Diel metatranscriptomes capture cyanobacteria-dominated Lake Erie community response to episodic events.

Here, we report on the raw and coassembled metatranscriptomes of 39 Lake Erie surface (1.0 m) water samples collected over a 2-day diel period encompassing episodic weather and bloom events. Preliminary taxonomic annotations and read mappings revealed that spp.

Controls on the photochemical production of hydrogen peroxide in Lake Erie.

In Lake Erie, toxin-forming harmful algal blooms (HABs) occur following high concentrations of hydrogen peroxide (HO). Correlation between HO concentrations and HABs revealed knowledge gaps on the controls of HO production in Lake Erie. One way HO is produced is upon absorption of sunlight by the chromophoric fraction of dissolved organic matter (CDOM).

Heterotrophic Bacteria Dominate Catalase Expression during Blooms.

In the oligotrophic oceans, key autotrophs depend on "helper" bacteria to reduce oxidative stress from hydrogen peroxide (HO) in the extracellular environment. HO is also a ubiquitous stressor in freshwaters, but the effects of HO on autotrophs and their interactions with bacteria are less well understood in freshwaters. Naturally occurring HO in freshwater systems is proposed to impact the proportion of microcystin-producing (toxic) and non-microcystin-producing (nontoxic) in blooms, which influences toxin concentrations and human health impacts.

Efficacy of selected pretreatment processes in the mitigation of low-pressure membrane fouling and its correlation to their removal of microbial DOM.

Membrane fouling by dissolved organic matter (DOM), especially microbially-derived DOM, is a major challenge for ultrafiltration (UF) membranes in water purification. Fouling may be mitigated by pretreating feed waters; however, there are no comprehensive studies that compare the fouling reduction efficacies across different pretreatment processes. Further, there is a limited understanding of the relationship between fouling reduction efficacy and microbially-derived DOM removal from source waters.

Experimental metatranscriptomics reveals the costs and benefits of dissolved organic matter photo-alteration for freshwater microbes.

Microbes and sunlight convert terrigenous dissolved organic matter (DOM) in surface waters to greenhouse gases. Prior studies show contrasting results about how biological and photochemical processes interact to contribute to the degradation of DOM. In this study, DOM leached from the organic layer of tundra soil was exposed to natural sunlight or kept in the dark, incubated in the dark with the natural microbial community, and analysed for gene expression and DOM chemical composition.

Assessing the prevalence, products, and pathways of dissolved organic matter partial photo-oxidation in arctic surface waters.

In sunlit waters, photodegradation of dissolved organic matter (DOM) yields completely oxidized carbon (i.e., CO) as well as a suite of partially oxidized compounds formed from oxygen incorporation (i.

Direct noninvasive H NMR analysis of stream water DOM: Insights into the effects of lyophilization compared with whole water.

NMR spectroscopy is widely used in the field of aquatic biogeochemistry to examine the chemical structure of dissolved organic matter (DOM). Most aquatic DOM analyzed by proton NMR ( H NMR) is concentrated mainly by freeze-drying prior to analysis to combat low concentrations, frequently <100 μM C, and eliminate interference from water. This study examines stream water with low dissolved organic carbon content by H NMR with a direct noninvasive analysis of whole water using a water-suppression technique.

Effects of vertical hydrodynamic mixing on photomineralization of dissolved organic carbon in arctic surface waters.

Photomineralization, the transformation of dissolved organic carbon (DOC) to CO2 by sunlight, is an important source of CO2 in arctic surface waters. However, quantifying the role of photomineralization in inland waters is limited by the understanding of hydrologic controls on this process. To bridge this gap, this study evaluates mixing limitations, i.

Solar UV radiation in a changing world: roles of cryosphere-land-water-atmosphere interfaces in global biogeochemical cycles.

Global change influences biogeochemical cycles within and between environmental compartments (i.e., the cryosphere, terrestrial and aquatic ecosystems, and the atmosphere).

Environmental effects of ozone depletion, UV radiation and interactions with climate change: UNEP Environmental Effects Assessment Panel, update 2017.

