We attempted to characterize zooplankton community response following spills of the unconventional crude oil, diluted bitumen (dilbit), into 10-m diameter, ~ 100 m
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, ~ 1.5-m deep boreal lake ...limnocorrals, including two controls and seven dilbit treatments ranging from 1.5 to 180 L (1:100,000 to 1:1,000 v/v, dilbit:water). Community composition and abundances were monitored weekly to bi-weekly over three months. Total zooplankton biomass and abundance seemingly collapsed in all limnocorrals, regardless of treatment, though some rotifer species persisted. As a result, it was not possible to determine the impacts of dilbit. We theorize several potential non-oil-related reasons for the sudden community collapse – including elevated zinc levels, fish grazing pressures, and sampling biases – and provide guidance for future work using in-lake enclosures.
Large-scale, in-lake enclosures (limnocorrals) were used to simulate spills of diluted bitumen (dilbit) in a boreal lake. In this study we use these simulated spills, which covered a range of sizes ...(oil:water ratio) representative of the upper 25% of onshore crude oil spills in North America (2008–2019), to assess the fate of dilbit-derived hydrocarbons and metals as well as the impacts of the spills on standard water quality parameters. The systems were monitored over 70 days following the application of dilbit amounts ranging between 1.5 and 179.8 L into 10-m diameter, ~100 m3 limnocorrals. The concentration of total petroleum hydrocarbons (TPH) in the water column increased rapidly over the first two weeks reaching a plateau that ranged between 200 μg/L and 2200 μg/L for the lowest and highest treatment respectively. The concentration of total polycyclic aromatic compounds (PACs) also increased over the first two weeks, prior to a slow decrease until day 70. The maximum measured concentrations in the highest treatment were 2858 ng/L for the sum of all 46 quantified PACs, 2716 ng/L for alkylated PACs and 154 ng/L for the 16 EPA priority PAHs. The concentrations of PACs in the sediment increased continuously over the study in the three highest treatments with maximum observed concentrations of 189 ng/g for ΣPAC46, 169 ng/g for ΣPACalk. No significant treatment-related changes in the 16 EPA priority PAHs were observed in the sediment. Of the 25 metals quantified in the water column, only manganese, molybdenum, and vanadium displayed a significant treatment effect with increases of 280, 76 and 25% respectively in the total fraction. These results can help us understand and predict the fate of oil-derived contaminants following a spill and characterize the exposure of freshwater organisms living within them. These results should help inform the risk assessment of future dilbit transportation projects.
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•The fate and effects of dilbit spills was monitored in large in-lake limnocorrals.•Total Petroleum Hydrocarbons in water increased in the first week, reaching a plateau.•Sediment Total Polycyclic Aromatic Compounds (PACs) increased over the study.•Water-column PACs increased to a maximum after the first week, decreasing afterward.•V, Mn, and Mo showed a treatment-dependent increase in the water column.
The rush sedge caddisfly Phryganea cinerea Walker, 1852 (Phryganeidae, the giant casemakers), is a widespread and adaptable North American caddisfly. Genome skimming by Illumina sequencing permitted ...the assembly of a complete 15,043 bp circular mitogenome from P. cinerea consisting of 78.2% AT nucleotides, 22 tRNAs, 13 protein-coding genes, 2 rRNAs and a control region in the ancestral insect gene order. Phryganea cinerea COX1 features an atypical CGA start codon and COX1, NAD1, NAD4, and NAD5 exhibit incomplete stop codons completed by the addition of 3′ A residues to the mRNA. Phylogenetic reconstruction reveals a monophyletic Order Trichoptera and Family Phyrganeidae.
This draft article outlines a prediction challenge where the target is to forecast the number of fatalities in armed conflicts, in the form of the UCDP `best' estimates, aggregated to the VIEWS units ...of analysis. It presents the format of the contributions, the evaluation metric, and the procedures, and a brief summary of the contributions. The article serves a function analogous to a pre-analysis plan: a statement of the forecasting models made publicly available before the true future prediction window commences. More information on the challenge, and all data referred to in this document, can be found at https://viewsforecasting.org/research/prediction-challenge-2023.
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