Occurrence and patterns of metals in mangrove forests from the Oman Sea, Iran.

Concentrations of selected metals were investigated in roots, stems, leaves and sediments from mangrove forests situated along the coast of the Oman Sea, Iran. Results showed that the overall average concentrations of lead, nickel, copper, and zinc in sediments were 47.90, 54.12, 42.13 and 44 µg/g dry weight (dw) and 3.81, 16.41, 29.23 and 25 µg/g dw in plant tissues, respectively. In addition, the bioconcentration factors (BCFs) of root, stem and leaf ranged from 0.5 to 1.7, 0.2 to 1.5, and 0.4 to 1.3, respectively. Pollution indices showed that all investigated sites were in the category of low to moderate pollution (pollution load index: 1.5-0.11), with a 21 % probability of biological toxicity.

Intrinsic and extrinsic techniques for quantification uncertainty of an interpretable GRU deep learning model used to predict atmospheric total suspended particulates (TSP) in Zabol, Iran during the dusty period of 120-days wind.

Total suspended particulates (TSP), as a key pollutant, is a serious threat for air quality, climate, ecosystems and human health. Therefore, measurements, prediction and forecasting of TSP concentrations are necessary to mitigate their negative effects. This study applies the gated recurrent unit (GRU) deep learning model to predict TSP concentrations in Zabol, Iran, during the dust period of the 120-day wind (3 June - 4 October 2014). Three uncertainty quantification (UQ) techniques consisting of the blackbox metamodel, heteroscedastic regression and infinitesimal jackknife were applied to quantify the uncertainty associated with GRU model. Permutation feature importance measure (PFIM), based on the game theory, was employed for the interpretability of the predictive model's outputs. A total of 80 TSP samples were collected and were randomly divided as training (70%) and validation (30%) datasets, while eight variables were used in the TSP prediction model. Our findings showed that GRU performed very well for TSP prediction (with r and Nash Sutcliffe coefficient (NSC) values above 0.99 for both datasets, and RMSE of 57 µg m-3 and 73 µg m-3 for training and validation datasets, respectively). Among the three UQ techniques, the infinitesimal jackknife was the most accurate one, while all the observed and predicted TSP values fell within the continence limitation estimated by the model. PFIM plots showed that wind speed and air humidity were the most and least important variables, respectively, impacting the predictive model's outputs. This is the first attempt of using an interpretable DL model for TSP prediction modelling, recommending that future research should involve aspects of uncertainty and interpretability of the predictive models. Overall, UQ and interpretability techniques have a key role in reducing the impact of uncertainties during optimization and decision making, resulting in better understanding of sophisticated mechanisms related to the predictive model.

Comparison of Cd, Cu, Se, and Zn Concentration in the Muscle and Hepatopancreas of Sepia pharaonis and Uroteuthis duvauceli in the North of Persian Gulf (Iran).

The objective of this research was to examine and contrast the levels of cadmium (Cd), copper (Cu), zinc (Zn), and selenium (Se) in the muscle and hepatopancreas tissues of two species, namely pharaoh cuttlefish (Sepia pharaonis) and Indian squid (Uroteuthis duvauceli), from the Persian Gulf. A total of thirty individuals of each species were gathered in January 2009 from the northern waters of the Persian Gulf. The metal concentrations were significantly higher in muscle tissue (p < 0.05) than in other tissues. S. pharaonis had higher metal concentrations than U. duvauceli. In the muscle and hepatopancreas samples of S. pharaonis, the highest mean concentrations were found to be for Zn (58.45 ± 0.96 µg/g dw) and Cu (1541.47 ± 192.15 µg/g dw), respectively. In U. duvauceli, the highest concentration of measured elements was seen for Zn in both muscle (36.52 ± 0.56 µg/g dw) and hepatopancreas (60.94 ± 2.65 µg/g dw). Se had the lowest concentration among the elements measured in both species. There was a negative and significant correlation between Cu and biometrical factors (total body length and weight) in both muscle and hepatopancreas samples of S. pharaonic and only in the muscle samples of U. duvauceli (p < 0.01, R2 = - 052; p < 0.01, R2 = - 0.055). However, there was a strong correlation between Zn and biometrical factors in hepatopancreas samples of both species. The comparison of metal concentrations with standards revealed that only Cd levels in S. pharaonis exceeded the ESFA and WHO standards, whereas other metals were below the standards.

