To clean or not to clean: A geostatistical approach for evaluating contaminated soils

Indicator kriging is used to estimate the probability that a discrete area of soil (known as an exposure unit) lies either above or below an action level, warranting a response of either remediation or “no further action.” Resampling procedures are introduced as a way to optimize the number of additional samples needed to meet desired Type I and Type II error rates. This article provides the reader a step-by-step guide to the kriging analysis and a case study illustrating the procedures.     

Conservation on private land: a review of global strategies with a proposed classification system

With parks and protected areas insufficient to sustain global biodiversity, the role of private land in biodiversity conservation is becoming increasingly significant. This paper reviews global voluntary and involuntary strategies for private land conservation. Involuntary strategies can achieve effective conservation outcomes, but often lack social acceptability. In contrast, voluntary strategies enjoy greater social acceptance but may not achieve sufficient uptake to have meaningful conservation objectives. Based on the review, we propose a classification system for private land conservation as a complement to the International Union for Conservation of Nature's (IUCN's) classification of global protected areas. The classification system provides a framework for identifying and describing conservation strategies on private land on the dimension of tenure and security. It also identifies opportunities and vulnerabilities in achieving conservation on private land while emphasising the need for systematic data collection similar to IUCN's efforts for protected areas.     

Multiple impact pathways of the 2015–2016 El Niño in coastal Kenya

The 2015–2016 El Niño had large impacts globally. The effects were not as great as anticipated in Kenya, however, leading some commentators to call it a ‘non-event’. Our study uses a novel combination of participatory Climate Vulnerability and Capacity Analysis tools, and new and existing social and biophysical data, to analyse vulnerability to, and the multidimensional impacts of, the 2015–2016 El Niño episode in southern coastal Kenya. Using a social-ecological systems lens and a unique dataset, our study reveals impacts overlooked by conventional analysis. We show how El Niño stressors interact with and amplify existing vulnerabilities to differentially impact local ecosystems and people. The policy significance of this finding is that the development of specific national capacities to deal with El Niño events is insufficient; it will be necessary to also address local vulnerabilities to everyday and recurrent stressors and shocks to build resilience to the effects of El Niño and other extremes in climate and weather.Electronic supplementary materialThe online version of this article (10.1007/s13280-020-01321-z) contains supplementary material, which is available to authorized users.     

Occurrence of <Emphasis Type="Italic">Pepper Mild Mottle Virus</Emphasis> (PMMoV) in Groundwater from a Karst Aquifer System in the Yucatan Peninsula,Mexico

The Yucatan Peninsula of Mexico hosts a karst aquifer system that is the only source of freshwater for the area; however, it is vulnerable to human-mediated contamination. Pepper mild mottle virus (PMMoV) is one of the most abundant RNA viruses associated with human feces, making it a viable indicator for tracking fecal pollution in aquatic environments, including groundwater. In this study, groundwater samples collected from a karst aquifer from fresh and brackish water locations were analyzed for fecal indicator bacteria, somatic and male F+ specific coliphages, and PMMoV during the rainy and dry seasons. Total coliform bacteria were detected at all sites, whereas Escherichia coli were found at relatively low levels <40 MPN/100 ml. The highest average concentrations of somatic and male F+ specific coliphages were 920 and 330 plaque forming units per 100 ml, respectively, detected in freshwater during the rainy season. PMMoV RNA was detected in 85% of the samples with gene sequences sharing 99–100% of nucleotide identity with PMMoV sequences available in GenBank. Quantification of PMMoV genome copies (GC) by quantitative real-time PCR indicated concentrations ranging from 1.7 × 10¹ to 1.0 × 10⁴ GC/L, with the highest number of GC detected during the rainy season. No significant correlation was observed between PMMoV occurrence by season or water type (p > 0.05). Physicochemical and indicator bacteria were not correlated with PMMoV concentrations. The abundance and prevalence of PMMoV in the karst aquifer may reflect its environmental persistence and its potential as a fecal indicator in this karst aquifer system.     

Feasibility Demonstration of Electrostatic Precipitation at 1700°F

An experimental high-temperature, high-pressure electrostatic precipitator module has been designed, fabricated and then evaluated in a gaseous environment having the characteristics anticipated for the combustion chamber of a system for generating electric power from the incineration of municipal solid wastes.

Stable positive and negative corona discharges were established in combustion gases from the burning of methanol and air (temperature and pressure approximately 1700°F and 100 psig, respectively) without any apparent deleterious effects due to thermal ionization and/or emission. At gas conditions of about 1700°F and 50 psig, positive polarity energization of the discharge electrode appeared superior to that of negative polarity in terms of voltage level that could be applied and electrical stability.

However, precipitator performance on removal of alumina dust injected under controlled conditions with the methanol fuel, showed negative polarity to be superior to positive polarity at the selected conditions of 1650°F and 100 psig which closely correspond to those required for optimum operation of the gas turbine presently under consideration. Removal efficiencies ranging from 25% for positive polarity to as high as 87% with negative polarity were measured.

In order to check whether materials having a low ionization potential would thermally ionize to such an extent that the voltage-corona current characteristics of the precipitator would be impaired, rendering it ineffective, potassium chloride salt in solution was injected with the fuel. Results indicated that amounts of approximately one part by weight of potassium ion in 2500 to 3000 parts by weight of gas at 1700°F tripled the current measured for a given voltage when compared to non-injection.

Although a limited test program was conducted, sufficient data were obtained to allow preliminary design and sizing of larger scale units.