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| 2. |
- Baho, Didier L., et al.
(författare)
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A single pulse of diffuse contaminants alters the size distribution of natural phytoplankton communities
- 2019
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Ingår i: Science of the Total Environment. - : Elsevier BV. - 0048-9697 .- 1879-1026. ; 683, s. 578-588
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Tidskriftsartikel (refereegranskat)abstract
- The presence of a multitude of bioactive organic pollutants collectively classified as pharmaceuticals and personal care products (PPCPs) in freshwaters is of concern, considering that ecological assessments of their potential impacts on natural systems are still scarce. In this field experiment we tested whether a single pulse exposure to a mixture of 12 pharmaceuticals and personal care products, which are commonly found in European inland waters, can influence the size distributions of natural lake phytoplankton communities. Size is one of the most influential determinants of community structure and functioning, particularly in planktonic communities and food webs. Using an in-situ microcosm approach, phytoplankton communities in two lakes with different nutrient levels (mesotrophic and eutrophic) were exposed to a concentration gradient of the PPCPs mixture at five levels. We tested whether sub-lethal PPCPs doses affect the scaling of organisms' abundances with their size, and the slope of these size spectra, which describe changes in the abundances of small relative to large phytoplankton. Our results showed that a large proportion (approximately 80%) of the dataset followed a power-law distribution, thus suggesting evidence of scale invariance of abundances, as expected in steady state ecosystems. PPCPs were however found to induce significant changes in the size spectra and community structure of natural phytoplankton assemblages. The two highest treatment levels of PPCPs were associated with decreased abundance of the most dominant size class (nano-phytoplankton: 2-5 mu m), leading to a flattening of the size spectra slope. These results suggest that a pulse exposure to PPCPs induce changes that potentially lead to unsteady ecosystem states and cascading effects in the aquatic food webs, by favoring larger non-edible algae at the expense of small edible species. We propose higher susceptibility due to higher surface to volume ratio in small species as the likely cause of these structural changes.
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| 3. |
- Baho, Didier L., et al.
(författare)
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Resilience of Natural Phytoplankton Communities to Pulse Disturbances from Micropollutant Exposure and Vertical Mixing
- 2019
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Ingår i: Environmental Toxicology and Chemistry. - : Wiley. - 0730-7268 .- 1552-8618. ; 38:10, s. 2197-2208
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Tidskriftsartikel (refereegranskat)abstract
- Freshwaters are increasingly exposed to complex mixtures of pharmaceutical and personal care products (PPCPs) from municipal wastewater, which are known to alter freshwater communities' structure and functioning. However, their interaction with other disturbances and whether their combined effects can impact ecological resilience (i.e., the ability of a system to tolerate disturbances without altering the system's original structure and processes) remain unexplored. Using in situ mesocosms in 2 lakes with different nutrient levels (mesotrophic and eutrophic), we assessed whether a pulse exposure to sublethal concentrations of 12 PPCPs affects the ecological resilience of natural phytoplankton communities that experienced an abrupt environmental change involving the destabilization of the water column through mixing. Such mixing events are predicted to increase as the effects of climate change unfold, leading to more frequent storms, which disrupt stratification in lakes and force communities to restructure. We assessed their combined effects on community metrics (biomass, species richness, and composition) and their relative resilience using 4 indicators (cross-scale, within-scale, aggregation length, and gap length), inferred from phytoplankton communities by discontinuity analysis. The mixing disturbance alone had negligible effects on the community metrics, but when combined with chemical contaminants significant changes were measured: reducing total biomass, species richness, and altered community composition of phytoplankton. Once these changes occurred, they persisted until the end of the experiment (day 20), when the communities' structures from the 2 highest exposure levels diverged from the controls. The resilience indicators were not affected by PPCPs but differed significantly between lakes, with lower resilience found in the eutrophic lake. Thus, PPCPs can significantly alter community structures and reinforce mechanisms that maintain ecosystems in a degraded state.
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| 4. |
- Gopakumar, Deepu A., et al.
(författare)
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Nanocellulose-Based Membranes for Water Purification
- 2019
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Ingår i: Nanoscale Materials in Water Purification. - 9780128139271 ; , s. 59-85
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Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- Scarcity and contamination of worldwide drinking water demand advanced, effective water purification methodologies. Eliminating numerous contaminants, such as heavy metals, toxic textile dyes, pesticides, oil, and other industrial, as well as agricultural, wastes, from water has become a serious concern because of their adverse effects on human health and the ecosystem. Recently, developments in nanoscience and nanotechnology propose that several of the present problems relating to water quality could be greatly reduced by using nanomaterials because of their good adsorption efficiency, higher surface area, and greater active sites for interaction with contaminants in water. In this context, nanocellulose is the most abundant and renewable polymer available globally and consists of repeating β-d-glucopyranose units covalently linked through acetal functions between the hydroxyl groups of C4 and C1 carbon atoms that provide it chirality and reactivity properties. Nanocellulose is a fascinating material for practical applications because it is cost-effective, is renewable, and can be handled at huge scale using conventional wood industry techniques. Nanocellulose is a valuable filtration material because it is affordable, sustainable, inert, and stable at a broad range of pH/ionic strength. Moreover, the abundant availability of the surface hydroxyl groups on the nanocellulose facilitates various surface chemistries that can be explored for targeting various contaminants in water. This chapter covers the recent developments and literature of nanocellulose in the field of water purification.
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| 5. |
- Zhou, Nerve, et al.
(författare)
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Coevolution with bacteria drives the evolution of aerobic fermentation in Lachancea kluyveri
- 2017
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Ingår i: PLoS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 12:3
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Tidskriftsartikel (refereegranskat)abstract
- The Crabtree positive yeasts, such as Saccharomyces cerevisiae, prefer fermentation to respiration, even under fully aerobic conditions. The selective pressures that drove the evolution of this trait remain controversial because of the low ATP yield of fermentation compared to respiration. Here we propagate experimental populations of the weak-Crabtree yeast Lachancea kluyveri, in competitive co-culture with bacteria. We find that L. kluyveri adapts by producing quantities of ethanol lethal to bacteria and evolves several of the defining characteristics of Crabtree positive yeasts. We use precise quantitative analysis to show that the rate advantage of fermentation over aerobic respiration is insufficient to provide an overall growth advantage. Thus, the rapid consumption of glucose and the utilization of ethanol are essential for the success of the aerobic fermentation strategy. These results corroborate that selection derived from competition with bacteria could have provided the impetus for the evolution of the Crabtree positive trait.
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