Effects of stable aqueous fullerene nanocrystal (nC60) on Daphnia magna: Evaluation of hop frequency and accumulations under different conditions

We investigated the effects of environmental factors and properties of water-stable crystal fullerene (nC60) on the uptake of nC60 by Daphnia magna based on known accumulation in our laboratory. This study was performed for seven days using different environmental factors including temperature, pH, water hardness, concentration (density of particle), and particle size. Results demonstrated that body burden of C60 increased with time in all experiments. Body burden of C60 increased with increasing concentration and particle size, and uptake of particles >100 nm reached their maximums more quickly than those <100 nm. Under high hardness in aqueous systems with lower pH and high temperature, uptake was higher than those under opposite conditions. Uptake in all batch tests reached balance within five days. Both nC60 properties and environmental factors influenced uptake of nC60 by D. magna in an aqueous system. Additionally, environmental factors may have affected accumulation by changing nC60 properties, which are critical to understand the accumulation of fullerenes in aqueous systems.     

A spatial analysis of pit latrine density and groundwater source contamination

This study aims to assess the relationship between chemical and microbial contamination of groundwater sources and a range of potential hazards in two peri-urban areas of Kisumu, Kenya where shallow wells and pit latrines are widely used. From 1998 to 2004, 263 samples were taken from 61 groundwater sources and tested for thermotolerant coliforms. Eighteen of these sources were also tested for chemical contaminants, including nitrate, chloride and fluoride. The locations of all water sources, buildings and pit latrines in the study area were surveyed. Local pit latrine densities were calculated using a geographic information system. Ten out 18 samples were above the World Health Organization guideline values for nitrate, 236 out of 263 were positive for thermotolerant coliforms, and all were above the guideline values for fluoride. There was neither a relationship between thermotolerant coliform levels and daily rainfall patterns nor with sanitary risk inspection scores for samples from shallow wells (r?=?0.01, p?=?0.91, n?=?191). The density of pit latrines within a 100-m radius was significantly correlated with nitrate and chloride levels (r?=?0.64, p?=?0.004 and r?=?0.46, p?=?0.05, respectively) but not with thermotolerant coliforms (r?=?0.22, p?=?0.11). These results illustrate both the public health risks associated with shallow groundwater sources, on-site sanitation and high population density. These findings have implications for current policies that promote latrine construction, especially in peri-urban areas of high population density. More comprehensive studies of larger communities should be commissioned to extend this analysis of the links between latrine density and groundwater contamination and so identify the contingent policy risks.     

Mapping and Eradication Prioritization Modeling of Red Sesbania (Sesbania punicea) Populations

Red sesbania is an invasive South American shrub that has rapidly expanded its range along California waterways, emphasizing the need to prioritize eradication sites at a regional scale. To accomplish this, we updated baseline location data in summer 2010 using field surveys throughout the state. We collected relevant GPS attribute data for GIS analysis and eradication prioritization modeling. The regional survey identified upstream and downstream extents for each watershed, as well as outliers in urban areas. We employed the Weed Heuristics: Invasive Population Prioritization for Eradication Tool (WHIPPET) to prioritize red sesbania sites for eradication, and revised the WHIPPET model to consider directional propagule flow of a riparian species. WHIPPET prioritized small populations isolated from larger infestations, as well as outliers in residential areas. When we compared five experts’ assessments of a stratified sample of the red sesbania populations to WHIPPET’s prioritization results, there was a positive, but nonsignificant, correlation. The combination of WHIPPET and independent expert opinion suggests that small, isolated populations and upstream source populations should be the primary targets for eradication. Particular attention should be paid to these small populations in watersheds where red sesbania is a new introduction. The use of this model in conjunction with evaluation by the land manager may help prevent the establishment of new seed sources and protect uninfested riparian corridors and their adjacent watersheds.     

Why keep lions instead of livestock? Assessing wildlife tourism‐based payment for ecosystem services involving herders in the Maasai Mara,Kenya

This paper examines the effects of wildlife tourism‐based payments for ecosystem services (PES) on poverty, wealth inequality and the livelihoods of herders in the Maasai Mara Ecosystem in south‐western Kenya. It uses the case of Olare Orok Conservancy PES programme in which pastoral landowners have agreed to voluntary resettlement and exclusion of livestock grazing from their sub‐divided lands. These lands are set aside for wildlife tourism, in return for direct monetary payments by a coalition of five commercial tourism operators. Results show that, on the positive side, PES is the most equitable income source that promotes income diversification and buffers households from the livestock income declines during periods of severe drought, such as in 2008‐2009. Without accounting for the opportunity costs, the magnitude of the PES cash transfer to households is, on average, sufficient to close the poverty gap. The co‐benefits of PES implementation include the creation of employment opportunities in the conservancy and provision of social services. There is however a need to mitigate the negative effects of PES, including the widening inequality in income between PES and non‐PES households and the leakages resulting from the displacement of settlements and livestock to currently un‐subdivided pastoral commons.     

