Non-target analysis of crude oil photooxidation products at high latitudes and their biological effects.

With new oil and gas lease sales in high-latitude regions, there exists a need to better understand the chemical fate of spilled oil and its effects on biological life. To address this need, laboratory simulations of crude oil spills under sub-Arctic conditions were conducted using artificial seawater and exposure to solar irradiation to create Hydrocarbon Oxidation Products (HOPs). HOPs characterization and their biological effects were assessed using ultra high-performance liquid chromatography (UHPLC) with high resolution mass Orbitrap spectrometry and the aryl hydrocarbon receptor (AhR) chemically activated luciferase gene expression (CALUX) assay. Non-target UHPLC-Orbitrap mass spectrometry analysis identified 251 HOPs that were in greater abundance in light-exposed samples than dark controls. Oxidized polycyclic aromatic hydrocarbons were also detected, including phenanthrene quinone, anthraquinone, hydroxyanthraquinone, and 9-fluoreneone. The composition of HOPs were consistent with photo-products of alkylated two to four ring PAHs, primarily compounds between 1 and 3 aromatic rings and 1-3 oxygens. The HOP mixture formed during photochemical weathering of Cook Inlet crude oil induced greater AhR activity than parent petroleum products solubilized in dark controls, indicating that HOPs, as a complex mixture, may contribute to petroleum toxicity more than the parent petroleum compounds. These non-targeted approaches provide the most comprehensive analysis of hydrocarbon oxidation products to date, highlighting the diversity of the complex mixture resulting from the photooxidation of crude oil and the limitations of targeted analyses for adequately monitoring HOPs in the environment. Taken together, these data identify a critical "blind spot" in environmental monitoring and spill clean-up strategies as there is a diverse pool of HOPs that may negatively impact human and ecosystem health.

Reactive Oxygen Species and Chromophoric Dissolved Organic Matter Drive the Aquatic Photochemical Pathways and Photoproducts of 6PPD-quinone under Simulated High-Latitude Conditions.

The photochemical degradation pathways of 6PPD-quinone (6PPDQ, 6PPD-Q), a toxic transformation product of the tire antiozonant 6PPD, were determined under simulated sunlight conditions typical of high-latitude surface waters. Direct photochemical degradation resulted in 6PPDQ half-lives ranging from 17.5 h at 20 °C to no observable degradation over 48 h at 4 °C. Sensitization of excited triplet-state pathways using Cs+ and Ar purging demonstrated that 6PPDQ does not decompose significantly from a triplet state relative to a singlet state. However, assessment of processes involving reactive oxygen species (ROS) quenchers and sensitizers indicated that singlet oxygen and hydroxyl radical do significantly contribute to the degradation of 6PPDQ. Investigation of these processes in natural lake waters indicated no difference in attenuation rates for direct photochemical processes at 20 °C. This suggests that direct photochemical degradation will dominate in warm waters, while indirect photochemical pathways will dominate in cold waters, involving ROS mediated by chromophoric dissolved organic matter (CDOM). Overall, the aquatic photodegradation rate of 6PPDQ will be strongly influenced by the compounding effects of environmental factors such as light screening and temperature on both direct and indirect photochemical processes. Transformation products were identified via UHPLC-Orbitrap mass spectrometry, revealing four major processes: (1) oxidation and cleavage of the quinone ring in the presence of ROS, (2) dealkylation, (3) rearrangement, and (4) deamination. These data indicate that 6PPDQ can photodegrade in cool, sunlit waters under the appropriate conditions: t1/2 = 17.4 h tono observable decrease (direct); t1/2 = 5.2-11.2 h (indirect, CDOM).

1H NMR-based metabolomics investigation on the biological effects of paralytic shellfish toxin in mussel Mytilus trossulus.

