Formation and mobilization of methylmercury across natural and experimental sulfur deposition gradients

We investigated the influence of sulfate (SO42-) deposition and concentrations on the net formation and solubility of methylmercury (MeHg) in peat soils. We used data from a natural sulfate deposition gradient running 300 km across southern Sweden to test the hypothesis posed by results from an experimental field study in northern Sweden: that increased loading of SO42- both increases net MeHg formation and redistributes methylmercury (MeHg) from the peat soil to its porewater. Sulfur concentrations in peat soils correlated positively with MeHg concentrations in peat porewater, along the deposition gradient similar to the response to added SO42- in the experimental field study. The combined results from the experimental field study and deposition gradient accentuate the multiple, distinct and interacting roles of SO42- deposition in the formation and redistribution of MeHg in the environment. (c) 2020 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/)

Многоэлектродный емкостной датчик уровня

Материалы XIII Междунар. науч.-техн. конф. (науч. чтения, посвящ. 125-летию со дня рождения П. О. Сухого), Гомель, 22 окт. 2020 г

Stickprovsstorlek vidövervakning av kryptogamer i ädellövskog Del 1 och del 2

Stickprovsstorlek vid övervakning av kryptogamer i ädellövskog Del 1 och del

Estimation of WTP with point and self-selected interval responses Estimation of WTP with point and self-selected interval responses

Abstract In contingent valuation studies regarding willingness to pay (WTP) the respondents usually give an exact value as his/her WTP-value. Unfortunately, the non-response rate has a tendency to be quite high. As an attempt to reduce that rate the respondents will have a possibility to give a self-selected interval instead of a fixed value as their WTP. In this paper we will study different approaches to estimate the mean willingness to pay under these conditions. First we consider the nonparametric and a parametric approach where the intervals are treated as if the respondent gives an exact value but we cannot observe it. Next we will give a different interpretation of the intervals: Included in the respondent's answer is information about his/her uncertainty about what would be a reasonable value of WTP. For illustration purposes we will use data from a small study in Bollnäs municipality. In all three situations we first estimate the mean WTP and its standard error for those giving a positive answer and finally we add zero-responses