Human health risk assessment of arsenic and trace metals in atmospheric dust of Arak industrial area, Iran.

In order to investigate concentrations, variability, sources, and human health risk of trace elements, 38 atmospheric dust samples were collected around Arak industrial area. The average concentrations of Cd~Zn, As, and Pb were 3.3, 2.5, and 2.4 times higher than the corresponding geochemical background, respectively, while concentrations of Co, Cu, Ni, and Hg were lower. Based on geo-accumulation index (Igeo), trace elements were classified between practically uncontaminated to moderate contaminated levels. The potential risk (RI) map showed that about 86% of the study area for all trace elements was in the moderate risk class. According to the results of positive matrix factorization (PMF) model, four factors were extracted for trace elements, including industrial sources, natural sources, mining, and transportation, that contributed about 30, 27, 26, and 17% to pollution of the area, respectively. The carcinogenic risks for inhalation exposure to Cd, As, Ni, and Co were lower than the permissible risk limit than the EPA recommend (10-6), indicating an acceptable level of risk. Results of the health risk evaluation indicated that the non-carcinogenic health risk (i.e., hazard quotient, HQ) for children and adults decrease following: As > Pb > Ni > Zn > Cd > Cu > Co > Hg. When excluding As, the hazard index (HI) was lower than the safe level (HI < 1) for all the trace elements, whereas HQ values of As for children and adults were 17.1 and 1.6, respectively, indicating a potential risk for children. In sum, several remedial actions to eliminate or to reduce the dust pollution are urgently required in the industrial area of Arak.

Modeling Sediment Ni and V Spatial Distribution to Identify Hotspots in the Shadegan Wildlife Refuge, at the Head of the Persian Gulf.

The distribution and origins of Ni and V were assigned in the surficial sediments from 160 stations in Shadegan international wetlands with 537,700 ha. The findings showed that the mean total content of Ni and V in the surface sediments were 45.08 ± 12.09 and 25.25 ± 20.8 µg g-1 dw, respectively. According to the analysis chemical speciation, the Ni and V residual fraction in the surface sediments were calculated for > 80% of the total level of metals, indicating that the metals may be an indicator for the input of natural resources. The analysis of the interpolation maps according to their chemical fractionation manifested that the Ni and V pollution hotspots have been happened in the northern, southern, and western points. Interpolation maps also highlighted that Ni and V are often controlled by natural factors like parent material; however, anthropogenic inputs have also caused the accumulation of these metals in the sediment.

Pollution assessment and spatial distribution of trace elements in soils of Arak industrial area, Iran: Implications for human health.

Emerging industrial hubs have resulted in soil and dust pollution by trace elements, being a potential source and pathway for human exposure to nearby cities. The aim of this study was to determine the spatial distribution, levels, sources and health risk assessment of metals and arsenic in soils of Arak industrial area, Iran. A total of 235 topsoil (0-5 cm) samples were collected from the vicinity of Arak, and the concentrations of As, Zn, Ni, Pb, Cu and Cd were 152, 104, 93, 38, 14 and 1.2 mg kg-1, respectively, and exceeded the background values, with the exception of Cu. Values of pollution indexes revealed that most of the soils are especially enriched by As and Cd. Multivariate statistical analysis showed that Pb and Zn originated from common anthropogenic sources related to industrialization and mining, whereas Cu and Ni are probably associated with geological sources. Cd was mainly derived from the input of agricultural and industrial activities, and As should be attributed to residues in mining. Spatial risk maps showed the high risk of trace elements pollution in the order of As (100%) > Cd (62%) > Ni (12%) > Pb (5%) > Zn (4%) > Cu (0%). The results of the noncarcinogenic risk assessment showed that chronic daily intake in children and adults for ingestion pathway was higher than for dermal contact and inhalation. Values of hazard index (HI) for trace elements were below the safe level (HI ≤ 1), indicating that no noncarcinogenic risk threaten children and adults. Likewise, the total carcinogenic risk of Cd in both groups is less than the EPA threshold (1 × 10-6), indicating a low carcinogenic risk, however As (1 × 10-6 to 1 × 10-4) indicates an acceptable risk.

Using GIS, geostatistics and Fuzzy logic to study spatial structure of sedimentary total PAHs and potential eco-risks; An Eastern Persian Gulf case study.

GIS, geo-statistics and autocorrelation analysis were employed to reveal spatial structure of sedimentary ∑16PAHs. Global Moran's I index outlined significant ∑16PAHs clusters for the entire region (Moran's I index =0.62, Z-score = 25.6). Anselin Moran's I index specified locations of the significant low/high spatial clusters. The levels of random and structural variance of ∑16PAHs were about 0.083 and 0.154, respectively. Nugget to sill ratio confirmed that ∑16PAHs has a moderate level of spatial structure and the major part of PAHs variability is not random. Prediction and standard error maps of ∑16PAHs, produced by ordinary kriging, highlighted that more samples should be taken from high cluster region for next studies. Fuzzy logic functions (OR and AND) were used to develop eco-risk maps. It revealed that the potential hazards of PAHs are considerable at the vicinity of petrochemical facilities.

