dichlorodiphenyltrichloroethane, (+) trans-chlordane, and (−) cis-chlordane in both the O- and A-horizons. The enantiomeric fraction (EF) distributions of chiral OCPs displayed no differences across the forest sites in the O-horizon or the A-horizon. Comparing the deviation of EFs from racemic (DEVrac = absolute value of 0.500 - EF) with environmental parameters, we found that DEVrac of cis-chlordane demonstrated a strong positive correlation with TOC (p < 0.05) and the C/N ratio (p < 0.01). This relationship suggests that these factors could affect the microbial activity and significantly impact the extent of enantioselective degradation of chiral compounds in the soils. Fresh and historical applications of DDT and historical chlordane and endosulfan uses may be prominent sources of OCP accumulation in Chinese forest soils.

Collaborative involvement of woody plant roots and rhizosphere microorganisms in the formation of pedogenetic clays.

Previous studies have described the laying down of specific B horizons in south-western Australian ecosystems. This paper presents biomolecular, morphological and physicochemical analyses elucidating the roles of specific woody plant taxa and rhizosphere bacteria in producing these phenomena. Clayey deposits within lateral root systems of eucalypts and appropriate background soil samples were collected aseptically at multiple locations on sand dunes flanking Lake Chillinup. Bacterial communities were profiled using tagged next-generation sequencing (Miseq) of the 16S rRNA gene and assigned to operational taxonomic units. Sedimentation, selective dissolution and X-ray diffraction analyses quantitatively identified clay mineral components. Comparisons were made of pedological features between the above eucalypt systems, giant podzols under proteaceous woodland on sand dunes at the study site of Jandakot and apparently similar systems observed elsewhere in the world. Bacterial communities in clay pods are highly diverse, resolving into 569 operational taxonomic units dominated by Actinobacteria at 38.0-87.4 % of the total reads. Multivariate statistical analyses of community fingerprints demonstrated substrate specificity. Differently coloured pods on the same host taxon carry distinctive microfloras correlated to diversities and abundances of Actinobacteria, Acidobacteria, Firmicutes and Proteobacteria. A number of these microbes are known to form biominerals, such as phyllosilicates, carbonates and Fe-oxides. A biogenic origin is suggested for the dominant identified mineral precipitates, namely illite and kaolinite. Comparisons of morphogenetic features of B horizons under eucalypts, tree banksias and other vegetation types show remarkably similar developmental trajectories involving pods of precipitation surrounding specialized fine rootlets and their orderly growth to form a continuous B horizon. The paper strongly supports the hypothesis that B-horizon development is mediated by highly sophisticated interactions of host plant and rhizosphere organisms in which woody plant taxa govern overall morphogenesis and supply of mineral elements for precipitation, while rhizosphere microorganisms execute biomineralization processes.

Risk Assessment of Trace Metals in Soils in the Vicinity of NPA Expressway Open Dump in Warri Metropolis, Delta State, Nigeria

Heavy metals are non-biodegradable. They accumulate in the environment and subsequently contaminate the food chain. It is therefore essential to monitor heavy metals content in the soil, so as to prevent too much accumulation in human beings and animals through food chain. Test soil samples were collected from Nigeria Ports Authority (NPA) Expressway open dump, and background (control) soil samples were also collected at about 2 km from the open dump and spatial test samples were also collected. The physicochemical properties of the soil were determined. Tessier’s sequential extraction protocols were used to assess the geochemical forms of Cr, Pb, Zn, and Mn in the soil of the open dump. The concentrations of the heavy metals in the extracts were determined in a pre-calibrated atomic absorption spectrophotometer and they are above the background sample values. The metal assessment index (Igeo) evaluated, indicated that the soil in the vicinity of the open dump was highly polluted. The results obtained showed the mobile metal pools which are available to plants roots.

Long-term leaching of arsenic from pressure-treated playground structures in the northeastern United States

Wood used in playground structures built prior to 2004 was pressure-treated with chromated copper arsenate (CCA) which has been associated with negative health and environmental impacts. Given the prevalence and lack of maintenance of these aging play structures in rural northeastern US, the aim of this study was to determine the distribution of As (total, speciated and bioaccessible) in surface soil collected near and underneath four CCA-treated playground structures 16- and 26-years following installation. Note that one playground in southeastern MA was studied where surface soil samples were collected at various distances from the structures (0, 5, 15, and 30 cm). Total As in surface soil was measured by graphite furnace atomic absorption spectroscopy, whereas As speciation and bioaccessible As were determined by HPLC-ICPMS and in vitro SBRC-gastric assay, respectively. Near (≤5 cm) and underneath CCA-treated structures total As concentration in surface soil ranged from 143.4–213.5 mg/kg after 26 years of installation compared to 101.3–166.6 mg/kg ten years earlier. These concentrations exceeded the Massachusetts Residential Risk-Based Soil Standard by 5–10 times. In comparison, total As in background soil samples ranged from 4.6–6.6 mg/kg during the two study periods. While most of the As in surface soil were in the form of As(V), ≤29% was bioaccessible. Overall, our findings demonstrated that arsenic accumulation in soil surrounding aging playground structures continues to be a source of elevated exposure to children through contact with contaminated soil.

