scholarly journals Vertical transport of sediment-associated metals and cyanobacteria by ebullition in a stratified lake

2020 ◽  
Vol 17 (12) ◽  
pp. 3135-3147
Author(s):  
Kyle Delwiche ◽  
Junyao Gu ◽  
Harold Hemond ◽  
Sarah P. Preheim
Keyword(s):  
Surface Waters ◽  
Particulate Material ◽  
Freshwater Ecosystems ◽  
Freshwater Lakes ◽  
Cell Recruitment ◽  
Stratified Lake ◽  
Marine Systems ◽  
Stratified Lakes ◽  
Transport Particle ◽  
Arsenic Transport

Abstract. Bubbles adsorb and transport particulate matter in a variety of natural and engineered settings, including industrial, freshwater, and marine systems. While methane-containing bubbles emitted from anoxic sediments are found widely in freshwater ecosystems, relatively little attention has been paid to the possibility that these bubbles transport particle-associated chemical or biological material from sediments to surface waters of freshwater lakes. We triggered ebullition and quantified transport of particulate material from sediments to the surface by bubbles in Upper Mystic Lake, MA, and in a 15 m tall experimental column. Particle transport was positively correlated with the volume of gas bubbles released from the sediment, and particles transported by bubbles appear to originate almost entirely in the sediment, rather than being scavenged from the water column. Concentrations of arsenic, chromium, lead, and cyanobacterial cells in bubble-transported particulate material were similar to those of bulk sediment, and particles were transported from depths exceeding 15 m, implying the potential for daily average fluxes as large as 0.18 µg arsenic m−2 and 2×104 cyanobacteria cells m−2 in the strongly stratified Upper Mystic Lake. Bubble-facilitated arsenic transport currently appears to be a modest component of total arsenic cycling in this lake. Although more work is needed to reduce uncertainty in budget estimates, bubble-facilitated cyanobacterial transport has the potential to contribute substantially to the cyanobacteria cell recruitment to the surface of this lake and may thus be of particular importance in large, deep, stratified lakes.

scholarly journals Vertical transport of sediment-associated metals and cyanobacteria by ebullition in a stratified lake

2019 ◽  
Author(s):  
Kyle Delwiche ◽  
Junyao Gu ◽  
Harold Hemond ◽  
Sarah P. Preheim
Keyword(s):  
Surface Waters ◽  
Aquatic Ecosystems ◽  
Particulate Material ◽  
Freshwater Lakes ◽  
Stratified Lake ◽  
Marine Systems ◽  
Stratified Lakes ◽  
Transport Particle ◽  
Sediment Particles ◽  
Arsenic Transport

Abstract. Bubbles adsorb and transport particulate matter both in industrial and marine systems. While methane-containing bubbles emitted from anoxic sediments are found extensively in aquatic ecosystems, relatively little attention has been paid to the possibility that such bubbles transport particle-associated chemical or biological material from sediments to surface waters of freshwater lakes. We quantified transport of particulate material from sediments to the surface by bubbles in Upper Mystic Lake, MA and in a 15 m tall experimental column. Vertical particle transport was positively correlated with the volume of gas bubbles released from the sediment. Particles transported by bubbles originated almost entirely in the sediment, rather than being scavenged from the water column. Concentrations of arsenic, chromium, lead, and cyanobacterial cells in bubble-transported particulate material were similar to those of bulk sediment, and particles were transported from depths exceeding 15 m, resulting in daily fluxes as large as 0.005 µmol of arsenic m−2 and 4 × 104 cyanobacterial cells m−2 in the strongly stratified Upper Mystic Lake. While bubble-facilitated arsenic transport currently appears to be a modest component of total arsenic cycling in this lake, bubble-facilitated cyanobacterial transport could comprise as much as 17 % of recruitment in this lake and may thus be of particular importance in large, deep, stratified lakes.

scholarly journals Knowledge about Microplastic in Mediterranean Tributary River Ecosystems: Lack of Data and Research Needs on Such a Crucial Marine Pollution Source

