Nitrous oxide (N2O) emissions from inland waters remain a major source of uncertainty in global greenhouse gas budgets. N2O emissions are typically estimated using emission factors (EFs), defined as ...the proportion of the terrestrial nitrogen (N) load to a water body that is emitted as N2O to the atmosphere. The Intergovernmental Panel on Climate Change (IPCC) has proposed EFs of 0.25% and 0.75%, though studies have suggested that both these values are either too high or too low. In this work, we develop a mechanistic modeling approach to explicitly predict N2O production and emissions via nitrification and denitrification in rivers, reservoirs and estuaries. In particular, we introduce a water residence time dependence, which kinetically limits the extent of denitrification and nitrification in water bodies. We revise existing spatially explicit estimates of N loads to inland waters to predict both lumped watershed and half‐degree grid cell emissions and EFs worldwide, as well as the proportions of these emissions that originate from denitrification and nitrification. We estimate global inland water N2O emissions of 10.6–19.8 Gmol N year−1 (148–277 Gg N year−1), with reservoirs producing most N2O per unit area. Our results indicate that IPCC EFs are likely overestimated by up to an order of magnitude, and that achieving the magnitude of the IPCC's EFs is kinetically improbable in most river systems. Denitrification represents the major pathway of N2O production in river systems, whereas nitrification dominates production in reservoirs and estuaries.
Nitrous oxide (N2O) emissions from inland waters remain a major source of uncertainty in global greenhouse gas budgets. In this work, we develop a mechanistic modeling approach to explicitly predict N2O production and emissions via nitrification and denitrification in rivers, reservoirs and estuaries. Our results indicate that IPCC emissions predictions are likely overestimated by up to an order of magnitude, and that achieving the magnitude of the IPCC's estimates is kinetically improbable in most river systems.
Inadequate health and nutritional literacy is a common problem among adults, associated with poor health outcomes. Therefore, this study aimed to investigate the relationship between health literacy ...and nutritional literacy to sun exposure behaviour.
We conducted a cross-sectional study on 261 adults (18-65 years) in Iran. Data was collected on knowledge, motivation, health literacy, nutritional literacy, and sun exposure behaviour using an interview-assisted questionnaire. Using the information-motivation-behavioural skills model and structural equation modeling, we tested whether health and nutritional literacy were associated with the relationships between knowledge of vitamin D, attitudes toward sun exposure, and sun exposure behaviour. Different models using structural equation modeling were performed to analyze the data.
The finding showed that health literacy (β = 0.29, p < 0.001) and nutritional literacy (β = 0.14, p = 0.02) was directly associated with sunlight exposure. Indirect relationships also existed between knowledge and sunlight exposure through health literacy (β = 0.33, p < 0.001) and nutritional literacy (β = 0.22, p = 0.01). The model had good fit (x
/df = 1.422; RMSEA = 0.040; CFI = 0.851; NFI = 0.657). There was no significant relationship between health literacy and motivation (β = 0.11, p = 0.16), nutritional literacy and motivation (β = 0.06, p = 0.42) and motivation and sun exposure (β = 0.01, p = 0.91).
The findings showed that individuals with sufficient health literacy and nutritional literacy were more likely to have exposure to sunlight. Health and nutritional literacy should be considered when educating adults about vitamin D supplements and sunlight exposure.
Context: Given the high prevalence of metabolic syndrome (MetS) among children and adolescents, the role of dietary habits on MetS development, and formation of food preferences from childhood, it is ...highly important to determine the association of dietary habits with pediatric MetS. Objective: This study aimed at systematically reviewing the association of different dietary patterns with MetS in a pediatric age group. Data Sources and Study Selection: An electronic search was conducted in international electronic databases including PubMed, Cochrane, Scopus, Google Scholar, and domestic data sources. The following keywords were used ;((“Child”(Mesh) OR “Adoles- cent”(Mesh) AND (“Metabolic Syndrome”(Mesh) AND “Diet”(Mesh) OR “Dietary Pattern” (Mesh)).We included all published data on the association of MetS (presence of a cluster of 3 or more metabolic abnormalities) with dietary pattern in the pediatric age group aged 3 to 18 years. Data Extraction: At first, 4194 articles were identified (PubMed: 566; Scopus: 60; Google scholar: 3550; domestic data source: 18). Results: After quality assessment, 17 studies were selected for text appraisal, of which 15 qualified articles were evaluated at the final step. The number of total population and points of data were 19 298. From reported studies, 10 had a cross- sectional design, 3 were interventional studies, 1 was cohort study, and 1 was a systematic review on Korean adolescents. Conclusion: Our results indicated that the Mediterranean diet or diets with a higher score of healthy eating index, i.e., with higher content of grains, vegetables, fruits, milk, and meat/meat alternatives, have inverse associations with the prevalence of MetS, whereas Western type diets are associated with higher frequency of MetS in children and adolescents.
