Simulating regimes of chemical disturbance and testing impacts in the ecosystem using a novel programmable dosing system

Qualitative and quantitative simulation of best management practices (BMPs) for contaminated megasite remediation using the SiteWise™ tool

Remediation activities, particularly in megasites, may induce substantial secondary environmental impacts that must be addressed for green and sustainable remediation (GSR) practices. Only limited studies are available quantitatively assessing the environmental footprint and environmental benefits of implementing Best Management Practices (BMPs) in megasite remediation. This study used the SiteWise™ tool, a quantitative environmental footprint assessment for scenario simulation and benefit quantification of BMPs, on a contaminated megasite in Hebei Province, China. We observed a considerable environmental footprint and energy from the remediation. Taking the final implementation alternative (Alt 1) as an example, which is characterized by combining multiple remediation techniques, the greenhouse gas (GHG) emissions reached 113,474 t, the energy used was 2,082,841 million metric British thermal units (MMBTU), and other air pollutant emissions (NOx, SOx, and PM10) amounted to 856 t. Further BMP analyses highlighted the benefits of substituting the conventional solidification/stabilization agent with willow woodchip-based biochar, which could reduce GHG emissions by 50,806 t and energy used by 926,648 MMBTU. The overall environmental benefits of implementing all applicable BMPs in the remediation were significant, with a 66.85%, 50.15%, and 56.05% reduction in GHG emissions, energy used, and other air pollutants, respectively. Our study provides insights into quantifying the environmental footprint and exploring emission reduction pathways for contaminated megasite remediation. It also offers a feasible path for quantifying the environmental benefits of BMPs, promoting the development of GSR of contaminated sites.

Plastic Debris As a Vector for Bacterial Disease: An Interdisciplinary Systematic Review

Pathogens and polymers can separately cause disease; however, environmental and medical researchers are increasingly investigating the capacity of polymers to transfer pathogenic bacteria, and cause disease, to hosts in new environments. We integrated causal frameworks from ecology and epidemiology into one interdisciplinary framework with four stages (colonization, survival, transfer, disease). We then systematically and critically reviewed 111 environmental and medical papers. We show 58% of studies investigated the colonization-stage alone but used this as evidence to classify a substratum as a vector. Only 11% of studies identified potential pathogens, with only 3% of studies confirming the presence of virulence-genes. Further, 8% of studies investigated μm-sized polymers with most (58%) examining less pervasive cm-sized polymers. No study showed bacteria can preferentially colonize, survive, transfer, and cause more disease on polymers compared to other environmental media. One laboratory experiment demonstrated plausibility for polymers to be colonized by a potential pathogen (Escherichia coli), survive, transfer, and cause disease in coral (Astrangia poculata). Our analysis shows a need for linked structured surveys with environmentally relevant experiments to understand patterns and processes across the vectoral stages, so that the risks and impacts of pathogens on polymers can be assessed with more certainty.

Sublethal effects of contaminants on marine habitat-forming species: a review and meta-analysis

Contaminants may affect ecosystem functioning by reducing the fitness of organisms and these impacts may cascade through ecosystems, particularly if the sensitive organisms are also habitat-forming species. Understanding how sub-lethal effects of toxicants can affect the quality and functions of biogenic habitats is critical if we are to establish effective guidelines for protecting ecosystems. We carried out a global systematic review and meta-analysis critically evaluating contaminant effects on properties of habitat-formers linked to ecosystem functioning. We reviewed a total of 95 publications. However, 40% of publications initially captured by the literature search were identified as having flaws in experimental design and ~11% did not present results in an appropriate way and thus were excluded from the quantitative meta-analysis. We quantitatively reviewed 410 studies from 46 publications, of which 313 (~76%) were on plants and seaweeds, that is macro-algae, saltmarsh plants and seagrasses, 58 (~14%) studied corals and 39 (~10%) looked at toxicant impacts on bivalves, with 70% of those on mussels and the remaining studies on oysters. Response variables analysed were photosynthetic efficiency, amount of chlorophyll a (as a proxy for primary production) and growth of plants, seaweeds and corals as well as leaf area of plants. We also analysed filtration, growth and respiration rates of bivalves. Our meta-analysis found that chemical contaminants have a significant negative impact on most of the analysed functional variables, with the exception of the amount of chlorophyll a. Metals were the most widely harmful type of contaminant, significantly decreasing photosynthetic efficiency of kelps, leaf area of saltmarsh plants, growth of fucoids, corals and saltmarsh plants and the filtration rates of bivalves. Organic contaminants decreased the photosynthetic efficiency of seagrass, but had no significant effects on bivalve filtration. We did not find significant effects of polycyclic aromatic hydrocarbons on any of the analysed functional variables or habitat-forming taxa, but this could be due to the low number of studies available. A meta-regression revealed that relationships between concentrations of metal contaminants and the magnitude of functional responses varied with the type of metal and habitat-former. Increasing concentrations of contaminants significantly increased the negative effects on the photosynthetic efficiency of habitat-formers. There was, however, no apparent relationship between ecologically relevant concentrations of metals and effect sizes of photosynthetic efficiency of corals and seaweeds. A qualitative analysis of all relevant studies found slightly different patterns when compared to our quantitative analysis, emphasising the need for studies to meet critical inclusion criteria for meta-analyses. Our study highlights links between effects of contaminants at lower levels of organisation (i.e. at the biochemical and/or physiological level of individuals) and ecological, large-scale impacts, through effects on habitat-forming species. Contaminants can clearly reduce the functioning of many habitat-forming marine species. We therefore recommend the adoption of routine measures of functional endpoints in monitoring and conservation programs to complement structural measures.