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Abstract: There is growing evidence that the earth’s climate is changing and will likely continue to change in the future. It is still debated whether these changes are due to natural variability of the climate system or a result of increases in the concentration of greenhouse gases in the atmosphere. Black carbon (BC) has become the subject of interest for a variety of reasons. BC aerosol may cause environmental as well as harmful health effects in densely inhabited regions. BC is a strong absorber of radiation in the visible and near-infrared part of the spectrum, where most of the solar energy is distributed. Black carbon is emitted into the atmosphere as a byproduct of all combustion processes, viz., vegetation burning, industrial effluents and motor vehicle exhausts, etc. In this paper, we present results from our measurements on black carbon aerosols, total aerosol mass concentration and aerosol optical depth over an urban environment namely Hyderabad during January to May, 2003. Diurnal variations of BC indicate high BC concentrations during 6:00–9:00 and 19:00–23:00h. Weekday variations of BC concentrations increase gradually from Monday to Wednesday and gradually decrease from Thursday to Sunday. Analysis of traffic density along with meteorological parameters suggests that the primary determinant for BC concentration levels and patterns is traffic density. Seasonal variations of BC suggest that the BC concentrations are high during dry season compared to rainy season due to the scavenging by air. The fraction of BC to total mass concentration has been observed to be 7% during January to May. BC showed positive correlation with total mass concentration and aerosol optical depth at 500nm. Radiative transfer calculations suggests that during January to May, diurnal averaged aerosol forcing at the surface is −33Wm2 and at the top of the atmosphere (TOA) above 100km it is observed to be +9Wm−2. The results have been discussed in detail in the paper. [Copyright &y& Elsevier]

Coastal morphodynamics and environmental changes have been obviously altered by global warming, sea-level fluctuations, and human activities. Palynological analysis is one of the most important tools for providing information on vegetation, climate, and environmental change, which can be relatively sensitive indicators of human activity during the Holocene. However, Holocene coastal morphodynamics and palynological evidence from the Pearl River Delta and coastal areas has not been sufficiently studied. In this paper, we carry out analyses using detailed grain-size and palynological records of pollen, spores, freshwater algae, and marine dinoflagellate cysts from Borehole QZK13 in the Pearl River Estuary (PRE), southern China. The results show information relating coastal morphodynamics, vegetation evolution, climate changes, and anthropogenic activities during the Holocene based on radiocarbon chronology. In general, the PRE experienced marine transgressive processes; sea-level and the coastline tended to migrate landward between 10,700 and 4250 cal yr BP. Meanwhile, abundant arboreal pollen (mainly Castanopsis , Quercus -evergreen, Oleaceae, and Castanea) and small amounts of non-arboreal pollen (mainly Poaceae, Cyperaceae, and Artemisia) were observed in Borehole QZK13, which suggests that subtropical evergreen broadleaved forests were distributed throughout the PRE and adjacent areas, and relatively warm and moist climatic conditions were present during the early-middle Holocene. After that, there were relatively cool and wet climatic conditions, and marine regressive processes occurred in the PRE during the Late Holocene (ca. 4250–960 cal yr BP) indicated by an abrupt increase in aquatic herbs and Dicranopteris. Moreover, we hypothesize that the Neolithic "cultural fault" in the PRE is likely related to frequent storm surges induced by extreme typhoon events that occurred ca. 3000–2700 yr BP. • Grain size, pollen, spores, freshwater algae and dinoflagellate cysts from the Pearl River Estuary were investigated. • Three major phases shown by palynological results were corresponding to the changes in vegetation and climate. • We hypothesized that the Neolithic "cultural fault" is probably related to the storm surges induced by extreme typhoon events. • Natural vegetation cover has suffered large-scale destruction by ancient humans during the Late Holocene. [ABSTRACT FROM AUTHOR]

• Knowledge of human impact on ecosystem services (ES) is derived from ethnography. • Landscape factors were examined to study human impacts on subsistence and logging ES. • Impact of variables were stronger at landscape-level than at village-level. • Both subsistence and commercial logging ES were distributed in similar locations. • Spatial analysis reinforced evidences of human impact on ES distributions. Indigenous peoples have long shaped the distributions of plants from which they derive ecosystems services (ES) critical to their subsistence lifestyles. Yet, much of our knowledge on how anthropogenic activities influence these ES by extension has been derived from ethnographic studies. In this paper we examined whether signals of the human presence could be detected from the distributions of two types of provisioning ecosystem services (PES) derived from plants – subsistence uses and commercial logging – in the Rupununi, Southern Guyana. The Rupununi landscape is dominated by indigenous peoples who have strong historical reliance on their forests for subsistence purposes; at the same time, many of the forest species hold considerable commercial timber values. Indices that quantified the subsistence and commercial logging PES were regressed against the five variables intended to estimate the human presence within the landscape – distance-to-village, distance-to-road, distance-to-water, elevation, and slope – at the landscape- and village-level. The analysis showed that the impact of the variables on both types of PES were stronger at the former level than at the latter. At the landscape-level, three variables (distance-to-village, distance-to-road, and elevation) significantly influenced the distributions of subsistence services while four variables (distance-to-village, distance-to-road, distance-to-water, and elevation) significantly influenced the distributions of logging services. On the other hand, at the village-level the effects of each variable on the two PES varied from village to village. In general, although the presence of subsistence services appeared to be more favorable than logging services, the distributions of both types of PES were still comparable across the landscape. The analysis supports earlier observations from ethnographic studies that suggested the human presence does influence the distributions of ES associated with plants and has implications for how logging is practiced in the tropics. [ABSTRACT FROM AUTHOR]

The contamination of ground water with arsenic is a great public health concern. This paper discusses the possible formation mechanism of high As groundwater; identify the main influences of natural and anthropogenic factors on As occurrence in groundwater; and finally estimates As-induced potential health hazards in an intensive agricultural region, Datong Basin (Northern China). Our findings indicate that the predominant controlling factors of As in groundwater can be divided into natural factors and anthropogenic activities. Natural factors can be classified as natural potential source of As, environmental geological characteristics and hydrochemical conditions; anthropogenic activities are manifested in industrial coal mining, domestic coal burning, agricultural irrigation return flow and excessive application of fertilizers, and groundwater exploitation. Microbial and/or chemical reduction desorption of arsenate from Fe-oxide/hydroxide and/or clay minerals, As-bearing Fe-oxide/hydroxide reduction coupled with sulfate reduction, and competition with phosphorus are postulated to be the major process dominating As enrichment in the alkaline and anoxic groundwater. In addition, age-dependent human health risk assessment (HHRS) was performed, and high risk values reveal a high toxic and carcinogenic risk of As contaminate for population who is subject to the continuous and chronic exposure to elevated As. Image 1 • Arsenic occurrence mechanism interpretation from natural and anthropogenic factors. • Arsenic pollution sources identification. • Human health risk assessment (HHRS) for age-dependent population. [ABSTRACT FROM AUTHOR]