Origin and comprehensive risk assessment of heavy metals in surface sediments along the Caspian Sea.

Metal concentrations (Cu, Zn, Cr, Fe, As, Pb, Ni, V, and Co) in surface sediments were determined in the southern Caspian Sea. Sediment pollution was investigated using geochemical index such as Enrichment Factor (EF) and ecological risk indices like modified Hazard Quotient (mHQ) and Toxic Risk Index (TRI). The highest calculated geochemical index was observed in sediments near the cities of Chalus and Ramsar, which are highly polluted due to human activities. The ecological potential indices indicated that Ni contents in all the studied stations would impose harmful effects on aquatic organisms, while other metals had a low risk. Principal component and cluster analyses suggested that As and Pb emanated from anthropogenic sources, and other metals probably originated from lithogenic sources.

Biomarkers for monitoring heavy metal pollution in the Anzali Wetland.

This research aims to investigate biochemical activities of Phragmites australis, as a biomarker of heavy metals including Cr, Ni, V, Zn and Co. In order to determine and analyze biochemical parameters including flavonoids, Non-Protein Thiols (NPTs), chlorophyll a and b and total chlorophyll pigments in the roots, stems and leaves of P. australis, sediment and plant samples were collected from 7 stations in the Anzali wetland. Based on the obtained results, there were positive and significant correlation coefficients among the concentrations of the heavy metals in the sediments with non-protein thiols and flavonoids, also negative and significant correlation coefficients were found between the heavy metal contents and the total chlorophyll in the leaves in all the sampling stations. Therefore, it can be concluded that these parameters are appropriate biomarkers to evaluate the heavy metal pollution in the sediments of the aquatic ecosystem.

Contamination and ecological risk assessment of trace elements in sediments of the Anzali Wetland, Northern Iran.

In this paper, concentrations of some heavy metals in surficial sediments of the International Anzali Wetland were measured, this wetland is located in the northern part of Iran. Sediment pollution levels were examined and analyzed using reliable pollution indices including Pollution Load Index (PLI), Geoaccumulation Index (Igeo) and Enrichment Factor (CF), and finally it was revealed that heavy metal pollution ranged from low to moderate loads in the wetland. According to Sediment Quality Guidelines (SQGs) and Ecological Risk Index (ERI), it was concluded that As and Ni may have significant toxic impacts on aquatic organisms and also according to Effect Range Median (ERM), the toxicity probability of sediments in the Anzali wetland was estimated at 21%.

Heavy metal pollution status in surface sediments of the Khajeh Kory River, north Iran.

This study aimed at exploring the extent of likely sources of heavy metal pollution in sediments of the Khajeh Kory riverbed in the north of Iran. In order to assess the heavy metal contamination, samples from surface sediments in 10 stations covering the river were collected and analysed to determine heavy metal contents including Cd, Cu, Ni, Pb, Zn, Mn, Co, Al, and Fe. Three guidelines were applied to assess the heavy metal contamination. Compared with the global average values, the calculated enrichment factors indicated high values for Fe, Mn, Cd, Co, and Cu, and very high values for Pb and Zn. The results obtained from principal component analysis revealed that the geogenic and anthropogenic sources were the main causes of the widespread enrichment of heavy metals in the riverbed sediments. The results suggested that the riverbed sediments were contaminated with heavy metals, which contribute to the freshwater toxicity in the ecosystem of the Khajeh Kory River.

Assessment of Heavy Metal Pollution and Human Health Risks Assessment in Soils Around an Industrial Zone in Neyshabur, Iran.