MMI partial extraction geochemistry for the resolution of anthropogenic activities across the archaeological Roman town of Calleva Atrebatum

Sixty three soils samples, fourteen samples of previously excavated archaeological material, and five background soil samples taken at the Silchester Roman Town of Calleva Atrebatum in the County of Hampshire, United Kingdom were analysed by the Mobile Metal Ion (MMI) method for a total of fifty three elements. Samples from within the town walls showed considerably higher concentrations than samples outside for many elements; Au, Ag, Cu and Sn were in extremely anomalous concentrations, Bi, Cd, Hg, Mo, P and Pb were anomalous and Sb and Zn in elevated concentrations. The overall pattern of element distribution is one of an annulus of higher elemental concentrations surrounding a centre of generally lower values centred on the previously excavated Forum basilica. The elements Zr, Ti, Th, Ti, Tl, Nb, Sn, Sc, Cr, Co, Sb, Bi, Ce, Nd (and all other REEs), show similar distributions to one another, and their distribution and that of the noble and base metals, as highlighted by various additive indices, is considered to be the result of metallurgical processing on site. The low values for most elements around the Forum basilica are the result of disturbance of the soil geochemical profile in this area by previous archaeological excavation.

Distribution Assessment and Source Identification Using Multivariate Statistical Analyses and Artificial Neutral Networks for Trace Elements in Agricultural Soils in Xinzhou of Shanxi Province, China

Multivariate statistical analyses were used to assess the contents and distributions of trace elements in agricultural soils in Xinzhou of Shanxi Province, China, and to identify their sources. Samples with high levels of trace elements were concentrated in eastern Xinzhou, with contents declining from the east to west. Principal component and redundancy analyses revealed strong correlations among Co, Cu, Mn, Ni, Se, V, and Zn contents, suggesting that these elements were derived from similar parent materials. There were also strong correlations between the contents of these elements and soil properties. Contents of Cd and Pb were significantly higher in the agricultural soil samples than in the background soil samples (P < 0.05), and were higher in areas with higher levels of gross domestic product but decreased with distance to the nearest road. Therefore, human activities appear to have a strong influence on the Cd and Pb distribution patterns. A novel artificial neural network (ANN) model, using environmental input data, was used to predict the soil Cd and Pb contents of specified test dates. The performances of the ANN model and a traditional multilinear model were compared. The ANN model could successfully predict Cd and Pb content distributions, projecting that soil Cd and Pb contents will increase by 128% and 25%, respectively, by 2020. The results thus indicated that the economic condition of an area has a greater effect on trace element contents and distributions in the soil than the scale of the economy itself.

Background concentrations of PAHs and metals in surface and subsurface soils collected throughout Manhattan, New York

ABSTRACTThis article summarizes the results from a survey of polycyclic aromatic hydrocarbon (PAH) and metal concentrations measured in surface and subsurface soil samples that were collected from background locations throughout Manhattan, New York, between August 2005 and May 2006. The 95th percentile total 16 US EPA Priority Pollutant PAH concentrations in surface and subsurface soils were 24.8 and 53.1 mg/kg, respectively. Diagnostic PAH source ratios for surface and subsurface soils are presented, which provide plausible bounds for where these ratios would and would not be able to confidently differentiate background soils from soil samples that are impacted by PAH contamination. The 95th percentile concentrations for lead in surface and subsurface soils were 891 and 2,540 mg/kg, respectively, and the 95th percentile concentrations for mercury in surface and subsurface soils were 1.9 and 2.7 mg/kg, respectively. A not-unexpected finding of the study was that most surface soils and all subsurface soils contained a relatively high fraction of anthropogenic carbon, in addition to the presence of historic fill materials such as glass, brick, coal, and slag from more than 400 years of human activity on Manhattan Island. The concentration ranges for PAHs and metals measured in these background soil samples, coupled with the visual observations of historic fill materials in nearly all soil samples, emphasize that soils in Manhattan are altogether different from rural soils and thus warrant a different framework for site management decisions than rural soils.

Potential risks of the residue from Samarco's mine dam burst (Bento Rodrigues, Brazil)

On November 5th, 2015, Samarco's iron mine dam – called Fundão – spilled 50–60 million m3 of mud into Gualaxo do Norte, a river that belongs to Rio Doce Basin. Approximately 15 km2 were flooded along the rivers Gualaxo do Norte, Carmo and Doce, reaching the Atlantic Ocean on November 22nd, 2015. Six days after, our group collected mud, soil and water samples in Bento Rodrigues (Minas Gerais, Brazil), which was the first impacted area. Overall, the results, water samples – potable and surface water from river – presented chemical elements concentration according to Brazilian environmental legislations, except silver concentration in surface water that ranged from 1.5 to 1087 μg L−1. In addition, water mud-containing presented Fe and Mn concentrations approximately 4-fold higher than the maximum limit for water bodies quality assessment, according to Brazilian laws. Mud particle size ranged from 1 to 200 μm. SEM-EDS spot provided us some semi quantitative data. Leaching/extraction tests suggested that Ba, Pb, As, Sr, Fe, Mn and Al have high potential mobilization from mud to water. Low microbial diversity in mud samples compared to background soil samples. Toxicological bioassays (HepG2 and Allium cepa) indicated potential risks of cytotoxicity and DNA damage in mud and soil samples used in both assays. The present study provides preliminary information aiming to collaborate to the development of future works for monitoring and risk assessment.

