High Nitrate Concentrations Research Articles

Selective generation of nitrate and nitrite in plasma activated water and its physicochemical parameters analysis

In this work, a surface dielectric barrier discharge-based cold plasma source is reported with the selective generation of Nitrate and Nitrite in the Plasma Activated Water (PAW). The physicochemical properties of the generated PAW have been analyzed on different process parameters such as applied voltage, frequency, treatment time, and volume of water. The generated PAW has a low pH value, with high conductivity, nitrite concentration, nitrate concentration, and nil concentration of hydrogen peroxide. It is inferred that the PAW is enriched with Nitrate and Nitrite, once hydrogen peroxide is nil in the activated water. This type of PAW can be highly useful for agricultural applications.

Chemical monitoring and risk assessment of 56 pesticides in the Ave River and adjoining Atlantic coastline (Iberian Peninsula, Portugal)

The Ave basin (North Atlantic Ocean Ecoregion) is highly disturbed by anthropogenic activities. The amounts and distribution patterns of 56 priority pesticides (fungicides, herbicides, and insecticides) dissolved in the aqueous phase (DAP) and suspended particle matter (SPM) were evaluated seasonally along the river, estuary and coastline. Over 83 % of the GC–MS/MS-identified pesticides were quantified in DAP and 91 % in SPM. Pesticides' average annual amounts were ≅316 ng/L and 1.3 μg/g (fungicides), ≅272 ng/L and 2.2 μg/g (herbicides) and ≅1344 ng/L and 6.6 μg/g (insecticides). Invertebrates were the most vulnerable trophic level in the theoretical assessment of pesticide mixture hazards. This hypothesis was strengthened by acute in vivo assays using Artemia salina and Daphnia magna. These data, and the fact that 38 % of pesticides showed concentrations above the maximum established by the European legislation, plus the high concentrations of nitrates, nitrites, ammonia and phosphates, request further depollution actions in this region.

Nitrous Oxide Fluxes in Permafrost Peatlands Remain Negligible After Wildfire and Thermokarst Disturbance

AbstractThe greenhouse gas (GHG) balance of boreal peatlands in permafrost regions will be affected by climate change through disturbances such as permafrost thaw and wildfire. Although the future GHG balance of boreal peatlands including ponds is dominated by the exchange of both carbon dioxide (CO2) and methane (CH4), disturbance impacts on fluxes of the potent GHG nitrous oxide (N2O) could contribute to shifts in the net radiative balance. Here, we measured monthly (April to October) fluxes of N2O, CH4, and CO2 from three sites located across the sporadic and discontinuous permafrost zones of western Canada. Undisturbed permafrost peat plateaus acted as N2O sinks (−0.025 mg N2O m−2 d−1), but N2O uptake was lower from burned plateaus (−0.003 mg N2O m−2 d−1) and higher following permafrost thaw in the thermokarst bogs (−0.054 mg N2O m−2 d−1). The thermokarst bogs had below‐ambient N2O soil gas concentrations, suggesting that denitrification consumed atmospheric N2O during reduction to dinitrogen. Atmospheric uptake of N2O in peat plateaus and thermokarst bogs increased with soil temperature and soil moisture, suggesting sensitivity of N2O consumption to further climate change. Four of five peatland ponds acted as N2O sinks (−0.018 mg N2O m−2 d−1), with no influence of thermokarst expansion. One pond with high nitrate concentrations had high N2O emissions (0.30 mg N2O m−2 d−1). Overall, our study suggests that the future net radiative balance of boreal peatlands will be dominated by impacts of wildfire and permafrost thaw on CH4 and CO2 fluxes, while the influence from N2O is minor.

