An In Situ Bioreactor for the Treatment of Petroleum Hydrocarbons in Groundwater

Two pilot tests of an aerobic in situ bioreactor (ISBR) have been conducted at field sites contaminated with petroleum hydrocarbons. The two sites differed with respect to hydrocarbon concentrations. At one site, concentrations were low but persistent, and at the other site concentrations were high enough to be inhibitory to biodegradation. The ISBR unit is designed to enhance biodegradation of hydrocarbons by stimulating indigenous microorganisms. This approach builds on existing Bio‐Sep^® bead technology, which provides a matrix that can be rapidly colonized by the active members of the microbial community and serves to concentrate indigenous degraders. Oxygen and nutrients are delivered to the bioreactor to maintain conditions favorable for growth and reproduction, and contaminated groundwater is treated as it is circulated through the bed of Bio‐Sep^® beads. Groundwater moving through the system also transports degraders released from Bio‐Sep^® beads away from the bioreactor, potentially increasing biodegradation rates throughout the aquifer. Groundwater sampling, Bio‐Traps, and molecular biological tools were used to assess ISBR performance during the two pilot tests. Groundwater monitoring indicated that contaminant concentrations decreased at both sites, and the microbial data suggested that these decreases were due to degradation by indigenous microorganisms rather than dilution or dispersion mechanisms. Taken together, these lines of evidence showed that the ISBR system effectively increased the number and activity of indigenous microbial degraders and enhanced bioremediation at the test sites. © 2013 Wiley Periodicals, Inc.     

Selenium speciation and localization in chironomids from lakes receiving treated metal mine effluent

A lake system in northern Saskatchewan receiving treated metal mine and mill effluent contains elevated levels of selenium (Se). An important step in the trophic transfer of Se is the bioaccumulation of Se by benthic invertebrates, especially primary consumers serving as a food source for higher trophic level organisms. Chironomids, ubiquitous components of many northern aquatic ecosystems, were sampled at lakes downstream of the milling operation and were found to contain Se concentrations ranging from 7 to 80 mg kg⁻¹ dry weight. For comparison, laboratory-reared Chironomus dilutus were exposed to waterborne selenate, selenite, or seleno-DL-methionine under laboratory conditions at the average total Se concentrations found in lakes near the operation. Similarities in Se localization and speciation in laboratory and field chironomids were observed using synchrotron-based X-ray fluorescence (XRF) imaging and X-ray absorption spectroscopy (XAS). Selenium localized primarily in the head capsule, brain, salivary glands and gut lining, with organic Se species modeled as selenocystine and selenomethionine being the most abundant. Similarities between field chironomids and C. dilutus exposed in the laboratory to waterborne selenomethionine suggest that selenomethionine-like species are most readily accumulated, whether from diet or water.     

Towards a renewed research agenda in ecotoxicology

New concerns about biodiversity, ecosystem services and human health triggered several new regulations increasing the need for sound ecotoxicological risk assessment. The PEER network aims to share its view on the research issues that this challenges. PEER scientists call for an improved biologically relevant exposure assessment. They promote comprehensive effect assessment at several biological levels. Biological traits should be used for Environmental risk assessment (ERA) as promising tools to better understand relationships between structure and functioning of ecosystems. The use of modern high throughput methods could also enhance the amount of data for a better risk assessment. Improved models coping with multiple stressors or biological levels are necessary to answer for a more scientifically based risk assessment. Those methods must be embedded within life cycle analysis or economical models for efficient regulations. Joint research programmes involving humanities with ecological sciences should be developed for a sound risk management.     

Unanswered questions on the airborne transmission of COVID-19

Environmental Chemistry Letters - Policies and measures to control pandemics are often failing. While biological factors controlling transmission are usually well explored, little is known about...     

Waves of pharmaceutical waste

Environmental Chemistry Letters -     

Planting trees to combat global warming

Environmental Chemistry Letters -     

Integrating larval connectivity into the marine conservation decision-making process across spatial scales

Larval dispersal connectivity is typically integrated into spatial conservation decisions at regional or national scales, but implementing agencies struggle with translating these methods to local scales. We used larval dispersal connectivity at regional (hundreds of kilometers) and local (tens of kilometers) scales to aid in design of networks of no-take reserves in Southeast Sulawesi, Indonesia. We used Marxan with Connectivity informed by biophysical larval dispersal models and remotely sensed coral reef habitat data to design marine reserve networks for 4 commercially important reef species across the region. We complemented regional spatial prioritization with decision trees that combined network-based connectivity metrics and habitat quality to design reserve boundaries locally. Decision trees were used in consensus-based workshops with stakeholders to qualitatively assess site desirability, and Marxan was used to identify areas for subsequent network expansion. Priority areas for protection and expected benefits differed among species, with little overlap in reserve network solutions. Because reef quality varied considerably across reefs, we suggest reef degradation must inform the interpretation of larval dispersal patterns and the conservation benefits achievable from protecting reefs. Our methods can be readily applied by conservation practitioners, in this region and elsewhere, to integrate connectivity data across multiple spatial scales.     

Helping to improve suggestion systems: predictors of making suggestions in companies

Predictors of submitting suggestions and their quality were studied in a Dutch company with a well‐developed suggestion system (n=207 blue collar workers). A model with person variables (initiative at work, higher order need strength, control aspirations, and interest in work innovation), work characteristics (control and complexity), motives (better work, reward), self‐efficacy, and system factors (system inhibitors, system responsiveness, and supervisor support) was developed and tested. They are related to the three process variables, deemed to be important in making a suggestion: having ideas, submitting suggestions and quality of the suggestions. A path analysis revealed that the most important factors related to these process variables were initiative at work, higher order need strength, self‐efficacy, expected improvements in work and suggestion inhibitors (negatively). Copyright © 1999 John Wiley & Sons, Ltd.     

Bioaccumulation factors and multivariate analysis of heavy metals of three edible fish species from the Barekese reservoir in Kumasi,Ghana

The Barekese reservoir has seen persistent degradation for decades through anthropogenic activities within its catchment. In spite of this, heavy metal pollution profile of fish species of the reservoir is not well studied. Total concentrations of Hg, Cd, Ni, and Cr were analyzed in muscle tissues of 45 edible fish species comprising (Tilapia zilli, Oreochromis niloticus, and Heterotis niloticus) from the reservoir. The examined fish species showed varying bioaccumulative factors for detected metals. A PCA biplot revealed that Cd showed association with all examined fish species used in the study indicating that Cd in the reservoir is biologically available for uptake by all examined fish species. A dendrogram of cluster analysis also revealed that Cd and Cr are in one cluster indicating their associations and similarities to a common anthropogenic source. The study suggests that anthropogenic activities are possible sources of heavy metal pollution in the Barekese reservoir and, hence, the examined fish species could be used to monitor the levels of Ni, Cr, Hg, and Cd in the reservoir.