Farmers’ risk preference and the adoption of risk management strategies in Northern Ghana

The study used the hypothetical lottery-choice questions to measure risk aversion and a detailed survey collected data on input use, farm production and non-farm activities to specifically assess whether risk aversion, risk perceptions, and socioeconomic factors affect the risk management strategies of farm households in Northern Ghana. Risk aversion significantly increases crop diversification strategies of households but marginally reduces herbicide use by households. Market risk significantly increases the use of improved seed varieties and the application of inorganic fertiliser but reduces diversification into livestock production. Production risk largely increases diversification into livestock production. Farmers’ risk management strategies are affected by socioeconomic variables such as access to extension services, area cultivated, age and gender. Policy effort focused on building pliable on-farm crop related risk management strategies should aim at considering the risk aversion and the perception of market risk whilst those focused on livestock should focus on production risk.     

A hybrid process for manufacturing surgical-grade knife blade cutting edges from bulk metallic glass

The demand for precision surgical knives is enormous. Currently, diamond knives have been the preferred choice among surgeons for use in precision surgeries, owing to the extreme hardness of diamond and the sharpness that can be achieved in single crystal diamond blades, but material and processing costs are high. Bulk metallic glass (BMG) has the potential to be an economically viable material of similar performance for use in precision surgical knives. To this end, a novel hybrid manufacturing process integrating thermally assisted micro-molding and micro-drawing has been developed for producing BMG surgical-grade knife blade cutting edges with edge radii <50 nm. A hybrid process testbed was designed and used to successfully run tests over a range of the key process variables. Through this testing the deformation of BMG under different strain rates and temperatures was studied in terms of the quality of edge formation. The hybrid process was shown to be capable of producing cutting edges of radius at or below 100 nm.     

Material flow accounting in an Irish city-region 1992–2002

This paper aims to measure raw material inputs and waste flows in an Irish city-region in order to analyse (i) whether there was absolute dematerialisation in the particular case study over the period 1992–2002 and (ii) whether material consumption and waste generation were decoupled from economic growth and increases in disposable income over the same period. It was found that the selected material flow indicators showed no evidence of absolute dematerialisation over the given study period, although more recent evidence at the national level suggests that a decline in construction activity and extraction of non-metallic minerals has resulted in an absolute reduction in material consumption and it is likely that this will be mirrored at the system boundary level.It was found that Domestic Material Consumption (DMC) per capita and Direct Material Input (DMI) per capita increased at a faster rate than Domestic Processed Output (DPO) per capita and Direct Material Output (DMO) per capita between 1992 and 2002, which indicates relative decoupling of consumption from waste generation. In addition, it was found that there was relative decoupling of consumption and waste generation from disposable income growth over the study period. Finally, it was found that average DMC and DMI figures for the selected case study were lower than the national averages but broadly similar to results for other city-regions in the European Union (EU). On a methodological note, it was concluded that material flow accounting (MFA) for city-regions in Ireland is constrained due to a lack of disaggregated data for material flows, with the exception of local waste data, and it is recommended that bottom-up analysis should be used to complement disaggregated top-down data.     

Drought can offset potential water use efficiency of forest ecosystems from rising atmospheric CO2

Increasing atmospheric CO₂ is both leading to climate change and providing a potential fertilisation effect on plant growth. However, southern Australia has also experienced a significant decline in rainfall over the last 30 years, resulting in increased vegetative water stress. To better understand the dynamics and responses of Australian forest ecosystems to drought and elevated CO₂, the magnitude and trend in water use efficiency (WUE) of forests, and their response to drought and elevated CO₂ from 1982 to 2014 were analysed, using the best available model estimates constrained by observed fluxes from simulations with fixed and time-varying CO₂. The ratio of gross primary productivity (GPP) to evapotranspiration (ET) (WUEe) was used to identify the ecosystem scale WUE, while the ratio of GPP to transpiration (Tr) (WUEc) was used as a measure of canopy scale WUE. WUE increased significantly in northern Australia (p < 0.001) for woody savannas (WSA), whereas there was a slight decline in the WUE of evergreen broadleaf forests (EBF) in the southeast and southwest of Australia. The lag of WUEc to drought was consistent and relatively short and stable between biomes (≤3 months), but notably varied for WUEe, with a long time-lag (mean of 10 months). The dissimilar responses of WUEe and WUEc to climate change for different geographical areas result from the different proportion of Tr in ET. CO₂ fertilization and a wetter climate enhanced WUE in northern Australia, whereas drought offset the CO₂ fertilization effect in southern Australia.     