Using appropriate Kappa statistic in evaluating inter-rater reliability. Short communication on “Groundwater vulnerability and contamination risk mapping of semi-arid Totko river basin, India using GIS-based DRASTIC model and AHP techniques”

In this article, some misuses of Kappa statistic in the original paper [Chemosphere, 307, 135831] are discussed. By using DRASTIC and Analytic Hierarchy Process (AHP) models, the authors have assessed the groundwater vulnerability of Totko, India. High nitrate concentrations in groundwater have been found in highly vulnerable areas, and the accuracy of the models has been assessed through Pearson's correlation coefficient and Kappa coefficient. However, using Cohen's Kappa to estimate the intra-rater reliabilities (IRRs) of the two models is not appropriate on the condition of ordinal categorical variables in five categories in the original paper. We briefly introduce the Kappa statistic and propose to use weighted Kappa to compute IRRs under such conditions. To conclude, we recognize that this does not significantly alter the conclusions of the original paper, but it is necessary to ensure that the appropriate statistical tools are used.

A GIS-based analysis of groundwater manganese and nitrate concentration for sustainable water supply

Groundwater is the main source of water supply in Sleman Regency. Although the water quantity is not an issue, the quality of groundwater should be understood to ensure the sustainability of the water supply. A previous study shows an increase in manganese (Mn) and nitrate (NO3) concentration in groundwater, yet the concentration distribution is unknown. Therefore, this study aims to develop a map of the spatial distribution pattern and to analyze the potential source of manganese and nitrate in groundwater in Sleman Regency in Yogyakarta Province. The method used is mapping groundwater quality using the ArcGIS application, analyzing groundwater pollution with water quality standards in the Indonesian Ministry of Health regulation number 492/Menkes/per/IV/2010 regarding drinking water quality requirements, and identifying the potential source of high pollution. Data processing uses the ArcGIS 10.8 application by performing the IDW (Inverse Distance Weighting) Interpolation technique. The result of this study has obtained a map of the distribution of groundwater quality for manganese and nitrate from 2017-2019. Manganese contamination may come from industrial and/or agricultural waste, while higher nitrate concentration might be a result of a septic tank leak and/or pesticide/fertilizer residue in paddy fields.

Analysis of the quality of groundwater in the Sverdlovsk region

Introduction. The quality and availability of drinking water is a prerequisite for the protection of health and ensuring the necessary living conditions of modern man.
 The aim of this work is to assess the quality of groundwater from sources of non-centralized water supply in in the Sverdlovsk region.
 Materials and methods. Water samples were taken from various groundwater sources including springs, wells, boreholes in the Sverdlovsk region. Water quality was assessed by the following indicators: hardness, oxidizability, pH, content of heavy metals (copper, lead, cadmium, nickel and zinc), nitrate ions. The studies were carried out by titrimetry (hardness and oxidizability), potentiometry (pH and nitrate ion content) and inversion voltammetry (heavy metal content). The degree of contamination of these groundwater with heavy metals was estimated by the Cd pollution index.
 Results. The pH values in the studied water samples are within acceptable values. (except for one sample). The hardness values of the studied groundwater (with the exception of one sample) correspond to the maximum permissible concentration (MPC). A high content of nitrates due to the application of mineral fertilizers and industrial effluents was found in two samples studied. Excess of the standard values of oxidizability due to penetration of municipal wastewater into the groundwater was detected in three samples.
 The revealed strong contamination of a number of underground sources with lead, cadmium and zinc is caused by the action of various technogenic factors.
 Limitations. The number of analyzed samples, the variety of sampling sites, the number of indicators of the quality of the studied water samples, and methods of their determination are limited.
 Conclusion. Thus, the groundwater of the Sverdlovsk region from seven sources of non-centralized water supply were revealed to be contaminated with nitrates, organic pollutants, heavy metals (lead, zinc, cadmium) and characterized by increased rigidity. MPC of lead, cadmium and zinc was repeatedly found to be exceeded in three water samples. The anthropogenic nature of water pollution has been established, mainly due to the proximity of highways and industrial enterprises to water intake sources. The calculated indices of groundwater pollution allowed estimating the level of their pollution as high.

