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1.
Accumulation of metals in both sediments and Phragmites australis organs was studied. Samples were collected from seven stations located in Anzali wetland, Iran. The samples were analyzed by inductively coupled plasma mass spectrometry (ICP-MS). The results showed that concentration of the studied metals (except As and Cd) were higher in sediments than in P. australis organs. Metal accumulation was found to be significantly (P <0.05) higher in roots than in above-ground organs of P. australis. The bioaccumulation factor (BAF) and the transfer factor (TF) also verified the highest rate of metal accumulation in roots and their reduced mobility from roots to the above-ground organs. Pearson correlation coefficient showed significant relationships between metal concentrations in sediments and those in plant organs. It should be pointed out that sediment and plant samples exhibited higher metal concentrations in eastern and central parts than in western and southern parts of the wetland. The mean concentrations of all studied elements (except for Fe, V and Al) were higher in these sediment samples than in the Earth’s crust and shale. High accumulation of metals in P. australis organs (roots and shoots) is indicative of their high bioavailability in sediments of the wetland. The correlation between metal concentrations in sediments and in P. australis indicates that plant organs are good bioindicators of metal pollution in sediments of Anzali wetland.  相似文献   
2.
Development of higher welfare could not be realized unless by energy consumption and other natural resources. Growth of industrial complexes has shown an unprecedented trend during recent years. Many of these towns have no treatment systems for the industrial wastes leachates. Besides, the chemical composition of wastes in such complexes varies considerably due to the different kinds of industries. It is endeavored in the present work to study the natural potential of soil to treat leachate of such industrial wastes. For this purpose, the Aliabad industrial complex in Tehran — Garmsar road was selected as the study area. The potential of adsorption of elements such as nickel, copper, cadmium, zinc, chromium, lead and manganese was investigated. The results indicated that the soil potential to adsorb heavy metals (except for manganese) was very high (95 %) in the adsorption of heavy metals (except for manganese). Further, chemical partitioning studies revealed that heavy metals are associated with various soil phases such as loosely bonded ions, sulfide and organics to various extents. Among the mentioned soil phases, one can deduce that major portion of metal contaminants is absorbed as loosely bonded ions. Organic bond and sulfide bond are in the 2nd and 3rd positions of metal contaminants adsorption, respectively. The results of the present study apparently showed that soil column had ample capacity to adsorb metal contaminants. Thus, determination of soil potential in adsorption of heavy metals during site selection is as important criteria.  相似文献   
3.
In the present study, the removal of dissolved and colloidal Cd, Co, Cu, Ni and Zn in Arvand River water during estuarine mixing with the Persian Gulf water is investigated. The flocculation process was investigated for a series of mixtures with salinities ranging from 0.48 to 30.3^. The flocculation rates were indicative of the non-conservative behavior of studied metals during estuarine mixing. Rapid flocculation in the low salinity regimes was observed. The order of the final flocculation rate of metals in the river water was as follows: Co (91.2%)> Cd (86.9%)> Zn (83%)> Cu (75.2%)> Ni (74.3%). Salinity, pH, EC and dissolved oxygen do not govern the flocculation of metals during estuarine mixing. The results of the present investigation show that estuarine processes can be considered as an effective mechanism in self purification of colloidal metals that are anthropogenically introduced into the fresh water ecosystem.  相似文献   
4.
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5.
