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Abstract
This study was carried out to determine whether the changes in dust concentration (DC) in Iran were attributed to changes in aridity index (AI) from 1990 to 2018. Long-term precipitation and potential evapotranspiration were used to compute the United Nations Environment Program AI and horizontal visibility data were used to calculate the DC in the study area. The DC spatial distribution maps were prepared to better identify areas affected by sand-dust events. Pearson’s correlation analysis was performed to explore the association between DC and AI in Iran and study stations during the monitoring period. Spatiotemporal variations in DC showed that more than 60 percent of Iran’s area experienced severe wind erosion events in 2001, 2008, and 1990 when AI was less than 0.2. The results also showed that approximately 45 percent of Iran’s area has suffered from the average DC over the study period (565 µg/m3). The incremental changes in DC were observed in almost half of the entire area of Iran during the second period (2000–2008) and one third of this area during the third period (2009–2018). Areas affected by decreasing changes in AI during the second and third periods were 90 percent and 73 percent of the area affected during the previous period, respectively. Overall, there was a significant negative correlation between AI and DC in Iran over the monitoring period (r = −0.51, p value < 0.01). Insignificant positive correlations were observed in humid regions, whereas negative correlations were mostly detected in arid and semiarid regions of Iran.
本研究旨在确定伊朗粉尘浓度的变化是否归因于1990至2018年干旱指数的变化。利用长期降水量和潜在蒸散量, 计算了联合国环境规划署的干旱指数。利用水平能见度数据, 计算了研究区的粉尘浓度。本文还编制了粉尘浓度空间分布图, 以便更好地确定沙尘事件的影响区域。采用Pearson相关性分析, 探讨了监测期间伊朗和研究站点的粉尘浓度与干旱指数的相关性。粉尘浓度的时空变化表明, 在2001年、2008年和1990年, 当干旱指数小于0.2时, 60%以上伊朗地区经历了严重的风蚀事件。结果还表明, 在研究期间, 大约45%伊朗地区经历了平均水平（565毫克/立方米）的粉尘浓度影响。在第二个时期（2000-2008年）, 近一半伊朗地区观测到了粉尘浓度的增量变化。在第三个时期（2009-2018年）, 三分之一的伊朗地区出现了粉尘浓度的增量变化。在第二个和第三个时期, 干旱指数变化减少的区域分别为前一时期受影响面积的90%和73%。总体而言, 在监测期间, 伊朗的干旱指数和粉尘浓度之间存在着显著的负相关（r=-0.51, p值<0.01）。湿润地区具有非显著的正相关, 而负相关则主要出现在伊朗的干旱和半干旱地区。
Se realizó este estudio para determinar si los cambios en la concentración de polvo (DC) en Irán se pueden atribuir a cambios en el índice de aridez (AI) entre 1990 y 2018. La precipitación y la evapotranspiración potencial en el largo plazo fueron usadas para cuadrar dentro del Programa Ambiental de las Naciones Unidas. Datos del AI y de visibilidad horizontal se usaron para calcular la DC en el área de estudio. Los mapas de la distribución espacial de la DC fueron preparados para identificar mejor las áreas afectadas por eventos de arena y polvo. Se realizó un análisis de correlación de Pearson para explorar la asociación entre la DC y el AI en Irán y en estaciones de estudio durante el período de monitoreo. Las variaciones espaciotemporales en la DC mostraron que más del 60 por ciento del área iraní experimentó severos eventos de erosión eólica en 2001, 2008 y 1990, cuando el AI estuvo por debajo de 0.2. Los resultados muestran también que aproximadamente el 45 por ciento del área de Irán ha sufrido de la DC promedio durante el período de estudio (565 µg/m3). Los cambios de incremento en la DC fueron observados en casi la mitad de la superficie total de Irán durante el segundo período (2000–2008) y en un tercio de esta área durante el tercer período (2009–2018). Las áreas afectadas con cambios por disminución en el AI durante los períodos segundo y tercero fueron el equivalente del 90 y 73 por ciento del área afectada durante el período precedente, respectivamente. En general, se registró una correlación negativa significativa entre el AI y la DC en Irán durante el período de monitoreo (r = –0.51, valor p < 0.01). Se observaron correlaciones positivas insignificantes en áreas húmedas, mientras que las correlaciones negativas en su mayoría se detectaron en regiones áridas y semiáridas del país.
Acknowledgments
We appreciate the detailed feedback provided by anonymous reviewers on previous versions of this article. Zohre Ebrahimi-Khusfi is now with the Department of Ecological Engineering, Faculty of Natural Resources, University of Jiroft, Jiroft, Iran.
Additional information
Notes on contributors
Zohre Ebrahimi-Khusfi
ZOHRE EBRAHIMI-KHUSFI is now an Assistant Professor in the Department of Ecological Engineering at the University of Jiroft, 78671-61167 Jiroft, Iran. E-mail: [email protected]. Her research interests include wind erosion, air pollution, geographic information systems, remote sensing, spatial data science, and modeling.
Maryam Mirakbari
MARYAM MIRAKBARI is a PhD Graduate in the Department of Arid and Mountainous Regions Reclamation at Tehran University, 891546-3849 Tehran, Iran. E-mail: [email protected]. Her research interests include natural hazards, climate change, and modeling.
Mojtaba Soleimani-Sardo
MOJTABA SOLEIMANI-SARDO is an Assistant Professor in the Department of Natural Science at Jiroft University, 78671-61167 Jiroft, Iran. E-mail: [email protected]. His research interests include land degradation, land evaluation, and geographic information systems.