Source, spatial distribution, and toxicity potential of Polycyclic Aromatic Hydrocarbons in sediments from Iran's environmentally hot zones, the Persian Gulf.

Surface sediments, sampled from Iranian coast of the Persian Gulf (n = 134), were analyzed in order to track spatial distribution of PAHs and their related eco-hazards. The levels of PAHs were in the range of 1.98-814 ng g-1 dw and the region was lowly to moderately polluted. The profile of PAHs was mainly composed of 2,3-ring chemicals and suggested a local source of PAHs and relatively fresh inputs. Statistical analysis and molecular fingerprints proposed that the basin receives PAHs from multiple origins including petrogenic and pyrogenic (traffic and auto emission) ones. Spatial distribution of organic matter and fine fraction of the sediments had a horizontally increasing trend in the studied basin. ∑16PAHs showed significant positive correlation with TOC and fine fraction (p < 0.05) and the spatial deposition of ∑16PAHs followed the spatial trends of TOC and fine fraction. Spatial mapping techniques confirmed that Pars Special Economic Energy Zone (PSEEZ) is the hot zone of PAH pollution. A combination of source availability, finer sediments, and great organic matter levels were the main effective factors that highlighted the deposition of PAHs in the PSEEZ. The Nayband Bay, as the Iran's first national marine Park, possibly received PAHs from its adjacent zone, the PSEEZ. On the other hand, low organic matter and sandy nature of the Nayband Bay was not suitable for effective sequestration of PAHs. Thus, the biota of Nayband Park was encountering with relatively severe multiple eco-hazards due to both ecological and economic factors.

Distribution of linear alkylbenzenes as a domestic sewage molecular marker in surface sediments of International Anzali Wetland in the southwest of the Caspian Sea, Iran.

Due to directly receiving high volume of untreated urban and industrial sewage and in turn transferring the pollutants to fish and back to humans, the International Anzali Wetland has been considered to be urgently registered in the Montreux Record. Hence, the present study was aimed to determine the spatial distribution of the linear alkylbenzenes (LABs) in surface sediments of the wetland and its sewage contamination situation. The surface sediments (sampling stations = 167) were collected from the western, eastern, southwest, and central regions of the wetland. The samples were extracted, fractioned, and then analyzed using gas chromatography-mass spectrometry (GC-MS). The concentration of LABs in the sediment samples revealed a range from 394.12 to 109,305.26 ng g-1 dw. The concentrations of ΣLABs in the eastern region were significantly higher than that in the other regions. The occurrence of low ratio of internal to external isomers (I/E ratio) of LABs (from 0.65 to 1.30) and D% (from - 0.07 to 24.13) implied effluent row or poorly untreated sewage into the wetland. No correlation was observed between the detected LAB concentrations with total organic carbon (TOC) and grain size. Taken together, regional anthropogenic inputs are the controlling factors for the observed spatial distributions of ∑LABs in the International Anzali Wetland. The findings suggested that LABs are powerful indicators to trace anthropogenic sewage contamination and also highlighted the necessity of sewage treatment plants to be founded around the International Anzali Wetland, especially in the vicinity of the eastern and central regions.

Characterization and ecological risk of polycyclic aromatic hydrocarbons (PAHs) and n-alkanes in sediments of Shadegan international wetland, the Persian Gulf.

The distribution and sources of PAHs and n-alkanes were determined in the surface sediments from 202 locations in Shadegan international wetland with 537,700ha. The concentrations of total n-alkanes and PAHs ranged from 395.3 to 14933.46µgg-1dw and 593.74 to 53393.86ngg-1dw, respectively. Compared with other worldwide surveys, the concentration and contamination of sedimentary hydrocarbons were classified very high. A common petrogenic hydrocarbon source was strongly suggested in all sites by n-alkanes' profile with a Cmax at n-C20, Pr/Ph and CPI ratios<1 in all sites, and high percentage of UCM. Typical profile of petrogenic PAHs with alkyl-substituted naphthalenes and phenanthrenes predominance, various PAH ratios and multivariate analysis indicated that PAHs were mainly derived from petrogenic source. Naphthalene-derived compounds in all sites were significantly above their ERL, and adversely affected benthic biota. 92% of the sites had mean ERM values<0.1, indicating high ecological risk on the wildlife of the wetland.

Geochemical fractionation and pollution assessment of Zn, Cu, and Fe in surface sediments from Shadegan Wildlife Refuge, southwest of Iran.

