Potential effects of environmental change on mining wastes in a hyperarid climate

Three desert washes were sampled to evaluate the transport of contaminated sediments from abandoned mining sites to downwash environments. The area of concern is an extreme arid climate considered stable and not to pose pathways for contaminated sediments to impact downwash environments. Research of mine wastes in Nelson, Nevada has shown that residual geogenic and anthropogenic trace elements have been mobilized in surface sediments as a result of storm event. Cyanide and trace elements, especially mercury and lead, have transported to 6000 m downwash from source areas. Short term environmental impacts appear to be minimal because of present-day environmental conditions. However, climate shifts caused by the El Nino Southern Oscillations or even a dramatic climate shift might increase regional precipitation promoting a more rapid erosion of contaminated sediment. Currently, wash sediments do not contain levels of CN- or trace elements that pose threats to the environment; however, if erosion and transport of mining waste increased because of additional precipitation, then CN- and trace elements loading in storm water would increase, with their possibly delivery to Lake Mohave

Greenhouse gas emissions of waste management processes and options : a case study

Increasing concern about climate change is prompting organisations to mitigate their greenhouse gas emissions. Waste management activities also contribute to greenhouse gas emissions. In the waste management sector, there has been an increasing diversion of waste sent to landfill, with much emphasis on recycling and reuse to prevent emissions. This study evaluates the carbon footprint of the different processes involved in waste management systems, considering the entire waste management stream. Waste management data from the Royal Borough of Kingston upon Thames, London (UK), was used to estimate the carbon footprint for its (Royal Borough of Kingston upon Thames) current source segregation system. Second, modelled full and partial co-mingling scenarios were used to estimate carbon emissions from these proposed waste management approaches. The greenhouse gas emissions from the entire waste management system at Royal Borough of Kingston upon Thames were 12,347 t CO2e for the source-segregated scenario, and 11,907 t CO2e for the partial co-mingled model. These emissions amount to 203.26 kg CO2e t(-1) and 196.02 kg CO2e t(-1) municipal solid waste for source-segregated and partial co-mingled, respectively. The change from a source segregation fleet to a partial co-mingling fleet reduced the emissions, at least partly owing to a change in the number and type of vehicles

Climate change enhances the mobilisation of naturally occurring metals in high altitude environments

Manmade climate change has expressed a plethora of complex effects on Earth's biogeochemical compartments. Climate change may also affect the mobilisation of natural metal sources, with potential ecological consequences beyond mountains' geographical limits; however, this question has remained largely unexplored. We investigated this by analysing a number of key climatic factors in relationship with trace metal accumulation in the sediment core of a Pyrenean lake. The sediment metal contents showed increasing accumulation trend over time, and their levels varied in step with recent climate change. The findings further revealed that a rise in the elevation of freezing level, a general increase in the frequency of drier periods, changes in the frequency of winter freezing days and a reducing snow cover since the early 1980s, together are responsible for the observed variability and augmented accumulation of trace metals. Our results provide clear evidence of increased mobilisation of natural metal sources - an overlooked effect of climate change on the environment. With further alterations in climate equilibrium predicted over the ensuing decades, it is likely that mountain catchments in metamorphic areas may become significant sources of trace metals, with potentially harmful consequences for the wider environment

Phosphorus and emerging micro-pollutants in surface waters: challenges and prospects for water quality improvement

An oversupply of Phosphorus in water bodies accelerates growth of algae and higher forms of plant life to produce undesirable impacts on overall water quality. Phosphorus inputs to surface waters arise from a variety of point and nonpoint sources. However much of the P is contributed by agricultural runoff and outfall of treated (or untreated) wastewater in receiving water-bodies. Point sourced-P inputs to waters have considerably decreased in recent years, at least partly driven by regulatory requirements, e.g. the EU Water Framework Directive. This has largely been achieved by removing P from treated wastewaters at sewage treatment works (STWs). Studies have shown that introducing an additional treatment step (“P-stripping”) can significantly reduce P in STW outfalls. Given P deposits are depleting, there is much interest in phosphorus recovery from wastewaters. A few STWs have already started to recover P as struvite (NH4MgPO4.6H2O) mineral – a substitute for commercially produced P-fertilizers. This requires major investment and is not economically viable at small STWs. Nonetheless it is a major breakthrough in terms of P recovery and its use. Effluents from sewage treatment works (STW) can often contain a complex mixture of residual microcontaminants, not removed during wastewater treatment. Organic micro-pollutants have been found in rivers receiving STW effluents. Such residual contaminants have become the focus of an emerging field of water quality study and are collectively referred to as pharmaceuticals and other personal healthcare products, PPHCPs. Many of these chemicals have the ability to effect the hormonal signaling of organisms and are called endocrine disrupting compounds (EDC). Such chemicals have shown some of the most damaging biological effects in aquatic organisms. Biological effects in the aquatic environment are typically related to the development of intersex in fish. Recent research shows the use of STW practices such as upgrading from using a combined trickling filter contact process to activated sludge treatment, ozonation, membrane filtration and use of suspended biofilm reactors reduces the amount of EDCs in waste effluent. It is thus possible to remove contaminants from STW effluents, but it will not be possible without major infrastructure improvements. This paper presents the challenges and prospects of P and micro-organic pollutants in surface waters

Microbial biomass responses to soil drying-rewetting and phosphorus leaching

Soil drying-rewetting is known to enhance soil phosphorus leaching, which in part is due to osmotic shock and lysis of microbial cells upon rewetting. However, it is not entirely clear how this may be influenced by the intensity and duration of soil drying. We hypothesized that the intensity and duration of soil drying play important roles in determining the extent of dissolved reactive phosphorus (DRP) leaching resulting from microbial biomass mortality. To test this hypothesis soil sub-samples of a loamy grassland soil were dried (30 or 40°C for 2 or 14-days), rewetted, and the leachate was analyzed for DRP. Soil drying at 30°C for 2 and 14-days resulted in leachate DRP concentrations which were 71 and 271%, respectively, higher than those in leachate from a control moist counterpart. Relatively greater DRP leaching losses occurred from the soil dried at 40°C for 2 and 14-days (143 and 300%, respectively). To determine the contribution of the microbial biomass to the DRP in leachate, soil sub-samples were fumigated with chloroform either before or after drying (30 or 40°C for 2 or 14-days). All soil treatments were then either leached with water and analyzed for DRP or extracted with 0.5 M sodium bicarbonate solution and analyzed for microbial biomass phosphorus. Fumigating soil samples before or after drying reduced microbial biomass phosphorus. However, the effect of chloroform fumigation was more pronounced in terms of microbial biomass reduction in the DF (drying followed by fumigation) treatment. Moreover, results revealed that in the DF treatment, soils dried at 30°C for 2-days and 14-days had 22 and 13%, respectively, more microbial biomass phosphorus than their counterparts dried at 40°C for 2 and 14-days, respectively. These results suggest that soil drying at higher intensity and for prolonged periods significantly (p < 0.05) affect microbial biomass and subsequently increases soil phosphorus leaching following rewetting, due to enhanced contributions from the microbial biomass. These findings, however, need to be verified over a range of soil types under natural field conditions to better assess soil drying-rewetting effects on nutrient leaching