Mercury (Hg) is a highly toxic metal, which is known as a global pollutant due to its ability to undergo long-range transport in the atmosphere. Methylated mercury can pose serious adverse effects on human health and environment. Mercury is emitted into the atmosphere by various natural and anthropogenic sources. The largest anthropogenic source of mercury is coal combustion, which contributes ~62% of global emissions. Total global emissions of atmospheric mercury are estimated to be 5600 Mg/year from natural and anthropogenic sources, respectively, contributing around 37% and 63% of total atmospheric mercury. About 40% of global anthropogenic emissions are contributed by East and Southeast Asia with the largest emissions from China (75%) followed by South America and Sub-Saharan Africa. Latter regions are mainly responsible due to increase in artisanal and small scale gold mining. The present estimates of mercury emissions have large uncertainties in global budget, which are mainly due to lack of knowledge of mercury exchange between various components of ecosystem with its speciation in spatial and temporal distribution. Special efforts are needed in the regions of growing economy especially in South Asia where atmospheric mercury is almost unattempted. In order to reduce uncertainties and get more realistic emission figures, there is need to develop an extensive monitoring network to measure various forms of mercury in air, soil and aquatic systems in south Asia. Controlling the emissions of global atmospheric mercury is a big challenge to the scientists and policymakers. Probably, it can be achieved by focusing on implementation of the available technologies and by developing new technologies for mercury removal through developing an extensive partnership between industries and governmental organizations.

Recently, air quality has become a matter of concern of everyone. According to the reports, atmospheric aerosols play very crucial role in air quality. PM 10 and PM 2.5 aerosols are integral parts of total suspended particulate matter which affect our health. Often air quality has been reported very poor due to violation of National Ambient Air Quality Standard (NAAQS) limits. PM 10 and PM 2.5 limits are crossed for both residential as well as sensitive sites. This is one of the major reasons of increasing cases of respiratory diseases in urban areas. However, aerosol loadings alone are not the factor for deciding or predicting toxic and harmful effects of aerosols. Chemical composition and size ranges do matter. Aerosol loadings can be due to three major source categories viz. marine, crustal and anthropogenic. Since, marine and crustal content of aerosols are generally non-toxic and hence, degree of toxicity of air needs to be decided on the basis of anthropogenic fraction having metals, PAHs and other harmful content. Apart from air quality and health, atmospheric aerosols play vital role in other atmospheric processes such as cloud formation, radiative transfer and monsoon etc. Though there are several studies reported on different aspects of atmospheric aerosols, but most of the findings are sort of data reporting based on short term observations. Hence, there is need to investigate the atmospheric aerosols in order to demonstrate local and regional phenomenon on the basis of long term datasets.

Crop residue burning is a major environmental issue and their potential long‐term impact on the climate is a global concern. A laboratory experiment was carried out to study the impact of biochar on carbon loss from tropical soils. Residues of two important foodgrain crops viz, rice and wheat were used to prepare respective biochar and added as amendments in two different tropical agricultural soils (red and alluvial). In general carbon loss was more from alluvial soil than red soil. In alluvial soil, carbon loss was more when biochars were applied along with N fertilizer (urea) than biochar alone. Increasing rate of application of rice biochar without urea showed potential carbon protection in alluvial soil. Interestingly, unlike rest of the treatments, carbon loss was more in red soil when wheat biochar was applied without urea than with it. While physicochemical characteristics of biochars play crucial role in carbon protection, the intrinsic nature and properties of soil largely regulates it. © 2015 American Institute of Chemical Engineers Environ Prog, 35: 183–188, 2016