2020 ◽  
Vol 8 (3) ◽  
pp. 216 ◽  
Author(s):  
Cristiana Guerranti ◽  
Guido Perra ◽  
Tania Martellini ◽  
Luisa Giari ◽  
Alessandra Cincinelli
Keyword(s):  
Marine Pollution ◽  
Distribution Patterns ◽  
Pollution Source ◽  
Freshwater Ecosystems ◽  
Abundance Distribution ◽  
Plastic Pollution ◽  
Marine Systems ◽  
Final Destination ◽  
Lack Of Information ◽  
Freshwater Environments

Plastic debris occurring in freshwater environments, which can either come from the surrounding terrestrial areas or transported from upstream, has been identified as one of the main sources and routes of plastic pollution in marine systems. The ocean is the final destination of land- based microplastic sources, but compared to marine environments, the occurrence and effects of microplastics in freshwater ecosystems remain largely unknown. A thorough examination of scientific literature on abundance, distribution patterns, and characteristics of microplastics in freshwater environments in Mediterranean tributary rivers has shown a substantial lack of information and the need to apply adequate and uniform measurement methods.

scholarly journals Edge-of-Field Technologies for Phosphorus Retention from Agricultural Drainage Discharge

2020 ◽  
Vol 10 (2) ◽  
pp. 634 ◽  
Author(s):  
Lipe Renato Dantas Mendes
Keyword(s):  
Surface Waters ◽  
Organic Phosphorus ◽  
Freshwater Ecosystems ◽  
Phosphorus Retention ◽  
Buffer Strips ◽  
Large Variability ◽  
Agricultural Catchments ◽  
Limiting Nutrient ◽  
Phosphorus Form ◽  
Subsurface Drains

Agriculture is often responsible for the eutrophication of surface waters due to the loss of phosphorus—a normally limiting nutrient in freshwater ecosystems. Tile-drained agricultural catchments tend to increase this problem by accelerating the transport of phosphorus through subsurface drains both in dissolved (reactive and organic phosphorus) and particulate (particle-bound phosphorus) forms. The reduction of excess phosphorus loads from agricultural catchments prior to reaching downstream surface waters is therefore necessary. Edge-of-field technologies have been investigated, developed and implemented in areas with excess phosphorus losses to receive and treat the drainage discharge, when measures at the farm-scale are not able to sufficiently reduce the loads. The implementation of these technologies shall base on the phosphorus dynamics of specific catchments (e.g., phosphorus load and dominant phosphorus form) in order to ensure that local retention goals are met. Widely accepted technologies include constructed wetlands, restored wetlands, vegetated buffer strips and filter materials. These have demonstrated a large variability in the retention of phosphorus, and results from the literature can help targeting specific catchment conditions with suitable technologies. This review provides a comprehensive analysis of the currently used edge-of-field technologies for phosphorus retention in tile-drained catchments, with great focus on performance, application and limitations.

Zinc marine biogeochemistry in seawater: a review

2012 ◽  
Vol 63 (7) ◽  
pp. 644 ◽  
Author(s):  
Marie Sinoir ◽  
Edward C. V. Butler ◽  
Andrew R. Bowie ◽  
Mathieu Mongin ◽  
Pavel N. Nesterenko ◽  
...  
Keyword(s):  
Surface Waters ◽  
Phytoplankton Community ◽  
Conceptual Models ◽  
Biogeochemical Cycles ◽  
Phytoplankton Growth ◽  
Laboratory Studies ◽  
Marine Systems ◽  
Subtle Effect ◽  
Marine Biogeochemistry ◽  
Marine Surface

The interest in trace element biogeochemistry has arisen from the well demonstrated iron hypothesis that revealed the central role that iron exerts on oceanic primary and associated biogeochemical cycles. The essentiality of zinc for key biological enzymes, coupled with a nutrient-like vertical distribution with low dissolved concentrations in many marine surface waters, provided motivation to study zinc in marine systems. Laboratory studies have confirmed the importance of zinc to sustain phytoplankton growth and its influence on the composition of the phytoplankton community. However, mixed results were obtained in the field, which suggest a more subtle effect of zinc on oceanic phytoplankton growth than iron. As a consequence, consensus on its biological role, mechanisms at play or regional versus global relevance is currently lacking and highlights the need for new conceptual models of zinc in marine systems. The recent GEOTRACES program is generating new data approaches to discuss and understand further zinc behaviour in the ocean.

