هیدروژئوشیمی زیست محیطی کانال آب خروار بهبهان، جنوب غرب ایران

کانال آب خروار بهبهان که شامل فاضلاب شهری و صنعتی و روان آبها می باشد، به طول 7 کیلومتردر دشت بهبهان در منطقه خشک و نیمه خشک واقع شده و از نظر منابع آبی محدود می باشد، لذا حفظ کیفیت آب و جلوگیری از آلوده شدن آن از اهمیت خاصی برخوردار است. به منظور بررسی میزان آلودگی کانال آب خروار بهبهان و تاثیر آلودگی احتمالی بر رودخانه مارون، از 5 محل در مسیر کانال و یک نقطه در مکان ورود به رودخانه مارون نمونه برداری انجام گرفت. نمونه های آب برای تعیین غلظت عناصر سنگین as، fe، pb، se، zn، mn، cr، آنیون های cl ، so42 ، no3 ، co2 ، hco3 ، و کاتیون های  ca2+، na+، mg2+، k+، و پارامترهای مهم کیفی آب شامل ph، ec و tds مورد آنالیز قرار گرفتند. میزان ph در همه نمونه ها در حد استاندارد آب آشامیدنی who و استاندارد فاضلاب خروجی تخلیه به آب های سطحی و مصارف کشاورزی سازمان محیط زیست ایران می باشند. غلظت آنیون ها و کاتیون های اصلی در بیشتر نمونه ها مقدار بالاتر از حد مجاز استاندارد را نشان می دهد. روند تغییرات غلظت آنیونها به ترتیب co32< no3clˉ>hco3ˉ، کاتیون ها ca2+> mg2+> k+ mn>fe> zn> cr> pb >as می باشد. میزان ec، tds و غلظت یون های so42 ، hco3، cl، ca2+،mg2+،na+ و k+، در نمونه برداشت شده از محل ورود آبخروار به رودخانه مارون بالاتر از حد استاندارد آب آشامیدنی who است، در حالیکه میزان نیترات و همچنین سایر عناصر سنگین در این نمونه، در حد مجاز استاندارد آب آشامیدنی who است. روند تغییرات یون های کلسیم و سولفات و کل جامدات محلول، در منطقه مورد مطالعه مشابه است، که می تواند نشان دهنده منبع مشترکی، مانند انحلال کانی های ژیپس، کلسیت، انیدرید و همچنین ورود فاضلاب های شهری و صنعتی، برای این یون ها باشد. غلظت یونهای نیترات، سولفات و بیکربنات در مرکز شهر روند افزایشی دارد، که این امر را میتوان در اثر ورود فاضلاب غنی از مواد آلی دانست.

environmental hydrogeochemistry of abkharvar behbahan channel, southwest of iran

abstractthe abkharvar channel is 7 km long in behbahan plain located in an arid to semi arid zone. since it has restricted water resources, preserving its quality is very important. to investigate the contamination possibility, 6 places were sampled in the studied area. the water samples were analyzed for heavy elements as, fe, pb, se, zn, mn, cr, anions cl , so42 , no3 , co3 , hco3 , and cations ca2+, na+, mg2+, k+, and important water quality parameters including ph, ec, and tds, using icp oes, faes, oas, titration, drying and conductivity methods. the ph levels in all samples are within the who standard and the standard of wastewater discharged to surface water and agricultural uses. the concentration of so42 anion and mg2+, na+, ca2+ cations, and important water quality factors including ec, and tds in the sample taken from the maroon river (s6) exceeds the allowed levels of who standard for drinking water. geochemical data show that water chemistry is influenced by processes including evaporation, water rock interactions, and human activities.  introductionthe importance of water resources, especially surface runoff, and their protection against pollution is a very controversial issue. the use of chemical fertilizers and pesticides in agricultural activities, the entry of urban and industrial wastewater, as well as fossil fuels as man made factors, and the effect of geological formations, such as carbonate and chalk formations that have a high solubility in water, as natural factors can reduce the quality of water resources  materials and methodsin this research, to investigate the level of water pollution of the kharvar behbahan water channel, sampling was done from 6 points estimated as the main places of sewage discharge, from the upstream (s1) to the entrance to the maron river (s6). in each section, three samples were taken in 250 ml acid washed polyethylen sampling containers, to analyze and measure the amount of anions and cations, heavy metals, and nitrat concentration. immediately after sampling, the ph and ec values of the samples were determined at the same sampling location by hach semsion5 ec meter and genway ph meter. 6 samples from each station were chemically analyzed to determine the concentration of as, fe, mn, zn, pb, se, and cr elements by inductively coupled optical emission spectroscopy (icp oes) in zanjan earth science laboratory. two other series were sent to arvand khak azma laboratory to measure the concentration of main anions and cations, total dissolved solids (tds), and nitrate, and were analyzed by faes, oas, titration, drying methods, and spectrum methods. atomic absorption spectroscopy and optical emission spectroscopy were analyzed.  resultsaccording to the water analysis results of the kharvar behbahan water channel, the amount of ph changes is between 1.8 and 3.8 and the average is 2.8, which shows that the water is alkaline. in all samples, this parameter is within the standard level of wastewater discharged into the surface waters of iran's environmental protection organization (5.8 5.6). the ec value of the samples varies from 2030 to 4010 µmoh/cm and the average shows 3023 µmoh/cm. according to the who standard, the ec limit for drinking water is 1500 µmoh/cm, and all samples have an electrical conductivity higher than the limit of this standard and the standard of the wastewater discharge to surface water and agricultural and irrigation purposes of iran's environmental protection organization. also, as the water travels a longer path, the amount of ec increases due to the presence of lahbari and aghajari producers and the dissolution of evaporative minerals.  discussion and conclusionthe water pollution of abkhorvar behbahan channel, located in behbahan plain, was investigated and studied. the results of the chemical analysis of 6 samples taken from the water of abkhorvar and the maroon river inlet were compared with the drinking water standard belonging to the world health organization (who) and the standards of the wastewater discharged to surface water and agricultural and irrigation purposes of the environmental protection organization of iran. the ph levels in all samples are within the who drinking water standard and the standard for wastewater discharged to surface water and agricultural uses. the concentration of the main anions and cations in most of the samples is higher than the standard limits. the trend of changes in the concentration of anions is co32< no3< so42 >clˉ>hco3ˉ, cations ca2+> mg2+> k+ mn>fe> zn> cr> pb>as. the amount of ec, tds, and the concentration of so42 , hco3, co32, no3, ca2+, mg2+, na+, and k+ ions in the sample taken from the water inlet to the maroon river is higher than the who drinking water standard, while the amount of nitrate as well as other heavy elements in this sample is within the limit of the who drinking water standard. the trend of changes of calcium and sulfate ions and total dissolved solids is similar in the studied area, which can indicate a common source, such as the dissolution of gypsum, calcite, and anhydride minerals, as well as the entry of urban and industrial wastewater, for these ions. the concentration of nitrate, sulfate, and bicarbonate ions in the center of the city is increasing, which can be attributed to the entry of wastewater rich in organic substances.