Quantitative evaluation of Heterodera avenae females in soil and root extracts by digital image analysis

Heterodera avenae and other cyst-producing nematode species are traditionally counted manually by visual inspection, a laborious and time consuming process. A method to detect and count cereal cyst nematodes based on image analysis techniques and statistical identification was designed and tested on H. avenae white females. Nematodes at the white female stage and free of soil particles were isolated from a contaminated wheat field. Known quantities of white females were mixed with different pre-treated background soil samples from non infested fields. Pre-treatment consisted of typical sieving and centrifugation procedures for white female extraction. Image analysis techniques were then used to detect, count and characterize white females in the mixtures. Over 96% of the H. avenae white females and substrate particles were correctly identified showing that a clear distinction can be drawn between the two groups. The results confirmed the validity of the proposed method to identify and count H. avenae females in backgrounds of different origins. This study establishes the basis for the design of a standardized method that is easily incorporated into a stand-alone system to facilitate the detection and quantification of nematode inoculum. This method can be applied to evaluate infestation level in crop fields and also to detect resistance/tolerance in breeding lines.

A geochemical survey of heavy metals in agricultural and background soils of the Isfahan industrial zone, Iran

There is a growing public concern about the potential accumulation of heavy metals in agricultural soils of Iran. This is mainly the result of rapid urban, mining and industrial discordant development over the last several decades, which has jeopardized the ecology, food safety, human health, and sustainable development of agriculture. To investigate the soil pollution, a total of 105 agricultural soil samples and 40 background soil samples were collected from the Isfahan industrial zone. Accordingly, total concentrations of 7 heavy metals (including Cu, Pb, Zn, Cd, Ni, Co and Cr), associated with Al, Fe, Mn and some physicochemical properties of soils were determined. The geochemical background and threshold was predicted using the Median Absolute Deviation (MAD) method. The median concentrations of heavy metals in agricultural soil were nearly similar to those of background soil, with some outlier data in the vicinity of the industrial and mining areas. Based on correlation coefficient and factor analyses, the primary source of Ni, Co, Cr, Fe and Al was determined to be geogenic, whereas the source of Pb, Zn and Cd is substantially controlled by anthropic activity. Our observations proved that in the Isfahan industrial zone, both human and natural sources affect the concentrations of Cu and Mn. Maps of heavy metal pollution indices in agricultural soils reveal high level of pollution in the vicinity of BamaPb-Zn mining area along with Esfahan and Mobarakeh Iron-Steel plants.

Evaluation of Total Petroleum Hydrocarbons (TPH) Measurement Methods for Assessing Oil Contamination in Soil

The most commonly used total petroleum hydrocarbons (TPH) analysis method measures petroleum hydrocarbon concentrations in soil by carbon range that can be detected by gas chromatography/flame ionization detection (GC/FID). Different cleanup procedures have been performed for removing some naturally occurring organics from petrogenic hydrocarbons prior to GC/FID analysis. To evaluate the different pre-treatment methods, more than 60 samples (including background soil and plant samples, as well as oil contaminated soil samples) were sampled from 2008 to 2010 in Canada. TPH values without cleanup (TPH-T), with column cleanup (TPH-F 3) and with in-situ cleanup (TPH-F) were compared to evaluate the effects of different pre-treatment methods on the TPH analysis values. Different total solvent extractable materials (TSEM) loading amounts were applied for in-situ silica gel cleanup method to evaluate the effect of the TSEM loading amount on the measured TPH-F values. The column cleanup method was evaluated by comparing the representative polar biogenic organic compounds (BOCs) and TPH in polar fraction (designated as TPH-F 4). Qualitatively, cleanup procedures removed most of the BOCs for background samples with high content of BOCs, but the GC/FID chromatograms did not show significant alteration for samples with heavy oil contamination. The quantified TPH-T, TPH-F 3 and TPH-F showed good agreement for oil contaminated samples, even though the loading dosage exceeded the maximum TSEM limits of silica gel (16.7 mg TSEM on per gram silica gel). For background samples, the measured TPH values were ranked as: TPH-T > TPH-F > TPH-F 3 when the TSEM loading amount exceeded 16.7 mg/g of silica gel, but no obvious difference was observed when the TSEM loading amount was less than 16.7 mg/g. Therefore, the TSEM loading capacity played an important role for the cleanup of background samples. The comparison of the measured TPH-T and TPH-F 3 obtained from background soil and plant samples did not show an obvious relationship, thus TPH values of soil samples can not be replaced by those from plants grown in the soil sampled area. The evaluation of column cleanup method showed that this method can effectively remove most of the BOCs, but the removal of the hydrocarbons which contribute to the measured TPH-F 3 can be negligible.