Paralytic shellfish poisoning is a global issue that would benefit from additional screening methods and rapid testing capacities. In this study, we applied 1H NMR spectroscopy-based metabolomics to identify biomarkers of Paralytic Shellfish Toxin (PST) exposure. We characterized the metabolic phenotypes of field-collected Alaskan mussels Mytilus trossulus across a wide range of bioaccumulated PST levels, from 0 to 1590 µg/100 g. A between-level grouping emerged for high (740-1590 µg/100 g) compared to low/non-detect (0-3.91 µg/100 g) PST levels. High levels of PST contamination in mussels were consistent with alterations to energy and amino acid metabolism, and disturbances in osmoregulation. This research demonstrates the effectiveness of 1H NMR-based metabolomics in elucidating the biological effects of paralytic shellfish toxin on the health of wild mussel populations, spatial variation, and identifies a metabolic signature indicative of PST contamination in Mytilus trossulus for potential use in a PSP biomarker panel.

Field and laboratory characterization of rotenone attenuation in eight lakes of the Kenai Peninsula, Alaska.

Rotenone is a pesticide commonly used to eradicate Northern Pike (Esox lucius), an invasive species, in Southcentral Alaska. The present work incorporates a field investigation of rotenone attenuation in eight lakes of the Kenai Peninsula, following a CFT Legumine® treatment in October 2018 and a laboratory simulation to determine persistence under light/dark and sterile/nonsterile conditions representative of Southcentral Alaskan winters. In the field, rotenone degraded within <60 days of application in all lakes, while rotenolone, the primary product of rotenone degradation, persisted for up to <280 days post-treatment at two locations. Prolonged rotenolone attenuation was most likely caused by short days and ice cover between October and April. This hypothesis was supported by a laboratory simulation which revealed photolysis as the dominant process driving the overall degradation of rotenone and that microbial degradation will significantly contribute in the absence of sunlight under simulated "winter" conditions of 4 °C. Degradation model fit comparisons (pseudo-first order, multi-parameter linear, and gamma) indicate the most accurate prediction occurred when modeling all eight lakes grouped together in a single dataset, combined and treated with pseudo-first order model kinetics, based on Akaike information criteria (AIC) scores.

Dissolved organic matter production from herder application and in-situ burning of crude oil at high latitudes: Bioavailable molecular composition patterns and microbial community diversity effects.

Chemical herders and in-situ burning (ISB) are designed to mitigate the effects that oil spills may have on the high latitude marine environment. Little information exists on the water solubilization of petroleum residues stemming from chemically herded ISB and whether these bioavailable compounds have measurable impacts on marine biota. In this experiment, we investigated the effects of Siltech OP40 and crude oil ISB on a) petroleum-derived dissolved organic matter (DOMHC) composition and b) seawater microbial community diversity over 28 days at 4 °C in aquarium-scale mesocosms. Ultra-high resolution mass spectrometry and fluorescence spectroscopy revealed increases in aromaticity over time, with ISB and ISB+OP40 samples having higher % aromatic classes in the initial incubation periods. ISB+OP40 contained a nearly 12-fold increase in the number of DOMHC formulae relative to those before ISB. 16S rRNA gene sequencing identified differences in microbial alpha diversity between seawater, ISB, OP40, and ISB+OP40. Microbial betadiversity shifts were observed that correlated strongly with aromatic/condensed relative abundance and incubation time. Proteobacteria, specifically from the genera Marinomonas and Perlucidibaca experienced -22 and +24 log2-fold changes in ISB+OP40 vs. seawater, respectively. These findings provide an important opportunity to advance our understanding of chemical herders and ISB in the high latitude marine environment.

Identification of Rotenone and Five Rotenoids in CFT Legumine Piscicide Formulation via High Resolution Mass Spectrometry and a New High-Throughput Extraction Procedure.

