Since the Indus and Ganges flow into the Indian Ocean I doubt that plastics washed from India and Pakistan end up in the Pacific Ocean. But from China's Huang He and Yangzi and other Rivers, yeah.
Hotan is in Xinjiang "province", the westernmost "province" of China. The sand storms are more likely the result of local climate change and desertification due to cutting down trees and such. Large scale tree-cutting also caused local climate change in Qinghai Province, and is being reversed by several years of a mass tree planting program.