This research focuses on the fractionation and distribution patterns of heavy metals (Zn, Cu, and Fe) in surficial sediments collected from Shadegan Wildlife Refuge, the biggest wetland in southern part of Iran, to provide an overall classification for the sources of metals in the study area using a sequential extraction method. For this purpose, a four-step sequential extraction technique was applied to define the partitioning of the metals into different geochemical phases of the sediment. The results illustrated that the average total level of Zn, Cu, and Fe in surface sediments were 55.20 ± 16.04, 22.86 ± 5.68, and 25,979.01 ± 6917.91 µg/g dw, respectively. On the average, the chemical partitioning of all metals in most stations was in the order of residual >oxidizable-organic > acid-reducible > exchangeable. In the same way, the results of calculated geochemical indices revealed that Cu, Zn, and Fe concentrations are mainly influenced by lithogenic origins. Compared with consensus-based SQGs, Cu was likely to result in occasionally harmful biological effects on the biota.

Geochemical partitioning and pollution assessment of Ni and V as indicator of oil pollution in surface sediments from Shadegan wildlife refuge, Iran.

The total concentrations and chemical partitioning of Ni, V and Fe have been assessed in surface sediments from 160 sites along the Shadegan wildlife refuge. The results showed that the average total level of Ni, V and Fe in surface sediments were 45.08±12.09, 25.25±20.8 and 25,979.01±6917.91µg/g dw, respectively. On the average, the chemical speciation of Ni, V and Fe in most stations were in the order of residual>oxidisable-organic>acid-reducible>exchangeable. In all fractions, the residual was accounted the highest proportion for the metals analyzed. Among the non-residual phases, the proportion of heavy metals in organic matter fraction was higher than other phases collected from all locations. The comparison between measured values in this study and some fresh water sediment quality guidelines indicated that the levels of nickel would be expected to sporadically cause harmful biological impacts on biota in the Shadegan wildlife refuge.

The status of lead and cadmium in soils of high prevalenct gastrointestinal cancer region of Isfahan.

BACKGROUND: Cadmium and lead compounds are classified as human carcinogens by several regulatory agencies. Twenty five percent of all cancer-related deaths are attributed to gastrointestinal cancers (GI Ca). We investigated the levels of 2 different heavy metals (Cd and Pb) in the soils of the Lenjanat region, Isfahan province, Central Iran where intensive agriculture is surrounded by different industries like steel and cement-making factories and mining and gastrointestinal cancers are very common in this province. MATERIALS AND METHODS: Two hundred topsoil samples (0-20 cm depth) were collected from agricultural and non-agricultural soils of the region and were analyzed for heavy metals. The metal contents were determined by flame atomic absorption spectrometry. RESULTS: The findings of this study showed that frequency of gastrointestinal cancers in the study area have been increased in the recent years. Results of soil samples in this region showed that the mean concentration of Pb and Cd were more than 16 and 1 mg kg(-1), respectively. The total Cd concentration in most of the samples exceeded the suggested Swiss thresholds (0.8 mg kg(-1)) but the mean value of Pb concentration in soil was less than the threshold of 50 mg kg(-1) set by Swiss Federal Office of Environmental, Forest and Landscape. Compared to the threshold values for heavy metals (Cd and Pb) in soils, data showed that the studied fields were contaminated especially by Cd. CONCLUSION: High heavy metals content in the soils seems to play an important etiological role in the carcinogenesis. Excessive accumulation of heavy metals in agricultural soils may not only result in soil contamination, but also lead to elevated heavy metal uptake by crops, and thus affect food quality and safety. Thus, analyzing heavy metals content in crops, water and dust could provide us a better insight to solve the problem.

Spatial distribution of cadmium and lead in the sediments of the western Anzali wetlands on the coast of the Caspian Sea (Iran).

Spatial distribution patterns of total cadmium (Cd) and lead (Pb), their bioavailable fractions and total organic matter in sediment from Anzali wetlands are provided. Total sediment Pb was higher than Cd (34.95 versus 0.024 µg/g dry weight). The geoaccumulation index indicated that the sediment was "uncontaminated", but some stations were categorized as "unpolluted" to "moderately polluted". Less than 0.01 of Pb existed in exchangeable and carbonate fractions. The sum of exchangeable and carbonate-bound fractions of Cd was 42%, suggesting that Cd poses high risk to the aquatic ecosystems. Total Cd and Pb exhibited positive relationships with total organic matter. Considering spatial distribution maps of total and bioavailable fractions of metals suggested that high concentrations of metals does not necessarily indicate high bioavailable fraction. The methodologies we used in this study can be in more effective management of aquatic ecosystems, as well as ecological risk assessment of metals, and remediation programs.