Objective:
We aimed to evaluate the association between the dietary and lifestyle inflammation score (DLIS) and metabolic syndrome (MetS) and its components in a sample of Iranian adults.
Design:
...Population-based cross-sectional study.
Setting:
General adult population living in Tehran, Iran.
Subjects:
We included 827 adult men and women with an age range of 18–59 years who were referred to health centers in different districts of Tehran, Iran. Dietary intake was assessed by a semiquantitative food frequency questionnaire with 168 items. The DLIS was calculated based on four components, including dietary inflammation score, physical activity, cigarette smoking, and general obesity. Higher DLIS represents a more proinflammatory diet and lifestyle. The odds ratio (OR) and 95% confidence interval (CI) of the MetS across quartiles of the DLIS was calculated by using logistic regression analysis, controlling for age, sex, energy intake, marital status, education status, and occupation.
Results:
A total of 827 participants (31% men) were included, with a mean age of 44.7 ± 10.7 years. The prevalence of the MetS was 30.5%. The DLIS ranged between −2.35 and +3.19 (mean ± SD: 0.54 ± 1.09). There was a significant positive association between the DLIS and odds of MetS (OR
fourthvs.thefirstquartile
: 1.57, 95% CI: 1.01–2.45) in the fully adjusted model.
Conclusion:
Our results showed a significant positive association between the DLIS and odds of MetS. The results of the present crosssectional study suggested that having a more proinflammatory lifestyle can be associated with MetS. More prospective studies are needed to confirm the findings.
River damming alters nutrient fluxes along the land‐ocean aquatic continuum as a result of biogeochemical processes in reservoirs. Both the changes in riverine nutrient fluxes and nutrient ratios ...impact ecosystem functioning of receiving water bodies. We utilize spatially distributed mechanistic models of nitrogen (N), phosphorus (P), and silicon (Si) cycling in reservoirs to quantify changes in nutrient stoichiometry of river discharge to coastal waters. The results demonstrate that the growing number of dams decouples the riverine fluxes of N, P, and Si. Worldwide, preferential removal of P over N in reservoirs increases N:P ratios delivered to the ocean, raising the potential for P limitation of coastal productivity. By midcentury, more than half of the rivers discharging to the coastal zone will experience a higher removal of reactive Si relative to reactive P and total N, in response to the rapid pace at which new hydroelectric dams are being built.
Plain Language Summary
The damming of rivers is one of the most impactful modifications of the flows of water and associated materials from land to sea. Included in these materials are nutrient elements like nitrogen and phosphorus, which are elements required by all life on Earth, and silicon, which is required by diatoms, the algae that account for the largest fraction of biological productivity of the oceans. Past studies have shown that if you alter the ratios in which these nutrient elements enter the coastal oceans, plankton communities can change, even causing harmful algal blooms or “red tides” to occur. Here, we use models of nitrogen, phosphorus, and silicon cycling in dam reservoirs to determine how dams change the ratios delivered to coastal zones worldwide. We predict that by midcentury, more than half of the rivers flowing to the sea will experience greater removal of silicon over nitrogen and phosphorus, in response to ongoing construction of many new hydroelectric dams. This will impact the role of diatoms in nearshore marine production, as they are increasingly outcompeted by other, potentially harmful, algae that do not need silicon to grow.
