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In India, rain water and atmospheric aerosols are observed to be alkaline in nature due to the influence of soil-derived particles which are rich in components like Ca and Mg. These components increase the neutralization potential of rain water and have a greater influence at rural site compared to urban site. However, if there are continuous rains, the concentration of crustal components becomes lower resulting in lower pH of rain water. Unlike the characteristics of rain water on continent, the pH of rain water has been observed to be acidic in all the events over the Indian Ocean during Pre-campaigns of Indian Ocean Experiment (INDOEX). The possible reason for acidic rains over Indian Ocean could be the anthropogenic contribution from continent transported by NE winds coming towards the ocean during this period.

Fluxes of nitrous oxide (N2O) were measured in situ monthly for two years from a tropical shallow urban pond, receiving influx of agricultural run-off from the surrounding water shade and domestic sewage, located in Ujjain city, Madhya Pradesh. Results revealed that the shallow pond is a continuous source of N2O with relatively low efflux value (0.00 to 0.51 mg m-2 d-1) and maximum emission generally occurred during the hot seasons (77% of annual emission), with annual mean of 1.0 kg N2O ha-1 yr-1. Several influencing factors like pH, temperature, total nitrogen, inorganic nitrogen stock and organic carbon were studied concomitantly with N2O gas flux measurement. N2O emissions were positively and significantly correlated with sediment total nitrogen and surface water temperature. The study concludes that the shallow tropical water body is a source of N2O flux, but does not have significant efflux compared to the terrestrial habitats.

During INDOEX IFP-99, the samples of aerosols were collected onboard ORV Sagar Kanya over Indian Ocean along the cruise track, for chemical characterization and identification of dominating sources of aerosols. The concentrations of nss-SO4, nss-Ca, nss-Mg, NO3, K, NH4 and SO2 were observed to be significantly higher before ITCZ in northern hemisphere than across ITCZ in southern hemisphere. In this study, variation of concentrations of nss-SO4, nss-Ca and nss-K with respect to change in latitude, wind direction, wind speed and relative humidity have been highlighted. North of ITCZ, nss-SO4 varied from 2.20 to 18.31 μg/m3 and south of ITCZ from 0.50 to 2.79 μg/m3 while nss-Ca varied from 0.02 to 0.72 μg/m3 north of ITCZ and from 0.01 to 0.14 μg/m3 south of ITCZ. nss-K ranged 0.09–1.43 μg/m3 and 0.07–0.60 μg/m3 before ITCZ and across ITCZ respectively. nss-Ca and nss-SO4 were contributed mainly by NNW and ENE winds while nss-K was observed to be contributed mainly by SSW and ENE winds. Wind speed greater than 4.5 m/s negatively influenced the concentration of nss-Ca concentrations. Correlation coefficients of nss-SO4 with SO2 (r = 0.7) and RH (r = 0.5) suggested a significant contribution of nss-SO4 by aqueous phase oxidation of SO2. Using PCA, four major sources namely sea salt, biogenic combustion, secondary SO4 and crustal contribution were identified over Indian Ocean during INDOEX period.

The starting point for a good design of any building project is the analysis of the macroclimate and microclimate of the building site that encompasses an understanding of temperature, radiation, wind, precipitation, topography, vegetation, ground cover, etc., which together describe the site climate. Although urban context somewhat unifies, climate and topography prevalent in India are varied and diverse. Most part of the country is hot, while some regions are dry throughout the year, some are humid and some others are composite. The building design features, therefore, need to vary with the diversity to provide comfortable environments naturally. The context and the requirements for thermal comfort provide the basis for building siting, selection of building form and envelope, fenestration design, choice of materials, and other aspects. The paper proposes and discusses the various climate-responsive design strategies that are best adapted for the different climatic zones of India and presents such design interventions and features as a comparative matrix. Such a comparative presentation is novel, convenient, easy to comprehend, and provides a useful toolkit for building designers. The climate-responsive interventions in building design proposed in this study have the potential to enhance built environments naturally, thereby mitigating the adverse environmental impact. The proposed strategies are also validated through a sample field survey responded by building professionals from various climatic zones of the country.

