Effect of teeth amalgam on mercury levels in the colostrums human milk in Lenjan

Human milk is usually the only source of food for infants during the first 4 to 5 months of their life. Maternal environmental mercury exposure is directly related to fish consumption or amalgam filling. In this research, 38 human milk samples were collected from mothers of Lenjan area who were not occupationally exposed with mercury. Mercury concentration in human milk was determined by AMA254 Mercury Analyzer. A level of mercury was examined in relation to somatometric, demographic and dental amalgam parameters. Obtained results showed that only dental amalgam significantly increased the mercury level in human milk (p < 0.001). The mean mercury concentrations in milk of mothers without teeth fillings (n = 13), with one to three teeth fillings (n = 10), and four to eight teeth fillings (n = 15) were 2.87, 5.47, and 13.33 μg/l, respectively. The result of this study also showed a positive correlation of mercury milk levels with the number of teeth fillings of the mother (p < 0.05, r = 0.755). The estimated weekly intake of mercury of a breastfed infant in this study was, in some cases, higher than provisional tolerance weekly intake recommended by FAO/WHO, which pose a threat to their health.     

Non-point source contribution and dynamics of soluble and particulate phosphorus from main tributaries of the Zarivar Lake watershed,Iran

The temporal variability of phosphorus (P) transport and the relationships between discharge, suspended sediment concentration and particulate (PP), and soluble (SP) phosphorus were examined. The study was conducted at the event scale in seven tributaries of the Zarivar Lake watershed in Kurdistan Province (Iran) from March 2011 to April 2012. Based on eight runoff events, 82% of the total P was the PP carried out by suspended sediment. Results showed a high variability of P transport during different runoff events. It was found that soil erosion was the source of the high P load. For all tributaries, PP was linearly related to both discharge and suspended sediment concentration. However, the relationships of SP and PP with discharge and suspended sediment concentration showed different hysteresis patterns. The relationship between PP and discharge was generally characterized by a clockwise pattern (i.e., lower part contribution of the sub-watersheds) but the patterns between SP and discharge were mainly anticlockwise (i.e., upper part contribution of the sub-watersheds or perhaps due to a subsurface flow contribution).     

Health risk assessment of heavy metal intake due to fish consumption in the Sistan region,Iran

The heavy metal (Pb, Cd, Cr, and Ni) content of a fish species consumed by the Sistan population and its associated health risk factors were investigated. The mean concentrations of Pb, Cd, and Cr were slightly higher than the standard levels. The Ni content of fish was below the maximum guideline proposed by the US Food and Drug Administration (USFDA). The average estimated weekly intake was significantly below the provisional tolerable intake based on the FAO and WHO standards for all studied metals. The target hazard quotients (THQ) of all metals were below 1, showing an absence of health hazard for the population of Sistan. The combined target hazard quotient for the considered metals was 26.94 × 10^?3. The cancer risk factor for Pb (1.57 × 10^?7) was below the acceptable lifetime carcinogenic risk (10^?5). The results of this study reveal an almost safe level of Pb, Cd, Cr, and Ni contents in the fish consumed by the Sistan population.

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Cumulative effects of developed road network on woodland—a landscape approach

Population growth, during the twentieth century, has increased demand for new farmlands. Accordingly, road networks have rapidly been developed to facilitate and accelerate human access to the essential resources resulted in extensive land use changes. The present study aims at assessing cumulative effects of developed road network on tree cover of Golestan Province in northern Iran. In order to detect changes over the study period of 1987–2002, the LULC map of the study area was initially prepared from the satellite images of Landsat TM (1987) and ETM+ (2002) using maximum likelihood supervised classification method. Afterwards, a total number of seven landscape matrices were selected to detect cumulative effects of the developed road network on woodland cover. The obtained results indicated that the fragile patches are mainly located at a distance of 171–342 m from the roadside. Furthermore, the majority of the patches affected by cumulative effects of development activities are situated at a distance of 342–684 m from the roadside, over an approximate area of 55 ha. The analysis of landscape metrics revealed that the developed road network has increased the landscape metrics of “the number of patches” and “patches perimeter-area ratio”. It has also followed by a decrease in metrics such as “patches area”, “Euclidean nearest neighbor distance”, “patches proximity”, “shape index”, “contiguity”, and “mean patches fractal dimension”. The road network has also increased the “number of patches” and decreased the “mean patches area” representing further fragmentation of the landscape. With identification of highly affected wooldland cover patches, it would be possible to apply adaptive environmental management strategies to preserve and rehabilitate high-priority patches.     

An improved optimization model for predicting Pb recovery efficiency from residual of liberator cells: a hybrid of support vector regression and modified tunicate swarm algorithm

Journal of Material Cycles and Waste Management - In this study, a hybrid of support vector regression and a modified tunicate swarm algorithm (SVR-MTSA) strategy is developed to optimize the...     

Trophic transfer of CuO nanoparticles from brine shrimp (Artemia salina) nauplii to convict cichlid (Amatitlania nigrofasciata) larvae: uptake,accumulation and elimination

Environmental Science and Pollution Research - We investigated the trophic transfer potential of CuO-NPs from Artemia salina to Amatitlania nigrofasciata. The Cu uptake was investigated by exposure...     

