Rates and controls of nitrous oxide and nitric oxide emissions following conversion of forest to pasture in Rondônia

Tropical soils are important sources of nitrous oxide (N₂O) and nitric oxide (NO) emissions from the Earths terrestrial ecosystems. Clearing of tropical rainforest for pasture has the potential to alter N₂O and NO emissions from soils by altering moisture, nitrogen supply or other factors that control N oxide production. In this review we report annual rates of N₂O and NO emissions from forest and pastures of different ages in the western Brazilian Amazon state of Rondônia and examine how forest clearing alters the major controls of N oxide production. Forests had annual N₂O emissions of 1.7 to 4.3 kg N ha^-1 y^-1 and annual NO emissions of 1.4 kg N ha^-1 y^-1. Young pastures of 1–3 years old had higher N₂O emissions than the original forest (3.1–5.1 kg N ha^-1 y^-1) but older pastures of 6 years or more had lower emissions (0.1 to 0.4 kg N ha^-1 y^-1). Both soil moisture and indices of soil N cycling were relatively poor predictors of N₂O, NO and combined N₂O + NO emissions. In forest, high N₂O emissions occurred at soil moistures above 30 water-filled pore space, while NO emissions occurred at all measured soil moistures (18–43). In pastures, low N availability led to low N₂O and NO emissions across the entire range of soil moistures. Based on these patterns and results of field fertilization experiments, we concluded that: (1) nitrification was the source of NO from forest soils, (2) denitrification was not a major source of N₂O production from forest soils or was not limited by NO- supply, (3) denitrification was a major source of N₂O production from pasture soils but only when NO₃^- was available, and (4) nitrification was not a major source of 3 NO production in pasture soils. Pulse wettings after prolonged dry periods increased N₂O and NO₃^- emissions for only short periods and not enough to appreciably affect annual emission rates. We project that Basin-wide, the effect of clearing for pasture in the future will be a small reduction in total N₂O emissions if the extensive pastures of the Amazon continue to be managed in a way similar to current practices. In the future, both N₂Oand NO fluxes could increase if uses of pastures change to include greater use of N fertilizers or N-fixing crops. Predicting the consequences of these changes for N oxide production will require an understanding of how the processes of nitrification and denitrification interact with soil type and regional moisture regimes to control N₂O and NO production from these new anthropogenic N sources.     

Diurnal variation in the water-soluble inorganic ions,organic carbon and isotopic compositions of total carbon and nitrogen in biomass burning aerosols from the LBA-SMOCC campaign in Rondônia,Brazil

Aerosol particles (PM_2.5) were collected during the day (n=6) and nighttime (n=9) from a tropical pasture site in Rondônia, Brazil during an intensive biomass burning period (16–26 September, 2002). Higher normalized (by K⁺, levoglucosan, or apparent elemental carbon, EC_a) mass concentrations of SO₄^2? and CH₃SO₃^? in daytime suggest their photochemical production, while the opposite trend for NO₃^? suggests its transfer to the aerosol phase at lower temperatures and higher humidities, as well as possibly production through hydrolysis of N₂O₅ on aqueous aerosol particles. About 4.2–7.5% of OC (5–13% of water-soluble organic carbon (WSOC)) could be characterized at the molecular level using GC-MS and GC-FID. Among the detected organic compound classes, abundances of anhydrosugars and aromatics were higher in night samples, but sugars/sugar alcohols, diacids, oxoacids and α-dicarbonyls were more abundant in day samples. Consecutive day and night samples showed that δ¹³C values of total carbon (TC) were lower in daytime samples, which can be interpreted as resulting from higher contributions of refractory TC depleted in ¹³C due to predominantly flaming combustion. The δ¹⁵N values of total nitrogen (TN) ranged from +23.5‰ to +25.7‰, however, there was no trend in day and night samples. Higher values of δ¹³C and δ¹⁵N for biomass burning particles than those of unburned vegetation reflect positive isotopic enrichment either during the formation of particles or after the emission of particles in the atmosphere.     