Growth conditions impact particulate absorption and pigment concentrations in two common bloom forming cyanobacterial species

Remote sensing using satellite imagery has been promoted as a method to broaden the scale and frequency of cyanobacterial monitoring. This relies on the ability to establish relationships between the reflectance spectra of water bodies and the abundance of cyanobacteria. A challenge to achieving this comes from a limited understanding of the extent to which the optical properties of cyanobacteria vary according to their physiological state and growth environment. The aim of the present study was to determine how growth stage, nutrient status and irradiance affect pigment concentrations and absorption spectra in two common bloom forming cyanobacterial taxa: Dolichospermum lemmermannii and Microcystis aeruginosa. Each species was grown in laboratory batch culture under a full factorial design of low or high light intensity and low, medium, or high nitrate concentrations. Absorption spectra, pigment concentrations and cell density were measured throughout the growth phases. The absorption spectra were all highly distinguishable from each other, with greater interspecific than intraspecific differences, indicating that both D. lemmermannii and M. aeruginosa can be readily differentiated using hyperspectral absorption spectra. Despite this, each species exhibited different responses in the per-cell pigment concentrations with varying light intensity and nitrate exposure. Variability among treatments was considerably higher in D. lemmermannii than in M. aeruginosa, which exhibited smaller changes in pigment concentrations among the treatments. These results highlight the need to understand the physiology of the cyanobacteria and to take caution when estimating biovolumes from reflectance spectra when species composition and growth stage are unknown.

Spatial-temporal difference between nitrate in groundwater and nitrogen in soil based on geostatistical analysis

The study of temporal and spatial variations of nitrate in groundwater under different soil nitrogen environments is helpful to the security of groundwater resources in agricultural areas. In this paper, based on 320 groups of soil and groundwater samples collected at the same time, geostatistical analysis and multiple regression analysis were comprehensively used to conduct the evaluation of nitrogen contents in both groundwater and soil. From May to August, as the nitrification of groundwater is dominant, the average concentration of nitrate nitrogen is 34.80 mg/L; The variation of soil ammonia nitrogen and nitrate nitrogen is moderate from May to July, and the variation coefficient decreased sharply and then increased in August. There is a high correlation between the nitrate nitrogen in groundwater and soil in July, and there is a high correlation between the nitrate nitrogen in groundwater and ammonium nitrogen in soil in August and nitrate nitrogen in soil in July. From May to August, the area of low groundwater nitrate nitrogen in 0–5 mg/L and 5–10 mg/L decreased from 10.97% to 0, and the proportion of high-value area (greater than 70 mg/L) increased from 21.19% to 27.29%. Nitrate nitrogen is the main factor affecting the quality of groundwater. The correlation analysis of nitrate nitrogen in groundwater, nitrate nitrogen in soil and ammonium nitrogen shows that they have a certain period of delay. The areas with high concentration of nitrate in groundwater are mainly concentrated in the western part of the study area, which has a high consistency with the high value areas of soil nitrate distribution from July to August, and a high difference with the spatial position of soil ammonia nitrogen distribution in August.

Growing and non-growing season nitrous oxide emissions from a manured semiarid cropland soil under irrigation

Dairy manure is used in semiarid southern Idaho to improve soil fertility, but campaigns to measure resulting nitrous oxide (N2O) emissions over the complete year have not been conducted to date. The objective of this study was to measure N2O fluxes throughout the growing (April to Sept) and non-growing (Oct to Mar) seasons in 2020 (sugarbeet) and 2021 (silage corn and triticale) in a field that received inorganic N fertilizer or was previously treated with dairy manure solids on an annual and biennial basis for 8 years. Gas fluxes were measured daily using automated chambers that were connected to a gas chromatograph for in situ analysis of N2O. The N2O emissions were found to be highly episodic and major pulses were associated with irrigation during the growing season, warming events in the winter, and soil disturbance at harvest. Emissions were greatest from soil that had received manure at the highest annual application rate of 52 Mg ha−1 (dry wt.), with cumulative totals of 3.6 and 3.0 kg N2O-N ha−1 in 2020 and 2021, respectively. These cumulative totals were about 3-fold greater than emissions from plots treated with inorganic fertilizer or manure at 17 Mg ha−1 annually or 35 Mg ha−1 biennially. This outcome can be attributed to high concentrations of nitrate produced through mineralization of organic N in manure. Emission factors indicated that up to 1.2% of the total N applied was lost as N2O-N, with the greatest loss from inorganic fertilizer treated soil. When breaking down the emissions by season, anywhere from 49%–63% (2020) and 37–58% (2021) of the N2O-N emissions occurred during the non-growing season. Growing and non-growing season N2O emissions were found to be statistically equivalent for each of the respective fertilizer or manure treatments. This finding stresses the need to also measure N2O emissions during the non-growing season as a way to improve the accuracy of annual emission estimates.