The Environmental Effects Assessment Panel (EEAP) is one of three Panels of experts that inform the Parties to the Montreal Protocol. The EEAP focuses on the effects of UV radiation on human health, terrestrial and aquatic ecosystems, air quality, and materials, as well as on the interactive effects of UV radiation and global climate change. When considering the effects of climate change, it has become clear that processes resulting in changes in stratospheric ozone are more complex than previously held.

Photochemical alteration of organic carbon draining permafrost soils shifts microbial metabolic pathways and stimulates respiration.

In sunlit waters, photochemical alteration of dissolved organic carbon (DOC) impacts the microbial respiration of DOC to CO. This coupled photochemical and biological degradation of DOC is especially critical for carbon budgets in the Arctic, where thawing permafrost soils increase opportunities for DOC oxidation to CO in surface waters, thereby reinforcing global warming. Here we show how and why sunlight exposure impacts microbial respiration of DOC draining permafrost soils.

Cyanobacterial harmful algal blooms are a biological disturbance to Western Lake Erie bacterial communities.

Human activities are causing a global proliferation of cyanobacterial harmful algal blooms (CHABs), yet we have limited understanding of how these events affect freshwater bacterial communities. Using weekly data from western Lake Erie in 2014, we investigated how the cyanobacterial community varied over space and time, and whether the bloom affected non-cyanobacterial (nc-bacterial) diversity and composition. Cyanobacterial community composition fluctuated dynamically during the bloom, but was dominated by Microcystis and Synechococcus OTUs.

Minimization of short-term low-pressure membrane fouling using a magnetic ion exchange (MIEX(®)) resin.

Two challenges to low-pressure membrane (LPM) filtration are limited rejection of dissolved organic matter (DOM) and membrane fouling by DOM. The magnetic ion exchange resin MIEX(®) (Ixom Watercare Inc.) has been demonstrated to remove substantial amounts of DOM from many source waters, suggesting that MIEX can both reduce DOM content in membrane feed waters and minimize LPM fouling.

Complete and Partial Photo-oxidation of Dissolved Organic Matter Draining Permafrost Soils.

Photochemical degradation of dissolved organic matter (DOM) to carbon dioxide (CO2) and partially oxidized compounds is an important component of the carbon cycle in the Arctic. Thawing permafrost soils will change the chemical composition of DOM exported to arctic surface waters, but the molecular controls on DOM photodegradation remain poorly understood, making it difficult to predict how inputs of thawing permafrost DOM may alter its photodegradation. To address this knowledge gap, we quantified the susceptibility of DOM draining the shallow organic mat and the deeper permafrost layer of arctic soils to complete and partial photo-oxidation and investigated changes in the chemical composition of each DOM source following sunlight exposure.

Detection of emergent strains of West Nile virus with a blood screening assay.

Background: West Nile virus (WNV) is a threat to transfusion safety. WNV Kunjin strain (WNVKUN ) is endemic across parts of Australia; however, human infection is believed to be infrequent and is often associated with relatively minor symptoms. A virulent strain, closely related to WNVKUN (termed WNVNSW2011 ) was recently identified as the etiologic agent of encephalitis in Australian horses.

Seroprevalence of hepatitis E virus (HEV) and detection of HEV RNA with a transcription-mediated amplification assay in blood donors from Catalonia (Spain).

Background: Hepatitis E virus (HEV) is an emerging threat to the safety of blood transfusion. The aim of this study was to determine HEV immunoglobulin (Ig)G and RNA prevalence in Catalan blood donors.

Study Design And Methods: Nearly 10,000 samples were collected from anonymized, unpaid donors at the Banc de Sang i Teixits (Barcelona, Spain) from June to December 2013.

Disentangling the interactions between photochemical and bacterial degradation of dissolved organic matter: amino acids play a central role.

Photochemical and bacterial degradation are important pathways to carbon mineralization and can be coupled in dissolved organic matter (DOM) decomposition. However, details of several mechanisms of the coupled photochemical and biological processing of DOM remain too poorly understood to achieve accurate predictions of the impact of these processes on DOM fate and reactivity. The aim of this study was to evaluate how photochemical degradation of amino acids affects bacterial metabolism and whether or not photochemical degradation of DOM competes for amino acids with biological processes.

