JWSS - Journal of Water and Soil Science

Many studies have been done on various properties of dust and one of the most important characteristics of dust is the ability to carry different microorganisms from the source points. The aim of this study was to investigate the bacterial and fungal community of dust and to identify its dominance species in a single event of intense dust storm, in the northern regions of Sistan and Blauchestan Province (Sistan plain). Dust samples were accordingly collected by Siphon dust samplers after one of the most intense dust storms in 28-31 August, 2015, from 5 cities in the northern regions of Sistan and Blauchestan Province; after that, the microbial community of dust was determined by culturing in petri dish and its dominant bacterial and fungal species were identified. The results showed maximum aerobic and anaerobic bacteria population was observed in the Hirmand city dust (1875000 CFU/g and 156667 CFU/gr, respectively). The maximum aerobic fungi population was observed in the Zabol city (833 CFU/g) and the maximum anaerobic fungus population was observed in Zahak city (2167 CFU/g). The most frequent type of bacteria was Bacillus sp, which was followed by Streptomyces pactum. The most frequent type of fungi in this research was Penicillium sp and the second one was Aspergillus. The results showed the high and variated microbial community, especially pathogenic fungi associated with dust in this region.

The Helmand River is the main source of water for the Sistan Plain and underpins the provision of key ecosystem services, including water supply, agricultural production, forage provision, soil protection, and wildlife habitat. The operation of the Kamal Khan Dam and the diversion of river flow toward Goud-e Zereh have reduced downstream water availability and accelerated land degradation in Sistan. This study aimed to assess land-use and land-cover changes associated with Helmand River water availability before and after the operation of the dam. Land-use/land-cover maps for 2019, 2020, 2024, 2025, and 2026 were produced using Landsat imagery, supervised classification, and the Random Forest algorithm, and their accuracy was evaluated using field-based reference samples. The results showed that, after dam operation, the Hamoun-e Hirmand water body completely dried up, whereas the water-covered area around Kamal Khan Dam and in the Goud-e Zereh region increased from 3,039 ha in 2019 to 62,794 ha in 2026. In the Sistan Plain, agricultural land reached its maximum extent of 69,025 ha in 2020 but declined to 5,776 ha in 2025. In addition, the area of saline lands in the Sistan Plain and Hamoun increased from a minimum of 110,414 ha in 2020 to a maximum of 274,708 ha in 2026. These changes were accompanied by a reduction in rangelands, an expansion of barren lands, increased soil salinity, and greater soil susceptibility to wind erosion. The findings indicate that the diversion of water toward Goud-e Zereh, together with associated declines in agricultural land, rangelands, and soil moisture and the expansion of saline and barren lands, has weakened the ecosystem services provided by the Helmand River.