Industrial development has lead to higher energy consumption, emission of greenhouse gases, as well as air pollutants. Cement factories play an important role in over all greenhouse emissions. This study aims to investigate the role of Iranian cement industries and their contribution of greenhouse gases contribution. The measured emission factors for oil and fuel gas shows that carbon dioxide contribution from fuel oil based cement industries is almost 2.7 times higher than gas based cement factories. The strength, weakness, opportunity and threat technique analysis showed that the best strategy to combat greenhouse gases from Iranian cement factory is to implement energy efficiency measures. Further, strategic position and action evaluation matrix analysis indicates that Iranian cement industries fall within invasive category. Therefore, exploitation of opportunities must carefully be used. One of these opportunities is the utilization of financial assistance provided by clean development mechanism. The results show that replacement of ball mills with vertical roller mill can reduce the electricity consumption from 44.6 to 28 kWh/ton. As a result of such substitution about 720 million kWh/y of electricity would be saved (almost a power plant of 125 MW capacities). Though implementation of new mills may not be economic for the cement industries’ owner, but the overall gain for the government of Iran will be about US$ 304 million. If the duration of such efficiency measure is considered as about 12 y, then the overall CO2 reduction/phase-out would be around 4.3 million tons.  相似文献   
6.
In the present investigation down core variations of heavy metals such as; Zn, Ni, Co, Mn, Fe and Al in a sediment core from Bay of Gorgan adjacent to the Caspian Sea was studied. Inter-relationship amongst various parameters was brought out through correlation coefficients and cluster analysis. The results of present study reveals that Zn, Ni, Co and Mn possess both lithogenous and non-lithogenous sources. The increasing trend of Al towards top of sediment core is indicative higher erosion in the recent years. Interestingly, concentration of all studied metals increases toward core top (except for Fe) that might be indicative of influence of man’s activities residing in catchment area of Gorgan Bay and also oil exploration in the Caspian Sea. Further, 210Pb and 137Cs techniques were used to find out rate of sedimentation. The result of dating is indicative of sedimentation rate between 1.4 to 2.45 mm/yr. based on 210Pb and 137Cs activities respectively.  相似文献   
7.
Origin and chemical partitioning of heavy metals in riverbed sediments   总被引：2，自引：0，他引：2  
In the present investigation, bulk and chemical partitioning of elements in the Shefa-Rud riverbed sediments are studies. Higher concentrations of elemental concentrations have been observed in estuarine zone when compared with riverine sediments (except for AI, Fe, Pb and Mn). Manganese is mobilized under anoxic conditions prevailing in the Caspian Sea. Lithogenous materials are greatly diluted in the estuarine zone by various pollutants present in the Caspian Sea. Organic metallic bonds are not significantly present in the area of study. Geological units of the area of study have resulted in the lower concentrations of elemental concentrations of riverbed sediments when compared with published values for mean crust and world sediments ones. Though, cluster analysis has clearly shown the importance of alumina-silicates in controlling the distribution of Fe and Mn in riverbed sediments but it could not depict controlling mechanism for other studied elements. Geochemical Index (Igeo) and Enrichment Factor (EF) values are indicative of a clean environment throughout the river course. These values are in a well agreement with results of chemical partitioning data. Quantification of EF values is not logically possible and therefore Igeo values can be used more effectively.  相似文献   
8.
Organophosphate pesticides are compounds that are not only toxic to both humans and wildlife but also difficult to degrade under natural environmental conditions. In Iran, agricultural practices are strongly dependent on the use of pesticides due to climatic and soil conditions, thus posing a potential risk to groundwater quality standards. Evaluating the concentration of organophosphate pesticides namely diazinon, fenitrothion, dichlorvos, ethion, profenofos, malathion and azinphos methyl in water samples in May (low precipitation rate), December (high precipitation rate) as well as the concentration in sediments along the Haraz River is taken into consideration in this study. Generally the pesticides concentration in water samples are relatively higher in May in comparison with that in December; this fact may be due to two major reasons: the first reason is attributed to the prompt raining after the treatment period of most orchards and dry farming lands that will terminate in more wash out of such pesticides towards the branches and main river channel, while the second reason may be considered as the less river water dilution rate in May because of lower precipitation rate. Furthermore, the relatively higher concentrations in downstream stations may be contributed to more intensified agricultural (specially rice paddies), urban and rural land uses in this region in comparison with upstream areas which contain mainly dry farming, grazing lands and orchards with relatively lower loads of pesticides. Additionally, as the Henry’s law constant of all pesticides considered in this study are relatively low, volatilization may not be regarded as an important route of dissipation. Diazinon, azinphos methyl and dichlorvos showed the highest water concentrations in comparison with other pesticides that may be justified by their extended use within the basin during last decades. Based on the chemical properties as well as remarkably higher values in sediment samples in comparison with water ones, it is concluded that the two pesticides, ethion and fenitrothion, persist in the environment due to non-degradable tendencies. Although the concentration of mentioned pesticides is not so high in the water samples, more precautions must be considered in their future use. Regarding the sorption coefficient variation alongside the river, the higher values in upstream and central parts may be attributed to the higher potential of different types of erosion regarding deeper slopes and also sand, gravel and carbonate mining activities at the banks and also river bed in such regions which is considered as an anthropogenic disturbance. In case of central parts, in addition to mentioned reasons, the existence of coal outcrops in the geologic texture of the study area may also be considered as a key role in augmentation of the sorption coefficient. Finally, the dominant clayey and loamy soils containing more organics may be attributed as the major reason of sorption tendency in downstream.  相似文献   
9.
