The need for bioaugmentation after thermal treatment of a TCE-contaminated aquifer: Laboratory experiments

A microcosm study was conducted to evaluate the need for bioaugmentation after a thermal treatment to anaerobically dechlorinate trichloroethene (TCE) to ethene. The microcosms were either: heated to 100 degrees C and slowly cooled to simulate thermal remediation while bioaugmenting when the declining temperature reached 10 degrees C; or kept at ambient groundwater temperatures (10 degrees C) and bioaugmented for comparison. Aquifer samples from three sediment locations within a TCE-polluted source zone were investigated in duplicate microcosms. In biostimulated (5 mM lactate) and heated microcosms, no conversion of TCE was observed in 4 out of 6 microcosms, and in the remaining microcosms the dechlorination of TCE was incomplete to cDCE (cis-dichloroethene). By comparison, complete TCE dechlorination to ethene was observed in 4 out of 6 heated microcosms that were bioaugmented with a highly enriched dechlorinating mixed culture, KB-1, but no electron donor, and also in 4 of 6 microcosms that were augmented with KB-1 and an electron donor (5 mM lactate). These data suggest that electron donor released during heating, was capable of promoting complete dechlorination coincident with bioaugmentation. Heated microcosms demonstrated less methanogenesis than unheated microcosms, even with elevated H2 concentrations and addition of KB-1, which contains methanogens. This suggests that the heating process suppressed the native microbial community, which can decrease competition with the bioaugmented culture and increase the effectiveness of dechlorination following a thermal treatment. Specifically, cDCE removal rates were four to six times higher in heated than unheated bioaugmented microcosms. This study confirms the need for bioaugmentation following a laboratory thermal treatment to obtain complete dechlorination of TCE.     

Nonstructural Urban Stormwater Quality Measures: Building a Knowledge Base to Improve Their Use

This article summarizes a research project that investigated the use, performance, cost, and evaluation of nonstructural measures to improve urban stormwater quality. A survey of urban stormwater managers from Australia, New Zealand, and the United States revealed a widespread trend of increasing use of nonstructural measures among leading stormwater management agencies, with at least 76% of 41 types of nonstructural measures being found to be increasing in use. Data gathered from the survey, an international literature review, and a multicriteria analysis highlighted four nonstructural measures of greatest potential value: mandatory town planning controls that promote the adoption of low-impact development principles and techniques; development of strategic urban stormwater management plans for a city, shire, or catchment; stormwater management measures and programs for construction/building sites; and stormwater management activities related to municipal maintenance operations such as maintenance of the stormwater drainage network and manual litter collections. Knowledge gained on the use and performance of nonstructural measures from the survey, literature review, and three trial evaluation projects was used to develop tailored monitoring and evaluation guidelines for these types of measure. These guidelines incorporate a new evaluation framework based on seven alternative styles of evaluation that range from simply monitoring whether a nonstructural measure has been fully implemented to monitoring its impact on waterway health. This research helps to build the stormwater management industry’s knowledge base concerning nonstructural measures and provides a practical tool to address common impediments associated with monitoring and evaluating the performance and cost of these measures.     

一株异养脱氮菌的脱氮性能及其影响因素研究

研究异养硝化过程中分离得到一株具有异养脱氮性能的菌株,经16S rRNA鉴定后为Providencia rettgeri菌属,命名为Providencia rettgeri strain YL。在实验室条件下,初步探讨了不同碳氮源、温度、pH值、摇床转速和微量元素对Providencia rettgeri strain YL菌株脱氮作用的影响,研究结果显示,Providencia rettgeri strain YL菌株在葡萄糖和氯化铵为碳氮源的培养基中生长最好,温度为30℃、pH值为7、摇床转速为120 r/min时具有最佳的脱氮效果,微量元素Mg²⁺最有利于Providencia rettgeri strain YL菌株的生长和脱氮。     

Estimating the Impact of Temperature and Rainfall on Malaria Incidence in Ghana from 2012 to 2017

Environmental Modeling & Assessment - Malaria has a significant impact on the lives of many in Ghana. It is one of the key causes of mortality and morbidity, resulting in 32.5% of outpatient...     

Assessing conservation status with extensive but low-resolution data: Application of frequentist and Bayesian models to endangered Athabasca River rainbow trout

Use of extensive but low-resolution abundance data is common in the assessment of species at-risk status based on quantitative decline criteria under International Union for Conservation of Nature (IUCN) and national endangered species legislation. Such data can be problematic for 3 reasons. First, statistical power to reject the null hypothesis of no change is often low because of small sample size and high sampling uncertainty leading to a high frequency of type II errors. Second, range-wide assessments composed of multiple site-specific observations do not effectively weight site-specific trends into global trends. Third, uncertainty in site-specific temporal trends and relative abundance are not propagated at the appropriate spatial scale. A common result is the propensity to underestimate the magnitude of declines and therefore fail to identify the appropriate at-risk status for a species. We used 3 statistical approaches, from simple to more complex, to estimate temporal decline rates for a designatable unit (DU) of rainbow trout in the Athabasca River watershed in western Canada. This DU is considered a native species for purposes of listing because of its genetic composition characterized as >0.95 indigenous origin in the face of continuing introgressive hybridization with introduced populations in the watershed. Analysis of abundance trends from 57 time series with a fixed-effects model identified 33 sites with negative trends, but only 2 were statistically significant. By contrast, a hierarchical linear mixed model weighted by site-specific abundance provided a DU-wide decline estimate of 16.4% per year and a 3-generation decline of 93.2%. A hierarchical Bayesian mixed model yielded a similar 3-generation decline trend of 91.3% and the posterior distribution showed that the estimate had a >99% probability of exceeding thresholds for an endangered listing. We conclude that the Bayesian approach was the most useful because it provided a probabilistic statement of threshold exceedance in support of an at-risk status recommendation.