Heavy metal pollution of soils in industrial zones continues to attract attention because of its potential human health risks. The present research is an attempt to assess the pollution status of heavy metals including As, Cd, Cr, Ni, and Pb using various indices like contamination factor (CF), pollution index (IPOLL), and geo-accumulation index (Igeo). In total, 60 surface soil samples were collected from four area (north, south, east, and west) in Khayyam industrial zone from depths of 10-20 cm. The results indicated that average metal concentration ranges (in mg/kg) observed in study soils were 8.84, 1.9, 37.66, 15.77, and 57.33 for As, Cd, Cr, Ni, and Pb, respectively. The concentrations of heavy metals As, Cr, Ni, and Pb with the exception of Cd in soils of southern areas of the industrial zone were higher. Cd concentration vary negligibly in sampling sites of north, south, east, and west. Based on the CF, IPOLL, and Igeo indices, the pollution of soil in regard to concentration of heavy metals was in the following order: Cd > As > Pb > Ni > Zn. Industrial activities have therefore resulted in elevated concentrations of so in the soil environments in the Khayyam industrial zone. Based on the results of human health risk assessments, the soil metals pose negligible carcinogenic and non-carcinogenic risks to the adults and children living in this area. The need for the monitoring of the soil around the industrial zone, especially for Cd and As, is needed to reduce potential environmental issues.

Evaluating of heavy metal pollution in Amir-Kalayeh wetland using geochemical and statistical analyses.

Metal pollution in aquatic ecosystems has created concern due to its toxicity, environmental stability and ability to transfer into the food chain, and monitoring the metal source is one way to decrease the environmental impact. The present study aimed to investigate metal concentrations of Al, Fe, Mg, P, As, Cd, Co, Cr, Cu, Mn, Mo, Ni, Pb, V and Zn, their spatial distribution, origin of the contaminants, contamination factor (CF), pollution load index (PLI), enrichment factor (EF), and geoaccumulation index (Igeo) in surface sediments of the Amir-Kalayeh wetland. Using statistical methods such as Pearson correlation coefficient, cluster analysis and factor analysis, the natural or anthropogenic origin of these elements was determined. According to the results, As, Cd, Mn, Mo And Pb have CFs higher than 1, which means they have contaminated the area. In this research, PLI was 0.9, which means the sediments of Amir-Kalayeh wetland are not polluted. The highest EF belongs to Mn and Mo. Determining Igeo showed that none of the metals in Amir-Kalayeh wetland are within the pollution range. However, the enrichment of elements in the sediments shows that continuous monitoring and managing of metal pollution source in this wetland is an essential step.

Bioavailability and geochemical speciation of phosphorus in surface sediments of the Southern Caspian Sea.

The purpose of this study was to quantify phosphorus bioavailability and various forms of this element in surface sediments of the southern Caspian Sea. To do, sediment samples were collected from different depths in autumn 2015 using a Van Veen Grab. Phosphorus forms were recognized by a sequential extraction procedure (SEDEX). Results revealed that the range of total phosphorus (TP) was between 431ppm and 594ppm with a mean value of 535.25±45.05ppm. Organic phosphorus (OP) ranged from 62 to 99ppm and contributed 14.85±2.21% of total phosphorus in average. The contents of loosely phosphorus, iron-bound phosphorus, authigenic phosphorus and detrital phosphorus varied 35-55ppm, 50-94ppm, 125-189ppm and 152-217ppm, respectively. Generally, inorganic phosphorus (IP) was between 365 and 522ppm which comprised 81.9-88.53% of total phosphorus. Findings showed levels of different phosphorus forms in a descending order: detrital P>Authigenic P>Organic P>Fe-P>Loosely P. Bioavailable phosphorus concentration was between 153ppm and 240ppm and consisted 37.21±3% of total phosphorus. Based on molar ratio of TOC/OP, organic matter obtained from the studied stations suggested a terrestrial origin.

Antioxidant response to metal pollution in Phragmites australis from Anzali wetland.

