Heavy metals and soil microbes

Heavy metal pollution is a global issue due to health risks associated with metal contamination. Although many metals are essential for life, they can be harmful to man, animal, plant and microorganisms at toxic levels. Occurrence of heavy metals in soil is mainly attributed to natural weathering of metal-rich parent material and anthropogenic activities such as industrial, mining, agricultural activities. Here we review the effect of soil microbes on the biosorption and bioavailability of heavy metals; the mechanisms of heavy metals sequestration by plant and microbes; and the effects of pollution on soil microbial diversity and activities. The major points are: anthropogenic activities constitute the major source of heavy metals in the environment. Soil chemistry is the major determinant of metal solubility, movement and availability in the soil. High levels of heavy metals in living tissues cause severe organ impairment, neurological disorders and eventual death. Elevated levels of heavy metals in soils decrease microbial population, diversity and activities. Nonetheless, certain soil microbes tolerate and use heavy metals in their systems; as such they are used for bioremediation of polluted soils. Soil microbes can be used for remediation of contaminated soils either directly or by making heavy metals bioavailable in the rhizosphere of plants. Such plants can accumulate 100 mg g^?1 Cd and As; 1000 mg g^?1 Co, Cu, Cr, Ni and 10,000 mg g^?1 Pb, Mn and Ni; and translocate metals to harvestable parts. Microbial activity changes soil physical properties such as soil structure and biochemical properties such as pH, soil redox state, soil enzymes that influence the solubility and bioavailability of heavy metals. The concept of ecological dose (ED₅₀) and lethal concentration (LC₅₀) was developed in response to the need to easily quantify the influence of pollutants on microbial-mediated ecological processes in various ecosystems.     

Achieving sustainable homes by 2016 in the UK: the current status

The code for sustainable homes (CSH), which came into existence in 2006, has not yet been investigated to determine whether its rate of adoption is on course to meet the UK government’s 2016 target for full implementation. Therefore, the aim of this investigation is to ascertain the level to which CSH has been implemented and the barriers preventing this. A questionnaire survey was sent to 71 of the Home Builders Federation (HBF) member organisations in the UK, to gauge and ascertain the following: the barriers to the implementation of CSH; the implications of implementation; and the general awareness of CSH amongst practitioners. The results from the analysis of the survey reveal that full implementation by 2016 appears a rather difficult target, as factors like economic downturn are hitting HBF and similar organisations quite hard. However, a government-driven injection of sustainable schemes is helping to bring back confidence to house builders, while also enhancing the way that barriers are handled within the industry. The key findings of the literature review identify barriers preventing the housing sector from achieving zero carbon homes by 2016. These include cost, and legislative, cultural and technical barriers, and are concordant with the results from the data obtained during the primary research. The analysis suggests that with the current trend, achieving full implementation will be difficult. However, comments made by some practitioners appear to suggest that the appointment of a CSH champion for implementation would accelerate the process of full implementation and that the target could be reached by 2016.     

The relationship between air pollution,fossil fuel energy consumption,and water resources in the panel of selected Asia-Pacific countries

The objective of the study is to examine the relationship between air pollution, fossil fuel energy consumption, water resources, and natural resource rents in the panel of selected Asia-Pacific countries, over a period of 1975–2012. The study includes number of variables in the model for robust analysis. The results of cross-sectional analysis show that there is a significant relationship between air pollution, energy consumption, and water productivity in the individual countries of Asia-Pacific. However, the results of each country vary according to the time invariant shocks. For this purpose, the study employed the panel least square technique which includes the panel least square regression, panel fixed effect regression, and panel two-stage least square regression. In general, all the panel tests indicate that there is a significant and positive relationship between air pollution, energy consumption, and water resources in the region. The fossil fuel energy consumption has a major dominating impact on the changes in the air pollution in the region.     

Cement-based batteries design and performance. A review

Environmental Chemistry Letters - Lithium batteries are increasingly used to store energy, but are limited by high cost, safety concerns, leaking of electrolytes, and low capacity....     

Use of glazed ceramic waste as additive in mortar and the mathematical modelling of its strength

This study investigated the reusability of waste material from the tile manufacturing industry as an alternative material to natural pozzolan trass. Yield strength values of mortar made from Portland cement (CEM 142.5), were measured by adding glazed ceramic waste and trass at various weight ratios (5 to 40%). The test results proved that the strength values at 2, 7, and 28 days gave good results for concentrations of waste materials less than 5-10% in the cement. A decrease in strength was observed at higher concentrations. Mathematical modelling results showed a logarithmic correlation between the mortar strength and weight fraction of cement.