نشریه اکوبیولوژی تالاب
سال سیزدهم شماره 4 (پیاپی 50، زمستان 1400)

The release of heavy metals in the environment due to industrialization and urbanization has caused great problems around the world. This pollution causes serious concerns due to their carcinogenicity, inseparability and biological accumulation. Eynak Wetland is one of the most attractive natural attractions in the province of Guilan, Rasht. So, investigation on the concentration of heavy metals is necessary for its good management. Sampling of Eynak wetland sediment and water was carried out of 12 sampling stations in summer 2019. Samples were acid-digested and metals were determined through ICP-OES. To determine the contamination, the indices Igeo, Cf, PLI and Cdeg were used. In water samples, concentration of manganese in all stations and iron at stations 3B and B4 are higher than the standards of the Environmental Protection Agency for drinking and farming. The other metals in water samples of the wetland are less than standard. In sediment samples, the average concentrations of arsenic, cobalt, copper, zinc and lead in some stations were higher than global sediment standards. Iron, manganese and nickel concentrations were lower in comparison with global sediments. Concentration of the elements in the wetland sediments indicates that copper, lead and zinc in the sediments of the Eynak wetland, especially the third part of the wetland, is above the global average. Station C3 has higher concentration of metals and is introduced as the most polluted station that can be due to proximity to industrial workshops and repair shops, industrial and urban wastewater discharges to the wetland.

The aim of this study is to assess River ecosystem and its zoning using water physicochemical factors and the distribution of benthic macroinvertebrate communities in the Haraz River in Iran. In this study, benthic macroinvertebrate communities along the stream were sampled in 2015 at each of the nine stations with three replicates using Surber net samplers (30.5×30.5 cm2). BMWP (Biologic Monitoring Working Party) biotic Index, ASPT (Average Score Per Taxon) biotic Index, Hilsenhoff biotic Index were used to assess water quality. Physicochemical factors of water and zoning maps in GIS softwarewas also prepared. In the present study, 5 families of Diptera order named Chironomidae, Simuliidae, Tipulidae, Limnoidae and Culicidae were identified, which had the highest number of families compared to other orders. The family Chironomidae was the only family observed in all stations and had the highest frequency in stations 2 and 3 and the lowest frequency in stations 5 and 6. Calculated results of the stations 1 to 6 (Especially stations 5 and 6) indicated water quality conditions were suitable and substantial level of organic pollutions were observed in stations 7 and 8 and also, station 9 indicates water quality was fairly poor, that indicates the unsuitable conditions of the river at this station.

The water quality of dam reservoirs is constantly changing for various reasons such as thermal stratification, accumulation of dissolved solids, long residence time, and stratification. For this reason, the present study uses CE-QUAL-W2 software to investigate the thermal pattern and water quality of the Alaviyan Dam reservoir for 2016. The results illustrate that from mid-June to mid-September, the reservoir experiences relatively strong thermal stratification so that in this period, the temperature difference between the upper and lower layers of the dam averages 12.31 degrees Celsius. Also, due to the active ecosystem in the downstream river and the identification of certain species of fish in it, the difference between the temperature of the river water and the reservoir outlet water is calculated, which is an average of about 6.7 degrees Celsius for the outlet elevation 1530 m in summer, and this value is higher than the allowable value. Due to the occurrence of water quality stratification in the reservoir simultaneously with thermal stratification and reduction of dissolved oxygen concentration in the lower layers of the reservoir in summer to 5.35 mg/L, predicting the reservoir situation for 2021 under different scenarios (climate change and declined River's dissolved oxygen) has chosen as the next aim of this research. The results show that in the most critical conditions (10% increase in air temperature and 10% decrease in dissolved oxygen) the value of this parameter will drop to 4.4 mg/L, which is to be expected in anaerobic conditions and the production of odor, color, and unpleasant taste. Regarding with salinity changes, the results show that the lower layers have more solutes than the upper layers, but due to the low salinity levels in the Sufichai River, this amount in the reservoir in the most critical state does not exceed 125.45 mg/L. In fact, there is a significant difference with the allowable amount announced in the Water Quality Standard of Iran.

Wetlands are valuable biological resources and reservoirs for any country that performs special services and functions Shadegan Wetland is one of the purest, most valuable and largest ecosystems in Iran, which has been registered in the Ramsar Convention List due to its special importance and rich nature but recently, due to various natural and human factors, this ecosystem has been exposed to change and destruction. In order to observe the environmental changes caused by different pressures on the wetland, a quantitative measurement of land use changes is felt. The purpose of this paper is to investigate and compare changes in land use coverage in the time before and after the flood using Landsat 8 satellite images and their processing in ENVI 5.3 and Arc GIS 10.5 software environment with the help of supervised classification method in March and September 1998. The results of this study show a decrease,16.29% Water coverage level,2.72% of land, 1.39% vegetation level and increase, 12.59% saline lands and 7.81% Plant cover area of the weter part of the wetland. Recently, the Khuzestan Plain has been one of the most important areas of drought in Iran. One of the effects of drought is the creation of an impermeable layer of dense soil on the ground, which reduces the permeability of the area against rainfall and allows more water to flow in the form of runoff. However, the wetland is in good water conditions in winter 2019 and spring 2019 compared to previous years, However, due to the drought in recent years and the reserves of the wetland's water supply resources have not been in high water conditions for a long time, the water is still not irrigated and the authorities need to pay special attention to this issue and the wetland's water supply, follow up vigorously to prevent the wetland from drying up again and flooding again.