Garcinia gummi-gutta (L.) Robs.: A promising feedstock for biodiesel production

In the present study crude Garcinia gummi-gutta seed oil was evaluated as a potential feedstock for biodiesel production. Due to the high acid value (29.73 mg KOH/g) the oil was converted to biodiesel by using acid catalyzed esterification process. Further, biodiesel properties of the sample were evaluated, which fulfilled the biodiesel specifications laid by ASTM D6751, EN 14214 and IS 15607. The biodiesel possessed excellent cetane number (66.09) and a high flash point (158°C). In addition, the calorific value (41.03 MJ/kg) was very close to diesel fuel. The results suggest that the G. gummi-gutta can be an alternative source for diesel and can be used as a potential feedstock for biodiesel in India.     

Melanin pattern morphs do not differ in metabolic rate: implications for the evolutionary maintenance of a melanophore polymorphism in the green swordtail, <Emphasis Type="Italic">Xiphophorus helleri</Emphasis>

Variation in melanin patterns among individuals, populations, and species is common in fishes of the genus Xiphophorus. In the variable platyfish, Xiphophorus variatus, variation in metabolic rate is associated with melanin coloration and the color morphs appear to be physiological specialists adapted to particular environmental conditions. This study investigates whether a melanin polymorphism in the green swordtail, Xiphophorus helleri, is likewise associated with variation in metabolic rate. We measured metabolic rate as oxygen consumption rate of both adult male and juvenile X. helleri in static respirometers. The oxygen consumption rate does not differ significantly between the spotted and nonspotted morphs in either group, suggesting that-unlike in X. variatus-selection on metabolic rate is not involved in maintaining the polymorphism in X. helleri. We suggest that explanations need to be sought for the evolution of melanophore diversity in Xiphophorus that are pertinent to each melanin pattern polymorphism or groups of similar polymorphisms.     

Diurnal changes in photosynthetic parameters of Populus tremuloides, modulated by elevated concentrations of CO2 and/or O3 and daily climatic variation

The diurnal changes in light-saturated photosynthesis (Pn) under elevated CO₂ and/or O₃ in relation to stomatal conductance (g_s), water potential, intercellular [CO₂], leaf temperature and vapour-pressure difference between leaf and air (VPD_L) were studied at the Aspen FACE site. Two aspen (Populus tremuloides Michx.) clones differing in their sensitivity to ozone were measured. The depression in Pn was found after 10:00 h. The midday decline in Pn corresponded with both decreased g_s and decreased Rubisco carboxylation efficiency, Vc_max. As a result of increasing VPD_L, g_s decreased. Elevated [CO₂] resulted in more pronounced midday decline in Pn compared to ambient concentrations. Moreover, this decline was more pronounced under combined treatment compared to elevated CO₂ treatment.The positive impact of CO₂ on Pn was relatively more pronounced in days with environmental stress but relatively less pronounced during midday depression. The negative impact of ozone tended to decrease in both cases.     

Differential response of aspen and birch trees to heat stress under elevated carbon dioxide

The effect of high temperature on photosynthesis of isoprene-emitting (aspen) and non-isoprene-emitting (birch) trees were measured under elevated CO₂ and ambient conditions. Aspen trees tolerated heat better than birch trees and elevated CO₂ protected photosynthesis of both species against moderate heat stress. Elevated CO₂ increased carboxylation capacity, photosynthetic electron transport capacity, and triose phosphate use in both birch and aspen trees. High temperature (36-39 °C) decreased all of these parameters in birch regardless of CO₂ treatment, but only photosynthetic electron transport and triose phosphate use at ambient CO₂ were reduced in aspen. Among the two aspen clones tested, 271 showed higher thermotolerance than 42E possibly because of the higher isoprene-emission, especially under elevated CO₂. Our results indicate that isoprene-emitting trees may have a competitive advantage over non-isoprene emitting ones as temperatures rise, indicating that biological diversity may be affected in some ecosystems because of heat tolerance mechanisms.     

Spatial and temporal variation in suspended sediment, organic matter, and turbidity in a Minnesota prairie river: implications for TMDLs

The Minnesota River Basin (MRB), situated in the prairie pothole region of the Upper Midwest, contributes excessive sediment and nutrient loads to the Upper Mississippi River. Over 330 stream channels in the MRB are listed as impaired by the Minnesota Pollution Control Agency, with turbidity levels exceeding water quality standards in much of the basin. Addressing turbidity impairment requires an understanding of pollutant sources that drive turbidity, which was the focus of this study. Suspended volatile solids (SVS), total suspended solids (TSS), and turbidity were measured over two sampling seasons at ten monitoring stations in Elm Creek, a turbidity impaired tributary in the MRB. Turbidity levels exceeded the Minnesota standard of 25 nephelometric units in 73% of Elm Creek samples. Turbidity and TSS were correlated (r ²?=?0.76), yet they varied with discharge and season. High levels of turbidity occurred during periods of high stream flow (May–June) because of excessive suspended inorganic sediment from watershed runoff, stream bank, and channel contributions. Both turbidity and TSS increased exponentially downstream with increasing stream power, bank height, and bluff erosion. However, organic matter discharged from wetlands and eutrophic lakes elevated SVS levels and stream turbidity in late summer when flows were low. SVS concentrations reached maxima at lake outlets (50 mg/l) in August. Relying on turbidity measurements alone fails to identify the cause of water quality impairment whether from suspended inorganic sediment or organic matter. Therefore, developing mitigation measures requires monitoring of both TSS and SVS from upstream to downstream reaches.