The sunlit lunar atmosphere: A comprehensive study by CHACE on the Moon Impact Probe of Chandrayaan-1

The altitudinal/latitudinal profile of the lunar atmospheric composition on the sunlit side was unraveled for the first time by the Chandra’s Altitudinal Composition Explorer (CHACE) on the Moon Impact Probe, a standalone micro-satellite that impacted at the lunar south pole, as a part of the first Indian mission to Moon, Chandrayaan-1. Systematic measurements were carried out during the descent phase of the impactor with an altitude resolution of ∼250 m and a latitudinal resolution of ∼0.1°. The overall pressure on the dayside and the neutral composition in the mass range 1-100 amu have been measured by identifying 44 and 18 amu as the dominant constituents. Significant amounts of heavier (>50 amu) species also have been detected, the details of which are presented and discussed.     

Biogeochemical cycling in the Taiwan Strait

Based on repeat observations made during 2001–2003 along two transects in the Taiwan Strait this study aims at understanding factors controlling primary productivity with an emphasis on biogeochemical cycling of nitrogen, the major bio-limiting macronutrient. The Taiwan Strait receives copious supplies of nutrients through river runoff and upwelling in its western and northeastern parts, respectively, but the phytoplankton biomass, as inferred from the Chl a concentration, does not appear to be commensurately high. It is proposed that high water turbidity results in light limitation of primary productivity, especially in the western part of the strait. The accumulation of nitrite in the surface mixed layer appears to be due to nitrate reduction during phytoplankton assimilation, whereas in the near-bottom waters nitrite is most likely produced during nitrification. The net balance between input and loss of nitrogen is inferred from the nitrogen tracer N*. The Taiwan Strait is found to be a net recipient of combined nitrogen.     

Primary description of surface water phytoplankton pigment patterns in the Bay of Bengal

Spatial and temporal variations in surface water phytoplankton pigment distribution in the Bay of Bengal were studied during the spring intermonsoon (SpIM, February–April) and the commencement of the summer monsoon (CSM, May–June), using pigment and diagnostic indices. The Prokaryotic pigment index (Prok_DP) was dominant at all the oceanic stations whereas the Flagellate pigment index (Flag_DP) was dominant at the near coastal stations. However, during the commencement of summer monsoon, an oscillation in the dominance of Prok_DP and Flag_DP was observed in the central oceanic bay, whereas flagellates and diatoms were dominant at the near coastal stations. This change in pigment pattern is possibly related to the influence of rainfall. Comparison of pigment data with microscopic cell counts indicated a significant relationship between the diatom pigment index (Diat_DP) and diatom abundance. However, the relationship between the dinoflagellate pigment index (Dino_DP) and dinoflagellate abundance was not significant. Studies coupling pigment composition analysis with microscopic analysis of phytoplankton in natural conditions should thus be a prerequisite in establishing valid biogeochemical and ecosystem models.     

Trace elements in the atmospheric aerosols at Delhi,North India

The total suspended particulate (TSP) levels at Delhi (north India) were measured on 116 days between February and October 1980. The observations were stratified according to season and the values of cross-correlation of the TSP and its components were evaluated. High TSP (209 g m^-3) levels were found during the summer period associated with hot and dry weather in the region and low TSP (109 g m^-3) were found during the monsoon period. Most of the TSP mass was associated with natural soil elements, such as Fe, Al, Mn, Ca, and K. Only a fraction of the mass of the TSP was comprised of elements from anthropogenic sources, e.g., Pb, Ni, Cd, Sb, Cu, and Zn. The aerosols at Delhi were potentially basic in nature, unlike those in European countries which are acidic in nature and cause acid rainfall.     

Influence of atmospheric pollutants on cloud microphysics and rainfall

For investigating the physical reasons for the observed increase in rainfall, field observational programmes have been undertaken in the upwind and downwind of industrial complexes of the Bombay region. During these programmes, surface observations of trace gases ( SO₂ and NO_x), giant size hygroscopic and nonhygroscopic aerosols and rain water samples have been made in the years 1972, 1973 and 1974. Aircraft observations of trace gases (SO₂ and NH₃), giant size aerosols, cloud condensation nuclei as well as of cloud liquid water content, cloud droplet spectra and temperature have been made on limited days during August 1974. Results of the analysis of the surface and aircraft observations have indicated that the chemical, thermal and microphysical conditions of clouds are markedly different in the upwind and downwind regions of the industrial complexes in the Bombay region. It is hypothesised that observed increase in rainfall in the region following the industrialisation is due to the differences in the chemical and physical conditions in the downwind clouds.     

Assessment of vulnerability zones for ground water pollution using GIS-DRASTIC-EC model: A field-based approach

Assessment of groundwater vulnerability to pollution is an essential pre-requisite for better planning of an area. We present the groundwater vulnerability assessment in parts of the Yamuna Nagar District, Haryana State, India in an area of about \(800 \hbox { km}^{2}\), considered to be a freshwater zone in the foothills of the Siwalik Hill Ranges. Such areas in the Lower Himalayas form good groundwater recharge zones, and should always be free from contamination. But, the administration has been trying to promote industrialization along these foothill zones without actually assessing the environmental consequences such activities may invite in the future. GIS-DRASTIC model has been used with field based data inputs for studying the vulnerability assessment. But, we find that inclusion electrical conductivity (EC) as a model parameter makes it more robust. Therefore, we rename it as GIS-DRASTIC-EC model. The model identifies three vulnerability zones such as low, moderate and high with an areal extent of 5%, 80% and 15%, respectively. On the basis of major chemical parameters alone, the groundwater in the foothill zones apparently looks safe, but analysis with the help of GIS-DRASTIC-EC model gives a better perspective of the groundwater quality in terms of identifying the vulnerable areas.