Household and climate factors influence Aedes aegypti presence in the arid city of Huaquillas, Ecuador

Arboviruses transmitted by Aedes aegypti (e.g., dengue, chikungunya, Zika) are of major public health concern on the arid coastal border of Ecuador and Peru. This high transit border is a critical disease surveillance site due to human movement-associated risk of transmission. Local level studies are thus integral to capturing the dynamics and distribution of vector populations and social-ecological drivers of risk, to inform targeted public health interventions. Our study examines factors associated with household-level Ae. aegypti presence in Huaquillas, Ecuador, while accounting for spatial and temporal effects. From January to May of 2017, adult mosquitoes were collected from a cohort of households (n = 63) in clusters (n = 10), across the city of Huaquillas, using aspirator backpacks. Household surveys describing housing conditions, demographics, economics, travel, disease prevention, and city services were conducted by local enumerators. This study was conducted during the normal arbovirus transmission season (January—May), but during an exceptionally dry year. Household level Ae. aegypti presence peaked in February, and counts were highest in weeks with high temperatures and a week after increased rainfall. Univariate analyses with proportional odds logistic regression were used to explore household social-ecological variables and female Ae. aegypti presence. We found that homes were more likely to have Ae. aegypti when households had interruptions in piped water service. Ae. aegypti presence was less likely in households with septic systems. Based on our findings, infrastructure access and seasonal climate are important considerations for vector control in this city, and even in dry years, the arid environment of Huaquillas supports Ae. aegypti breeding habitat.

Investigation of groundwater contamination in relation to septic systems in Kitwe West Township, Kitwe, Zambia

This study investigated the quality of groundwater with respect to septic systems in Kitwe West township located in the western part of Zambia's Kitwe district. The study area was selected because most households in the township use boreholes and septic systems as sources of drinking water and waste disposal facilities respectively. The study showed presence of total coliforms in 90% of the boreholes while only 30% of the boreholes were contaminated with fecal coliforms rendering the water unsafe for drinking. The study revealed that there was no distinct relationship between distance from borehole to septic tank system and the quality of borehole water. It was however observed that for boreholes within a 15 m proximity to individual home owned dump sites the level of fecal contamination increased as the distance from the boreholes to the dump sites decreased. The study has vividly shown that the location of boreholes and septic tank systems in the same plot of land exacerbated by the presence of solid waste dump sites in a residential plot that depends on groundwater is not advisable. This is because the safety of groundwater cannot be guaranteed even if technical specifications are followed for boreholes and septic tank systems.

Persistant Organic Pollutants in Soil and Its Phytoremediation

Persistent organic pollutants (POPs) of soil mainly exhibit toxic characteristics that posses hazard to whole mankind. These toxic pollutants includes several group of compound viz., polychlorinated biphenyls, polybrominated biphenyls, polychlorinated dibenzofurans, polycyclic aromatic hydrocarbons, organophosphorus and carbamate insecticides, herbicides and organic fuels, especially gasoline and diesel. They can also be complex mixture of organic chemicals, heavy metals and microbes from septic systems, animal wastes and other sources of organic inputs. Phytoremediation is an emerging technology which can be used for remediation of soil from organic pollutants. In this chapter an attempt has been made to discuss about the sources of organic pollutants, factors that influenced the uptake of organic pollutants by plants, the different mechanism responsible for organic pollutants, phytoremediation of organic pollutants and their advantages and limitation.

Frontiers in assessing septic systems vulnerability in coastal Georgia, USA: Modeling approach and management implications

Threats to public health and environmental quality from septic systems are more prevalent in areas with poorly draining soils, high water tables, or frequent flooding. Significant research gaps exist in assessing these systems’ vulnerability and evaluating factors associated with higher rates of septic systems replacement and repair. We developed a novel GIS-based framework for assessing septic system vulnerability using a database of known septic system specifications and a modified Soil Topographic Index (STI) that incorporates seasonal high groundwater elevation to assess risks posed to septic systems in coastal Georgia. We tested the hypothesis that both the modified STI and septic system specifications such as tank capacity per bedroom and drainfield type would explain most of the variance in septic system repair and replacement using classification inference tree and generalized logistic regression models. Our modeling results indicate that drainfield type (level vs. mounded) is the most significant variable (p-value < 0.001) in predicting septic systems functionality followed by septic tank capacity per bedroom (p-value < 0.01). These show the importance of septic system design regulations such as a minimum requirement for horizontal separation distance between the bottom of trenches and seasonal water table, and adequate tank capacity design. However, for septic systems with a mounded drainfield and a larger tank capacity per bedroom, the modified STI representing hydrological characteristics of septic system location is a significant predictor of a high septic system repair and replacement rate. The methodology developed in this study can have important implications for managing existing septic systems and planning for future development in coastal areas, especially in an environment of rapid climatic change.