Key Points
Damming decouples the global river fluxes of N, P, and Si
Dams increase N:P ratios delivered to the global coastal zone
Current hydroelectric dam construction may drive coastal productivity toward increased Si limitation
Damming creates biogeochemical hotspots along rivers that modify the riverine flow of nutrients, including nitrogen (N). Here, we quantify the impact of dams on global riverine N fluxes using a ...reservoir N mass balance model. In‐reservoir processes represented in the model include primary production, mineralization of organic N, denitrification, and sedimentary burial. In addition, we explicitly account for N fixation as a source of N, assuming that the N to phosphorus (P) ratio of the inflow regulates the magnitude of N fixation in reservoirs. The model is scaled up via a Monte Carlo analysis that yields global relationships between N elimination in reservoirs, either by denitrification or burial, and the hydraulic residence time. These relationships are then combined with N loads to the world's dam reservoirs generated by the Global‐NEWS model and the estimated N fixation fluxes. According to the results, in year 2000, worldwide N fixation in reservoirs was on the order of 70 Gmol yr−1, while denitrification and burial in reservoirs eliminated around 270 Gmol yr−1, equal to 7% of N loading to the global river network. The latter is predicted to double to 14% by 2030, mainly as a result of the current boom in dam building. The results further imply that, largely due to N fixation in reservoirs, damming causes a global upward shift in riverine N:P ratios, thus lessening N limitation in receiving water bodies.
Key Points
Globally, denitrification and burial in reservoirs exceed N fixation, hence causing a reduction in riverine N export to the coastal ocean
Damming increases riverine N:P ratios, thus reducing the degree of N limitation in downstream water bodies
In the coming decades, the largest changes in in‐reservoir N fixation, N burial, and denitrification fluxes will happen in Asia
Background: Maternal diabetes is associated with increased teratogenic effects on fetuses; it affects the structure and functions of fetal heart and alters the fetal-placental circulation. Although ...several articles have demonstrated fetal cardiac malformation and defects in diabetic mothers, ventricular systolic and diastolic function has not been properly investigated, particularly in Iran. Objectives: The aim of this study was to assess ventricular function using tissue Doppler imaging (TDI) in fetuses of diabetic mothers compared with fetuses of non-diabetic mothers in the Iranian population. Patients and Methods: Twenty-one diabetic pregnantwomenat 28 weeks' gestation were enrolled as the case group, and 35 healthy pregnant women at the same gestation were considered as the control group. Fetal echocardiography, including TDI, was carried out for all cases. The variables measured by echocardiography were as follows: the systolic annular peak velocity (Sa), late-diastolic annular peak velocity (Aa), and diastolic annular peak velocity (Ea) waves on the lateral and septal walls of the left ventricle (LV) at the mitral valve annulus using TDI; mitral inflow E and A waves using pulse Doppler; and inter-ventricular septum thickness using two-dimensional (2D) echocardiography. Results: According to cut-off value of 6.3% for hemoglobin A1C (HbA1c), only one patient with HbA1c = 8 had uncontrolled diabetes. In 20 other patients with controlled diabetes, the mean HbA1c was 4.78 ± 1.22%. There was no significant difference between groups according to maternal age (29.24 ± 5.86 in the case group vs. 28.58 ± 4.42 in the control group, P = 0.6). No significant difference was found in the septal thicknesses between the two groups (P = 0.39). Moreover, there were no statistically significant differences between groups in terms of other echocardiography variables (P > 0.05). Conclusions: We did notfindsignificant differences in ventricular function or ventricular septal thickness in the fetuses of mothers whowere referred to our hospital with a previous diagnosis of diabetes mellituscompared with the fetuses of non-diabetic mothers. This could be due to early identification, appropriate treatment, and tightly controlled diabetes in our study population. It should be noted that only pregnant women who were being closely monitored by their gynecologist were referred to us, so there may be some bias in our case selection; moreover, only patients who have taken steps to control their diabetes, so that only one of them had an abnormal HbA1c level. Other possible reasons for our results are over-diagnosis of gestational diabetes by gynecologists and an inadequate number of participants in our study.
•Two new MgH2-10 wt% (50Ce-50Ni) and MgH2-10 wt% (25Ce-75Ni) nanocomposites prepared.•Ce significantly reduce crystallite size and particle size of MgH2.•The hydrogen desorption temperature of MgH2 ...decreases with addition of Ce.•The activation energy was decreased with the formation of nanocomposite.
