Comprehensive study of the occurrence and characteristics of organic matter, nitrogen, and phosphorus in sediments and riparian soils of a large drinking water reservoir.

The contamination of nutrients has caused considerable worry about the environment, resource value, and ecological worth of drinking water reservoirs. Therefore, we comprehensively studied the abundance, sources, distribution, and environmental behavior of carbon, nitrogen, and phosphorus in Fengshuba Reservoir (FSBR) (a large drinking reservoir, China). A graded leaching technique (introduced in 2003), the European Standard, Measurement and Testing (SMT) protocol, and spectrometry combined with parallel factor analysis (EEMs-PARAFAC) were used to assess nitrogen, phosphorus forms, and spectra data in the sediment and soil phases, respectively. The study demonstrates that seasonal hydrological variation had no significant effect on the nutrient abundance and nutrient structure composition of the FSBR, while different environmental media (e.g., sediment and soil phase) exhibited considerable differences in nutrient abundance, composition, and environmental behavior. The abundance of colored dissolved organic matter (CDOM), as well as molecular weight, aromatization degree, and humification degree of dissolved organic matter (DOM) were all lower in sediments than in soils, whereas the authigenic component was greater than in soils. Microbial-derived humus (C1), terrestrial-derived humus (C2), and protein-like tryptophan (C3) were identified as the three primary fluorescence components. Principal component analysis indicated that three components were closely associated with phosphorus in the sediment phase, whereas nitrogen and phosphorus in the soil phase were mainly related to C1 and C2. In summary, soil media (drawdown area) must be carefully considered in the management and control of water environment nutrients in reservoirs.

Silver nanomaterials in the natural environment: An overview of their biosynthesis and kinetic behavior.

Silver nanomaterials (Ag NMs) are fabricated by many biological components in our environment. Recently, research on their biosynthesis and reactions has become a focus of attention. Due to the complexity of biological systems and samples, specific processes and mechanisms involving Ag NMs are difficult to identify and elucidate on the molecular and chemical-bond level. The microorganisms and composite components of plant extracts are of great interest in many biological syntheses. Although potential biomolecules have been shown to play essential roles in biological systems in Ag NM biosynthesis, the detailed mechanism of the electron transfer process and crucial molecules that control this reaction have only recently come into focus. The reactive behavior of the Ag NMs is of great significance for understanding their overall behavior and toxicity. Additionally, only limited knowledge is available about their kinetics. All reactions involve chemical bond formation, electron transfer, or electrostatic interactions. An overview is presented of the biosynthesis of Ag NMs based on molecular supports including a nitrate reductase/NADH oxidase-involved electron transfer reaction and their mechanisms in Ag+ reduction: quinol-mediated mechanism and superoxide-dependent mechanism, and molecular supports in plant extracts, is presented. The environmental reaction kinetics and mechanisms of the interactions of Ag NMs with substances are introduced based on the formation and classification of chemical bonds. The particle-particle reaction kinetics of Ag NMs in the environment are discussed to directly explain their stability and aggregation behavior. The toxicity of Ag NMs is also presented. In addition, future prospects are summarized. This review is the first to provide an insight into the mediating molecules and chemical bonds involved in the biosynthesis, kinetics, and mechanisms of action of Ag NMs.

Eye care utilisation in Newfoundland and Labrador: access barriers and vision health outcomes.

OBJECTIVE: Our prior study revealed significantly lower use of eye care providers in Newfoundland and Labrador (NFLD). This study reports factors associated with this low use and related vision health outcomes. DESIGN: Cross-sectional survey. PARTICIPANTS: A total of 14 925 Caucasian respondents to the Canadian Community Health Survey - Healthy Aging 2008/2009 aged ≥65 years. METHODS: Univariate and multivariate analyses were performed using self-reported survey data. RESULTS: NFLD, along with 3 other provinces, does not insure seniors for routine eye examinations. Among seniors without self-reported glaucoma, cataracts, and diabetes, the use of eye care providers in NFLD (36.3%) is the lowest compared with provinces with (50.7%, p < 0.05) and without (42.2%, p > 0.05) government-insured eye examinations. Among seniors with known eye disease insured for eye care in all provinces, eye care utilisation in NFLD (63.1%) is still the lowest across all provinces (69.4%-71.3%, p > 0.05). Compared with the national average, NFLD seniors have significantly higher proportions of low income (61.7% vs 47.4%), no postsecondary education (53.6% vs 42.2%), and rural residency (40.6% vs 18.9%). These factors are all associated with low levels of eye care utilisation. Compared with insured provinces, NFLD has a significantly lower prevalence of self-reported cataracts (16.7% vs 23.1) and glaucoma (3.8% vs 7.0%), and a slightly higher prevalence of presenting visual impairment (4.0% vs 3.5%). CONCLUSIONS: Lack of government insurance, low socioeconomic status, and living in nonurbanised areas all contribute to the underutilisation of eye care providers in NFLD. This underutilisation appears to be associated with reduced detection of eye diseases.