Applying the isotope pairing technique to evaluate how water temperature and habitat type influence denitrification estimates in Breton Sound, Louisiana

The upper Breton Sound estuary was hydrologically reconnected to the Mississippi River via the Caernarvon freshwater diversion structure in 1991. The Caernarvon structure can provide controlled freshwater pulses to the upper Breton Sound estuarine ecosystem, replicating historic freshwater pulsed events, although the original authorization was to control salinity isohalines at specific locations in the estuary. However, unlike historic freshwater pulsed events prior to the construction of levees, the current freshwater pulse contains an unprecedented amount of inorganic nitrogen, predominately as nitrate (annual average 71.4 µM NO3-). Denitrification is a microbial process, which can potentially remove excess nitrate entering coastal Louisiana ecosystems due to these riverine pulsed events. This study presents the first 15N isotope pairing technique (IPT) denitrification estimates from coastal sediments in Louisiana, and evaluates the influence water temperature and different habitat types have on denitrification rates. Three IPT assumptions were tested in the current study and were fulfilled; however, the fourth assumption, the influence of annamox, was not evaluated. The three IPT assumptions evaluated were fulfilled in the benthic and marsh habitat sediments. However, the marsh habitat sediments from upper Breton Sound provide a dilemma for the current IPT design; 15NO3- diffusion will not reach deep into the plant rhizosphere where optimal conditions persist for coupled nitrification-denitrification activity. There was a significant interaction between habitat (marsh and benthic) and water temperature (8 and 22 °C) treatments on denitrification rates. Mean total denitrification (direct + coupled denitrification) estimates from a 70 µM 15NO3- incubation concentration were 17.5 (± 3.1) and 5.1 (± 1.5) ìmol N m-2 h-1 for benthic and marsh habitat sediments at 22 °C, and were 7.8 (± 1.9) and 2.1 (± 0.45) ìmol N m-2 h-1 for benthic and marsh habitat sediments at 8 °C, respectively. Overall, total denitrification rates ranged from 0.28 to 284.1 ìmol N m-2 h-1 for both habitats at 22 °C over a 2 to 200 µM 15NO3- incubation concentration range. Coupled denitrification comprised the majority of the total denitrification rate measured. Mean direct denitrification rates did not exceed 2 ìmol N m-2 h-1, and suggests direct denitrification measured by the isotope pairing technique in my study is not a major pathway for NO3- removal in upper Breton Sound benthic and marsh habitats

Primary Sources of Polycyclic Aromatic Hydrocarbons to Streambed Sediment in Great Lakes Tributaries Using Multiple Lines of Evidence

Polycyclic aromatic hydrocarbons (PAHs) are among the most widespread and potentially toxic contaminants in Great Lakes (USA/Canada) tributaries. The sources of PAHs are numerous and diverse, and identifying the primary source(s) can be difficult. The present study used multiple lines of evidence to determine the likely sources of PAHs to surficial streambed sediments at 71 locations across 26 Great Lakes Basin watersheds. Profile correlations, principal component analysis, positive matrix factorization source-receptor modeling, and mass fractions analysis were used to identify potential PAH sources, and land-use analysis was used to relate streambed sediment PAH concentrations to different land uses. Based on the common conclusion of these analyses, coal-tar-sealed pavement was the most likely source of PAHs to the majority of the locations sampled. The potential PAH-related toxicity of streambed sediments to aquatic organisms was assessed by comparison of concentrations with sediment quality guidelines. The sum concentration of 16 US Environmental Protection Agency priority pollutant PAHs was 7.4-196 000 mu g/kg, and the median was 2600 mu g/kg. The threshold effect concentration was exceeded at 62% of sampling locations, and the probable effect concentration or the equilibrium partitioning sediment benchmark was exceeded at 41% of sampling locations. These results have important implications for watershed managers tasked with protecting and remediating aquatic habitats in the Great Lakes Basin.Environ Toxicol Chem2020;00:1-17. (c) 2020 The Authors.Environmental Toxicology and Chemistrypublished by Wiley Periodicals LLC on behalf of SETAC.Peer reviewe

Providing Direct Services

Providing direct services centers on health-related services that are delivered in person or face-to-face and involves providing basic screening tests and basic services as well as meeting basic needs. The two authorship teams included describe ways Community Health Representatives (CHRs), Community Health Aides (CHAs), and Primary Dental Health Aides (PDHAs) are engaged in providing direct services. The lack of access to oral health care is of particular concern in Alaska, where a large proportion of the population are Alaska Native and live in the state’s 200 remote villages that are reachable only by boat, snowmobile, or bush plane. The Alaska team presents the Alaska Dental Health Aide Program (DHA program) and describes the training, work, and impact of PDHAs, who provide dental education and preventive dentistry services to their community members. The CHR team provides information on the roles, scope of work, and impacts of CHRs that primarily work in Native American communities on reservations and near reservations lands. Their stories share insight and information on the distinctive work of the culturally immersed roles of CHRs in various Southwest Tribes and Pueblos as they work to provide high-quality, culturally appropriate, clinically guided health, wellness, and social services. The diversity of tribal communities and the unique approaches CHRs take in providing services are highlighted

Impact of a Prenatal Vitamin D Supplementation Program on Vitamin D Deficiency, Rickets and Early Childhood Caries in an Alaska Native Population

Background: Early childhood rickets increased in Alaska Native children after decreases in vitamin D-rich subsistence diet in childbearing-aged women. We evaluated the impact of routine prenatal vitamin D supplementation initiated in Alaska’s Yukon Kuskokwim Delta in Fall 2016. Methods: We queried electronic health records of prenatal women with 25(OH) vitamin D testing during the period 2015–2019. We evaluated 25(OH)D concentrations, vitamin D3 supplement refills, and decayed, missing, and filled teeth (dmft) scores and rickets in offspring. Results: Mean 25(OH)D concentrations increased 36.5% from pre- to post-supplementation; the percentage with deficient 25(OH)D decreased by 66.4%. Women with ≥ 60 vitamin D3 refill days had higher late pregnancy 25(OH)D concentrations than those with no refill days (p < 0.0001). Women with late pregnancy insufficient 25(OH)D concentrations had offspring with higher dmft scores than those with sufficient 25(OH)D (RR 1.3, p < 0.0001). Three children were diagnosed with nutritional rickets during the period 2001–2021, and none after 2017. Conclusions: These findings suggest that prenatal vitamin D supplementation can improve childhood outcomes in high-risk populations with high rates of rickets