فصلنامه پژوهش در بهداشت محیط
سال چهارم شماره 1 (بهار 1397)

Antibiotics are a category of organic pollutants that can cause serious environmental problems through their disposal and uncontrolled release to the environment. The purpose of this study was to investigate the removal of sulfadimethoxine from aqueous solutions using carbon nanotubes.
The present work was an experimental study in which the effects of different parameters, such as PH, time, doses of carbon nanotubes, and different concentrations of sulfadimethoxine, on the removal of antibiotic from solutions were examined. All experiments were carried out in a 100-mL reactor at laboratory temperature (24 ± 2 ° C) using a magnetic stirrer at 350 rpm.
The results showed that the maximum removal efficiency (94.5%) was occurred at pH = 6, adsorbent dosage 0.04 g, contact time of 30 min, and initial concentration of 20 mg/L. The findings on the effect of pH showed that the adsorption capacity increases with increasing pH, and at pH = 6, it reaches its maximum and then decreases again. The extent of removal was increased by increasing the dose of carbon nanotubes and the optimum amount for initial concentration of 100 mg/L (50 mL) was 0.04 g. The amount of absorption increased with increasing contact time and the maximum absorption occurred when the contact time was 30 min. The sulfadimethoxine antibiotic isotherm followed the Langmuir isotherm model (R2 = 0.9800) and the pseudo-second-order kinetic model (R2 = 0.9937).
The results showed that carbon nanotubes have a high potential for removal of sulfadimethoxine from aqueous solutions, due to its properties like its high surface area.

Heavy metals contamination of soils is one of the main environmental problems. Heavy metals are considered as one most dangerous groups of pollutants because of their toxicity and stability. The biological and ecological importance of heavy metals is due to their characteristics of polluting, their toxicity, persistence and bioaccumulation. The aim of this study was to investigate the spatial distribution of heavy metals in the different north areas of Isfahan.
In the present study, 30 soil samples (0-20 cm depth) were randomly collected and the total concentration of Pb, Cd, Zn and Cu were measured using Perkin Elmer's atomic absorption device. Also, some other soil properties including pH, EC, organic carbon, soil texture and organic matter proportions were measured. The inverse distance weighting (IDW) method was used for interpolation and mapping of the heavy metals concentration.
Findings: The results showed that the average concentrations of Pb, Cd, Zn and Cu in the study area were 47/16, 2/26, 57/35 and 22/31 mg/kg respectively. Also the results of statistical analysis showed that the standard deviations of Pb, Cd, Zn and Cu in the study area were 7.13, 0.51, 5.56 and 2.84 respectively.
The results indicate that the averageconcentrations of Pb and Cd in the soil of study area were higher than the global standard and Cu and Zn were lower than the global standard.

Biological assessment of water resources is of particular importance and the presence of pathogens in these resources affects the health of consumers. The aim of this study was to determine the bacterial contamination of water including total coliforms, fecal coliforms and fecal streptococci in the Azad dam lake.
Methods and Materials: In this study, Sanandaj Azad dam water was evaluated for the indicator bacteria during one year (from May 2015 to June 2016). Sampling was performed from five stations in the areas of lake, transients and river. Statistical analysis of the obtained data was accomplished by ANOVA and Duncan tests using SPSS 18 software (P Monthly analyzes showed that the maximum and minimum mean of total bacteria were recorded in the months of January (6.7×105 CFU / 100ml) and September, (1.6×104 CFU100ml). The maximum total mean value of total coliform was 2.3 × 104 CFU / 100ml in December and the minimum one was 62 CFU100ml in July. Neither thermophilic coliforms nor fecal streptococcus were observed in the lake of the dam in taken samples.
Based on the obtained results, the collected water behind the dam can be used without any purification for agricultural purposes and fish farming. However, this water supply is not suitable for drinking due to the observed microbial load.