This research was conducted to examine variations of antioxidant enzyme activity in Phragmites australis as a biomarker for metals such as As, Pb, Cu, and Cd. Samples of sediment and plants were collected from 7 stations located in Anzali wetland. Biochemical parameters including Catalase, Peroxidase and Ascorbate Peroxidase activity were analyzed in the roots, stems and leaves of P. australis. The obtained results indicated that there were significant differences among activities of antioxidant enzymes in three organs (p<0.05). Antioxidant enzyme activities in the organs for all studied stations were as the following order: stem

Geochemical speciation, bioavailability and source identification of selected metals in surface sediments of the Southern Caspian Sea.

Geochemical speciation of As, Cd, Co, Cr, Cu, Ni, Pb, V and Zn were determined in the surface sediments of the southern Caspian Sea. A five-step sequential extraction technique was used to determine the chemical forms of metals. Mean concentrations (ppm) of heavy metals were (mean±S.D.) As: 9.94±1.71, Cd: 0.87±0.23, Co: 14.85±2.80, Cr: 72.29±19.48, Cu: 18.91±4.48, Ni: 32.87±5.25, Pb: 12.48±3.22, V: 86.07±20.71 and Zn: 66.85±10.11. Among the metals, Cu, As, Pb and Zn exhibited relatively higher mobility, while Cd, Co, Cr, Ni and V were found mainly in the residual fractions. Cu and As showed the highest percentages in the exchangeable phase while Co and Cr had the lowest percentages in the phase. The Risk Assessment Code (RAC) values indicated that As, Cu and V had medium risk at some sampling sites. According to pollution load index (PLI), sediments from some sampling sites were polluted.

Geochemical speciation and ecological risk assessment of selected metals in the surface sediments of the northern Persian Gulf.

The present study aimed to geochemical speciation of metals in the surface sediments of the northern Persian Gulf. Metal contents in the sediment were observed in the order: Al>Fe>Cr>Ni>V>Zn>Cu>Co>As>Pb>Cd. The results of sequential extraction procedure revealed that all metals were predominantly associated with the residual fraction. Among the metals, Cu and As exhibited higher bioavailability. The risk assessment code (RAC) indicated that Cu, As and Cd had medium environmental risk at some sampling sites. Based on enrichment factor (EF), Cd and As had moderate to significant enrichment.

Heavy metal accumulation in tissues of two sea cucumbers, Holothuria leucospilota and Holothuria scabra in the northern part of Qeshm Island, Persian Gulf.

The concentrations of some heavy metals (Cd, Cu, Zn andPb) were investigated in the sediments and the two species of sea cucumber (Holothuria leucospilota and Holothuria scabra) from northern part of Qeshm Island, Persian Gulf. The levels of Cu, Zn and Pb in sediment varied significantly among sampling sites (p<0.05). The highest levels of Zn and Pb in H. leucospilota were recorded in body wall whereas the highest contents of Zn and Pb in H. scabra were measured in respiratory tree organ, respectively. Cu and Cd were the most abundant elements in gonads of H. leucospilota while highest levels of Cd and Cu in H. scabra were measured in the gonad and derm, respectively. Cu and Zn concentrations were below permissible limits for human consumption while Cd and Pb were above permissible limits for human consumption.

Bioaccumulation and ecological risk assessment of heavy metals in the sediments and mullet Liza klunzingeri in the northern part of the Persian Gulf.

The concentrations of some heavy metals (Cu, Zn, Pb and Cd) were investigated in the sediments and in the mullet Liza klunzingeri from the northern part of the Persian Gulf. The levels of Cu, Zn and Pb in the sediment varied significantly among the sampling sites (P<0.05). Sediments from the northern part of the Persian Gulf had serious ecological risk when considering PER. The ranges of the average concentrations of Cu, Zn, Pb, and Cd in the tissue of L. klunzingeri were 10.00-16.66 mg/kg, 18.75-32.50 mg/kg, 3.25-14.16 mg/kg and 0.37-3.33 mg/kg, respectively. The health risk analysis of individual heavy metals in the fish tissue indicated dangerous levels of Pb and Cd for the general population at some sampling sites.