Diurnal oscillation in dissolved oxygen at sediment-water interface fuels denitrification-driven N removal in Ganga River

Human activities have substantially enhanced riverine nitrogen loads in many parts of the world. The processes such as denitrification remove a large fraction of N added to the system, and thus, are very helpful in mitigating the effects of increasing human N loads in aquatic ecosystems. No systematic studies, so far, are available on current magnitude and factors regulating efficiency of N removal by the Ganga River. Using three sub-sets of studies- main river course, two tributary confluence trajectories and two point source trajectories along 520 km middle stretch, we generated high spatio-temporal resolution data to show that spatially targeted river reaches with higher nitrate concentrations are acting as ‘hotspots’ of N removal in the Ganga River. The static core method was used to measure the rate of denitrification. Intact sediment core samples were incubated in the laboratory condition and efficiency adjusted. Pollution-impacted point sources showed higher rates of denitrification (0.40 mg N/m2/hr to 2.48 mg N/m2/hr) relative to main stream sites (0.32 mg N/m2/hr to 2.09 mg N/m2/hr). Our results indicate that increased level of carbon (C) and phosphorus (P), which often accompany nitrogen (N) inputs from human activities, have enhanced N removal by the river. Periodic oxic-hypoxic cycle at sediment-water interface (DOsw), which might link nitrification with denitrification, has stimulated N removal at study sites in an opportunistic manner. These results suggest that data on this natural process of N removal (denitrification), and factors thereof, especially those accounting for interactive effects at spatially targeted locations, should be taken into account to formulate policies for the management of nutrient and organic pollution.

Groundwater springs in the German Wadden Sea tidal flat: A fast-track terrestrial transfer route for nutrients and dissolved organic matter

Submarine groundwater discharge (SGD) connects fresh groundwater and marine ecosystems and conveys terrestrially derived dissolved organic matter (DOM) and nutrients from land to sea. The connectivity of terrestrial and marine ecosystems via SGD depends strongly on local environmental settings. For example, SGD composition is modified on its transit through the coastal aquifer, with spring-type SGD from highly permeable aquifers presumably being less affected than diffuse discharge systems from sedimentary environments. In our study, we investigated spring-type SGD near Sahlenburg/Cuxhaven, Northern Germany, which passes through fine, unconsolidated tidal sediments before entering the coastal ocean. We characterized groundwater, surface water and seawater endmembers from different seasons and assessed the potential of tidal sediments impacting the biogeochemistry of “fast-track”, point-source groundwater discharge systems. In addition to physicochemical parameters and nutrients, we analyzed the DOM molecular composition via ultrahigh-resolution mass spectrometry (FT-ICR-MS). Our data revealed a widespread physicochemical and geochemical influence of the groundwater springs on the tidal flat, producing low salinity and low dissolved organic carbon (DOC), and high nitrate and high oxygen concentrations not only in the springs, but also in adjacent porewater. From near- to offshore, salinity and DOC concentrations in springs decreased whereas nitrate and oxygen concentrations increased, resembling an inverse estuarine pattern. Furthermore, high nitrate values suggest anthropogenic sources (e.g., agricultural influence) in the surrounding watershed and may stimulate primary productivity in the tidal flat. Humic-like fluorescent DOM (FDOM) abundances and DOM molecular fingerprints indicated inputs of terrestrial DOM from nearshore saltmarsh plants, as well as from the nearby Elbe and Weser estuaries. Our study demonstrated that SGD had a strong geochemical impact even in the vicinity of large rivers, with productive springs actively hindering sulfate and nitrate reduction by flushing otherwise anoxic systems with oxygen. We posit that the geochemical influence of groundwater springs in tidal flats is underestimated because it can extend far beyond their visual discharge points.

