Pollution, spatial distribution, and health risks assessment of nutrient concentration in surface water resources of Maroon-Jarahi Basin in southwestern Iran.

Nowadays, the introduction of nutrients caused by human activities is considered an environmental issue and a significant problem in river basins and coastal ecosystems. In this study, the concentration of nutrients ( NO 3 - and PO 4 3 - ) in the surface water sources of the Maroon-Jarahi watershed in the southwest of Iran was determined, and the pollution status and health risk assessment were done. The average concentration of nitrate and phosphate in Ludab, Maroon, Zard, Allah, Jarahi rivers, and Shadegan wetland were obtained at 2.25-0.59, 4.59-1.84, 4.07-2.02, 5.40-2.81, 11.51-4.67, 21.63 and 6.20 (mg/l), respectively. A comparison of the results with the World Health Organization (WHO) limit showed that nitrate was lower than in all stations, but phosphate was higher than the limit in some stations of the Maroon, Allah, Jarahi rivers, and Shadegan wetland. Calculation of linear regression analysis showed significant positive relationships between nitrate and phosphate in all surface water sources (except Ludab) and based on the N/P ratio, nitrogen was estimated as the limiting factor in phytoplankton growth (N/P < 16). The evaluation of the status of the Nutrient pollution index (NPI) was observed as: Shadegan > Jarahi > Allah > Maroon > Zard > Ludab that the Jarahi River and Shadegan wetland were in the medium pollution class (1 < NPI ≤ 3) and other waterbodies were in the non-polluted to low pollution state (NPI < 1). Calculation of the chronic daily intake (CDI) showed that water body nutrients cause more non-carcinogenic health risks through the oral route than dermal exposure, and according to HI, children's health is more at risk than adults. Findings showed that surface water resources especially downstream of the Maroon-Jarahi watershed are at eutrophication risk, and to control the nearby human activities and as a result increase the nutrients in these water resources, measures should be taken.

Contamination, ecological, and health risk assessment of heavy metals and organophosphorus pesticides in single, double, and ratoon cropping of rice: a case study in Mazandaran, North of Iran.

This study investigated the contamination and health risk assessment of heavy metals and organophosphorus pesticides in single, double, and ratoon cropping of rice in Mazandaran province, north of Iran. A total of 17 sampling locations in rice farms were selected and soil and rice samples were collected from farms in 5 counties of Mazandaran. Soil and rice samples were then transferred to the lab for further analysis. The concentration of pesticides and heavy metals was then analyzed using gas chromatography-mass spectrometry (GC-MS) and inductively coupled plasma mass spectrometry (ICP-MS), respectively. Mercury was analyzed using a Leco mercury analyzer. Target hazard quotient (THQ), total target hazard quotient (TTHQ), carcinogenic risk (CR), and total carcinogenic risk (TCR) in children and adults were used. Potential ecological risk also was used to test the possible hazards of heavy metals to the environment. Heavy metals concentration in rice and soil samples in different farming steps revealed different levels. THQ showed no considerable risk in consuming contaminated rice to adults and children considered, while TTHQ revealed potential non-carcinogenic risks. Ni had the most carcinogenic risks to target human groups, and TCR showed carcinogenicity for carcinogenic heavy metals in all stations. Findings showed no ecological risks of metals to the environment. In conclusion, rice farmers in Mazandaran use the lands multiple times during the year to increase the performance, function, quality, and quantity of rice, but the possible toxic effects of heavy metals and pesticides on consumers and the environment should not be overlooked.

Spatio-temporal variation and risk assessment of polycyclic aromatic hydrocarbons (PAHs) in surface dust of Qom metropolis, Iran.

