Heavy metals from the River Adayar,India: infiltration into the adjacent groundwater aquifer

In the Adayar riverbed and its estuary 5 undisturbed sediment cores were drilled using a petrol-driven hammer. Cores of a depth of 4-5 m were sampled in 0.5 m steps. The distribution of heavy metals (Cr, Mn, Ni, Cu, Zn, Cd and Pb) in the top layers of fluvial and estuarine sediments indicates recent anthropogenic input: Revealing that the river acts as a sink for drainage from the residential and industrial zones. In this study, the mobilization of heavy metals into greater depths and their probable effects on the groundwater body are discussed. The high concentration of heavy metals and the influent character of the river Adayar allow the mobilization of metal ions and their transport into the deeper layers of the sediment. A changing environment due to effects such as saltwater intrusion and monsoon floods is the driving force for this phenomenon.     

New experimental methods for the development and evaluation of aerosol samplers

An understanding of the scaling laws governing aerosol sampler performance leads to new options for testing aerosol samplers at small scale in a small laboratory wind tunnel. Two methods are described in this paper. The first involves an extension of what is referred to as the "conventional" approach, in which scaled aerosol sampler systems are tested in a small wind tunnel while exposed to relatively monodisperse aerosols. Such aerosols are collected by test and reference samplers respectively and assessed gravimetrically. The new studies were carried out for a modified, low flowrate version of the IOM personal inhalable aerosol sampler. It was shown that such experiments can be carried out with a very high level of repeatability, and this supported the general validity of the aerosol sampler scaling laws. The second method involves a novel testing system and protocol for evaluating the performances of aerosol samplers. Here, scaled aerosol samplers of interest are exposed to polydisperse aerosols, again in a small wind tunnel. In this instance, the sampled particles are counted and sized using a direct-reading aerodynamic particle sizer (the APS). A prototype automated aerosol sampler testing system based on this approach was built and evaluated in preliminary experiments to determine the performance of another modified version of the IOM personal inhalable aerosol sampler. The design of the new test system accounts for the complex fluid mechanical coupling that occurs near the sampler inlet involving the transition between the external flow outside the sampler and the internal airflow inside the sampler, leading in turn to uncontrolled particle losses. The problem was overcome by the insertion of porous plastic foam plugs. where the penetration characteristics are well understood, into the entries of both the test and the reference samplers. Preliminary experiments with this new system also supported the general validity of the aerosol sampler scaling laws. In addition, they demonstrated high potential that this approach may be applied in a standardised aerosol testing method and protocol.     

Panel heterogeneous distribution analysis of trade and modernized agriculture on CO2 emissions: The role of renewable and fossil fuel energy consumption

In line with the global target of reducing climate change and its impact, this study explored the causal relationship between CO₂ emissions, modernized agriculture, trade openness, aggregate and disaggregate energy consumption in 14 African countries from 1990–2013 using a panel quantile estimation procedure. The empirical results showed that value addition to agricultural commodities declines CO₂ emissions in countries with high pollution levels. The study revealed a positive nexus between CO₂ emissions and energy consumption homogeneously distributed across quantiles. Trade openness was found to lower CO₂ emissions in countries with lower and higher levels of environmental pollution. While fossil fuel energy consumption was found to exacerbate CO₂ emissions, renewable energy consumption confirmed its mitigating effect on environmental pollution. The institution of climate‐smart agricultural options will sustainably increase productivity and income while adapting to climate change by reducing greenhouse gas emissions. Diversification of energy technologies with clean and modern energy sources like renewables avoid the over‐dependence on fossil fuels for agricultural purposes. Trade policies can stimulate flows of technology and investment opportunities for specialization in production and economies of scale. Hence, the consideration of policies that boost agricultural sector productivity and create an efficient market for international trade in Africa will help in improving livelihoods.     

Adaptation investments: a resource allocation framework

Additional finance for adaptation is an important element of the emerging international climate change framework. This paper discusses how adaptation funding may be allocated among developing countries in a transparent, efficient and equitable way. We propose an approach based on three criteria: the climate change impacts experienced in a country, a country’s adaptive capacity and its implementation capacity. Physical impact and adaptive capacity together determine a country’s vulnerability to climate change. It seems both efficient and fair that countries which are more vulnerable should have a stronger claim on adaptation resources. The third dimension, implementation capacity, introduces a measure of adaptation effectiveness. Rough indicators are proposed for each of the three dimensions. The results are indicative only, but they suggest a strong focus of initial adaptation funding on Africa. African countries are highly vulnerability in part because of the severity of expected impacts, but also because of their very low adaptive capacity. However, their implementation capacity is also limited, suggesting a need for technical assistance in project implementation.     