Effect of Different Cooking Treatments on the Residual Level of Nitrite and Nitrate in Processed Meat Products and Margin of Safety (MoS) Assessment

Nitrite and nitrate are well-known food additives used in cured meats and linked to different food safety concerns. However, no study about the possible effect of cooking treatment on the residual level of these compounds before consumption is available. In this work, 60 samples of meat products were analyzed in order to evaluate the variation in residual nitrite and nitrate level after baking, grilling and boiling. The analyses by ion chromatography demonstrated that meat cooking leads to a decrease in nitrite and an increase in nitrate residual levels in the final products. Meat boiling caused an overall decrease in two additives' concentration, while baking and particularly grilling caused an increase in nitrate and, in some cases, nitrite as well. Some regulatory aspects were also considered, such as the possibility of revising the legal limit of nitrate from the actual 150 mg kg-1 to a more cautious 100 mg kg-1. Indeed, several meat samples (bacon and swine fresh sausage) resulted in a higher nitrate concentration than the legal limit after cooking by grilling (eleven samples) or baking (five samples). Finally, the Margin of Safety evaluation demonstrated a good level of food safety, all values being higher than the protective threshold of 100.

Impact of an exceptional winter flood on benthic oxygen and nutrient fluxes in a temperate macrotidal estuary: Potential consequences on summer deoxygenation

Despite 20 years of control on eutrophication, episodes of summer hypoxia still occur in the Loire estuary, impacting water quality and posing a key scientific and management challenge. This work aimed to quantify the contribution of the benthic compartment to hypoxia in the Loire estuary by direct measurement of water–sediment fluxes and an in-depth understanding of the seasonal variations of oxides and phosphorus stocks. During the summer’s low-discharge period, results show that the iron oxide-rich deposit is stable under hypoxic conditions, limiting the release of dissolved phosphorus into the overlying water column. The high nitrate content of the water column appears to be an important oxidizer of iron during hypoxic periods, limiting dissolved phosphorus leakage and aggravation of hypoxia. During the exceptional winter flood, significant sediment erosion associated with bubbling phenomena (attributed to methane efflux) created severe fractures in the sediment and stimulated water–sediment exchange. During the following months, these fractures were progressively filled, which decreased the intensity of benthic fluxes. However, due to the high residence time in the water during the summer period, a simple model demonstrated that benthic contributions were sufficient to directly (by direct oxygen consumption) or indirectly (by promoting ammonia oxidation) affect the oxygen stock in the water column during the low-discharge period. Our study demonstrates the importance of the benthic compartment in the occurrence of hypoxia and the obvious lack of knowledge to illustrate and model the biogeochemical functioning of the estuary.

How anaerobic sludge microbiome respond to different concentrations of nitrite, nitrate, and ammonium ions: a comparative analysis.

High concentrations of ammonium, nitrite, and nitrate always induce inhibition in anaerobic wastewater treatment. Due to the complexity and vulnerability of the microbial community (especially methanogens) in anaerobic sludge, little is understood about its underlying microbial mechanism under such inhibition. In this study, the shifts of microbial communities in anaerobic sludge under increasing levels of nitrite, nitrate, and ammonium ions were compared. Results show that although half maximal inhibitory concentrations (methanogenesis) were different for nitrite, nitrate, and ammonium ions with EC50 values of 12, 30, and 3000mg N/L, respectively, bacteria genera Kosmotoga and Brooklawnia dominated in all of the three high-stress inhibitory systems. Network analysis and redundancy analysis (RDA) of the microbial community showed the treatments with nitrate and nitrite ions decreased the modularity of anaerobic microorganisms. RDA showed that specific methanogenic activity was positively related to coenzyme F420 under nitrite inhibition (rp = 0.833, p < 0.05) and closely correlated with viability under nitrate inhibition. Gram-positive and nonmotile Brooklawnia genus showed a negative correlation with physiological characteristics in the ammonia treatments, suggesting its high resistance to ammonia.

