بررسی تغییر مکانی نیترات و آرسنیک در آب زیرزمینی آبخیز جیرفت

نوع مقاله : پژوهشی

نویسندگان

استادیار بخش علوم و مهندسی آب، دانشکده‌ی کشاورزی، دانشگاه جیرفت، ایران

10.22092/wmrj.2023.361116.1518

چکیده

مقدمه و هدف
برای شناخت استعدادهای منطقه و روش مدیریت زمین‌ها، آگاهی از تغییر مکانی سنجه‌های کیفی ابزار مهمی است. با توجه به اینکه جیرفت روی کمربند آرسنیک کشور است و از آنجایی که آرسنیک عنصری سرطان­ زا است و بر کیفیت آب زیرزمینی تأثیر می­ گذارد، بررسی آن بسیار اهمیت دارد. هم‌چنین بیشتر مناطق روستایی آبخیز جیرفت از آب چاه‌ها برای شرب استفاده می‌کنند. ازاین‌رو، بررسی آن‌ها از دیدگاه شرب بسیار اهمیت دارد.
مواد و روش ها
در این پژوهش تغییرهای مکانی سنجه‌های نیترات، آرسنیک، منگنز و کل مواد جامد محلول در آب­ زیرزمینی در آبخیز جیرفت با استفاده از روش­ های زمین‌ آماری در طول دوره‌ی آماری 1398 بررسی و تحلیل شد. به‌ این منظور از آب 36 چاه کشاورزی و چاه‌هایی که برای شرب در روستاها استفاده می‌شد و هم‌چنین نمونه‌هایی از آب شرب شهری در سه تکرار نمونه‌برداری شد. روش ­های زمین ­آماری استفاده‌شده برای پهنه ­بندی سنجه‌های مزبور شامل کریجینگ معمولی، کریجینگ ساده، تابع پایه‌ی شعاعی (RBF) و روش وزن ­دهی معکوس فاصله (IDW) با توان­ های مختلف بود. برای ارزیابی روش­ های زمین‌آماری از روش ارزیابی متقابل با معیارهای مجذور میانگین مربعات خطا (RMSE) و میانگین انحراف خطا (MBE) میان داده­ های واقعی و برآوردشده استفاده شد.
نتایج و بحث
نتایج رتبه‌بندی معیارهای ارزیابی نشان داد که برآورد سنجه‌ی آرسنیک و TDS با مدل کروی روش کریجینگ ساده کمترین خطا را داشت و برآورد نیترات و منگنز با روش تابع پایه‌ی شعاعی (RBF) کمترین خطا را داشت. بررسی­ ها نشان ­داد که همبستگی مکانی سنجه‌های کیفی آبخیز جیرفت بسیار زیاد بود. به‌طوری‌که خطای مدل نیم تغییرنمای داده­ های اندازه­ گیری‌شده‌ی آرسنیک با اثر قطع ه­ای 0/00025 و دامنه‌ی تأثیر 36/7 کیلومتر 38/4 % و خطای مدل نیم تغییرنمای نیترات با اثر قطع ه­ای 0/3 و دامنه‌ی تأثیر 28/5 کیلومتر 4/9 % بود. در آبخیز جیرفت بر پایه‌ی معیار 1051 مؤسسه‌ی استاندارد و تحقیقات صنعتی ایران، به‌جز آب شهری، غلظت آرسنیک در آب مناطق دیگر بسیار بیشتر از اندازه‌ی مجاز برای مصرف شرب بود. هم‌چنین غلظت نیترات در تمام نمونه­ ها، کمتر از اندازه‌ی مجاز برای آب شرب بود و استفاده از آن مانعی ندارد.

کلیدواژه‌ها


عنوان مقاله [English]

Investigating Spatial Changes in Nitrate and Arsenic in Groundwater of the Jiroft Watershed

نویسندگان [English]

  • Mohammad Naderianfar
  • Arsalan Faryabi
Assistant Professor of Department of Water Engineering and Science, Faculty of Agriculture, University of Jiroft, Iran
چکیده [English]

Introduction and Goal
Awareness of spatial variations in groundwater quality parameters is an important tool for identifying the capacity of the region and land management. Jiroft is located on an arsenic belt in the country and considering the effect that arsenic has on underground water and the carcinogenic nature of this element, analysis of this element is very important. Moreover, most rural regions of Jiroft use the well water for drinking. Therefore, the analysis of groundwater in this region appears to be very important for drinking purpose.
Materials and Methods
Using geostatistical methods, the present study attempted to analyze the spatial variation of nitrate, arsenic, manganese, and all dissolved solid parameters in the groundwater of the Jiroft watershed during 2019. For this purpose, water from 36 agricultural wells and wells used for drinking in villages, as well as urban drinking water samples, were sampled in three replicates. The geostatistical methods used for zoning the above parameters include ordinary kriging (OK), simple kriging (SK), radial basis function (RBF), and inverse distance weighting (IDW) with different powers. Geostatistical methods were evaluated using the mutual evaluation technique applying the root mean square error (RMSE) and mean bias error (MBE) criteria between the actual and estimated data.
Results and Discussion
In this research, the spatial changes of nitrate, arsenic, manganese and total solids dissolved in groundwater in the Jiroft watershed were analyzed using the evaluation criteria ranking results showed that the estimation of arsenic and TDS with the spherical model of the simple kriging method had the least error and the estimation of nitrate and manganese with the radial basis function (RBF) method had the lowest error. The study showed that the spatial correlation of the quality metric of the Jiroft watershed is very high. Therefore, the error of the semivariable model of the measured data of arsenic with a partial effect of 0.00025 and a range of influence of 36.7 km was 38.4%, whereas the error of the semivariable model of nitrate with a partial effect of 0.3 and a range of influence of 28.5% was 4.9%. In the Jiroft watershed, the concentration of arsenic in the water of other areas was much higher than the permissible amount for drinking based on standard 1051 of the Iranian Institute of Standards and Industrial Research except for urban water. In addition, the concentration of nitrate in all the samples was lower than the permissible amount for drinking water, so there is no obstacle to its use.

کلیدواژه‌ها [English]

  • Arsenic
  • geostatistical
  • kriging
  • Nitrate
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