Development of Sediment and Nutrient Export Coefficients for U.S. Ecoregions

Water quality impairment due to excessive nutrients and sediment is a major problem in the United States (U.S.). An important step in the mitigation of impairment in any given water body is determination of pollutant sources and amount. The sheer number of impaired waters and limited resources makes simplistic load estimation methods such as export coefficient (EC) methods attractive. Unfortunately ECs are typically based on small watershed monitoring data, which are very limited and/or often based on data collected from distant watersheds with drastically different conditions. In this research, we seek to improve the accuracy of these nutrient export estimation methods by developing a national database of localized EC for each ecoregion in the U.S. A stochastic sampling methodology loosely based on the Monte‐Carlo technique was used to construct a database of 45 million Soil and Water Assessment Tool (SWAT) simulations. These simulations consider a variety of climate, topography, soils, weather, land use, management, and conservation implementation conditions. SWAT model simulations were successfully validated with edge‐of‐field monitoring data. Simulated nutrient ECs compared favorably with previously published studies. These ECs may be used to rapidly estimate nutrient loading for any small catchment in the U.S. provided the location, area, and land‐use distribution are known.     

Application of constructed wetlands for wastewater treatment in tropical and subtropical regions (2000-2013)

Constructed wetlands(CWs) have been successfully used for treating various wastewaters for decades and have been identified as a sustainable wastewater management option for developing countries. With the goal of promoting sustainable engineered systems that support human well-being but are also compatible with sustaining natural(environmental)systems, the application of CWs has become more relevant. Such application is especially significant for developing countries with tropical climates, which are very conducive to higher biological activity and productivity, resulting in higher treatment efficiencies compared to those in temperate climates. This paper therefore highlights the practice,applications, and research of treatment wetlands under tropical and subtropical conditions since 2000. In the present review, removal of biochemical oxygen demand(BOD) and total suspended solid(TSS) was shown to be very efficient and consistent across all types of treatment wetlands. Hybrid systems appeared more efficient in the removal of total suspended solid(TSS)(91.3%), chemical oxygen demand(COD)(84.3%), and nitrogen(i.e.,80.7% for ammonium(NH)4-N, 80.8% for nitrate(NO)3-N, and 75.4% for total nitrogen(TN))as compared to other wetland systems. Vertical subsurface flow(VSSF) CWs removed TSS(84.9%), BOD(87.6%), and nitrogen(i.e., 66.2% for NH4-N, 73.3% for NO3-N, and 53.3% for TN)more efficiently than horizontal subsurface flow(HSSF) CWs, while HSSF CWs(69.8%)showed better total phosphorus(TP) removal compared to VSSF CWs(60.1%). Floating treatment wetlands(FTWs) showed comparable removal efficiencies for BOD(70.7%),NH4-N(63.6%), and TP(44.8%) to free water surface(FWS) CW systems.     