High cell density culture of Neochloris oleoabundans in novel horizontal thin-layer algal reactor: Effects of localized aeration, nitrate concentration and mixing frequency

A horizontal thin-layer algal reactor was designed, constructed and tested for high cell density culture of an oil-rich green alga, Neochloris oleoabundans, at a thickness of 6 mm. A hollow fiber membrane sparger was used for localized aeration with CO2-enriched air, which allowed control of culture pH at a narrow range of pH 7.0–7.5. The optimal nitrate concentration under the investigated conditions was 345 mg-N/L with a cell density of ∼6.6 × 108 cells/mL and biomass concentration of ∼8 g/L. The volumetric and areal biomass productivities were 1.81 g/L/day and 10.85 g m− 2/day, respectively, and the maximum volumetric and areal productivities 3.57 g/L/day and 21.42 g m− 2/day, respectively. Intermittent mixing at a frequency of once every two hours (five min mixing each time) produced a cell growth profile similar to that of continuous mixing. Such intermittent mixing resulted in 98.38 % saving on mixing energy and 33.9 % reduction in water evaporation. It was observed that metabolic stress such as high pH and high nitrate concentration could inhibit cell division while causing cell size to enlarge abnormally. The results indicate that it is technically feasible to have high cell density culture of photoautotrophic microalgae with intermittent mixing and no culture circulation, opening the door towards the development of open algal farming systems of low capital, operational, and maintenance costs.

Increased Nitrogen Loading Facilitates Nitrous Oxide Production through Fungal and Chemodenitrification in Estuarine and Coastal Sediments.

Estuarine and coastal environments are assumed to contribute to nitrous oxide (N2O) emissions under increasing nitrogen loading. However, isotopic and molecular mechanisms underlying N2O production pathways under elevated nitrogen concentration remain poorly understood. Here we used microbial inhibition, isotope mass balance, and molecular approaches to investigate N2O production mechanisms in estuarine and coastal sediments through a series of anoxic incubations. Site preference of the N2O molecule increased due to increasing nitrate concentration, suggesting the changes in N2O production pathways. Enhanced N2O production under high nitrate concentration was not mediated by bacterial denitrification, but instead was mainly regulated by fungal denitrification. Elevated nitrate concentration increased the contribution of fungal denitrification to N2O production by 11-25%, whereas it decreased bacterial N2O production by 16-33%. Chemodenitrification was also enhanced by high nitrate concentration, contributing to 13-28% of N2O production. Elevated nitrate concentration significantly mediated nirK-type denitrifiers structure and abundance, which are the keystone taxa driving N2O production. Collectively, these results suggest that increasing nitrate concentration can shift N2O production pathways from bacterial to fungal and chemodenitrification, which are mainly responsible for the enhanced N2O production and have widespread implications for N2O projections under ongoing nitrogen pollution in estuarine and coastal ecosystems.

Quality and Health Risk Assessment of Groundwater for Drinking and Irrigation Purpose in Semi-Arid Region of India Using Entropy Water Quality and Statistical Techniques

The continuous intake of contaminated drinking water causes serious issues for human health. In order to estimate the suitability of groundwater for drinking and irrigation, and also conduct human risk assessments of various groups of people, a total of 43 sample locations in the semi-arid southern part of India were selected based on population density, and we collected and analyzed groundwater from the locations for major anions and cations. The present study’s novelty is integrating hydrochemical analysis with the entropy water quality index (EWQI), nitrate pollution index (NPI) and human health risk assessment. The results of the EWQI revealed that 44.19% of the sample locations need to be treated before consumption. About 37.20% of the study region has a high concentration of nitrate in the groundwater. NPI revealed that 41.86% of the samples had moderate or significant pollution levels. The non-carcinogenic risk evaluation showed that 6–12-year-old children are at a higher risk than teenagers, adults and elderly people in the study area. The natural sources of nitrate and other contamination of groundwater are rock–water interaction, weathering of rock, dissolution of carbonate minerals and evaporation processes, and the anthropogenic sources are the decomposition of organic substances in dumping yards, uncovered septic tanks and human and animal waste. The results suggest taking mitigation measures to reduce the contamination and improve the sustainable planning of groundwater management.