SETAC GLB and SETAC Europe SAC: a liaison promoting the next generation of ecotoxicologists and environmental chemists

This commentary is an introduction for students to the Society of Environmental Toxicology and Chemistry (SETAC) and its Student Advisory Council (SAC). As young academics face challenges while trying to develop their careers, SETAC and the SAC help facilitate student involvement in the various communities within the society that can help to develop the students’ careers within the environmental sciences [e.g. the German Language Branch (GLB)]. This piece would also like to emphasize and pay homage to the continual cooperation between the SAC and the ESEU, which provides a scientific platform to communicate internationally and beyond the borders of SETAC, as well as offer heartfelt congratulations from the SAC to the GLB for their “20 Years SETAC GLB” and deep gratitude for their strong advocacy and support of the SAC.     

Some issues of environmental concern in Kampala,the capital city of Uganda

Kampala, the capital city of Uganda is the administrative, political, commercial, industrial, educational and cultural centre of Uganda. The city has an area of 190 km² and is located 8 km north of Lake Victoria (the second largest fresh water lake in the world) and approximately 42 km north of the equator. The population varies from about 1.2 million during the day to perhaps 0.9 million at night. The anthropogenic activityof this population far exceeds the infrastructure capacity of the city, leading to the deterioration of the urban environment. This article highlights the major sources of environmental degradation and pollution in the city, which include solid waste,abattoir waste, sewage, sanitation, drainage, industrial pollution, traffic pollution, atmospheric pollution, urban agriculture, rapid urbanisation and water hyacinth.     

Model of coral population response to accelerated bleaching and mass mortality in a changing climate

We model coral community response to bleaching and mass mortality events which are predicted to increase in frequency with climate change. The model was parameterized for the Arabian/Persian Gulf, but is generally applicable. We assume three species groups (Acropora, faviids, and Porites) in two life-stages each where the juveniles are in competition but the adults can enter a size-refuge in which they cannot be competitively displaced. An aggressive group (Acropora species) dominates at equilibrium, which is not reached due to mass mortality events that primarily disadvantage this group (compensatory mortality, >90% versus 25% in faviids and Porites) roughly every 15 years. Population parameters (N individuals, carrying capacity) were calculated from satellite imagery and in situ transects, vital rates (fecundity, mortality, and survival) were derived from the model, field observations, and literature. It is shown that populations and unaltered community structure can persist despite repeated 90% mortality, given sufficiently high fecundity of the remaining population or import from connected populations. The frequency of disturbance determines the dominant group—in low frequency Acropora, in high frequency Porites. This is congruent with field observations. The model of an isolated population was more sensitive to parameter changes than that of connected populations. Highest sensitivity was to mortality rate and recruitment rate. Community composition was sensitive to spacing of disturbances and level of catastrophic mortality. Decreased mortality led to Acropora dominance, increased mortality led to Acropora extinction. In nature, closely spaced disturbances have severely disadvantaged Acropora populations over the last decade. Unless a longer (>10 years) disturbance-free interval can be maintained, a permanent shift away from Acropora dominance will be observed. A mortality rate of 99% in Acropora, as observed in 1996, is not sustainable if repetitive and neither is a disturbance frequency <15 years—each leading to population collapse. This shows that the severity and/or the spacing of the 1996–1998–2002 disturbances were unusual in frequency and duration.     

Forest succession suppressed by an introduced plant-fungal symbiosis

Microbial symbionts can affect plant nutrition, defensive chemistry, and biodiversity. Here we test the hypothesis that symbionts alter the speed and direction of plant succession in communities that are shifting from grasslands to forests. A widespread C3 grass introduced to the United States, Lolium arundinaceum (tall fescue), hosts a fungal endophyte that is toxic to herbivores. In replicated experimental grasslands, the presence of the endophyte in tall fescue reduced tree abundance and size, altered tree composition, and slowed plant species turnover. In addition, consumption of tree seedlings by voles (Microtus spp.) was 65% higher in plots with the endophyte at the one grassland site where these data were collected. Despite its negligible contribution to community biomass, a microbial symbiont suppressed tree establishment, posing an important constraint on the natural transition from grasslands to forests.     

Nestedness of remnant sonoran desert plant communities in metropolitan Phoenix, Arizona

Urbanization can have profound effects on the plant communities persisting in remnant habitats. That process can be explored by examining patterns of nestedness. Species composition for a set of communities exhibits a nested pattern if species present in progressively richer assemblages form a series of subsets. Nestedness can form as a result of the dynamic processes of extinction or colonization. It can also reflect a nested distribution of habitats among the sites or the differential abundance properties of species through passive sampling. This study investigated whether Sonoran Desert woody vegetation in remnant islands within metropolitan Phoenix is nested and explored which mechanisms are responsible for the pattern. It also examined whether vegetation is nested in similar habitat types across islands, and how species abundance relates to the nested pattern and hypothesized mechanisms. All data sets were significantly nested, indicating a nested pattern at the island and habitat levels. Community-level analyses did not indicate a primary mechanism leading to the nested pattern. Among species with abundances correlated with the nested rank-order of sites, abundance properties were significantly related to different variables. This suggests that individual taxa respond to divergent ecological mechanisms, leading to nestedness. Thus, nestedness in plant communities can result from a complex set of contributors and may not be attributable to a single factor.