Nitrogen dynamics in stockless organic clover–grass and cereal rotations

We applied a mechanistic ecosystem model to investigate the production and environmental performances of (1) current agricultural practice on two fields of a stockless organic cereal farm in southeast Norway and (2) alternative cereal-ley rotations and plowing time scenarios. Scenarios were simulated using historic weather data and a climate change scenario. Measured and simulated soil mineral N concentrations were generally low (1–4 g N m⁻²) and in good agreement. Simulated nitrate leaching was similar for the two fields, except when an extended period of black fallow weeding was practiced on one of them. Scenario simulations indicated that continuous cereal cropping undersown with a clover–grass winter cover crop performed best when evaluated by whole-rotation grain yield, the N yield/input-, and N loss/yield-ratios, and greenhouse gas emissions. However, the rotation had the largest soil organic matter losses. The N use and loss efficiency indicators were especially poor when ley years occurred consecutively and under fall plowing. Total greenhouse gas emissions were, however, smaller for the fall-plowed scenarios. In conclusion, our results indicated a modest potential for improving stockless systems by management changes in plowing time or crop rotation, which was hardly different in the climate change scenarios, although nitrate leaching increased substantially in the winter. Alternative strategies seem necessary to substantially improve the N-use efficiency in stockless organic grain production systems, e.g., biogas production from green manure and subsequent recycling of the digestate. Abandoning the stockless system and reintegrating livestock should also be considered.     

Placement effects on rice residue decomposition and nutrient dynamics on two soil types during wheat cropping in rice–wheat system in northwestern India

Crop residues are important sources of organic matter and plant nutrients and known to affect soil quality. Tillage affects residue decomposition and nutrient cycling processes. A 2 year field study was aimed to investigate the decomposition and nutrient dynamics from surface-placed and incorporated rice (Oryza sativa L.) residue on two soil types using the nylon mesh bag technique over wheat cropping cycle in rice–wheat system in northwestern India. A single-pool first-order exponential decay function showed R ² larger than 0.9. Over the wheat growing cycle about 20% of buried rice residue and 50% of surface-placed residue remained undecomposed. Nitrogen exponential decay models were significant at P < 0.01. At wheat boot stage (1,100 growing degree days, DGD) 12 kg N ha⁻¹ (27% of the initial N) was released from the buried residue losing 60–65% of its N at the end of decomposition cycle. Nitrogen in surface rice residue increased throughout the decomposition cycle due to microbiological immobilization. The change in P with time (DGD) was small and weakly defined by the exponential function. Nutrient dynamics of rice residue indicate that it is not a potential source of N and P for wheat over short-term. The change in K concentration was well described by exponential function (R ² 0.73–0.86). Potassium in rice residue decreased at a fast rate during the initial 20 days (400 DGD) and >80% was released by 40 days (680 DGD).     

Factors determining the breastfeeding in children attending public and not-for-profit daycare centers in São Paulo, Brazil

Cross-sectional study with 270 children and their mothers in eight public and philanthropic daycare centers in the city of S?o Paulo, Brazil. The objective is to identify the determinants of exclusive breastfeeding (EBF) and breastfeeding (BF). The Mann-Whitney/ Wilcoxon test and survival analysis; Kaplan Meier curves and Cox multiple regression models were used for statistical analyses. The median of exclusive breastfeeding duration was 79.1 +/- 55.6 days and breastfeeding was 185.3 +/- 174.2 days. In multivariate analysis, the following risk factors of early weaning for exclusive breastfeeding were identified: pacifier use (HR = 1.65, 95% CI = 1.24 to 2.2); previous hospital admission (HR = 1.35, 95% CI = 1.01 to 1.80); mother working outside home (HR = 1.33, 95% CI = 1.00 to 1.76). For breastfeeding were identified: pacifier use (HR = 2.54, 95% CI = 1.87 to 3.45) and mother who works outside the home (HR = 1.51, 95% CI = 1.14-1.99). The results show that it is necessary to continue to promote and support breastfeeding, mainly the exclusive breastfeeding until six months of age. The daycare centers should incorporate this idea, once they may have direct control over some of the early weaning determinants, and are also good places to deliver messages and guidance on nutrition education to mothers and caregivers in contact with children under three years old.     