Hydrochemical Investigation and Quality of Groundwater in Erbil-Pirmam Area, Kurdistan Region, Iraq

The chemical analysis of groundwater for any region is very important for water resources and estimating the suitability of this important natural resource. Sixty two groundwater samples were collected during two recharge periods in October 2021, which represent the minimum recharge period and May 2022 which represent the maximum recharge period. The physical analysis include electrical conductivity, pH, and temperature while the chemical analysis includes major cations and anions. A piper diagram was used to classify the groundwater water in the area to determine water type which all water samples are categorized as bicarbonate water type for both periods. To establish the appropriateness of groundwater as drinking water in the area, different standards were employed as standard of water use. All water samples in the study area are fresh water and of medium salinity water except one well which is high salinity water. The groundwater quality in the studied area is suitable for drinking because all parameters are under permissible limit except one well which have a high nitrate concentration. According to the Total Dissolved Solids the water is acceptable for irrigation and do not cause harmful effects on crops except two water samples that can be used and adversely affected crops that were susceptible to salt, and suitable according to SAR ratio and low sodium hazard. The aim of this study is to determine water quality and evaluate groundwater for different uses including drinking, agriculture and irrigation purposes.

Sample Stacking-Capillary Electrophoretic Analysis of Nitrate and Nitrite in Organic- and Conventional-Originated Baby Food Formulas from Turkey.

Commercially available baby food formulas represent a convenient alternative to homemade meals especially in the recent years. The main purpose of this study is the determination of nitrate and nitrite levels by a sample stacking-capillary electrophoresis technique in the baby foods. The baby foods analyzed were organic-originated, vegetable-based, fruit-based, mixed puree, and a vegetable soup. Vegetables and fruits have high nitrate and nitrite concentrations. Nitrate itself is not actually hazardous. However, nitrite has negative health effects. Thus, baby foods have to be strictly controlled due to the potential health risk of nitrite. In this study, the sample stacking method enhanced the sensitivities of both anions. Nitrate contents ranged from 16.1 to 285 mg/kg with a mean concentration of 149 mg/kg for all samples. The lowest nitrate amount belonged to red fruity milky baby food whereas the highest nitrate was found in organic pumpkin, banana, and carrot mixed puree. The nitrite levels in all the samples were below the LOQ value of the analyzed method. As a conclusion, there is no health risk of the analyzed baby foods regarding nitrate and nitrite levels considering the regulations.

Impacts of Deficit Irrigation on Photosynthetic Performance, Productivity and Nutritional Quality of Aeroponically Grown Tuscan Kale (Brassica oleracea L.) in a Tropical Greenhouse.

Tuscan kale was grown aeroponically with 5, 30 and 60 min nutrient spraying intervals (defined as 5 minNSIs, 30 minNSIs and 60 minNSIs). Four weeks after transplanting, some 5 minNSI plants were transferred to a 60 minNSI (5 minNSI → 60 minNSI) and 90 minNSI (5 minNSI → 90 minNSI) for one more week. Significantly lower light-saturated rates of photosynthesis and stomatal conductance were observed for plants grown with a 60 minNSI than with a 5 minNSI. However, all plants had similar internal CO2 concentrations and transpiration rates. Reduced light use efficiency but increased energy dissipation was observed in plants grown in a 60 minNSI. A higher nitrate concentration was observed in 60 minNSI plants compared to 5 minNSI and 30 minNSI plants, while all plants had similar concentrations of total reduced nitrogen, leaf soluble protein and Rubisco protein. Plants grown with prolonged NSIs (deficit irrigation) had lower biomass accumulation due to the inhibition of leaf initiation and expansion compared to 5 minNSIs. However, there was no substantial yield penalty in 5 minNSI → 60 minNSI plants. Enhancements in nutritional quality through deficit irrigation at pre-harvest were measured by proline and total soluble sugar. In conclusion, it is better to grow Tuscan kale with a 5 minNSI for four weeks followed by one week with a 60 minNSI before harvest to reduce water usage, yield penalty and enhance nutritional quality.