The objective of this research was to determine seasonal variation, distribution, potential health risk, and source identification of 16 polycyclic aromatic hydrocarbons (PAHs) in the surface dust of eight urban areas of Qom. The total levels of 16 PAHs ranged from 364.83 to 739.26 ng g-1, with an average of 478.27 ng g-1. Sites 1 and 8 showed the highest (491.33 ng g-1) and lowest (465.08 ng g-1) concentrations of PAHs, respectively. The PAHs demonstrated the highest and the lowest levels in autumn (553.41 ng g-1) and summer (402.30 ng g-1), respectively. Naphthalene (Nap) showed the highest amounts in all of the areas (75.57 ng g-1). Source apportionment indicated that vehicular emissions and combustion of fossil fuels (liquid fossil fuel, crude oil, and gas) are the main sources of the PAHs. Toxic equivalency quantities (TEQs) index exhibited a mean concentration of 47.41 ng g-1, and benzo[a]pyrene (BaP) and dibenzo[a,h]anthracene (DBA) together contributed more than 80% of TEQ, indicating high risk potential of these compounds. Total incremental lifetime cancer risk (ILCR) presented higher value (2.62 × 10-7) for children than for adults (2.53 × 10-7), one-fold lower than the threshold (10-6). The spatial ILCR for the study areas and seasons showed the highest cancer risk in site 2 and winter. Taken together, the carcinogenic risk of PAHs to children and adults, respectively, through direct ingestion and dermal contact pathways illustrated values close to the baseline, suggesting that more attention should be paid to the issue in the study area.

Total mercury and methylmercury concentrations in native and invasive fish species in Shadegan International Wetland, Iran, and health risk assessment.

Human exposure to mercury (Hg) mainly occurs through consumption of aquatics, especially fish. In aquatic systems, the bioaccumulation of Hg across trophic levels could be altered by invasive species through changing community composition. The present study is aimed at measuring total mercury (T-Hg) and methylmercury (MeHg) concentrations in non-native (redbelly tilapia (Tilapia zillii)) and native (Benni (Mesopotamichthys sharpeyi) and common carp (Cyprinus carpio)) fish species throughout Shadegan International Wetland and comparing health risk of their mercury contents to the local population. The concentrations were measured using a direct mercury analyzer (DMA 80). The average values of T-Hg and MeHg for native fishes were 19.8 and 10.49 µg/kg. These concentrations for the invasive fish were 28 and 14.62 µg/kg respectively. Despite having less length and weight than the native fish species, tilapia showed significantly higher T-Hg content, yet the lowest concentration of MeHg was observed in common carp with larger body length and weight. Concerning mercury health risk to consumers, tilapia demonstrated the highest estimated weekly intake (EWI) and percentages of tolerable weekly intake (%TWI) for both T-Hg and MeHg, while the highest hazard quotient (HQ) values were obtained for tilapia and Benni. Taken together, the mercury concentrations in the two native and non-native fishes were acceptable according to the international safety guidelines although the local people shall be warned for consumption of tilapia. Furthermore, the low calculated value of tissue residue criterion (TRC) for the wetland fishes sounds a warning.

Characterization, concentration and risk assessment of airborne particles using car engine air filter (case study: Tehran metropolis).

Atmospheric elements released into the atmosphere can enter the human body through inhalation, ingestion and dermal contact and are then deposited in the body. Trace elements have potential risks to human health. For this purpose, the particulate matter accumulated by car air filters (CAFs) was studied. The morphology and distribution of particle size were examined using scanning electron microscopy and energy-dispersive X-ray spectroscopy. The concentration of elements in CAFs and CAF-estimated air for 30 elements in Tehran, Iran, was analyzed in winter and summer, from February to July 2017. Samples were determined by inductively coupled mass plasma spectrometry. The most abundantly detected elements in both CAFs and air in both seasons were Ca, Mg, Na and Fe. The shape of the particles was mostly irregular and spherical. Most of the particles were between 0.5 and 1.0 µm. The carcinogenic risks of inhalation exposure to Cr and Co in winter and summer were higher than the acceptable level (< 1 × 10-4) for children and adults. The carcinogenic risks of As and Cr in both seasons were higher than 1 × 10-4 for children and adults via dermal contact. Also, the carcinogenic risks of Cr in both seasons of ingestion exposure were higher than 1.00E-04 for children and adults. The integrated noncarcinogenic risks of all trace elements were higher than the safe level (= 1) for children and adults in both seasons.