Light dependence of selenium uptake by phytoplankton and implications for predicting selenium incorporation into food webs

The potentially toxic element selenium is first concentrated from solution to a large but highly variable degree by algae and bacteria before being passed on to consumers. The large loads of abiotic and detrital suspended particles often present in rivers and estuaries may obscure spatial and temporal patterns in Se concentrations at the base of the food web. We used radiotracers to estimate uptake of both selenite (Se(IV)) and C by intact plankton communities at two sites in the Sacramento/San Joaquin River Delta. Our goals were to determine (1) whether C and Se(IV) uptake were coupled, (2) the role of bacteria in Se(IV) uptake, and (3) the Se:C uptake ratio of newly produced organic material. Se(IV) uptake, like C uptake, was strongly related to irradiance. The shapes of both relationships were very similar except that at least 42-56% of Se(IV) uptake occurred in the dark, whereas C uptake in the dark was negligible. Of this dark Se(IV) uptake, 34-67% occurred in the 0.2-1.0-μm size fraction, indicating significant uptake by bacteria. In addition to dark uptake, total Se(IV) uptake consisted of a light-driven component that was in fixed proportion to C uptake. Our estimates of daily areal Se(IV):C uptake ratios agreed very well with particulate Se:C measured at a site dominated by phytoplankton biomass. Estimates of bacterial Se:C were 2.4-13 times higher than for the phytoplankton, suggesting that bacteriovores may be exposed to higher dietary Se concentrations than herbivores

Organic sulfur: a spatially variable and understudied component of marine organic matter

© The Author(s), 2020. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Longnecker, K., Oswald, L., Soule, M. C. K., Cutter, G. A., & Kujawinski, E. B. Organic sulfur: a spatially variable and understudied component of marine organic matter. Limnology and Oceanography Letters, (2020), doi:10.1002/lol2.10149.Sulfur (S) is a major heteroatom in organic matter. This project evaluated spatial variability in the concentration and molecular‐level composition of organic sulfur along gradients of depth and latitude. We measured the concentration of total organic sulfur (TOS) directly from whole seawater. Our data reveal high variability in organic sulfur, relative to established variability in total organic carbon or nitrogen. The deep ocean contained significant amounts of organic sulfur, and the concentration of TOS in North Atlantic Deep Water (NADW) decreased with increasing age while total organic carbon remained stable. Analysis of dissolved organic matter extracts by ultrahigh resolution mass spectrometry revealed that 6% of elemental formulas contained sulfur. The sulfur‐containing compounds were structurally diverse, and showed higher numbers of sulfur‐containing elemental formulas as NADW moved southward. These measurements of organic sulfur in seawater provide the foundation needed to define the factors controlling organic sulfur in the global ocean.We thank Catherine Carmichael, Winifred Johnson, and Gretchen Swarr for assistance with sample collection and processing, and Joe Jennings for the analysis of inorganic nutrients. The help of the captain and crew of the R/V Knorr and the other cruise participants during the “DeepDOM” cruise is appreciated. Two anonymous reviewers and Patricia Soranno provided thorough comments that greatly improved the manuscript. The ultrahigh resolution mass spectrometry samples were analyzed at the WHOI FT‐MS Users' Facility that is funded by the National Science Foundation (grant OCE‐0619608) and the Gordon and Betty Moore Foundation (GMBF1214). This project was funded by NSF grants OCE‐1154320 (to EBK and KL), the W.M. Marquet Award (to KL), and OCE‐1435708 (to GAC). The authors declare no conflicts of interest

History of the town of Jaffrey, New Hampshire, from the date of the Masonian charter to the present time, 1749-1880: with a genealogical register of the Jaffrey families, and an appendix containing the proceedings of the centennial celebration in 1873.

Genealogical register: p. [209]-526

Properties of Char Produced from Pyrolysis of Southern Pine

Bench scale pyrolyses were carried out on southern pine at conditions of 250, 350, 400, 500, and 800 C for 1, 2, and 4 hours in a flowing nitrogen atmosphere at flow rates of 135 and 405 milliliters per minute. Data presented in this paper represent work on the properties of the chars produced under these conditions. Results of oxygen bomb calorimetry, density and specific gravity measurements, carbon and hydrogen analyses, and gravimetric yields were statistically analyzed to determine the influence of process conditions on char properties. In general, char yield and percentage of hydrogen and oxygen decreased, while the carbon percentage increased with increasing temperature

X-ray Scattering and X-ray Diffraction Techniques in Studies of Gamma-Irradiated Wood