scholarly journals acI Actinobacteria Assemble a Functional Actinorhodopsin with Natively-synthesized Retinal

2018 ◽  
Author(s):  
Jeffrey R. Dwulit-Smith ◽  
Joshua J. Hamilton ◽  
David M. Stevenson ◽  
Shaomei He ◽  
Ben O. Oyserman ◽  
...  
Keyword(s):  
Single Cells ◽  
Green Light ◽  
Eutrophic Lake ◽  
Freshwater Ecosystems ◽  
Proton Pumping ◽  
Freshwater Lakes ◽  
Major Step ◽  
Transcription Analysis ◽  
Change Models ◽  
Carotenoid Pathway

ABSTRACTFreshwater lakes harbor complex microbial communities, but these ecosystems are often dominated by acI Actinobacteria from three clades (acI-A, acI-B, acI-C). Members of this cosmopolitan lineage are proposed to bolster heterotrophic growth using phototrophy because their genomes encode actino-opsins (actR). This model has been difficult to experimentally validate because acI are not consistently culturable. In this study, using genomes from single cells and metagenomes, we provide a detailed biosynthetic route for many acI-A and -B members to synthesize retinal and its carotenoid precursors. Accordingly, these acI should be able to natively assemble light-driven actinorhodopsins (holo-ActR) to pump protons, in contrast to acI-C members and other bacteria that encode opsins but lack retinal-production machinery. Moreover, we show that all acI clades contain genes for a complex carotenoid pathway that starts with retinal precursors. Transcription analysis of acI in a eutrophic lake shows that all retinal and carotenoid pathway operons are transcribed and that actR is among the most highly-transcribed of all acI genes. Furthermore, heterologous expression of retinal pathway genes shows that lycopene, retinal, and ActR can be made. Model cells producing ActR and the key acI retinal-producing β-carotene oxygenase formed acI-holo-ActR and acidified solution during illumination. Our results prove that acI containing both ActR and retinal-production enzymes have the capacity to natively synthesize a green light-dependent outward proton-pumping rhodopsin.IMPORTANCEMicrobes play critical roles in determining the quality of freshwater ecosystems that are vital to human civilization. Because acI Actinobacteria are ubiquitous and abundant in freshwater lakes, clarifying their ecophysiology is a major step in determining the contributions that they make to nitrogen and carbon cycling. Without accurate knowledge of these cycles, freshwater systems cannot be incorporated into climate change models, ecosystem imbalances cannot be predicted, and policy for service disruption cannot be planned. Our work fills major gaps in microbial light utilization, secondary metabolite production, and energy cycling in freshwater habitats.

scholarly journals Rates of primary production in groundwater rival those in oligotrophic marine systems

2021 ◽  
Author(s):  
Will A Overholt ◽  
Susan Trumbore ◽  
Xiaomei Xu ◽  
Till L V Bornemann ◽  
Alexander J Probst ◽  
...  
Keyword(s):  
Primary Production ◽  
Surface Waters ◽  
Carbon Fixation ◽  
Euphotic Zone ◽  
Rate Data ◽  
Carbonate Aquifer ◽  
Marine Systems ◽  
Marine Surface ◽  
Terrestrial Subsurface

The terrestrial subsurface contains nearly all of Earth's freshwater reserves and harbors upwards of 60% of our planet's total prokaryotic biomass. While genetic surveys suggest these organisms rely on in situ carbon fixation, rather than the translocation of photosynthetically derived organic carbon, corroborating measurements of carbon fixation in the subsurface are absent. Using a novel ultra-low level 14C-labeling technique, we show that in situ carbon fixation rates in a carbonate aquifer reached 10% of the median rates measured in oligotrophic marine surface waters, and were up to six-fold greater than those observed in lower euphotic zone waters where deep chlorophyll levels peak. Empirical carbon fixation rates were substantiated by both nitrification and anammox rate data. Metagenomic analyses revealed a remarkable abundance of putative chemolithoautotrophic members of an uncharacterized order of Nitrospiria - the first representatives of this class expected to fix carbon via the Wood-Ljungdahl pathway. Based on these fixation rates, we extrapolate global primary production in carbonate groundwaters to be 0.11 Pg of carbon per year.

