Journal of Natural Environment
Year:2021 | Volume:73 | Issue:4|Papers Count:15

Khormarud is one of the Rivers in Azadshahr County in Golestan Province, which is originates from southeast elevations and discharges to the Gorganrud River that reach to the Caspian Sea. Diatoms constitute the dominant algal flora in aquatic ecosystems. In order to identifying diatom flora of Khormarud River, specimens were collected from stony and sediment substrates during summer and autumn of 2017. In total, 60 species belong to 32 genera and 20 families were identified, from which 59 species were belonging to class Bacillariophyceae and only one species to class Coscinodiscophyceae. Nitzschia with 7 species were the most species rich genus and Navicula and Gomphonema with 5 sp. were in the next order. The most abundant taxa were Achnanthidium gracillimum, Achnanthidium nanum, Cocconeis placentula, Cymbella affinis, Encyonopsis minuta, Gomphonema olivaceum and Nitzschia inconspicua. According to the results of diversity indices, site 3 which affected by runoff from fishery activities, had lowest species diversity and high pollution level. In total epipelic samples in all sites had high diversity than epilithic samples which could explain by the fact that algae on sediments are affected weakly by water column chemistry than epilithic algae.

In recent decades, rising sea temperatures have become one of the most important environmental hazards, endangering the lives of marine plants and creatures. Therefore, continuous, long-term, and real-time monitoring of sea water temperature is of great importance and can provide valuable information to environmental experts. Acoustic Tomography (AT) technology is one of the most effective tools for sea monitoring. AT systems are located around the aquatic environment and transmit sound waves simultaneously. Then, using the mean arrival time of the sound waves, the seawater temperature is calculated. In this study, the 10-kHz AT system was first tested in the Water Research Institutes’ channel and evaluated with a temperature sensor. The results showed that the water temperature between the two acoustic stations is 18 ˚ C and corresponds exactly to the one of the temperature sensor. In the second experiment, the temperature of the water currents between the two islands was measured at a distance of approximately 4, 500 m. The range-and depth averaged flow temperature passing between the two islands was measured per minute, and then using a moving average of 30 minutes (30 data), the temperature measurement error was reduced from 7. 2 to 1. 3 ˚ C. The temperature during the measurement period was approximately 28 ˚ C. Due to the existence of numerous islands in the Persian Gulf, the use of AT technique is recommended for continuous, long-term, and real-time monitoring of coastal temperature.

With increasing population, economic development and urbanization, waste production has grown rapidly, especially in developing countries. Due to the increasing rate of waste generation, high costs of waste, including collection, transportation, disposal, incineration, along with other heavy costs such as construction and maintenance of a waste treatment technology are imposed on the government and city managers. In this regard, knowing the energy and heat produced and consumed in different treatment technologies away from costly and lengthy laboratory methods can help city managers in making the right decision to be able to use different waste treatment technologies with all their dimensions in the shortest possible time. In this study, power, energy, heat production and consumption of total waste (for gasification technologies, incineration and anaerobic digestion) are calculated by recycling. Power and energy production of total waste in Tehran for combustion processes, 35. 102 MW and 1312. 88 kWh per ton, for anaerobic digestion process, 69. 66 MW and 83. 290 kWh per ton for gasification process, 130/58 MW and 1717/44 kWh per ton respectively. Also, at all stages, the potential amount of recycled materials is calculated for each recyclable waste component. Finally, it can be concluded that the energy produced by one ton of waste per day in the processes of incineration, anaerobic digestion and gasification is equivalent to the energy of 14 months and 12 days, 3 months and 18 days and 19 months and 6 days, respectively, which is used for home lighting. It should be noted that the uncertainty of the parameters used on the modeling results has also been investigated.