Social dilemmas and poor water quality in private water systems

Private water supply systems consisting of a domestic well and septic system are used throughout the world where households lack access to public water supply and sewers. In residential areas with high housing density, septic contamination of private wells is common and associated with multiple health concerns. This situation can give rise to social dilemmas, where individual costs dis-incentivize homeowners from investing in enhanced septic systems that would reduce well contamination and bring communal benefits. We combine a stylized game-theoretical model with a probabilistic groundwater model to characterize how economic and hydrogeological conditions interact to produce misaligned incentives conducive to social dilemmas. The occurrence of social dilemmas depends on the relative costs of well contamination versus the cost of installing an enhanced septic treatment system, and the relative probabilities of cross-contamination versus self-contamination. The game reveals three three types of social dilemmas that occur in such systems, with each calling for distinct policy solutions. We demonstrate how the model can be applied to existing systems using a case study of St Joseph County, Indiana, where high nitrate contamination rates have raised public health concerns. This analysis represents a step towards identifying alternative policy solutions for a problem that has remained difficult to address for decades.

Groundwater Protection Model at Niagara Using GIS Tools

Groundwater is the safest and most reliable source of available freshwater. Although traditionally groundwater has been assumed to be free from contamination, numerous discoveries, in recent years of toxic chemicals in well water have proven this assumption to be false. Groundwater contamination from chemical dump sites tends to attract the greatest public attention, but contamination from other sources such as septic systems, pesticides, and underground storage tanks also can be significant. Intensive agriculture in areas of high soil permeability and high water tables also causes groundwater contamination from the percolation of chemicals and nutrients through the soil profile. Protecting groundwater resources from pollution is therefore essential for its proper management and preventing probable hazards. Groundwater vulnerablility assessment is an issue of spatial distribution and therefore typically carried out using geographic information systems (GIS). Even when using a simple qualitative method, the complex processing of spatial information is completed faster using GIS Models are tools to simulate the behavior of physical systems. They can predict the future evolution of the systems, they can be used as interpretative tools in order to study system dynamics and they can give hints for data collection and design of experiments. Models are sometimes used to examine the evolution of generic natural systems, without a specific application to a definite site or population. ArcGis 9 provides new tolls to build protection model to study grounwater contamination isues of various watersheds that performs multiple geoprocessing operations. The study articulates the most vulnerable locations of Niagara for groundwater contamination, what geospatial data are needed to support these resource assessment activities, and how GIS tools are required to facilitate the generation of a best optimized model.

Groundwater Protection Model at Niagara Using GIS Tools

Groundwater is the safest and most reliable source of available freshwater. Although traditionally groundwater has been assumed to be free from contamination, numerous discoveries, in recent years of toxic chemicals in well water have proven this assumption to be false. Groundwater contamination from chemical dump sites tends to attract the greatest public attention, but contamination from other sources such as septic systems, pesticides, and underground storage tanks also can be significant. Intensive agriculture in areas of high soil permeability and high water tables also causes groundwater contamination from the percolation of chemicals and nutrients through the soil profile. Protecting groundwater resources from pollution is therefore essential for its proper management and preventing probable hazards. Groundwater vulnerablility assessment is an issue of spatial distribution and therefore typically carried out using geographic information systems (GIS). Even when using a simple qualitative method, the complex processing of spatial information is completed faster using GIS Models are tools to simulate the behavior of physical systems. They can predict the future evolution of the systems, they can be used as interpretative tools in order to study system dynamics and they can give hints for data collection and design of experiments. Models are sometimes used to examine the evolution of generic natural systems, without a specific application to a definite site or population. ArcGis 9 provides new tolls to build protection model to study grounwater contamination isues of various watersheds that performs multiple geoprocessing operations. The study articulates the most vulnerable locations of Niagara for groundwater contamination, what geospatial data are needed to support these resource assessment activities, and how GIS tools are required to facilitate the generation of a best optimized model.