Carbon cycle. Sunlight controls water column processing of carbon in arctic fresh waters.

Carbon in thawing permafrost soils may have global impacts on climate change; however, the factors that control its processing and fate are poorly understood. The dominant fate of dissolved organic carbon (DOC) released from soils to inland waters is either complete oxidation to CO2 or partial oxidation and river export to oceans. Although both processes are most often attributed to bacterial respiration, we found that photochemical oxidation exceeds rates of respiration and accounts for 70 to 95% of total DOC processed in the water column of arctic lakes and rivers.

Robust post-stall perching with a simple fixed-wing glider using LQR-Trees.

Birds routinely execute post-stall maneuvers with a speed and precision far beyond the capabilities of our best aircraft control systems. One remarkable example is a bird exploiting post-stall pressure drag in order to rapidly decelerate to land on a perch. Stall is typically associated with a loss of control authority, and it is tempting to attribute this agility of birds to the intricate morphology of the wings and tail, to their precision sensing apparatus, or their ability to perform thrust vectoring.

Evidence for dissolved organic matter as the primary source and sink of photochemically produced hydroxyl radical in arctic surface waters.

Hydroxyl radical (˙OH) is an indiscriminate oxidant that reacts at near-diffusion-controlled rates with organic carbon. Thus, while ˙OH is expected to be an important oxidant of dissolved organic matter (DOM) and other recalcitrant compounds, the role of ˙OH in the oxidation of these compounds in aquatic ecosystems is not well known due to the poorly constrained sources and sinks of ˙OH, especially in pristine (unpolluted) natural waters. We measured the rates of ˙OH formation and quenching across a range of surface waters in the Arctic varying in concentrations of expected sources and sinks of ˙OH.

Insights into the complete and partial photooxidation of black carbon in surface waters.

Increasing wildfire activity in the Alaskan Arctic may result in new sources of black carbon (BC) to arctic watersheds. Black carbon, primarily comprised of condensed aromatics, is one of the most chemically recalcitrant fractions of organic carbon. However, lateral transfer of particulate and dissolved BC from soils to sunlit surface waters is increasingly suggested to result in the photochemical mineralization of BC to CO₂.

Changes in dissolved organic matter fluorescence and disinfection byproduct formation from UV and subsequent chlorination/chloramination.

Ultraviolet (UV) irradiation is being increasingly used to help drinking water utilities meet finished water quality regulations, but its influence on disinfection byproduct (DBP) precursors and DBP formation is not completely understood. This study investigated the effect of medium pressure (MP) UV combined with chlorination/chloramination on the fluorescent fraction of dissolved organic matter (DOM) isolated from a United States surface water with median total organic carbon content. Parallel factor analysis was used to understand how UV may alter the capacity of DOM to form DBPs of potential human health concern.

Dark formation of hydroxyl radical in Arctic soil and surface waters.

Hydroxyl radical (•OH) is a highly reactive and unselective oxidant in atmospheric and aquatic systems. Current understanding limits the role of DOM-produced •OH as an oxidant in carbon cycling mainly to sunlit environments where •OH is produced photochemically, but a recent laboratory study proposed a sunlight-independent pathway in which •OH forms during oxidation of reduced aquatic dissolved organic matter (DOM) and iron. Here we demonstrate this non-photochemical pathway for •OH formation in natural aquatic environments.

Determination of specific types and relative levels of QPCR inhibitors in environmental water samples using excitation-emission matrix spectroscopy and PARAFAC.

Assays that utilize PCR offer powerful tools to detect pathogens and other microorganisms in environmental samples. However, PCR inhibitors present in nucleic acid extractions can increase a sample's limit of detection, skew calculated marker concentrations, or cause false-negative results. It would be advantageous to predict which samples contain various types and levels of PCR inhibitors, especially the humic and fulvic acids that are frequently cited as PCR inhibitors in natural water samples.