Modeling elephant-mediated cascading effects of water point closure

Contains fulltext : 142479.pdf (publisher's version ) (Open Access

Modeling exposure risk and prevention of mercury in drinking water for artisanal-small scale gold mining communities

The goal of this study was to evaluate the age-differentiated health risks associated with exposure to mercury in drinking water from artisanal small-scale gold mining (ASGM) sites on nearby communities in Yolombo, Colombia. In 2017, nine samples were collected from a local regulatory agency to report mercury concentrations in locations near mining sites. We performed a risk assessment to find 100% of the water samples collected downstream of mining sites exceed Hazard Quotient (HQ) risk thresholds (set by the US-Environmental Protection Agency and Health Canada). HQ model, coupled with global sensitivity and uncertainty analysis (GSUA), was used to conclude infants as the most vulnerable, with 50% of the population exceeding HQ thresholds. Length of exposure was the most significant input that contributed to risk variance, explaining 30-55% of risk across all age groups. Monte-Carlo filtering was used to identify effective strategies to reduce the number of individuals exceeding allowable HQ thresholds. After Monte-Carlo filtering intervention strategies, all individuals are below HQ thresholds. This work shows the importance of combining risk assessment tools with sensor data to inform the need for filters, stakeholder education, and alternative mining approaches to gain a multi-perspective risk approach. This work provides a valuable risk and decision modeling methodology and baseline information to gain a deeper understanding of the probability of experiencing detrimental health effects from water contamination in ASGM communities

PROMETHEE-GAIA Method as a Support of the Decision-Making Process in Evaluating Technical Facilities

Part 1: Environmental Application in the Scope of the Future InternetInternational audienceThis paper describes the application of PROMETHEE-GAIA methodology in a multiple criteria analysis to rank potential environmental investments in mineral-processing companies. The intent of the paper is to identify best technical facilities on the basis of preferential relations between a set of variants. The method of Total Cost Analysis (TCA) was chosen to define the criteria. The economic and environmental costs, as well as the benefits of these technical facilities, were determined by means of this method. PROMETHEE is one of the methods in the Multi Criteria Analysis (MCA) category. The MCA, as the name implies, deals with the evaluation of a number of variants by several criteria. The technical facility was selected by a comparative analysis involving five influential parameters (Investment Costs, Annual Operating Costs, Operating Income, Administrative Costs and Disposal Fees, Economic and Environmental Benefits). As expected, the analysis resulted in a preferential ranking of these technical facilities

Modeling elephant-mediated cascading effects of water point closure

Wildlife management to reduce the impact of wildlife on their habitat can be done in several ways, among which removing animals (by either culling or translocation) is most often used. There are however alternative ways to control wildlife densities, such as opening or closing water points. The effects of these alternatives are poorly studied. In this paper, we focus on manipulating large herbivores through the closure of water points (WPs). Removal of artificial WPs has been suggested to change the distribution of African elephants, which occur in high densities in national parks in Southern Africa and are thought to have a destructive effect on the vegetation. Here, we modeled the long-term effects of different scenarios of WP closure on the spatial distribution of elephants, and consequential effects on the vegetation and other herbivores in Kruger National Park, South Africa. Using a dynamic ecosystem model, SAVANNA, scenarios were evaluated that varied in (1) availability of artificial WPs, (2) levels of natural water, and (3) elephant densities. Our modeling results showed that elephants can indirectly negatively affect the distributions of mesomixed feeders, mesobrowsers and some mesograzers under wet conditions. The closure of artificial WPs hardly had any effect during these natural wet conditions. Only under dry conditions the spatial distribution of both elephant bulls and cows changed when the availability of artificial water was severely reduced in the model. These changes in spatial distribution triggered changes in the spatial availability of woody biomass over the simulation period of 80 years and this led to changes in the rest of the herbivore community, resulting in increased densities of all herbivores, except for giraffe and steenbok, in areas close to rivers. The spatial distributions of elephant bulls and cows showed to be less affected by the closure of WPs than most of the other herbivore species. Our study contributes to ecologically informed decisions in wildlife management. The results from this modeling exercise imply that long-term effects of this intervention strategy should always be investigated at an ecosystem scale

Modeling elephant-mediated cascading effects of water point closure

This dataset contains the underlying data for the study: Hilbers, J.P., van Langevelde, F., Prins, H.H.T., Grant, C.C., Peel, M., Coughenour, M.B., de Knegt, H.J., Slotow, R., Smit, I.P.J., Kiker, G.A., de Boer, W.F. 2014. Modeling elephant-mediated cascading effects of water point closure. Ecological Applications. http://dx.doi.org/10.1890/14-0322.1 Wildlife management to reduce the impact of wildlife on their habitat can be done in several ways, among which removing animals (by either culling or translocation) is most often used. There are however alternative ways to control wildlife densities, such as opening or closing water points. The effects of these alternatives are poorly studied. In this paper, we focus on manipulating large herbivores through the closure of water points (WPs). Removal of artificial WPs has been suggested to change the distribution of African elephants, which occur in high densities in national parks in Southern Africa and are thought to have a destructive effect on the vegetation. Here, we modeled the long-term effects of different scenarios of WP closure on the spatial distribution of elephants, and consequential effects on the vegetation and other herbivores in Kruger National Park, South Africa. Using a dynamic ecosystem model, SAVANNA, scenarios were evaluated that varied in (1) availability of artificial WPs, (2) levels of natural water, and (3) elephant densities. Our modeling results showed that elephants can indirectly negatively affect the distributions of mesomixed feeders, mesobrowsers and some mesograzers under wet conditions. The closure of artificial WPs hardly had any effect during these natural wet conditions. Only under dry conditions the spatial distribution of both elephant bulls and cows changed when the availability of artificial water was severely reduced in the model. These changes in spatial distribution triggered changes in the spatial availability of woody biomass over the simulation period of 80 years and this led to changes in the rest of the herbivore community, resulting in increased densities of all herbivores, except for giraffe and steenbok, in areas close to rivers. The spatial distributions of elephant bulls and cows showed to be less affected by the closure of WPs than most of the other herbivore species. Our study contributes to ecologically informed decisions in wildlife management. The results from this modeling exercise imply that long-term effects of this intervention strategy should always be investigated at an ecosystem scale