The declining quality of surface water resources has become a major concern in recent years. Therefore, the need to evaluate the Spatio-temporal variations of river water quality and also to assess different parameters affecting their water quality and identify the most important variables and factors significantly affecting water quality has been created. In the present study, to monitor the surface water quality of Karkheh River, a data set of Karkheh River water quality containing 16 parameters recorded during 17 Years (2003-2020) from seven different monitoring sites was prepared from the Water and Power Organization of Khuzestan Province. Then, to study and interpret this complex and large data matrix consisting of a large number of physicochemical parameters from long-term monitoring programs, trend analysis, multivariate statistical techniques, and also the use of some indicators to evaluate the suitability of river water quality for irrigation purposes were used. The results of trend analysis showed that the pattern of parameter changes in the annual and seasonal scales was similar, and except for the pH parameter, other water quality parameters such as EC, TDS, SO42-, Ca2+, and calcium hardness were significantly increased. PCA analysis identified three PCs as responsible for the data structure explaining 77/65% of the total variance in water quality. According to the results of PCA, TDS, EC, HCO3- and pH were the most important parameters contributing to spatial variations of surface water quality of Karkheh River. Results of cluster analysis revealed three significant groups of similarity among the 7 monitoring sites. Investigation and analysis of linear regression of cations, anions and other parameters as a dependent variable against river discharge as an independent variable showed a negative correlation. In this study, River Water quality for irrigation purposes was assessed through different indices including EC, sodium percent (SP), sodium adsorption ratio (SAR), Magnesium Hazard (MH), permeability index (PI), and Kelly’s ratio (KR). The interpreted results showed that the surface water quality in different stations based on the calculated indicators (except EC) in general is suitable for irrigation. The results of this study provide useful information in the interpretation of complex datasets, identification of pollution sources/factors, and understanding of temporal and spatial variations of water quality that can be used to manage projects for improving surface water quality at the study area.

Indices qualitative pollution is one of procedures involved in managing quality water can be a powerful management tool for decision-making, as an appropriate-use. In this paper, using done index quality water BCWQI and index pollution water Liou evaluate quality of river Bahmanshir. Sampling was within one year (2019) and 5 stations conducted. Quality parameters were investigated including: temperature, dissolved oxygen, biological oxygen demand, COD, pH, ammonia nitrogen, nitrate, phosphate, total dissolved solids, TSS, turbidity, electrical conductivity, total coliform and fecal coliform in the river. Data obtained from this study were analyzed by using Water Quality Index BCWQI and Liou. Results BCWQI index in five sampling stations show that all stations are in a state of quality water right to moderate. Most BCWQI index is in the second station in winter with score 34.13 and lowest BCWQI index is in the quarter station in summer with score 51.2. Results Liou index in five sampling stations show that best state of  Liou index are in  stations  first and second in summer with score 3.25 and lowest Liou index are in first station in autumn and winter  and in second station in winter with score 4.25 and all stations are in state relatively polluted quality water. Results of both BCWQI and Liou methods to assess quality water  have overlaps.

To determine the level and concentration zoning of total petroleum hydrocarbons (TPHs) and heavy metals (Pb, Co, V, Ni) in surface sediments of the Arvand River, is the purpose of this study. 10 sampling stations were selected for this purpose, along the river route, and sampling was done in winter of 2017. 90 sediment samples were taken by a Van Veen Grab with a cross section of 0.025 square meters. The amount of heavy metals and the concentration of total hydrocarbons were calculated according to the MOOPAM standard, and using atomic absorption (spectrophotometric) or AAS and a measuring Chromatography machine, and zoning was drawn. Based on the analysis, the highest and the lowest amount of hydrocarbons in station 2 (Dairy Farm pond platform) was 21.96 ± 0.50 mg / L and at station 1 (Nahre Khin) was 91.9 ± 0.19 mg / L. In the case of nickel, lead and vanadium, the highest values ​​at station 9 (Yademane Shohada) were 75.96± 0.05 mg / L, at station 6 (Khosrow Abad), 13.07 ± 0.10 mg / L, and at station 7 (The beginning of the menyouhi) was 18.88 ± 0.22 mg / L. According to international standards, the Arvand River banks, in terms of hydrocarbon, were in no-pollution conditions or exposed to little contamination conditions. The amount of cobalt at all stations was less than 0.1%, and in the case of nickel, vanadium and lead, the measured values ​​in the Arvand River sediments were higher than the regional standards of the ROPME Regional Organization (Persian Gulf).