Measurement and Comparison of Mercury Concentration in Different Length Groups of Common Carp Muscle Tissue from the Shadegan Wetland

Background: Due to the ecological importance of the Shadegan wetland as a valuable international wetland and some studies reporting high mercury concentration in its water and birds' tissues, this study was done to measure and compare the concentration of accumulated mercury in different length groups of common carp muscle tissue and to determine the correlation of mercury concentration with morphological parameters such as standard length, total length and total weight. Methods: In this cross-sectional study, 41 common carp fish were randomly captured in summer 2011 from the Shadegan wetland, and they were classified into three groups based on their lengths. Samples were prepared from their muscle tissues and mercury concentration was determined by Advanced Mercury Analyzer. The relation between mercury concentration in the samples and demographic characteristics was determined by Pearson’s Correlation Coefficient. Results: Mean (±Standard deviation) mercury concentration in groups of A, B and C were respectively 0.337±0.15, 0.556±0.21 and 0.798±0.19 µg gr-1 of dry weight basis. Comparison of mercury concentrations of muscle tissues among the three groups showed statistically significant difference (P=0.001); so that, mercury concentration was increased with increase of weight and length. Conclusion: Mercury concentration in fish weighing more than 500 grams were higher than the limit allowed by WHO and EPA, it is necessary to be more careful about consuming this fis

Assessment of Mercury Accumulation and Magnification in a Freshwater Food Chain: Sediment, Benthos and Benthivorous Fish

Background: Present study was conducted to measure the level of total mercury (tHg) in sediments, benthos and benthivorous fish (i.e., common carp) for determining Biota (Benthos)-Sediment Accumulation Factor (BSAF), as well as Biomagnification Factor (BMF) of tHg between two trophic levels of benthos and benthivorous fish caught from Sanandaj Gheshlagh Reservoir (SGR) in the west of Iran. Methods: Samples of sediments and benthos biomasses were collected from three sampling stations. Common carps were captured around the selected stations during July to December 2010. Results: Means accumulated tHg (±SE) in sediments, benthos masses and muscle tissue of common carp were 117.66±9.72, 94.3±5.02 and 233.21±20.67 ng g-1 dry weight, respectively. Means accumulated tHg in benthos masses and muscle tissue of the common carp during the studying months showed no significant differences (P>0.05), while it was significantly differed in sediment samples (P<0.05). Results showed that there were statistically significant differences between accumulated tHg between sediment and benthos mass samples collected from the study sites (P<0.05). Conclusion: During the study, all calculated BSAF measurements were less than one, indicating transmission of mercury from sediment to benthos was not considerable. However, mercury BMFs was higher than one, denoting mercury biomagnification occurred from the benthos trophic level to the higher trophic level (i.e., common carp) in study site. Hence, the health considerations have to be taken in to the account for consumption of fishery products of SGR

Mercury Biomagnification between Two Trophic Levels of a Grazing Food Chain (Plankton and Planktivorous Fish) in a Fresh Water Ecosystem

Background: The Present study was carried out to track and calculate Biomagnification Factor (BMF) of total mercury (T-Hg) between two different trophic levels (i.e., plankton and a planktivorous fish) in a fresh water grazing food chain. Methods: Experimental organisms were planktonic biomass and silver carp (Hypophthalmichthys molitrix) as a planktivorous fish. Silver carp samples were obtained from randomly selected points from different sampling stations. The concentrations of T-Hg in collected samples were determined by Advanced Mercury Analyzer. Results: Means of T-Hg in planktonic biomass and muscle tissue of silver carp were 78.21 ± 3.13 and 367.12 ± 26.43 ng g-1 dry weights, respectively. Mean T-Hg in plankton, sampled fish during the study months and amongst the sampling stations did not show significant differences. The BMFHg(plankton-fish) was differ among months; moreover, calculated BMF was greater than 1 during study months, which means biomagnification was occurring in SGR. The concentration of T-Hg in the muscle tissue of all fish samples that weighed more than 850 gr was higher than the acceptable limits based on EPA (300 ng g-1) and WHO (500 ng g-1) standards. The highest BMFHg was observed in August Conclusion: It seems that mercury pollution of SGR has a natural source. The calculated BMFs were greater than 1 and the concentrations of T-Hg in muscle tissues of those samples weighing more than 850 gr were higher than FAO and WHO standards. Therefore, consumption of the SGR's silver carp must be accompanied by serious health considerations

The concentration data of heavy metals in Iranian grown and imported rice and human health hazard assessment

The aim of this study was to review the prevalence of rice contamination to heavy metals in Iranian grown and imported rice brands by conducting a systematic review and assess the related human health risk. Multiple keywords such as ''rice, heavy metals, and Iran'' were used to search in related databases. The average concentration of Cd, Pb, As, Cu, Zn, Cr, Ni and Co for Iranian grown/imported rice were calculated as 0.16±0.08/0.13±0.05, 0.196±0.16/0.55±0.56, 0.046±0.002/0.057±0.0035,0.29±0.05/0.61±0.31, 26.13±10.3/3.46±2.49, 0.22±0.04/0.76±0.101, 16±7.3/2.08±0.34 and 0.29±0.047/0.29±0.07 mg kg−1, respectively. Except Co, there were significant differences between Iranian and imported rice brands. Estimated weekly intake for none of the metals exceeds the provisional tolerable weekly intake value. Accordingly, the rice types consumed in Iran have no health hazard for consumers. Keywords: Food safety, Heavy metals, Iran, Rice, Risk assessmen

Toxicity of biosynthesized silver nanoparticles to aquatic organisms of different trophic levels

Although biosynthesized nanoparticles are regarded as green products, research on their toxicity to aquatic food chains is scarce. Herein, biosynthesized silver nanoparticles (Alcea rosea-silver nanoparticles, AR-AgNPs) were produced by the reaction of Ag ions with leaf extract of herbal plant Alcea rosea. Then, the toxic effects of AR-AgNPs and their precursors such as Ag+ ions and coating agent (A.&nbsp;rosea leaf extract) on organisms of different trophic levels of a freshwater food chain were investigated. To the three studied aquatic organisms including phytoplankton (Chlorella vulgaris), zooplankton (Daphnia magna) and fish (Danio rerio), the coating agents of AR-AgNPs showed no toxic effects, and Ag+ ions were more toxic in comparison to AR-AgNPs. Further investigations revealed that the release of Ag+ ions from AR-AgNPs to the test media were not considerable due to the high stability of AR-AgNPs, thus the toxicity stemmed mainly from the particles of AR-AgNPs in all the three trophic levels. Based on values of 72-h EC50 for C.&nbsp;vulgaris, 48-h LC50 for D.&nbsp;magna and 96-h LC50 for D.&nbsp;rerio, the most sensitive organism to AR-AgNPs exposure was D.&nbsp;magna (the second trophic level)