The piscicide CFT Legumine is applied to freshwater systems around the world to control invasive fish species. Rotenone, a potent inhibitor of mitochondrial cellular respiration, is the active ingredient of the piscicide; however, other rotenoids of unknown persistence and toxicity account for an equivalent amount by weight. This work identified six distinct rotenoids in CFT Legumine using liquid chromatography coupled with high resolution orbitrap mass spectrometry and optimized a rapid surface water sampling procedure for their analysis. The rotenoids were identified as rotenone and its isomer deguelin, their 12α-hydroxylated products rotenolone and tephrosin, as well as 6α,12α-dehydrorotenone and 6α,12α-dehydrodeguelin. The optimized procedure, extraction with Spin-X nylon membrane microcentrifuge filters followed by elution with acetonitrile, achieved recoveries ranging from 101 - 107 % and 97 - 145 % for all six rotenoids at high (125 nM, ~50 ppb) and low (25 nM, ~10 ppb) concentrations of CFT Legumine, respectively. Overall, this method provides a rapid sampling procedure necessary for monitoring rotenoid persistence in surface water to ensure safe and efficacious application of the pesticide.

Photochemical Pathways of Rotenone and Deguelin Degradation: Implications for Rotenoid Attenuation and Persistence in High-Latitude Lakes.

The direct and indirect photochemical degradation of rotenone (ROT) and deguelin (DEG), the primary reduced nicotinamide adenine dinucleotide-inhibiting rotenoid components of the piscicide CFT Legumine, were investigated under simulated sunlight conditions relevant to their dissipation from high-latitude surface waters. Photochemical degradation dominated the elimination of ROT and DEG from surface waters with half-lives ranging from 1.17 to 2.32 and 4.18 to 20.12 h for DEG and ROT, respectively, when the rotenoids were applied in the formulation CFT Legumine. We assessed enhanced degradation processes using argon-purged and cesium chloride-amended water, which demonstrated the rotenoids to rapidly decompose from excited triplet states. We further assessed the influence of reactive oxygen species by hydroxyl radical quenching and thermal generation of singlet oxygen. The studied reactive oxygen species did not significantly contribute; however, alcohols such as isopropanol may inhibit degradation by quenching ROT excited states or preventing intersystem crossing. Finally, we compared photochemical degradation in water collected from Hope Lake, Alaska, to a solution of Suwanee River fulvic acids, which demonstrated that dissolved organic matter (DOM) quality is a major factor that modulates ROT attenuation through a combination of shielding (light attenuation) and excited-state quenching mechanisms and is temperature-dependent. Molecular-level characterizations of DOM may help account for the site-specific degradation of these rotenoids in the environment.

DOC export is exceeded by C fixation in May Creek: A late-successional watershed of the Copper River Basin, Alaska.

Understanding the entirety of basin-scale C cycling (DOC fluxes and CO2 exchanges) are central to a holistic perspective of boreal forest biogeochemistry today. Shifts in the timing and magnitude of dissolved organic carbon (DOC) delivery in streams and eventually into oceans can be expected, while simultaneously CO2 emission may exceed CO2 fixation, leading to forests becoming stronger CO2 sources than sinks amplifying rising trace gases in the atmosphere. At May Creek, a representative late-successional boreal forest watershed at the headwaters of the Copper River Basin, Alaska, we quantified the seasonality of DOC flux and landscape-scale CO2 exchange (eddy covariance) over two seasonal cycles. We deployed in situ fDOM and conductivity sensors, performed campaign sampling for water quality (DOC and water isotopes), and used fluorescence spectroscopy to ascertain DOC character. Simultaneously, we quantified net CO2 exchange using a 100 ft eddy covariance tower. Results indicate DOC exports were pulse-driven and mediated by precipitation events. Both frequency and magnitude of pulse-driven DOC events diminished as the seasonal thaw depth deepened, with inputs from terrestrial sources becoming major contributors to the DOC pool with decreasing snowmelt contribution to the hydrograph. A three-component parallel factorial analysis (PARAFAC) model indicated DOC liberated in late-season may be bioavailable (tyrosine-like). Combining Net Ecosystem Exchange (NEE) measurements indicate that the May Creek watershed fixes 142-220 g C m-2 yr-1 and only 0.40-0.57 g C m-2 yr-1 is leached out as DOC. Thus, the May Creek watershed and similar mature spruce forest dominated watersheds in the Copper River Basin are currently large ecosystem C sinks and exceeding C conservative. An understanding of DOC fluxes from Gulf of Alaska watersheds is important for characterizing future climate change-induced seasonal shifts.