Variations in breeding success and daily nest survival of Whiskered Tern (<Emphasis Type="Italic">Chlidonias hybrida</Emphasis>) at two Iranian colonies

Variations in breeding success of the Whiskered Terns (Chlidonias hybrida) were studied in two wetlands; Anzali (2005 and 2008) and Zarivar (2007–2008) in north and west Iran. Nesting success was modeled and compared using information-theoretic approach implemented in program Mark in order to assess effects of colony locations, years and nest initiation dates on the probability of daily nest survival. Clutch size did not vary between colonies and years. Breeding success varied between colonies (Zarivar > Anzali), and years only in Anzali (2005 > 2008). Overall daily nest survival was 0.977. (95% LCI 0.973, UCI 0.981), equivalent to a Mayfield nest survival of 0.317. (95% LCI 0.255, UCI 0.387). Egg-laying periods and colony site were important covariates affecting the daily survival rates (Σω _i = 0.86 and Σω _i = 0.83, respectively), while, the support for the effect of year was less (Σω _i = 0.41). We concluded that Lake Zarivar provides a more favorable nesting location for Whiskered Terns probably because of little changes in rainfall and water depth during the breeding seasons which influence breeding performance.     

Indirect forced solar drying of banana slices: phenomenological explanation of non-isotropic shrinkage and color changes kinetics

Solar drying technology is a noteworthy technique as it uses the renewable solar energy. In this study, thin slices of banana were dried by using an indirect forced solar dryer at air mass flow rates of 0.016, 0.041, and 0.082 kg s^?1. In order to assess the kinetics of shrinkage and color changes, image processing technique was applied for determining area, volume, density, total color difference and browning index. Shrinkage factor of the samples was less than 1 during drying indicating non-isotropic shrinkage with contraction of inner voids. Furthermore, product shrinkage showed two descending drying steps in which the volume change was more than the evaporated water volume in the first step and equal to that in the second step. The dimensionless evaporated water volume with respect to the dimensionless volume difference of the product also revealed that two steps of volume change existed during drying separated at critical moisture ratio 0.23. The area and volume changes were only related to the product moisture content and were independent of the air mass flow rate, and hence air temperature. In contrary to the browning index, the total color difference was not influenced by air mass flow rate and the least change in browning index occurred at mass flow rate of 0.041 kg s^?1.     

Sugarcane Bagasse Paper Reinforced by Cellulose Nanofiber (CNF) and Bleached Softwood Kraft (BSWK) Pulp

This study explores the effects of bleached softwood kraft pulp (BSWK) as a conventional reinforcing material in comparison with cellulose nanofiber (CNF) as an emerging bionanomaterial on the bleached soda sugarcane bagasse (BSSB) paper furnish. Cationic polyacrylamide was selected as a retention aid along with the CNF addition to retain it on fiber surfaces during the papermaking process. The results showed that though the effects of CNF were similar to those of BSWK in the most of properties but there were some important differences which can industrially be noticeable. In one hand, both of cellulosic elements, when substituted for the BSSB at the 5 or 10 % levels, gave increases in the paper strength, i.e. samples containing 10 % CNF yielded similar tensile strength (53 N m/g) and a more consolidated structure (14 % increment of the density) than those produced with 10 % BSWK. CNF addition had opposite effects on the air-permeability of the resulting paper. Unlike BSKW, the addition of CNF had a strong favorable effect on tear strength, but it was markedly slowed the rate of drainage time when it was especially added at 10 % level of the final furnish.     

Source apportionment of PAHs and n-alkanes in respirable particles in Tehran,Iran by wind sector and vertical profile

The vertical concentration profiles and source contributions of polycyclic aromatic hydrocarbons (PAHs) and n-alkanes in respirable particle samples (PM₄) collected at 10, 100, 200 and 300-m altitude from the Milad Tower of Tehran, Iran during fall and winter were investigated. The average concentrations of total PAHs and total n-alkanes were 16.7 and 591 ng/m³, respectively. The positive matrix factorization (PMF) model was applied to the chemical composition and wind data to apportion the contributing sources. The five PAH source factors identified were: ‘diesel’ (56.3 % of total PAHs on average), ‘gasoline’ (15.5 %), ‘wood combustion, and incineration’ (13 %), ‘industry’ (9.2 %), and ‘road soil particle’ (6.0 %). The four n-alkane source factors identified were: ‘petrogenic’ (65 % of total n-alkanes on average), ‘mixture of petrogenic and biomass burning’ (15 %), ‘mixture of biogenic and fossil fuel’ (11.5 %), and ‘biogenic’ (8.5 %). Source contributions by wind sector were also estimated based on the wind sector factor loadings from PMF analysis. Directional dependence of sources was investigated using the conditional probability function (CPF) and directional relative strength (DRS) methods. The calm wind period was found to contribute to 4.4 % of total PAHs and 5.0 % of total n-alkanes on average. Highest average concentrations of PAHs and n-alkanes were found in the 10 and 100 m samples, reflecting the importance of contributions from local sources. Higher average concentrations in the 300 m samples compared to those in the 200 m samples may indicate contributions from long-range transport. The vertical profiles of source factors indicate the gasoline and road soil particle-associated PAHs, and the mixture from biogenic and fossil fuel source-associated n-alkanes were mostly from local emissions. The smaller average contribution of diesel-associated PAHs in the lower altitude samples also indicates that the restriction of diesel-fueled vehicle use in the central area of Tehran has been effective in reducing the PAHs concentration.