Risk factors for growth retardation in children of low economic and social level in São Paulo, Brazil

Aiming to analyze the mild to moderate growth retardation associate factors in children at school age, a case control study was conducted with 153 pairs of seven and eight years old children from public schools of the outskirts of the city. The cases were defined as children with a height for age(H/A) between -1 and -2 Z score, according to NCHS/WHO standards, and matched with a H/A +/- 0.5 Z-score children of same age, gender, school, classroom and class time, as controls. The height was measured at school according to WHO rules by trained professionals, and household visits were carried out to obtain environmental and socio-economic data. Initially the data was analyzed by the univariate conditional method and then, the statistically significant variables were included in a model of multivariate logistic regression analysis. As a result, the risk factors remaining at the end of the multivariate analyses, by Odds Ratio and it's 95% Confidence Interval were respectively:--mother's height: for each decrease of one standard deviation the OR increased 1.84(CI: 1.35 to 2.49); inadequate feeding pattern: OR = 2.12; CI: 1.17 to 3.83, very low socio-economic level: OR = 9.2; CI: 3.35 to 25.13, low birth weight: OR = 2.59; CI: 1.44 to 4.63 and smoking during pregnancy: OR = 1.75; CI: 0.98 to 3.12. These results highlight the environment as a determinant factor for growth performance during the first years of the child's life. Despite this, the significant OR for Mother's height allows the assumption that besides the environment, the parent's height has to be considered as one of the determinants of height deficit, even for the low socioeconomic level.     

Nitrogen and sulphur fertilization effect on leaching losses, nutrient balance and plant quality in a wheat–rapeseed rotation under a humid Mediterranean climate

An unbalanced S and/or N fertilization may have low N and S use efficiency together with substantial negative implications for yield, nutrient losses and plant quality parameters. The effect of N and S fertilization and their interactions on N?CS balances, on N?CS losses and on some plant quality parameters were investigated in a field experiment with a wheat (Triticum aestivum L.)?Crapeseed (Brassica napus L.)?Cwheat rotation (2005?C2008). The study was conducted under humid Mediterranean climatic conditions on a potentially S deficient soil. The effects of N (0, 140, 180, 220?kg?N?ha^?1 in wheat; 0, 100, 140, 180, 220?N?ha^?1 in rapeseed) combined with S fertilizer rates (0, 16 and 32?kg S ha^?1 in wheat and 0, 30, 60?kg S ha^?1 in rapeseed) were studied. Nitrogen fertilization increased yield by 55?% in wheat and 60?% in rapeseed, N concentration in grain and straw and S concentration in the grain of wheat. However, it led to a reduction in the S concentration of straw and the oil content of the rapeseed seed. The S application did not increase yield but had a positive effect on S concentration in the wheat straw. Glucosinolate concentration, a potentially toxic secondary metabolite in rapeseed, was not influenced by N or S applications. Nitrate leaching tended to increase with N application while sulphate leaching decreased. A net N and S mineralization was observed in each growing season, except for the first year in which a net S immobilization was observed. To make N fertilizer recommendations, the N mineralization from the previous crop residues should be taken into account. For S fertilizer recommendations, N supply is the most important item both from a qualitative point of view (N/S ratio in wheat grain) and an environmental point of view (S leaching).     

Insight into nitric acid extraction and aggregation of N,N, N’, N’-Tetraoctyl diglycolamide (TODGA) in organic solutions by molecular dynamics simulation

The molecular dynamics (MD) simulation of TODGA in n-dodecane shows formation of nanostructures of TODGA aggregates with nitric acid and water. These aggregates are dispersed in dodecane phase or form well defined reverse micelles grown sufficient in size depending on the acid concentration. With increasing nitric acid concentration, aggregation number of TODGA in reverse micelles also increases which, however, is independent of TODGA concentration. Aggregation number rises from 2 to 8 in presence of 0–3.5 M nitric acid in corresponding aqueous phase. The formation of the aggregates explains remarkable acid co-extraction from aqueous phase to organic dodecane phase by TODGA.     

