Drivers of diatom production and the legacy of eutrophication in two river plume regions of the northern Gulf of Mexico

In the northern Gulf of Mexico (nGoM), the Louisiana Shelf (LS) and Mississippi Bight (MB) subregions are influenced by eutrophication to varying degrees. Despite recognition that dissolved silicon may regulate diatom productivity in the nGoM, there is only one published data set reporting biogenic silica (bSiO2) production rates for each subregion. We report that bSiO2 production rates on the LS and MB are high and appear to be controlled by different nutrients among seasons. Despite exceptional upper trophic level biomass regionally, which suggests significant primary production by diatoms (as in other systems), gross euphotic-zone integrated bSiO2 production rates are lower than major bSiO2 producing regions (e.g. upwelling systems). However, when normalizing to the depth of the euphotic zone, the bSiO2 production rates on the LS are like normalized rates in upwelling systems. We suggest local river-plume influenced hydrography concentrates diatom productivity within shallow euphotic zones, making production more accessible to higher trophic organisms. Comparison of rates between the LS and MB suggest that the fluvial nitrate within the LS stimulates bSiO2 production above that in the MB, which has a smaller watershed and is less eutrophic (relatively). Beyond understanding the factors controlling regional bSiO2 production, these data offer the most comprehensive Si-cycle baseline to date as the LS and MB will likely exchange freely in the mid to late century due to land subsidence of the Mississippi River delta and/or sea-level rise

Frailty of Māori, Pasifika, and non-Māori/non-Pasifika older people in New Zealand: a national population study of older people referred for home care services

Little is known about the prevalence of frailty in indigenous populations. We developed a frailty index for older New Zealand Māori and Pasifika who require publicly funded support services.A frailty index (FI) was developed for New Zealand adults aged ≥65 years who had an interRAI-Home Care assessment between 1 June 2012 and 30 October 2015. A frailty score for each participant was calculated by summing the number of deficits recorded and dividing by the total number of possible deficits. This created a FI with a potential range from 0 to 1. Linear regression models for FIs with ethnicity were adjusted for age and sex. Cox proportional hazards models were used to assess the association between the FI and mortality for Māori, Pasifika, and non-Māori/non-Pasifika.Of 54,345 participants, 3,096 (5.7%) identified as Māori, 1,846 (3.4%) were Pasifika, and 49,415 (86.7%) identified as neither Māori nor Pasifika. New Zealand Europeans (48,178, 97.5%) constituted most of the latter group. Within each sex, the mean FIs for Māori and Pasifika were greater than the mean FIs for non-Māori and non-Pasifika, with the difference being more pronounced in females. The FI was associated with mortality (Māori SHR 2.53, 95% CI 1.63 to 3.95; Pasifika SHR 6.03, 95% CI 3.06 to 11.90; non-Māori and non-Pasifika SHR 2.86, 95% 2.53 to 3.25).This study demonstrated differences in FI between the ethnicities in this select cohort. After adjustment for age and sex, increases in FI were associated with increased mortality. This suggests that FI is predictive of poor outcomes in these ethnic groups

The effects of rational and irrational coach team talks on the cognitive appraisal and achievement goal orientation of varsity football athletes

The effects of rational and irrational coach team talks on cognitive appraisal and achievement goal orientation were examined. During the half-time interval of a 60-minute football match, 25 male varsity football athletes (Mage = 20.20; SD ± 1.38 years) received a rational (n = 13) or an irrational (n = 12) team talk from a coach. Irrational and rational beliefs were measured before the football match. Task engagement, cognitive appraisal (challenge and threat), and achievement goal orientation (approach and avoidance) regarding second-half football performance were measured following team-talk delivery. Athletes in the rational team talk condition reported significantly lower threat appraisal and avoidance goal orientation than athletes in the irrational team talk condition. No significant between-condition differences emerged for challenge appraisal and approach goal orientation. For coaching practice, data suggest that communicating rational or irrational beliefs to football athletes through a half time team talk will influence appraisal and achievement goal orientation regarding upcoming performance. Keywords Rational emotive behaviour therapy, irrational beliefs, rational beliefs, appraisal, achievement goal

Wet scavenging of soluble gases in DC3 deep convective storms using WRF-Chem simulations and aircraft observations

We examine wet scavenging of soluble trace gases in storms observed during the Deep Convective Clouds and Chemistry (DC3) field campaign. We conduct high-resolution simulations with the Weather Research and Forecasting model with Chemistry (WRF-Chem) of a severe storm in Oklahoma. The model represents well the storm location, size, and structure as compared with Next Generation Weather Radar reflectivity, and simulated CO transport is consistent with aircraft observations. Scavenging efficiencies (SEs) between inflow and outflow of soluble species are calculated from aircraft measurements and model simulations. Using a simple wet scavenging scheme, we simulate the SE of each soluble species within the error bars of the observations. The simulated SEs of all species except nitric acid (HNO_3) are highly sensitive to the values specified for the fractions retained in ice when cloud water freezes. To reproduce the observations, we must assume zero ice retention for formaldehyde (CH_2O) and hydrogen peroxide (H_2O_2) and complete retention for methyl hydrogen peroxide (CH_3OOH) and sulfur dioxide (SO_2), likely to compensate for the lack of aqueous chemistry in the model. We then compare scavenging efficiencies among storms that formed in Alabama and northeast Colorado and the Oklahoma storm. Significant differences in SEs are seen among storms and species. More scavenging of HNO_3 and less removal of CH_3OOH are seen in storms with higher maximum flash rates, an indication of more graupel mass. Graupel is associated with mixed-phase scavenging and lightning production of nitrogen oxides (NO_x), processes that may explain the observed differences in HNO_3 and CH_3OOH scavenging

Detrital input sustains diatom production off a glaciated Arctic coast

In the Arctic and subarctic oceans, the relatively low supply of silicon (compared to other nutrients) can make it limiting for the growth of diatoms, a fundamental building block of the oceanic food web. Glaciers release large quantities of dissolved silicon and dissolvable solid amorphous silica phases into high-latitude estuaries (fjords), but the role of these glacially-derived silica phases in sustaining diatom growth in the coastal and open-water sectors remains unknown. Here we show how stable and radiogenic silicon isotopes can be used together to address this question, using southwest Greenland as a case study. This study finds enhanced levels of detrital (i.e., mineral) amorphous silica, likely glacially-sourced, sustaining a large portion of diatom growth observed off the coast, revealing how the phytoplankton community can function during high-meltwater periods