پهنه‌بندی مکانی تغییرات عناصر موجود در ذرات گرد و غبار حوضه آبریز دریاچه ارومیه

خشک شدن سطح وسیعی از دریاچه ارومیه و تشکیل مناطق مستعد به فرآیندهای فرسایش بادی و رخدادهای گرد و غبار می تواند باعث گسیل ذرات معلقی شود که بر شیمی جو و ترکیبات آب باران این حوضه آبریز تاثیرگذار باشند. جهت پایش آلودگی هوا و بررسی تغییرات کمی و کیفیّ آب باران از نظر عناصر با منشا دریاچه ای، 6 نمونه آب باران از مهرماه 1396 تا مهرماه 1397 از رخدادهای هم‌زمان به صورت رسوب تر از 13 ایستگاه اطراف دریاچه ارومیه شامل ایستگاه های ارومیه، برده سور و گلمانخانه در غرب دریاچه، باری، چوپانلوی سلماس و خوی در شمال دریاچه، آق گنبد، ایلخچی و تبریز در شرق دریاچه، آغداش، میاندوآب و کشاورز در جنوب و جزیره اشک در مرکز دریاچه ارومیه در جهت ها و فاصله های مختلف از حوضه آبریز دریاچه ارومیه جمع آوری شد. نتایج آماری حاصل از تجزیه واریانس داده های به‌دست آمده اختلاف معناداری را بین 13 ایستگاه از نظر غلظت عناصر با منشا دریایی شامل سدیم (na)، منیزیم (mg)، کلسیم (ca) و پتاسیم (k) نشان داد؛ به‌گونه ای که ارتباط بین عناصر سدیم، منیزیم و کلسیم نشان‌دهنده منشا انتشار یکسان این عناصر بوده است. با توجه به نتایج به‌دست آمده بیشترین پراکنش عناصر مورد مطالعه در محدوده حوضه آبریز دریاچه ارومیه در اولین حلقه شعاعی (حداقل فاصله از بستر دریاچه ارومیه) و بیشتر در جهت های جغرافیایی غرب و شمال دریاچه ارومیه مشاهده شد.

Spatial Mapping of Elemental Variabilities of Atmospheric Particulates throughout the Lake Urmia Basin

Due to the presence of elements such as Ca, Na, Mg and K, lakes can play an important role in the chemical properties of rainwater due to the evaporation of water droplets in the atmosphere. These marine aerosols can be transmitted by wind to areas far from their original source. Therefore, monitoring of the quality of rain water due to the transfer and sedimentation of marine aerosols as the best parameter for monitoring chemistry of the atmosphere has been important in extensive studies. This phenomenon occured with the drying of Lake Urmia, with the loss of 90 percent of its water volume and the formation of salt desert on its bed. This situation can overcome climate change in this area, increase respiratory diseases and, consequently, the lives of people living in these areas. Therefore, the present study intends to map the spatial variations of rainwater chemistry in terms of sodium, magnesium, calcium and potassium (as a representative of marine resources) by collecting rainwater from simultaneous events in 13 stations around the Lake of Urmia and damages are determined from the most acceptable area in terms of the impact of marine elements. This study selected the Lake Urmia watershed as the study area. About 129 rainwater samples were collected from 13 stations around Lake Urmia over a one year period. These stations are located in the four main geographical directions of north (Khoy, Bari and Chopanloo Salmas), southern (Aghdash, Miandoab and Keshavarz), East (Tabriz, Ilikhchi and Agh Gonbad) and West (Golmankhaneh, Urmia and Bardehsor) and the center of th lake )Ashk Island). Sampling from each event with the same volume of 250 ml at points away from contamination and then stored at 54°C to prevent physicochemical changes. The analysis of the elements was measured using the ICPMS model 8800 in ppb. In the present study, the meteorological data in two categories of wind speed and wind direction (meteorological glaciers) were considered for 13 study stations. the mapping of the studied elements were generated by the IDW method in the Arc GIS software version 10.4. Oneway ANOVA and Pearson correlation coefficient were used in SPSS software version 18 to examine the changes and correlation between the elements. The highest concentrations of Na and Mg were obtained at Golmankhaneh station. Also, the highest concentration of Ca element was observed at Golmankhaneh station, which in the second Bardehsor,Ashk Island, and Tabriz stations had the largest concentration. The study of windrose showed that stations located south of the lake and stations in the west were affected by very low wind speeds from the lake but the stations located on the north and east of the lake have been affected by relatively fast winds from the lake side. The mapping showed that the highest concentrations of the studied elements were in the north and west stations, as demonstrated by the oneway ANOVA results. The correlation results showed that there is a significant correlation between sodium, magnesium and calcium, indicating that these elements are likely to have the same source of propagation and originate from salt salts and have strongly  been affected by suspended particles with the origin of the lake, considering the climatic data of stations in the north of Lake Urmia (Khoy and Salmas stations). By investigation of rainwater samples in terms of concentration of studied elements and their spatial variations at different distances from Lake Urmia showed that the highest concentrations of the elements studied at nearby stations (Golmaneh, Barry, Tak Island and Agh Gonbad), it was observed that in the Lake Urmia  relatively large amounts of these elements are found at Salmas and Khoy stations that in general, it can be said that this distribution is more than a few kilometers to the lake and shows that the impact of Lake Urmia is currently high on nearby stations. As a general conclusion, the western and northern regions of the lake are more susceptible to dust and suspended particles from the driedup areas of Lake Urmia. Investigating the distance factor on the concentration of lake origin elements showed that the concentrations of these elements with increasing distance from the lake and the coastline are mainly  decreasing. Strong and positive correlation between sodium, magnesium and calcium elements is likely to indicate the sources of the same or close distribution of these elements, although this correlation is observed with a lower content of calcium element with sodium and magnesium elements, indicating enrichment calcium is a part of limestone and marl formation around the catchment area of Lake Urmia.