scholarly journals Linking Stoichiometric Organic Carbon–Nitrogen Relationships to planktonic Cyanobacteria and Subsurface Methane Maximum in Deep Freshwater Lakes

Water ◽  
2020 ◽  
Vol 12 (2) ◽  
pp. 402 ◽  
Author(s):  
Santona Khatun ◽  
Tomoya Iwata ◽  
Hisaya Kojima ◽  
Yoshiki Ikarashi ◽  
Kana Yamanami ◽  
...  
Keyword(s):  
Organic Carbon ◽  
Inorganic Nitrogen ◽  
Freshwater Ecosystems ◽  
Curvilinear Relationship ◽  
Freshwater Lakes ◽  
N Accumulation ◽  
Lake Ecosystems ◽  
Ch4 Production ◽  
Water Columns ◽  
Lake Waters

Our understanding of the source of methane (CH4) in freshwater ecosystems is being revised because CH4 production in oxic water columns, a hitherto inconceivable process of methanogenesis, has been discovered for lake ecosystems. The present study surveyed nine Japanese deep freshwater lakes to show the pattern and mechanisms of such aerobic CH4 production and subsurface methane maximum (SMM) formation. The field survey observed the development of SMM around the metalimnion in all the study lakes. Generalized linear model (GLM) analyses showed a strong negative nonlinear relationship between dissolved organic carbon (DOC) and dissolved inorganic nitrogen (DIN), as well as a similar curvilinear relationship between DIN and dissolved CH4, suggesting that the availability of organic carbon controls N accumulation in lake waters thereby influences the CH4 production process. The microbial community analyses revealed that the distribution of picocyanobacteria (i.e., Synechococcus), which produce CH4 in oxic conditions, was closely related to the vertical distribution of dissolved CH4 and SMM formation. Moreover, a cross-lake comparison showed that lakes with a more abundant Synechococcus population exhibited a greater development of the SMM, suggesting that these microorganisms are the most likely cause of methane production. Thus, we conclude that the stoichiometric balance between DOC and DIN might cause the cascading responses of biogeochemical processes, from N depletion to picocyanobacterial domination, and subsequently influence SMM formation in lake ecosystems.

scholarly journals acI Actinobacteria Assemble a Functional Actinorhodopsin with Natively Synthesized Retinal

2018 ◽  
Vol 84 (24) ◽  
Author(s):  
Jeffrey R. Dwulit-Smith ◽  
Joshua J. Hamilton ◽  
David M. Stevenson ◽  
Shaomei He ◽  
Ben O. Oyserman ◽  
...  
Keyword(s):  
Single Cells ◽  
Green Light ◽  
Freshwater Ecosystems ◽  
Proton Pumping ◽  
Freshwater Lakes ◽  
Major Step ◽  
Transcription Analysis ◽  
Content Type ◽  
Change Models ◽  
Carotenoid Pathway