This study employed mechanical alloying (MA) to synthesize magnesium-based nanocomposites for hydrogen storage. To fabricate the composite materials, firstly, the vacuum arc re-melting (VAR) method was used to make cerium–nickel (Ce-Ni) alloy with two compositions, including 50Ce-50Ni (wt%) (CN1) and 25Ce-75Ni (wt%) (CN2). Then, 10 wt% of these alloys was milled with magnesium hydride (MgH2) for 5 and 15 h. The impact of milling time on the hydrogen desorption features of the prepared nanocomposites was estimated by the thermal analyzer method and compared to pure MgH2. The molecular dynamics (MD) method was employed to describe the enthalpy change of the nanocomposites mentioned above and pure MgH2 at the atomic scale. Experimental enthalpy results calculated by measuring the peak area in DSC curves also confirmed the molecular dynamics data. Since the enthalpy values of the manufactured nanocomposites were significantly lower than pure MgH2 (−75 kJ/mol), the lower desorption temperature in these specimens was justified.
The present cross-sectional study aimed to assess the association of daily irregularity in energy intake and diet quality among apparently healthy adults in Iran. The research was conducted on 850 ...adult men and women (age range: 20-59 years) who attended health care centres in Tehran. Dietary intake was assessed by three, 24-h dietary recalls. Diet quality was assessed using the Dietary Approaches to Stop Hypertension (DASH) diet score and Healthy Eating Index-2015 (HEI-2015). An irregularity score of daily energy intake was calculated based on the deviation from the 3-d mean energy intake, with a higher score indicating more fluctuations in daily energy intake. Multiple linear regression analysis was used to assess the association of irregularity score of daily energy intake with food group intakes and DASH diet score and HEI-2015, controlling for age, sex, BMI, physical activity, education level and occupation status. The range of irregularity score was 0·55-133·3 (22·4 (sd 19·0)). Higher irregularity score of daily energy intake was significantly associated with a lower consumption of fruit, vegetables, legumes, low-fat dairy products and poultry, higher consumption of soft drinks, processed meat and nuts, and lower overall DASH diet score and HEI-2015. Overall, our findings showed that more day-to-day variations in energy intake may be correlated with a lower diet quality. More research is needed to confirm the associations observed in the present study and to clarify potential mechanisms explaining these associations.
Lake Wilcox (LW), a shallow kettle lake located in southern Ontario, has experienced multiple phases of land use change associated with human settlement and residential development in its watershed ...since the early 1900s. Urban growth has coincided with water quality deterioration, including the occurrence of algal blooms and depletion of dissolved oxygen (DO) in the water column. We analyzed 22 years of water chemistry, land use, and climate data (1996–2018) using principal component analysis (PCA) and multiple linear regression (MLR) to identify the contributions of climate, urbanization, and nutrient loading to the changes in water chemistry. Variations in water column stratification, phosphorus (P) speciation, and chl-a (as a proxy for algal abundance) explain 76 % of the observed temporal trends of the four main PCA components derived from water chemistry data. MLR results further imply that the intensity of stratification, quantified by the Brunt-Väisälä frequency, is a major predictor of the changes in water quality. Other important factors explaining the variations in nitrogen (N) and P speciation, and the DO concentrations, are watershed imperviousness and lake chloride concentrations that, in turn, are closely correlated. We conclude that the observed in-lake water quality trends over the past two decades are linked to urbanization via increased salinization associated with expanding impervious land cover, rather than increasing external P loading. The rising salinity promotes water column stratification, which reduces the oxygenation of the hypolimnion and enhances internal P loading to the water column. Thus, stricter controls on the application and runoff of de-icing salt should be considered as part of managing eutrophication symptoms in lakes of cold climate regions.
Display omitted
•Watershed urbanization causes salinization of Lake Wilcox.•Salinization intensifies lake stratification and internal phosphorus (P) loading.•Symptoms of eutrophication worsen even under declining external P loading.•Reducing road salt use should be a priority to protect cold climate urban lakes.
PDF