Sungun mine is the largest open-cast copper mine in northwest of Iran and is in the primary stages of extraction. The influence of mining activity on the quality of regional groundwater has been taken in to consideration in this study. Accordingly, sampling was done from 22 springs in the study area. The concentrations of major anions and cations as well as Al, Cu, Cd, Cr, Fe, Mn, and Zn were determined for all 22 spring samples in mid-August 2005. The results showed that the concentrations of most of these elements were below the USA Environmental Protection Agency (EPA) limits; however, Al and Fe concentrations are considered to be more than limits in a couple of samples. Despite the fact that geological formations are highly weathered and fractured, the dissolution of minerals within the study area is low. This may be justified by the relatively high alkalinity of local underground water which keeps metals in solid phase and does not let them enter dissolved phase. Additionally, this may be attributed to the high velocity of groundwater flows, which do not give enough time for minerals to dissolve. Correlation coefficients among water chemistry components were determined and the weighted-pair group method was chosen for cluster analysis. Accordingly, high correlation among Al, Fe and Cr, Cd ,and Cu, sodium absorption ratio (SAR) and Na as well as total hardness (TH), Ca, and Mg were observed. The chemical characteristics of water compositions on the basis of major ion concentrations were evaluated on a Schoeller and Piper diagram. Accordingly, the dominant type of water in the region is considered to be Ca-HCO3 (calcium-bicarbonate type). However, this type of water is also rich in Na, K, and especially Mg. Regarding Schoeller diagram, the current status of local underground water is good for drinking purposes. By commencing mining excavation with designed capacity in near future, the minerals will come into contact with air and water resulting in dissolution, especially in ponds, which, in turn, will increase the concentration of toxic metals in groundwater. Considering future uses of this water including for drinking, irrigation, industrial purposes, etc., precautions must be taken in to consideration.  相似文献   
10.
In this study, spatial and seasonal variations of water quality in Haraz River Basin were evaluated using multivariate statistical techniques, such as cluster analysis, principal component analysis and factor analysis. Water quality data collected from 8 sampling stations in river during 4 seasons (Summer and Autumn of 2007, Winter and Spring of 2008) were analyzed for 10 parameters (dissolved oxygen, Fecal Coliform, pH, water temperature, biochemical oxygen demand, nitrate, total phosphate, turbidity, total solid and discharge). Cluster analysis grouped eight sampling stations into three clusters of similar water quality features and thereupon the whole river basin may be categorized into three zones, i.e. low, moderate and high pollution. The principle component analysis/factor analysis assisted to extract and recognize the factors or origins responsible for water quality variations in four seasons of the year. The natural parameters (temperature and discharge), the inorganic parameter (total solid) and the organic nutrients (nitrate) were the most significant parameters contributing to water quality variations for all seasons. Result of principal component analysis and factor analysis evinced that, a parameter that can be significant in contribution to water quality variations in river for one season, may less or not be significant for another one.  相似文献   
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