Remediation of a chlorinated aromatic hydrocarbon in water by photoelectrocatalysis

Photoelectrocatalysis driven by visible light offers a new and potentially powerful technology for the remediation of water contaminated by organo-xenobiotics. In this study, the performance of a visible light-driven photoelectrocatalytic (PEC) batch reactor, applying a tungsten trioxide (WO₃) photoelectrode, to degrade the model pollutant 2,4-dichlorophenol (2,4-DCP) was monitored both by toxicological assessment (biosensing) and chemical analysis. The bacterial biosensor used to assess the presence of toxicity of the parent molecule and its breakdown products was a multicopy plasmid lux-marked E. coli HB101 pUCD607. The bacterial biosensor traced the removal of 2,4-DCP, and in some case, its toxicity response suggests the identification of transient toxic intermediates. The loss of the parent molecule, 2,4-DCP determined by HPLC, corresponded to the recorded photocurrents. Photoelectrocatalysis offers considerable potential for the remediation of chlorinated hydrocarbons, and that the biosensor based toxicity results identified likely compatibility of this technology with conventional, biological wastewater treatment.     

Tundra in the Rain: Differential Vegetation Responses to Three Years of Experimentally Doubled Summer Precipitation in Siberian Shrub and Swedish Bog Tundra

Precipitation amounts and patterns at high latitude sites have been predicted to change as a result of global climatic changes. We addressed vegetation responses to three years of experimentally increased summer precipitation in two previously unaddressed tundra types: Betula nana-dominated shrub tundra (northeast Siberia) and a dry Sphagnum fuscum-dominated bog (northern Sweden). Positive responses to approximately doubled ambient precipitation (an increase of 200 mm year^?1) were observed at the Siberian site, for B. nana (30 % larger length increments), Salix pulchra (leaf size and length increments) and Arctagrostis latifolia (leaf size and specific leaf area), but none were observed at the Swedish site. Total biomass production did not increase at either of the study sites. This study corroborates studies in other tundra vegetation types and shows that despite regional differences at the plant level, total tundra plant productivity is, at least at the short or medium term, largely irresponsive to experimentally increased summer precipitation.     

Extractability of water-soluble soil organic matter as monitored by spectroscopic and chromatographic analyses

Purpose

Cold and hot water processes have been intensively used to recover soil organic matter, but the effect of extraction conditions on the composition of the extracts were not well investigated. Our objective was to optimize the extraction conditions (time and temperature) to increase the extracted carbon efficiency while minimizing the possible alteration of water extractable organic matter of soil (WEOM).

Method

WEOM were extracted at 20°C, 60°C, or 80°C for 24?h, 10?C60?min, and 20?min, respectively. The different processes were compared in terms of pH of suspensions, yield of organic carbon, spectroscopic properties (ultraviolet?Cvisible absorption and fluorescence), and by chromatographic analyses.

Results

For extraction at 60°C, the time 30?min was optimal in terms of yield of organic carbon extracted and concentration of absorbing and fluorescent species. The comparison of WEOM 20°C, 24?h; 60°C, 30?min; and 80°C, 20?min highlighted significant differences. The content of total organic carbon, the value of specific ultraviolet absorbance (SUVA₂₅₄), the absorbance ratio at 254 and 365?nm (E ₂/E ₃), and the humification index varied in the order: WEOM (20°C, 24?h)?Conclusions For the soil chosen, extraction at 60°C for 30?min is the best procedure for enrichment in organic chemicals and minimal alteration of the organic matter.     

Ecosystem Impacts of Geoengineering: A Review for Developing a Science Plan

Geoengineering methods are intended to reduce climate change, which is already having demonstrable effects on ecosystem structure and functioning in some regions. Two types of geoengineering activities that have been proposed are: carbon dioxide (CO(2)) removal (CDR), which removes CO(2) from the atmosphere, and solar radiation management (SRM, or sunlight reflection methods), which reflects a small percentage of sunlight back into space to offset warming from greenhouse gases (GHGs). Current research suggests that SRM or CDR might diminish the impacts of climate change on ecosystems by reducing changes in temperature and precipitation. However, sudden cessation of SRM would exacerbate the climate effects on ecosystems, and some CDR might interfere with oceanic and terrestrial ecosystem processes. The many risks and uncertainties associated with these new kinds of purposeful perturbations to the Earth system are not well understood and require cautious and comprehensive research.