Heavy metals are one of the main groups of environmental pollutants; enter the aquatic environment through natural and human activities. These metals may accumulate in aquatic organisms including fish and be a potential danger to the health of the ecosystem and living organisms, especially for human beings. In the present study, the concentration of heavy metals (Zn, Cu, Pb and Ni) were measured in the muscle tissue of Oncorhynchus mykiss fish in three stations (Dehpabid, Bidaster and Eskalabad) of Khash city in spring 2019. After preparation and chemical digestion of fish tissue, the amounts of heavy metals studied were determined by the atomic absorption. The results of this study showed that the highest rate of accumulation in all stations studied was related to Zn> Cu> Pb >Ni, respectively. Average amount of heavy metal accumulation was compared within the international standards of WHO, FDA, NHMRC, FAO, UKMAFF and USEPA. The toxicity of heavy metals Zn, Cu and Pb were lower than the permitted concentration of international standards. According to the results, only nickel metal was close to the WHO standard limit in the Bidaster and Eskel Abad samples, indicating that more control should be carried out on the production resources this metal around the regions studied. Also, the daily absorption rates of the studied metals (EDI) for children and adults were lower than the reference dose set by the EPA and the TI provided by the FAO/WHO Organization. The results of this study showed that the consumption of Oncorhynchus mykiss fish was considered hygienically suitable for human consumption, but due to the bioaccumulation and toxicity of heavy metals, it is necessary to study risk assessment, considering all its possible routes exposure in these regions.

There are several methods for nitrate removal that are often very costly. The use of aquatic plants due to its low cost and environmental compatibility has attracted the attention of researchers for many years. To use two species of Myriophyllum spicatum and Ruppia maritima in nitrate removal, an experiment was conducted in three treatments and three replications with closed flow. After 2 months of in vitro test, a 30-day retention time was considered for the study. The results showed that there was a significant difference in nitrate uptake in all treatments except period 6. After 30 days, the uptake index of Myriophyllum spicatum was 87. 13 and Ruppia maritima was 92. 53. Dry weight of Ruppia maritima was significantly increased at the end of experiment, while it was not significant for Myriophyllum spicatum. The significant difference between the mean nitrate in the samples and the control sample during different time indicates the existence of a factor other than bacterial decomposition, which is the presence of plants in this study. Based on the results, these macrophytes are a suitable option to reduce the load of nitrates and organic matter in contaminated water. It should be noted that the need to improve water quality and maintain the quality level is to control these macrophytes to prevent the return of nutrients in their tissue to the environment during the decomposition process.

Planning and optimal use of resources and controlling and unprincipled changes in the future, requires studying the extent of change and destruction of resources. In fact, planners for principled decisions must have a full knowledge of land use, detection, prediction of land use change and land cover in order to better manage natural resources in the long time. The aim of this study was to evaluate the accuracy of different supervised classification algorithms of basic and object-oriented pixels in land use extraction in Samalghan watershed in three periods of time 1987, 2002 and 2019. The results showed that the support vector machine algorithms for the images of 1987 and 2019 and the neural network for the 2002 image in the pixel-based classification method have the highest overall accuracy and kappa coefficient. Also, the most obvious change that can be seen by comparing the prepared user maps is the change in the level of land uses with the growth of residential areas, thus this expansion has been continuously associated with a decrease in rangeland land use. Thus, from the years of 1987 to 2019, the residential land use area increased by more than 9. 197 km2 and dryland lands during these years increased by 130. 89 km2, irrigated agricultural lands also increased from 44. 45 km2 and Rangeland use has also decreased by 272. 3 km2.

Dust subsidence occurs widely in arid and semi-arid regions of the world. This study was conducted to investigate the temporal and spatial characteristics of atmospheric dust in Yazd. Dust was sampled seasonally from autumn 2018 to summer 2019 and from 30 points using sediment traps installed on the roofs of one-story buildings and the dust subsidence rate was determined. The results showed that the lowest dust subsidence rate in summer with an average of 13. 27 g /m2 and the highest value with an average of 23. 41 g/m2 was observed in spring and the average annual dust subsidence rate in the study area was found 72. 7 tons/km2. Correlation charts showed that there is a negative and low correlation coefficient between the dust subsidence rate with minimum temperature (R2 = 0. 28) and maximum temperature (R2 = 0. 19). However, positive and strong correlation was observed with mean wind data (R2 = 0. 941) and maximum wind speed (R2 = 0. 905) and positive but low correlation with the number of dust observations (R2 = 0. 09). Among the climatic parameters, wind speed in the study area seems to have had a greater impact on the occurrence of dust events as well as the rate of dust subsidence. According to the zoning maps, the prevailing winds, visiting different areas during the sampling, as well as the Google map of the area in the northern and northwestern and eastern areas of the region, there are deserts without vegetation and without buildings. In these areas, the subsidence rate has been higher and the lowest subsidence rate has been observed in the sampling stations of the city center with tall residential and office buildings in these areas. Interaction between different characteristics of dust sampling points such as altitude, proximity to high-traffic and high-traffic areas, proximity to areas of civil activities, distance from dust production areas, prevailing wind direction and amount and distribution of wind speed and wind speed on the rate dust subsidence has affected different parts of the study area, leading to an uneven distribution of dust subsidence rates in the area.