Therapeutic effect of Northern Labrador tea extracts for acute myeloid leukemia.

Acute myeloid leukemia (AML) is an aggressive hematological malignancy that is one of the more common pediatric malignancies in addition to occurring with high incidence in the aging population. Unfortunately, these patient groups are quite sensitive to toxicity from chemotherapy. Northern Labrador tea, or Rhododendron tomentosum Harmaja (a.k.a. Ledum palustre subsp. decumbens) or "tundra tea," is a noteworthy medicinal plant used by indigenous peoples in Alaska, Canada, and Greenland to treat a diversity of ailments. However, laboratory investigations of Northern Labrador tea, and other Labrador tea family members, as botanical sources for anticancer compounds have been limited. Utilizing an AML cell line in both in vitro and in vivo studies, as well as in vitro studies using primary human AML patient samples, this study demonstrated for the first time that Northern Labrador tea extracts can exert anti-AML activity and that this may be attributed to ursolic acid as a constituent component. Therefore, this medicinal herb holds the potential to serve as a source for further drug discovery efforts to isolate novel anti-AML compounds.

Aerobic versus Anaerobic Microbial Degradation of Clothianidin under Simulated California Rice Field Conditions.

Microbial degradation of clothianidin was characterized under aerobic and anaerobic California rice field conditions. Rate constants (k) and half-lives (DT50) were determined for aerobic and anaerobic microcosms, and an enrichment experiment was performed at various nutrient conditions and pesticide concentrations. Temperature effects on anaerobic degradation rates were determined at 22 ± 2 and 35 ± 2 °C. Microbial growth was assessed in the presence of various pesticide concentrations, and distinct colonies were isolated and identified. Slow aerobic degradation was observed, but anaerobic degradation occurred rapidly at both 25 and 35 °C. Transformation rates and DT50 values in flooded soil at 35 ± 2 °C (k = -7.16 × 10(-2) ± 3.08 × 10(-3) day(-1), DT50 = 9.7 days) were significantly faster than in 25 ± 2 °C microcosms (k= -2.45 × 10(-2) ± 1.59 × 10(-3) day(-1), DT50 = 28.3 days). At the field scale, biodegradation of clothianidin will vary with extent of oxygenation.

Field degradation of aminopyralid and clopyralid and microbial community response to application in Alaskan soils.

High-latitude regions experience unique conditions that affect the degradation rate of agrochemicals in the environment. In the present study, data collected from 2 field sites in Alaska, USA (Palmer and Delta) were used to generate a kinetic model for aminopyralid and clopyralid degradation and to describe the microbial community response to herbicide exposure. Field plots were sprayed with herbicides and sampled over the summer of 2013. Quantification was performed via liquid chromatrography/tandem mass spectrometry, and microbial diversity was assessed via next-generation sequencing of bacterial 16S ribosomal ribonucleic acid (rRNA) genes. Both compounds degraded rapidly via pseudo-first-order degradation kinetics between 0 d and 28 d (t1/2 = 9.1-23.0 d), and then degradation slowed thereafter through 90 d. Aminopyralid concentration was 0.048 µg/g to 0.120 µg/g at 90 d post application, whereas clopyralid degraded rapidly at the Palmer site but was recovered in Delta soil at a concentraction of 0.046 µg/g. Microbial community diversity was moderately impacted by herbicide treatment, with the effect more pronounced at Delta. These data predict reductions in crop yield when sensitive plants (potatoes, tomatoes, marigolds, etc.) are rotated onto treated fields. Agricultural operations in high-latitude regions, both commercial and residential, rely heavily on cultivation of such crops and care must be taken when rotating.