Accumulation and apparent recovery of N,P and K after the incorporation of gliricidia and manure in intercropping during the cultivation of corn–cowpea–cotton

Fertilization with manure is widely adopted by farmers in the semiarid region of northeastern Brazil, although the quantity of available manure is limited. Thus, among other alternatives, gliricidia has been used as an additional source of organic fertilizer. The objective of this study was to evaluate the accumulation and apparent recovery of N, P and K after using different forms of gliricidia and manure application in the intercropping of corn, cowpea and cotton in three crop cycles in the semi-arid northeast region of Brazil. The following treatments were used: gliricidia incorporated into the soil before planting; gliricidia spread on the surface of the soil at 45 days after planting; manure and gliricidia incorporated into the soil before planting; manure incorporated into the soil before planting and gliricidia spread on the surface of the soil at 45 days after planting; manure incorporated into the soil before planting; and no addition of organic fertilizer (control). Accumulations followed the same pattern as biomass production but differed greatly from the concentrations. Low apparent recoveries were obtained in the first and second cycles, and high apparent recoveries were obtained in the third cycle. The nutrient balances indicated that the incorporation of gliricidia before planting or spread on the surface does not meet crop needs. The incorporation of manure as well as manure and gliricidia when applied on the surface, were able to meet growth needs and maintain soil fertility.     

HSG400 – Design,implementation, and evaluation of a hybrid board game for aiding chemistry and chemical engineering students in the review of stereochemistry during and after the COVID-19 pandemic

This paper provides information about a hybrid multilingual (English, Portuguese, French, and Italian) game developed as an alternative learning method to the traditional problem-solving exercises model. The game comprises a physical board and a free-of-charge application for undergraduate students to review and reinforce concepts related to stereochemistry by answering questions, from a bank of 400 questions, in a ludic, competitive, and collaborative environment. Brazilian, French, and Italian undergraduate students played the game face-to-face before the disruption caused by the Covid-19 Pandemic and remotely during that. They also evaluated the game, and the quite positive results obtained from students’ self-assessment revealed that they felt the game contributed to their learning while playing.     

Many-body effects in some thermodynamic properties of supercritical CO2, CO2–Ar,and CO2–CH4 using HFD-like potentials from molecular dynamics simulation

Molecular dynamics simulation has been performed to obtain the pressure and self-diffusion coefficient of supercritical carbon dioxide using a two-body HFD (Hartree–Fock dispersion)-like potential determined via the inversion of reduced viscosity collision integrals at zero pressure. We have also obtained pressures of CO₂–Ar and CO₂–CH₄ fluid mixtures at constant temperatures at different densities using new accurate two-body HFD-like potential functions. To take many-body forces into account, the three-body potentials of Hauschild and Prausnitz [27], Wang and Sadus [30], [38], Oakley et al. [3], and Guzman et al. [33] have been used with the two-body potentials. The significance of this work is that the modified many-body potential of Hauschild and Prausnitz (extended as a function of density, temperature, and molar fraction) has been used with the two-body HFD-like potentials of CO₂, CO₂–Ar, and CO₂–CH₄ systems to improve the prediction of the pressure values without requiring an expensive three-body calculation. The results are in good agreement with experimental values.     

