Northwestern Indo-Gangetic Plain Research Articles

Transport of short-lived climate forcers/pollutants (SLCF/P) to the Himalayas during the South Asian summer monsoon onset

Over the course of six years (2006–2011), equivalent black carbon (eqBC), coarse aerosol mass (PM1–10), and surface ozone (O3), observed during the monsoon onset period at the Nepal Climate Observatory–Pyramid WMO/GAW Global Station (NCO-P, 5079 m a.s.l.), were analyzed to investigate events characterized by a significant increase in these short-lived climate forcers/pollutants (SLCF/P). These events occurred during periods characterized by low (or nearly absent) rain precipitation in the central Himalayas, and they appeared to be related to weakening stages (or ‘breaking’) of the South Asian summer monsoon system. As revealed by the combined analysis of atmospheric circulation, air-mass three-dimensional back trajectories, and satellite measurements of atmospheric aerosol loading, surface open fire, and tropospheric NOx, the large amount of SLCF/P reaching the NCO-P appeared to be related to natural (mineral dust) and anthropogenic emissions occurring within the PBL of central Pakistan (i.e., Thar Desert), the Northwestern Indo-Gangetic plain, and the Himalayan foothills. The systematic occurrence of these events appeared to represent the most important source of SLCF/P inputs into the central Himalayas during the summer monsoon onset period, with possible important implications for the regional climate and for hydrological cycles.

Nonexchangeable K release and supplying power of Indo-Gangetic alluvial soils

Nonexchangeable K release in facilitating its uptake from 12 alluvial soils of three distinct agroecozones of northwestern Indo-gangetic plain has been investigated. The initial exchangeable K contents of 53, 39 and 261 mg/kg, declined by 32%, 43% and 19% in soils of submontane, central plain and southwestern arid zone, respectively, after cropping successively with maize, wheat and guinea grass. We studied the nonexchangeable K release to plant roots in green house and to H +-resin in laboratory. Release of K was quantitatively recovered as cumulative uptake by maize, wheat and guinea grass. Cumulative K uptake was significantly related to nonexchangeable K released to plant roots ( r=0.85) and K released to H +-resin (0.71). Relationship between initial level of exchangeable K and cumulative K uptake in maize, wheat and guinea grass on these soils was highly significant ( r=98). A significant correlation between nonexchangeable K released to H +-resin and plant roots ( r=0.92) provides a commendable evidence for reliability of laboratory method for use in K release studies.