The existence of air pollution crisis in developing countries necessitates a comprehensive study in this field. The new city of Mohajeran is one of the newly established cities in Markazi province, where the sources of pollution in this city are mostly point and non-transferable sources. These sources of pollution, along with other polluting factors, have caused air pollution in this city. In the present study, the aim is to estimate the willingness of people to pay to improve the air quality of Mohajeran and to determine the factors affecting the willingness to pay. In this study, the conditional valuation method and the logit model have been used to estimate the willingness of individuals to pay. The required data have been extracted from the completion of 362 face-to – face two dimensional questionnaires in 1399 in the city of Mohajeran. The results showed that the variables of household income, age, history of disease due to air pollution and the index of attitudes and environmental tendencies of the respondent have a positive effect and the variable of the proposed amount has a negative and significant effect on the willingness to pay. Also, the average willingness of respondents to improve the air quality of this city was 12838 Tomans per month. The average willingness to pay monthly is 49170 Tomans per household and total economic value of 3135 million Tomans per year. Therefore, this issue requires more attention of officials in urban planning.

Noise pollution is one of the most important environmental problems in metropolitan areas which, threats humans' health in different aspects of mental and physical. Isfahan like other large cities faces to traffic congestion due to vehicles traffic and lack of an effective mechanism to restrict the use of personal vehicles. The purpose of this study was to investigate and map the distribution of noise pollution in areas 3 and 4 of Isfahan to determine the critical points. 16 stations were selected, and sound parameters were measured three times a day during the winter and spring by Bruel & Kjaer sound meter. The results showed that the highest rate of pollution in January recorded in station near Bozorgmehr bridge was 100 dB and the lowest pollution recorded in station before Roknodoleh street and station after Apadana intersection with 69 dB. The highest level of pollution in February was in station near Bozorgmehr bridge at 103 Db. In March, stationafter Mobarezan street had the highest pollution. In April, the highest pollution rate belonged to station near Bozorgmehr bridge at 106 dB. In June, stations 1, 2, 9, 10 and 11 were the most polluted stations w. The results of noise pollution emission mapping using Inverse distance weighted method showed that the highest noise emission was in the area of Bozorgmehr and Ahmadabad Square, which decreased with the distance from the main street. Geostatistical tools for preparing the map of sound dispersion is an useful tool. Results of this study are useful as reference and guideline for future planning and regulations on noise limit to be implemented for urban areas.

In recent decades, global trends in tourism have undergone a gradual transformation. In many social activities, the environmental aspect strengthens and relies more on individual and collective responsibility to protect the environment, leaving a deep trace in the tourist activity itself, and the need arises to create an entirely new alternative concept with the expressed ecological dimension of "ecotourism" in contrast to traditional, massive forms of tourism. The increasing growth of the tourism industry in parallel with rapid economic, political and technological developments has made tourism an important component of the economies of nations, and the benefits of tourism in all sectors have served economic growth. Dena region with countless potentials of tourism can contribute to improving the economic prosperity of Kohgiluyeh and Boyerahmad province and finally the country and provide a favorable environment for employment and sustainable use of the ecosystem. Thus the purpose of this study is the landscape evaluation of Dena protected area for the purpose of ecotourism, based on quantitative method of diversity (V-Wert method) Presented by Landscape Ecologist Hans Kiemstedt. In this method the natural elements of landscape (forests, water surfaces, relief, climate) and land use of considered area are taken as the main criteria for the evaluation. Results show that out of the total analyzed surface, which amounts to 832 km2, very favorable and favorable surfaces of landscape for ecotourism activities development comprise 34 and 48 km2 respectively, i. e. 10% of the territory, which are mainly distributed along the main rivers in the study area. Therefore, in order to develop nature tourism in the Dena Protected Area, it is necessary to select the most scenic spots with excellent visual quality at the very desirable and desirable levels identified in this research with the help of field surveys. Unfavorable lands for ecotourism development rrom an aesthetic point of view as well with 619 km2 (74%) cover the largest part of the region which in the development of ecotourism, it is necessary to pay serious attention to the visual and ecological limitations of this dominant part of the region. Comparison of the results of this study with other similar studies conducted in the Dena Protected Area showed that this model is more stringent than other evaluation models in separating the suitability of areas for the development of ecotourism, which in a way, it can indicate the accuracy of the model.