Changes in fertilizer and manurial practices during 1960–1990: implications for N and P inputs to the Ythan catchment, N.E. Scotland

A suggested increase in the growth of macrophytic algae within the Ythan estuary (N.E. Scotland) over recent years has been linked to the increased amounts of nitrogen in the form of NO₃–N entering the estuary from the river. The increased NO₃ concentration in the river has been associated with recent changes in farming practices in this predominantly agricultural catchment. Terrestrially derived phosphorus is also considered to contribute increasingly to eutrophication of fresh waters. Historical agricultural census data together with appropriate surveys of fertilizer practice were used to calculate the total quantities of fertilizer and manure derived N and P applied annually over the wholeYthan catchment during the period 1960 – 1990. While the total agricultural land area has remained similar, significant changes in cropping practice have occurred. In particular, a greater proportion of land is given to autumn sown crops while the area of grassland has declined. These changes in farming practice are associated with differences in both the total amounts and timing of fertilizer applied. The use of inorganic N in the catchment has trebled since 1960 and is currently approximately 6400 tonnes (104 kg N/ha). The use of P has decreased by more than a quarter to 1274 tonnes (21 kg P/ha) over a similar time period. There has been no obvious change in total quantity of N and P derived from animal manures, estimated to be 44 and 11 kg per ha, respectively, when averaged over the area of agricultural land. Cattle and sheep numbers have remained relatively constant and together account for approximately 80% of the manure N and 70% of the manure P produced annually. However, poultry have declined by 70% since 1960 while pig numbers have increased six-fold. The average annual application rate of manure derived N over the whole catchment (44 kg/ha) is considerably below that proposed at the farm scale in the EC Nitrate Directive (210–170 kg/ha). However, on a local scale difficulties may arise for large manure producing concerns such as dairy or pig units.     

Lipase C,Hepatic Type −250A/G (rs2070895) Variant Enhances Carotid Atherosclerosis in Normolipidemic and Asymptomatic Individuals from Brazil

The common genetic variant in the promoter region of the hepatic lipase gene [LIPC −250G/A(rs2070895)] has an ambiguous association with cardiovascular disease. In this context, our study was performed to identify the relationships between the rs2070895 with carotid atherosclerosis, plasma lipids, and parameters of reverse cholesterol transport. A total of 285 normolipidemic and asymptomatic participants from an initial sample of 598,288 individuals (inclusion criteria: LDL-C ≤130 mg/dL and triglycerides ≤150 mg/dL; age: 20–75 years, both genders; confirmation of clinical, anthropometric and laboratory data; attended all visits; DNA was achieved to perform genetic analysis) were enrolled and the rs2070895 variant was genotyped by TaqMan® OpenArray® Plataform. Carotid intima-media thickness and the screening of atherosclerotic plaques were determined by B-mode ultrasonography. The rs2070895 genotype frequencies were 0.44, 0.41, and 0.15 (GG, GA, and AA, respectively). Logistic regression analysis showed that the risk of having plaques was increased in participants carrying the AA or AG genotypes (OR = 3.90; 95% CI = 1.54–10.33), despite an increase in high-density lipoprotein cholesterol levels, HDL diameter and apolipoprotein A-I, as compared to the GG genotype. Hepatic lipase and endogenous lecithin cholesterol acyl transferase activities were reduced (38% and 19%, respectively) and lipoprotein lipase was increased by 30% (AA vs GG). Our results provide evidence that the AA or AG genotypes of the rs2070895 were associated with carotid atherosclerosis in apparently healthy participants, probably as a consequence of reduced reverse cholesterol transport and accumulation of HDL subfraction 2 rich in triglycerides and depleted in cholesteryl esters that could become dysfunctional.     

Effects of tillage systems on soil organic carbon dynamics, structural stability and crop yields in irrigated wheat (Triticum aestivum L.)–cotton (Gossypium hirsutum L.) rotation in semi-arid Zimbabwe