Tracing of Heavy Metals Embedded in Indoor Dust Particles from the Industrial City of Asaluyeh, South of Iran.

Assessment of indoor air quality is especially important, since people spend substantial amounts of time indoors, either at home or at work. This study analyzes concentrations of selected heavy metals in 40 indoor dust samples obtained from houses in the highly-industrialized Asaluyeh city, south Iran in spring and summer seasons (20 samples each). Furthermore, the health risk due to exposure to indoor air pollution is investigated for both children and adults, in a city with several oil refineries and petrochemical industries. The chemical analysis revealed that in both seasons the concentrations of heavy metals followed the order of Cr > Ni > Pb > As > Co > Cd. A significant difference was observed in the concentrations of potential toxic elements (PTEs) such as Cr, As and Ni, since the mean (±stdev) summer levels were at 60.2 ± 9.1 mg kg−1, 5.6 ± 2.7 mg kg−1 and 16.4 ± 1.9 mg kg−1, respectively, while the concentrations were significantly lower in spring (17.6 ± 9.7 mg kg−1, 3.0 ± 1.7 mg kg−1 and 13.5 ± 2.4 mg kg−1 for Cr, As and Ni, respectively). Although the hazard index (HI) values, which denote the possibility of non-carcinogenic risk due to exposure to household heavy metals, were generally low for both children and adults (HI < 1), the carcinogenic risks of arsenic and chromium were found to be above the safe limit of 1 × 10−4 for children through the ingestion pathway, indicating a high cancer risk due to household dust in Asaluyeh, especially in summer.

Organochlorine pesticide and polychlorinated biphenyl in feathers of resident and migratory birds of South-west iran.

Persistent organochlorine pesticides (OCPs), such as dichlorodiphenyltrichloroethane (DDT) and its metabolites, hexachlorobenzene (HCB), alpha-, beta-, and gamma-hexachlorocyclohexane (HCH) isomers, together with polychlorinated biphenyl (PCB) congeners (IUPAC Nos. 28, 52, 101, 138, 153, and 180) were determined in tail feathers from 35 birds belonging to 15 species, all originating from the southwest of Iran (Khuzestan, coast of the Persian Gulf) and kept in museum collections. The patterns of organochlorine contaminants (OCs) in birds varied depending on their migratory behavior. Resident birds contained higher median PCB concentrations (

Contamination by organochlorine compounds in the edible tissue of four sturgeon species from the Caspian Sea (Iran).

This study focused on accumulation of organochlorine compounds (OCs), including dichloro-diphenyl-trichloroethanes (DDTs), hexachlorobenzene (HCB), hexachlorocyclohexanes (HCHs), and polychlorinated biphenyls (PCBs) accumulation in the muscle of four sturgeon (Persian sturgeon, Acipenser persicus; Stellate sturgeon, Acipenser stellatus; Ship sturgeon, Acipenser nudiventris and Beluga sturgeon, Huso huso) from the southern Caspian Sea. The DDT group was prominent in all of the sturgeon muscle tested constituting almost half or more of the total organochlorine content. Contaminant concentration generally followed this order: DDTs>PCBs>HCHs>HCB. The OCs concentrations in Beluga sturgeon (H. huso) were the highest and over four times higher than in the next highest species (A. nudiventris). From an ecotoxicological point of view, the concentrations of OCs in experimental fishes do not reflect a comparatively clean and pollution-free environment; however, results from this study shown that the inflow of organic pollutants into the Caspian Sea has been reduced when compared with prior studies. Levels of measured OCs in sturgeon were relatively low, but the level of some OCs in some of the specimens tested exceeded the guidelines for food; therefore, the maximum allowable daily consumption rate for sturgeon from this watershed may be limited by DDTs and PCBs content for high risk populations.

Mercury contamination in commercial fresh and salt water fish of the Zabol Chahnimeh reservoirs and the Gulf of Oman (Iran).