During INDOEX pre-campaigns held in 1995–96, 1996–97 and FFP 1998, the pH of rainwater over the Indian Ocean was observed to be acidic (pH < 5.6). North of or across the Inter-Tropical Convergence Zone (ITCZ), the acidic pH might be caused by the long-range transport of gaseous pollutants such as SO2 and NO2 from the Indian subcontinent as well as east African region. The acidity is believed to be contributed by mainly sulphate which may have been produced during SO2 oxidation over the ocean or longdistance travelling of submicron size SO4 aerosols. Non-sea salt (nss) SO4 and nss Ca were higher near the continent and decreased towards the southern hemisphere. Measurements of total suspended particulate (TSP) matter during the period coinciding with INDOEX pre-campaign 1996 were done at Delhi and compared with the data obtained from the INDOEX pre-campaign-96. Surface measurements were also carried out at Delhi. The concentration of TSP varied greatly over the Indian Ocean during INDOEX pre-campaign 1996 as compared with Delhi. In addition Ca, Mg, SO4 and NH4 dominated at Delhi while Cl, Na and SO4 dominated over the ocean.

Concentrations of total carbon (TC) and black carbon (BC) in ambient air at Delhi (urban site) and over Indian Ocean (remote marine) were determined as a part of INDOEX programme. Over Indian Ocean, the TC and BC concentrations varied from 1.81 to 10.05 μg/m3 and 0.13 to 1.36 μg/m3 respectively during FFP-98. During the same season at Delhi, the TC and BC ranged from 7.50 to 40.27 μg/m3 and 0.49 to 2.84 μg/m3 respectively. In addition, at Delhi, the TC and BC concentrations were noticed very low during the monsoon season. However, the percentage BC during monsoon season was very high compared to winter season. High concentrations of TC were observed due to high organic carbon (OC) which might be due to biomass burning of various kinds. Similar to Delhi, near Indian coast, the concentration of OC was very high while towards ITCZ and across ITCZ, OC content was relatively lower.

Measurements of surface concentration of trace gas species including greenhouse gases, viz. CO, CH4, CO2, N2O have been carried out over the Indian Ocean region on board the research vessel Sagar Kanya (SK) from 4 January to 7 February 1996, 27 December 1996 to 31 January 1997 and 18 January to 31 March 1998, respectively. The positive latitudinal gradient from south to north has been observed for various measured trace species during the above precampaigns. It could be attributed to the continental air-mass flow across the Inter-Tropical Convergence zone (ITCZ).

Emissions of NOx, NH3 and N2O from anthropogenic activities in India have been estimated based on actual field measurements as well as available default methodologies. The NOx emissions are mainly from the transport sector and contribute about 5% of the global NOx emission from fossil fuel. NH3 emissions from urea seems to be highly uncertain. However, emissions of NH3 from fertilizers and livestock are estimated to be 1175 Gg and 1433 Gg, respectively. N2O emissions seem to be derived predominantly from fertilizer applications, resulting in the release of 199-279 Gg N2O. Other sources of N2O, viz. agricultural residue burning, biomass burning for energy and nitric acid production are estimated to be 3, 35-187 and 2-7 Gg, respectively.

Increased industrialization and urbanization lead to the atmospheric acidity which causes acid rain. However, in India, the nature of rain water has been observed to be alkaline. The reason for alkaline nature of rain water is found to be the buffering of acidity by soil-derived aerosols which are rich in Ca. Over the Indian Ocean where concentrations of soil dust are negligible, the acid rain has been observed to be a common phenomenon during INDOEX campaigns. In the Indian subcontinent, observations have indicated that rain becomes acidic when the buffering potential of rain water is weak. The weak buffering potential may be due to less interference of soil dust, acidic nature of soil or very high influence of industrial source.

Wetlands are the largest natural source of methane to the atmosphere. Methane emission from a polluted, tropical coastal wetland in Madras City was measured throughout the year adopting the closed-chamber technique. Distinct spatial and temporal variations in methane emission were observed in the wetlands, based on the degree of pollution, at each of these locations. The inhibiting influences of sulfate and salinity on methanogenesis were also obvious features in the present study. Soil temperature, sediment water content, salinity and sulfate were found to be critical natural variables influencing the methane emission rates. This study indicates that due to human interference in this ecosystem, on an average, ∼ 15.58 mg${\\rm m}^{-2}\\ {\\rm hr}^{-1}$of methane is emitted from the Adyar Estuary, which is significantly higher than that reported for similar unpolluted natural wetlands (∼ 6.02 mg${\\rm m}^{-2}\\ {\\rm hr}^{-1}$). At the confluence of the Adyar Estuary with the Bay of Bengal, the emission characteristics were significantly reduced (3.27 mg${\\rm m}^{-2}\\ {\\rm hr}^{-1}$) due to the influence of seawater.