In southern Africa, tillage research has focused on rainfed smallholder cropping systems, while literature on high-input irrigated cropping systems is limited. We evaluated the effects of conventional (CT), minimum (MT) and no-till (NT) tillage systems on soil organic carbon (SOC), bulk density, water-stable aggregates (WSA), mean weighted diameter (MWD) and crop yields in an irrigated wheat–cotton rotation. Soil data were monitored in the first and final year, while yields were monitored seasonally. Average bulk densities (1.5–1.7 Mg m⁻³) were similar among tillage systems, but often exceeded the critical limit (1.60 Mg m⁻³) for optimum root growth. Conversion from CT to MT and NT failed to ameliorate the high bulk densities associated with the alluvial soil. SOC (g kg⁻¹) at 0–15 cm was higher (P < 0.05) under MT (3.9–5.8) and NT (4.2–5.6) than CT (2.9–3.3). Corresponding horizon SOC stocks (Mg C ha⁻¹) for the tillage treatments were; 9.3–13.9 (MT), 9.3–13.5 (NT) and 7.3–7.7 (CT). In the final year, significant (P < 0.05) tillage effects on SOC stocks were also observed at 15–30 cm. Cumulative SOC stocks (Mg C ha⁻¹) in the 0–60 cm profile were higher (P < 0.05) under MT (32.8–39.9) and NT (32.9–41.6) than CT (27.8–30.9). On average, MT and NT sequestered between 0.55 and 0.78 Mg C ha⁻¹ year⁻¹ at 0–30 cm depth, but a net decline (0.13 Mg C ha⁻¹ year⁻¹) was observed under CT. At 0–30 cm, MT and NT had higher (P < 0.05) MWD (0.19–0.23 mm) and WSA (2.3–3.5%) than CT (MWD: 0.1–0.12 mm, WSA: ≈1.0%). Both MWD and WSA were significantly (P < 0.05) correlated to SOC. Seasonal yields showed significant (P < 0.05) tillage effects, but 6-year mean yields (t ha⁻¹) were similar (CT: 4.49, MT: 4.33, NT: 4.32 for wheat; CT: 3.30, MT: 2.82, NT: 2.83 for cotton). Overall, MT and NT improved soil structural stability and carbon sequestration, while impacts on crop productivity were limited. Therefore, MT and NT are more sustainable tillage systems for the semi-arid regions than conventional tillage. S. Chakanetsa—Deceased.     

Genotoxic and epigenotoxic effects in mice exposed to concentrated ambient fine particulate matter (PM<Subscript>2.5</Subscript>) from São Paulo city,Brazil

Background

The Metropolitan Area of São Paulo has a unique composition of atmospheric pollutants, and positive correlations between exposure and the risk of diseases and mortality have been observed. Here we assessed the effects of ambient fine particulate matter (PM_2.5) on genotoxic and global DNA methylation and hydroxymethylation changes, as well as the activities of antioxidant enzymes, in tissues of AJ mice exposed whole body to ambient air enriched in PM_2.5, which was concentrated in a chamber near an avenue of intense traffic in São Paulo City, Brazil.

Results

Mice exposed to concentrated ambient PM_2.5 (1 h daily, 3 months) were compared to in situ ambient air exposed mice as the study control. The concentrated PM_2.5 exposed group presented increased levels of the oxidized nucleoside 8-oxo-7,8-dihydro-2′-deoxyguanosine in lung and kidney DNA and increased levels of the etheno adducts 1,N⁶-etheno-2′-deoxyadenosine and 1,N²-etheno-2′-deoxyguanosine in kidney and liver DNA, respectively. Apart from the genotoxic effects, the exposure to PM_2.5 led to decreased levels of the epigenetic mark 5-hydroxymethylcytosine (5-hmC) in lung and liver DNA. Changes in lung, liver, and erythrocyte antioxidant enzyme activities were also observed. Decreased glutathione reductase and increased superoxide dismutase (SOD) activities were observed in the lungs, while the liver presented increased glutathione S-transferase and decreased SOD activities. An increase in SOD activity was also observed in erythrocytes. These changes are consistent with the induction of local and systemic oxidative stress.

Conclusions

Mice exposed daily to PM_2.5 at a concentration that mimics 24-h exposure to the mean concentration found in ambient air presented, after 3 months, increased levels of DNA lesions related to the occurrence of oxidative stress in the lungs, liver, and kidney, in parallel to decreased global levels of 5-hmC in lung and liver DNA. Genetic and epigenetic alterations induced by pollutants may affect the genes committed to cell cycle control, apoptosis, and cell differentiation, increasing the chance of cancer development, which merits further investigation.