In order to investigate bioaccumulation of mercury in Iranian coastal waters fish, tiger tooth croaker (Otolithes ruber) and yellowspotted trevally (Carangoides fulvoguttatus) from the Gulf of Oman and grass carp (Ctenopharyngodon idella) and silver carp (Hypophthalmichthys molitrix) from Zabol Chahnimeh reservoirs were sampled in May 2012. In these ecosystems, total mercury concentrations were measured in muscle and gill of these four fish species. Both regions did not reveal a significant difference. In H. molitrix and O. ruber, mercury concentrations in gill increased with increasing length (H. molitrix, r = 0.94, p < 0.005; O. ruber, r = 0.94, p > 0.005) and weight (H. molitrix, r = 0.94, p < 0.005; O. ruber, r = 0.82, p > 0.04). Generally, mercury levels in the analysed fish samples were higher than WHO, FDA and US-EPA legal limits.

Mercury exposure assessment in Iranian pregnant women's hair with respect to diet, amalgam filling, and lactation.

Our aim for carrying out this study was to estimate the levels of mercury in the hair of pregnant women and its association with fish consumption and amalgam fillings. From November 2007 to January 2008, 100 hair samples were collected randomly from three groups of pregnant women: Ahvaz in the south of Iran, Noushahr in the north, and the countryside of Noushahr. Significant differences were found in these three groups of pregnant women's samples (p>0.05). The mean mercury level in women's hair was found to be 0.37 µg/g (range, 0.11-3.57 µg/g). Only in 2 % of collected hair samples did the total mercury (THg) level exceed the United States Environmental Protection Agency-recommended 1.0 µg/g. In addition, there was a positive correlation of THg content in Ahvaz group's samples with respect to fish consumption (r=0.41, p=0.02) and a negative correlation of THg content in those who consumed vegetables and fruit. The level of education also played an indicating factor in this group. Moreover, significant association was found between the residence time and Hg concentration of women's hair samples collected from Noushahr (p>0.05). Similarly, the same correlations were found between hair mercury levels and the time since the first filling, number of dental fillings, pregnancy interval, and lactating period.

Mercury concentration in the breast milk of Iranian women.

Human milk is usually the only source of food for infants during the first 4 to 5 months of their life. In this research, 80 human milk samples were collected from mothers in Tehran, Noushahr and the countryside of Tabriz, Iran, who were not occupationally exposed to mercury. The mean concentration of mercury in breast milk obtained from mothers in the countryside of Tabriz, Noushahr and Tehran was 0.86, 0.15 and 0.12 µg/L, respectively. There was a significant difference in mercury concentration in human breast milk between that from the countryside of Tabriz with that from Tehran and Noushahr. Only 3.7% of infant samples (three infants) had mercury concentration higher than normal versus the WHO recommended limit (0.5 µg g(-1)). The fish consumption of these mothers in Tehran and Noushahr was a factor that significantly affected the mercury concentration in their breast milk. Also, their age affected the mercury levels in breast milk (p = 0.04).

Organochlorine pesticide and polychlorinated biphenyl residues in feathers of birds from different trophic levels of South-West Iran.

Persistent organochlorine pesticides (OCPs), such as dichlorodiphenyltrichloroethane (DDT) and its metabolites, hexachlorobenzene (HCB), alpha, beta and gamma-hexachlorocyclohexane (HCH) isomers, together with polychlorinated biphenyl (PCB) congeners (IUPAC Nos. 28, 52, 101, 138, 153 and 180), were determined in tail feathers from 37 birds belonging to 18 species, all originating from the South-West of Iran (Khuzestan, coast of the Persian Gulf). This is the first report on organochlorine contaminants in feathers from museum collections and it is an indication of the concentrations of OCPs and PCBs in the past (1991-1996). Median concentrations of HCHs, DDTs, PCBs and HCB were 22, 14, 11 and 10 ng/g feather, respectively. Significant correlations (p<0.05) were calculated between OCPs (except HCB) and PCBs in the bird feathers. p,p'-DDE and gamma-HCH were the most abundant OCPs, while CB 180, CB 138 and CB 101 were the predominant PCB congeners in almost all species. Significant differences (p<0.05) in the mean concentrations of DDTs and PCBs were detected among species grouped according to their feeding habits. Levels of DDTs and PCBs were highest in the carnivorous species and lowest in the herbivorous species. Levels of OCPs and PCBs in feathers of bids in the 1990s were generally below the thresholds reported to affect reproduction.