Background & objeftive: In the Rafsanjan sites have been considered in the studied region for landfill construction, where the leachate diffusion caused by landfill for groundwater resources, which is the only source of water supply in this region, is a serious threat. The aim of this research is to study the trend of changes in the contamination concentration due to diffusion of a hypothetical landfill based on the geological and hydrogeological conditions of Rafsanjan plain in order to represent the effect of leachate diffusion and contamination spread across groundwater resources.
Methods and Materials:Transmission of contamination has been studied on the basis of changes in concentration at two initial and final points of landfill by MT3DMS model daily and for 22 years period. The concentration of leachates has been considered 2 and 4 g / l, and its diffusion rate has been assumed 1.5 and 3 cm per day.
The slope of the concentration increase in the propagation process and delayed diffusion at the beginning of the landfill with 2 and 4 g/l concentration and 1.5 cm rate during 15 and 17 years have an increasing trend, respectively and later it would have a decreasing trend. At the end of landfill, 90% increase in contamination will occur for 2 g/l concentration in the first five years and 4 g/l concentration in the first 9 years and it will have a fixed trend over the next few years.
In the various transmission processes after the penetration of the infection into the aquifer, the concentration of contamination is initially low and increasing over time and if the concentration of the source of the penetrating source of constant intensity is constant, the maximum concentration of aquifer pollution is fixed at a certain value. the type of transmission process has a huge impact on this constant value. So that in the propagation-diffusion process, the average in the first 5 years of this value is fixed and in a delayed state, it reaches a constant value after close to 22 years.

Today, one of the most important environmental issues is dental solid wastes due to its high contents of toxic, pathogen and hazardous agents. The aim of this study was to quantity and quality analyses of dental solid waste in dental centers of Mashhad.
In this descriptive study 40 Dental centers were studied. From each Dental centers, three samples were analyzed at the successive working days (Sunday, Monday and Tuesday). The samples were manually sorted into 64 different components and measured by digital scale. Then, measured components were classified on the basis of characteristic and hazardous potential as well as material type. Data analyzed by using descriptive statistics, SPSS 16 software.
According to the results, total waste produced in dental centers in Mashhad was 224.137 kg/day. Per capita and the average generation rate of each dentistry center were 106.32 g/day-patient and 5603 g/day, respectively. Potential infectious, domestic-type, chemical & pharmaceutical, and toxic wastes consisted of 41.24, 44.17, 9.89, and 4.7% of the waste generated, respectively.
The per capita waste generation in dental clinics in Mashhad is high and the highest share are related to infectious and domestic-type wastes.

Background and Air pollution problem in metropolitan’s city caused by different sources pollutants. Dispersion of air pollutants in many city of Iran such Mashhad increased. This study aimed to investigate the trend of particular matter concentration changes with weather data in Mashhad air.
In this descriptive cross - sectional study, data were collected from 11 monitoring stations and synoptic stations in Mashhad during 2010-2016. Daily average concentration (PM 10, PM2.5) was calculated and then relations between pollutant and metrological data analyzed by Spss18 software.
Findings: The results showed that the maximum concentrations of particle matter occurred in october and autumn season. Numbers of unhealthy days has been increased during the years 2011-2013, decreased in 2014 - 2015 and increased again in 2016. The variation of PM10 and PM2.5 is significant with season, month and year (P According to results, in the autumn and October, the highest concentration of particulate matter has been observed. Also, maps GIS maps showed that eastern of Mashhad is more polluted than other areas.

Background and Changing the quality of groundwater and saltinating of water resources are Concerning a major threat for country's agricultural development, especially in arid and semi-arid lands. Preparing maps of both Same amount maps for salinity and salts can be an important step in the proper utilization of water resources. This research was carried out in Firoozabad plain in west of Fars province to evaluate the hydrogeochemical processes affecting groundwater quality.
Preparation of the map of the chemical parameters (isochromic) of Firoozabad plain using hydrodynamic data of wells measured in East and West of Firoozabad plain. Preparation of similar maps using Shooler and Wilcox methods to produce coincidence lines it placed.
Findings : Based on the maps of the chemical parameters in the studied areas and the diagrams of the changes and classification of the data based on the Schuler and Wilcox diagrams, the irrigation water classification according to Wilcox's diagram in 2004 and 2011 showed a decline trend in agricultural quality. Based on the results of the classification of drinking water, there were generally no significant changes in drinking quality except in 2011.
The amount of chlorine and electrical conductivity parameters in the west and east of the Firoozabad plain increased from north and northwest to the center and eastern plain from east to center, respectively, in the east and west of the plain, the highest values ​​were observed. Also, the results showed that the groundwater of the area based on the Schuler diagram was classified into three classes: good, acceptable and moderate, and quality, for use in agriculture in 2011 in C3S1, C1S1, C2S1 C3S2, C3S4, C3S3 and in the first period, 2004, in C3S1, C1S1, and C2S1 classes. The irrigation water classification according to Wilcox, in terms of 2004 and 2010, indicates a decrease in agricultural quality. The results of the classification of drinking water (Shooler classification) show that overall there is no significant change in the quality of drinking water and only in 2011, reduced quality.