X-ray scattering and diffraction techniques were used to evaluate degradation of oak wood by gamma radiation. Samples were exposed to 650, 950, and 1,900 Megarads radiation. Chemical analyses (lignin, extractives, and holocellulose content) and density measurements were made on the irradiated samples. Results indicate that cellulose crystallinity was reduced with increasing irradiation and is destroyed at a dosage of 1,900 Megarads. Small-angle X-ray scattering studies were clarified by the use of these additional analytical methods

Organic Sulfur: A Spatially Variable and Understudied Component of Marine Organic Matter

Sulfur (S) is a major heteroatom in organic matter. This project evaluated spatial variability in the concentration and molecular-level composition of organic sulfur along gradients of depth and latitude. We measured the concentration of total organic sulfur (TOS) directly from whole seawater. Our data reveal high variability in organic sulfur, relative to established variability in total organic carbon or nitrogen. The deep ocean contained significant amounts of organic sulfur, and the concentration of TOS in North Atlantic Deep Water (NADW) decreased with increasing age while total organic carbon remained stable. Analysis of dissolved organic matter extracts by ultrahigh resolution mass spectrometry revealed that 6% of elemental formulas contained sulfur. The sulfurcontaining compounds were structurally diverse, and showed higher numbers of sulfur-containing elemental formulas as NADW moved southward. These measurements of organic sulfur in seawater provide the foundation needed to define the factors controlling organic sulfur in the global ocean

Do readers maintain word-level uncertainty during reading? A pre-registered replication study

We present a replication of Levy, Bicknell, Slattery, and Rayner (2009). In this prior study participants read sentences in which a perceptually confusable preposition (at; confusable with as) or non-confusable preposition (toward) was followed by a verb more likely to appear in the syntactic structure formed by replacing at with as (e.g. tossed) or a verb that was not more likely to appear in this structure (e.g. thrown). Readers experienced processing difficulty upon fixating verbs like tossed following at, but not toward. Levy et al. argued that this suggests readers maintained uncertainty about previously fixated words’ identities. We argue that this finding has wide-ranging implications for language processing theories, and that a replication is required. On the basis of a Bayes Factor Design Analysis we conducted a replication study with 56 items and 72 participants in order to determine whether Levy et al.’s effects are replicable. Using Bayesian statistical techniques we show that in our dataset there is evidence against the existence of the interaction Levy et al. found, and thus conclude that this study is non-replicable

Syntactic prediction during self‐paced reading is age invariant

Controversy exists as to whether, compared to young adults, older adults are more, equally, or less likely to make linguistic predictions while reading. While previous studies have examined age effects on the prediction of upcoming words, the prediction of upcoming syntactic structures has been largely unexplored. We compared the benefit that young and older readers gain when syntactic structure is made predictable, as well as potential age differences in the costs involved in making predictions. In a self-paced reading study, 60 young and 60 older adults read sentences in which noun-phrase co-ordination (e.g. large pizza or tasty calzone) is made predictable through inclusion of the word either earlier in the sentence. Results showed a benefit of the presence of either in the second half of the co-ordination phrase, and a cost of the presence of either in the first half. We observed no age differences in the benefit or costs of making these predictions; Bayes factor analyses offered strong evidence that these effects are age-invariant. Together, these findings suggest that both older and younger adults make similar strength syntactic predictions with a similar level of difficulty. We relate this age-invariance in syntactic prediction to specific aspects of the ageing process

Online representations of non-canonical sentences are more than good-enough

Proponents of good-enough processing suggest that readers often (mis)interpret certain sentences using fast-and-frugal heuristics, such that for non-canonical sentences (e.g. The dog was bitten by the man) people confuse the thematic roles of the nouns. We tested this theory by examining the effect of sentence canonicality on the reading of a follow-up sentence. In a self-paced reading study 60 young and 60 older adults read an implausible sentence in either canonical (e.g. It was the peasant that executed the king) or non-canonical form (e.g. It was the king that was executed by the peasant), followed by a sentence that was implausible given a good-enough misinterpretation of the first sentence (e.g. Afterwards, the peasant rode back to the countryside), or a sentence that was implausible given a correct interpretation of the first sentence (e.g. Afterwards, the king rode back to his castle). We hypothesised that if non-canonical sentences are systematically misinterpreted then sentence canonicality would differentially affect the reading of the two different follow-up types. Our data suggested that participants derived the same interpretations for canonical and non-canonical sentences, with no modulating effect of age group. Our findings suggest that readers do not derive an incorrect interpretation of non-canonical sentences during initial parsing, consistent with theories of misinterpretation effects that instead attribute these effects to post-interpretative processes