High concentrations of polycyclic aromatic hydrocarbons (PAHs) in surface soils are a serious threat to human health and the environment. In this study, to determine the level of PAHs pollution in Ahvaz oil field, 66 surface soil samples were collected and the concentration of PAHs was analyzed by gas chromatography-mass spectrometry (GC-MS) method. The sum of PAHs16 concentration in the surface soils of Ahvaz oil field ranged from 913. 50 to 44452. 05 (μ g/kg), with a mean of 12872. 57 (μ g/kg). Combustion PAHs make up a significant portion of the total concentration of PAHs, ranging from 0. 61 to 0. 73. The ratio of carcinogenic compounds to total PAHs ranges from 0. 55 to 0. 59. The average concentration of PAHs with high molecular weight (HMW) is 10573. 13 (μ g/kg), which accounts for 82% of total PAHs, and their origin is generally due to the combustion of petroleum fuels. The average concentration of most PAHs is higher than ERL values and lower than ERM values, indicating that sometimes biological side effects from PAHs occur. However, the concentration of Ant and BaA compounds is higher than the value of ERM, so these two compounds in most cases cause biological side effects. The toxic equivalent concentration (TEQ) in surface soil ranged from 99. 44 to 5301. 86 (μ g/kg). ILCR is higher in children on pathways ingestion than in adults, but LCR is higher in adults than in children in pathways dermal contact and inhalation. The cancer risk (CR) for children (8. 95×10-4) is higher than for adults (8. 64×10-4), which shows the high potential for cancer risk in the study area.

Sustainable development is one of the important goals of countries in the present era. Education as one of the effective effects in improving technology in the production sector and modifying the consumption pattern in the consumer sector has a significant role in understanding the emission of carbon dioxide. The present study investigates the effect of education on carbon dioxide emissions using statistical evidence of Iranian provinces for the period 2005-2015 and the panel data approach. The results of the estimates show that Kuznets environmental theory can be confirmed in the Iranian economy, because the effect of production and production squares on carbon dioxide emissions are positive and negative, respectively. Also, the expansion of urbanization due to inappropriate structures of urban design and energy intensity has a positive and significant effect on carbon dioxide emissions. Finally, increasing the training costs first reduces carbon dioxide emissions, then by increases the level of education, carbon dioxide emissions will increase. Therefore, paying attention to the quality of education criteria plays an important role.

Today, due to the extensive consumption of cigarettes and the presence of cigarette butts in the environment as non-degenerative waste, collecting and converting them into a consumable is essential. Therefore, converting cigarette butts to activated carbon can be a win-win strategy for the environment. Because safe drinking water is a vital factor in the survival of communities, the presence of chromium, as a heavy metal, in the water can be very dangerous. Today, the use of activated carbon is one of the most common methods for removing chromium from water. The present study aimed at determination of the effectiveness of activated carbon produced by cigarette butts in removing hexavalent chromium from aqueous solutions. In this study, NaOH chemical activation was utilized and BET and SEM tests were used to determine the specific area. The effect of pH, adsorption value, reaction time, initial chromium concentration and temperature for chromium removal were investigated and the adsorption rate was determined using atomic adsorption device. The results showed that pre-treatment with NaOH and increasing its concentration led to an increase in the specific surface area of activated carbon. Absorption tests showed that the highest adsorption efficiency was observed at pH 2, 7 g/l of adsorbent, time of 60 min, initial chromium concentration of 50 mg/l and temperature of 25° C. The results showed that adsorption followed the Langmuir isotherm, and the quasi-first order equation is suitable for experimental data. The thermodynamic analysis of the adsorbent showed that the reaction is spontaneous and exothermal. This study showed that cellulose acetate fibers in cigarette filters can be a suitable material in carbonization operations to produce activated carbon with a specific surface area of about 1000 m2/g, which can be used to remove chromium from water.