Biodegradation of clomazone in a California rice field soil: carbon allocation and community effects.

Degradation pathways for the herbicide clomazone in a California rice field soil were characterized via pulse-labeling of anaerobic (flooded) and aerobic (moist) soil microcosms. Clomazone-derived (13)C in the major C pools of a rice ecosystem and soil phospholipid fatty acid (PLFA) profiles were analyzed over time to determine if (1) the compound accumulates in the microbial biomass, (2) it affects temporal microbial population dynamics, and (3) it is either preferentially metabolized or cometabolized. In anaerobic microcosms, the compound was rapidly biotransformed to ring-open clomazone, upon which it persisted in the aqueous phase, whereas aerobic microcosms degraded it slower but a greater percentage was mineralized. Anaerobic biomass decreased after clomazone was added, and aerobic actinomycete abundance differed between treatments and controls. Additionally, PLFA and (13)C PLFA were statistically similar between treatment and controls. Thus, microbial cometabolism is likely to be the dominant degrading mechanism governing clomazone fate in California rice fields.

Photolytic versus microbial degradation of clomazone in a flooded California rice field soil.

BACKGROUND: Clomazone is a popular herbicide used on California rice fields and exhibits rapid anaerobic microbial degradation (t(1/2) = 7.9 days). To test the potential of direct and indirect photolytic degradation as a cofactor in the overall degradation rate, sacrificial time-series microcosms were amended with water, non-sterilized soil + water and sterilized soil + water. Clomazone was added to each microcosm, which was then exposed to natural and artificial sunlight over 35 days. Water and acetonitrile extracts were analyzed for clomazone and metabolites via LC/MS/MS. RESULTS: The calculated pseudo-first-order degradation rate constants (k) were k(water) = 0-0.005 ± 0.003 day(-1) , k(sterile) = 0-0.005 ± 0.003 day(-1) and k(non-sterile) = 0.010 ± 0.002-0.044 ± 0.007 day(-1) , depending on light type. The formation of ring-open clomazone, a microbial metabolite, correlated with clomazone degradation. Trace amounts of 5-hydroxyclomazone (m/z = 256 → 125), aromatic hydroxyclomazone (m/z = 256 → 141) and an unknown product (m/z = 268 → 125) were observed. CONCLUSIONS: The photolytic degradation rate depends on both light type and the quality of the chromophores that induce indirect photolysis. Microbial degradation was found to be sensitive to temperature fluctuations. Overall, microbes are shown to be more detrimental to the environmental fate of clomazone than photolysis.

Microbial degradation of clomazone under simulated California rice field conditions.

Clomazone (trade names Cerano and Command) is a popular herbicide used on California rice fields to control aquatic weeds. Its physicochemical characteristics indicate that it will persist primarily in the water column, where microbial degradation may drive its environmental fate. The objectives were to determine microbial degradation rates and compare the metabolic products under aerobic and anaerobic conditions similar to those in California rice fields during the summer. Time-series samples were extracted and analyzed by LC/MS/MS. Metabolic profiling revealed the following clomazone-derived transitions: m/z 240 --> 125 (clomazone), m/z 242 --> 125 (ring-open clomazone), m/z 256 --> 125 (5-hydroxyclomazone), m/z 256 --> 141 (aromatic hydroxyclomazone), m/z 268 --> 125 (unknown metabolite), and m/z 272 --> 141 (4'5-dihydroxyclomazone). Results indicate an anaerobic half-life of 7.9 days, with ring-open clomazone reaching 67.4% of application at 38 days. Aerobically, clomazone degraded more slowly (t(1/2) = 47.3 days), forming mostly soil-bound residues. Thus, under summer conditions, clomazone is likely to dissipate rapidly from fields via anaerobic degradation.