ABSTRACTFreshwater lakes harbor complex microbial communities, but these ecosystems are often dominated by acIActinobacteria. Members of this cosmopolitan lineage are proposed to bolster heterotrophic growth using phototrophy because their genomes encode actino-opsins (actR). This model has been difficult to validate experimentally because acIActinobacteriaare not consistently culturable. Based primarily on genomes from single cells and metagenomes, we provide a detailed biosynthetic route for members of acI clades A and B to synthesize retinal and its carotenoid precursors. Consequently, acI cells should be able to natively assemble light-driven actinorhodopsins (holo-ActR) to pump protons, unlike many bacteria that encode opsins but may need to exogenously obtain retinal because they lack retinal machinery. Moreover, we show that all acI clades contain genes for a secondary branch of the carotenoid pathway, implying synthesis of a complex carotenoid. Transcription analysis of acIActinobacteriain a eutrophic lake shows that all retinal and carotenoid pathway operons are transcribed and thatactRis among the most highly transcribed of all acI genes. Furthermore, heterologous expression of acI retinal pathway genes showed that lycopene, retinal, and ActR can be made using the genes encoded in these organisms. Model cells producing ActR and the key acI retinal-producing β-carotene oxygenase formed holo-ActR and acidified solution during illumination. Taken together, our results prove that acIActinobacteriacontaining both ActR and acI retinal production machinery have the capacity to natively synthesize a green light-dependent outward proton-pumping rhodopsin.IMPORTANCEMicrobes play critical roles in determining the quality of freshwater ecosystems, which are vital to human civilization. Because acIActinobacteriaare ubiquitous and abundant in freshwater lakes, clarifying their ecophysiology is a major step in determining the contributions that they make to nitrogen and carbon cycling. Without accurate knowledge of these cycles, freshwater systems cannot be incorporated into climate change models, ecosystem imbalances cannot be predicted, and policy for service disruption cannot be planned. Our work fills major gaps in microbial light utilization, secondary metabolite production, and energy cycling in freshwater habitats.

scholarly journals Monitoring Extinction Risk and Threats of the World’s Fishes based on the Sampled Red List Index

2020 ◽  
Author(s):  
Rafael Miranda ◽  
Imanol Miqueleiz ◽  
William Darwall ◽  
Catherine Sayer ◽  
Nicholas Dulvy ◽  
...  
Keyword(s):  
Extinction Risk ◽  
Conservation Status ◽  
Marine Species ◽  
Freshwater Ecosystems ◽  
Red List ◽  
Species At Risk ◽  
Marine Systems ◽  
Species Groups ◽  
Global Biodiversity ◽  
Over Time

Abstract Global biodiversity targets require us to identify species at risk of extinction and quantify status and trends of biodiversity. The Red List Index (RLI) tracks trends in the conservation status of entire species groups over time by monitoring changes in categories assigned to species. Here, we calculate this index for the world’s fishes in 2010, using a sampled approach to the RLI based on a randomly selected sample of 1,500 species, and also present RLI splits for freshwater and marine systems separately. We further compare specific traits of a worldwide fish list to our sample to assess its representativeness. Overall, 15.1% of species in the sample were estimated to be threatened with extinction, resulting in an sampled RLI of 0.914 for all species, 0.972 in marine and 0.860 in freshwater ecosystems. Our sample showed fishing as the principal threat for marine species, and pollution by agricultural and foresty effluents for freshwater fishes. The sampled list provides a robust representation for tracking trends in the conservation status of the world’s fishes, including disaggregated sampled indices for marine and freshwater fish. Reassessment and backcasting of this index is urgent to check the achievement of the commitments proposed in global biodiversity targets.

scholarly journals Role of climate change in recovery of acidified surface waters

2008 ◽  
Vol 12 (2) ◽  
pp. 333-335 ◽  
Author(s):  
R. F. Wright ◽  
P. J. Dillon
Keyword(s):  
Surface Waters ◽  
Biological Effects ◽  
Freshwater Ecosystems ◽  
Interactive Effects ◽  
Special Issue ◽  
Carbon Recovery ◽  
Integrated Project ◽  
Eu Project ◽  
The Eu

Abstract. Surface waters in Europe and North America have begun to recover in response to decreases in emissions of acidifying pollutants to the atmosphere. Variations in climate influence chemical and biological recovery. Part of the EU project Eurolimpacs (Integrated project to evaluate the impacts of global change on European freshwater ecosystems) focuses on the interactive effects of acid deposition and climate on freshwater ecosystems. This special issue of Hydrology and Earth System Sciences is devoted to this topic, and consists of studies conducted in 8 countries on aspects regarding episodes, nitrate, dissolved organic carbon, recovery and biological effects.

Sign in / Sign up

Export Citation Format

Share Document