Elevated levels of anthropogenic sound may cause a broad range of negative effects on fish and other animals in aquatic habitats. In a laboratory study, we investigated the effect of five sound treatments (in the same frequency range 400-2000 Hz and exposure level of 121 dB re 1 µ Pa, only differing in temporal patterns) on swimming behaviour of adult zebrafish (Danio rerio). The number of startle response, brief swimming speed and prolonged swimming speed were measured for all thirty zebrafish individually. An aquarium with dimensions of 50 × 15 × 20 cm was used to perform this study and assess the behavioral responses of fish. Our results revealed prominent and clear sound-related effects on zebrafish behaviour. All sound exposure treatments induced a significant increase in the number of startle response, brief swimming speed and prolonged swimming speed for zebrafish in captive conditions (P<0. 05). This study highlights the potential impact of anthropogenic sound on fish behaviour. Further studies are needed to investigate whether anthropogenic sound may cause similar patterns in other fish species in captivity but also in outdoor conditions.

The main causes of global climate change and biodiversity is emission of greenhouse gases from various sources especially from agricultural sector. As one of agricultural hubs Khuzestan has major share in production greenhouse gases with high consumption of chemical fertilizers. Purpose of research present study is applied analytical study that used DAYCENT and DNDC models to determine growth rate of methane, oxidant nitrous and oxidantritic gases in citrus and palm groves of Khuzestan. For this purpose, area was divided into three sections and in each section sampling and determination gas concentration in gardens in each section was performed randomly. Sampling time was done in flowering stage in May 2020 which was peak of green cover for tree, concentration of exhaust gas was done using closed chamber method and gas chromatography in sampling sites. Global warming potential was also obtained based on observational data and DAYCENT and DNDC models. Then efficiency of DAYCENT and DNDC models was investigated using coefficients of determination coefficient, maximum error, root of mean error squares, model efficiency and residual mass coefficient. According to results of DAYCENT model was determined, highest average methane flux modeled in Dezful (ton/hectare in 0. 448) and nitrous oxide flux modeled at Abadan (0. 014 ton/ha per year) and oxidized nitric flux modeled at Dezful (ton/hectare in 0. 152). Also, in DNDC model, highest average of methane flux modeled at Dezful (ton/hectare in 0. 374) oxidized nitrous flux modeled at Abadan (ton/hectare at 0. 258) and oxidative flux modeled at Dezful (A ton per hectare was obtained in 0. 118. Highest global warming potential was determined based on observational data at Abadan (1339. 95 tons equivalent to carbon dioxide) and based on DAYCENT data at Dezful (58. 114 tons equivalent to carbon dioxide) and based on DNDC data at Abadan (111. 669 tons equivalent to carbon dioxide). According to results statistical indicators of DAYCENT model for three gases of oxidenitros, methane and oxidantitric respectively, coefficient of determination (0. 98, 0. 99 and 0. 77) root of mean error squares (0. 05, 0. 31 and 0. 03) and efficiency of model (0. 61, 0. 85 and 0. 76) and in DNDC model coefficients of determination coefficient (0. 98, 0. 98 and 0. 8) root of mean error squares (0. 01, 0. 45 and 0. 04) and efficiency of model (0. 95, 0. 68 and 0. 63) and both models showed acceptable accuracy in estimating said greenhouse gases. It is recommended that instead over-consumption of chemical fertilizers as a major source of greenhouse gas emissions, opinions experts and principles optimal use of fertilizers on farm be used.