Concentration Of Nitrite In Water Research Articles

The impact of environmental factors and contaminants on thyroid function and disease from fetal to adult life: current evidence and future directions.

The thyroid gland regulates most of the physiological processes. Environmental factors, including climate change, pollution, nutritional changes, and exposure to chemicals, have been recognized to impact thyroid function and health. Thyroid disorders and cancer have increased in the last decade, the latter increasing by 1.1% annually, suggesting that environmental contaminants must play a role. This narrative review explores current knowledge on the relationships among environmental factors and thyroid gland anatomy and function, reporting recent data, mechanisms, and gaps through which environmental factors act. Global warming changes thyroid function, and living in both iodine-poor areas and volcanic regions can represent a threat to thyroid function and can favor cancers because of low iodine intake and exposure to heavy metals and radon. Areas with high nitrate and nitrite concentrations in water and soil also negatively affect thyroid function. Air pollution, particularly particulate matter in outdoor air, can worsen thyroid function and can be carcinogenic. Environmental exposure to endocrine-disrupting chemicals can alter thyroid function in many ways, as some chemicals can mimic and/or disrupt thyroid hormone synthesis, release, and action on target tissues, such as bisphenols, phthalates, perchlorate, and per- and poly-fluoroalkyl substances. When discussing diet and nutrition, there is recent evidence of microbiome-associated changes, and an elevated consumption of animal fat would be associated with an increased production of thyroid autoantibodies. There is some evidence of negative effects of microplastics. Finally, infectious diseases can significantly affect thyroid function; recently, lessons have been learned from the SARS-CoV-2 pandemic. Understanding how environmental factors and contaminants influence thyroid function is crucial for developing preventive strategies and policies to guarantee appropriate development and healthy metabolism in the new generations and for preventing thyroid disease and cancer in adults and the elderly. However, there are many gaps in understanding that warrant further research.

An optimized back propagation neural network on small samples spectral data to predict nitrite in water

Accurate detection of pollutant levels in water bodies using fusion algorithms combined with spectral data has become a critical issue for water conservation. However, the number of samples is too small and the model is unstable, which often leads to poor prediction and fails to achieve the measurement goal well. To address these challenges, this paper proposes a practical and effective method to precisely predict the concentrations of nitrite pollution in aquatic environments. The proposed method consists of three steps. Firstly, the dimension of the spectral data is reduced using Kernel Principal Component Analysis (KPCA), followed by sample augmentation using Generative Adversarial Network (GAN) to reduce calculation cost and increase the diversity and scale of the data. Secondly, several improvement strategies, including multi-cluster competitive and adaptive parameter updating, are introduced to enhance the capability of the Particle Swarm Optimization (PSO) algorithm. The improved PSO algorithm is then applied to optimize the initialization weights and biases of the Back Propagation neural network, thereby improving the model fitting and training performance. Finally, the developed prediction model is employed to predict the test set samples. The result suggests that the R2, RMSE, and MAE values are 0.976290, 0.008626, and 0.006617, which outperform the state-of-the-art and provided a promising model for the prediction of nitrite concentration in water.

The eco enzyme application to reduce nitrite in wastewater as the sustainability alternative solution in garbage and wastewater problems

The increasing population growth has an impact on increasing problems in wastewater quality and garbage volume. It is a need to develop a sustainability solution for both problems. In this research, the papaya fruit and spinach vegetable garbage were used as raw organic materials and fermented for six months. This study objective was to determine whether eco enzymes can be used to reduce nitrite concentration in wastewater. The research method was conducted on a laboratory scale with the artificial samples in a batch system. The result showed that eco enzyme made from a mixture of papaya and spinach can reduce the nitrite concentration in the water sample. The t-test showed that the effect of eco enzyme application in reducing nitrite in water samples was significant. The application of eco enzyme 0%, 2%, 4%, and 6% respectively during 10 hours exposure showed the nitrite removal were 0.3 %, 20%, 29%, and 35 %. It can be seen that the reduction of nitrite concentration in samples added by eco enzyme was caused by eco enzyme activity. The application at a higher concentration of 10%, 15%, and 20% showed that nitrite removal efficiencies were 35.7%, 36.7%, 46.7%, 49.4% respectively during 7 hours exposure. It can be concluded that a longer time exposure, and also the more eco enzyme concentration, showed the more result in the effect of nitrite reduction concentration in water. 4. By this study it is proven that application of eco enzyme made from organic garbage can be an alternative solution for garbage and wastewater quality problem.

Development of Microfluidics-based Platform for Detection of Nitrite in Water using Optical Readout Method

The consumption of contaminated water in our daily life can cause adverse effects. Organic or inorganic pollutants may be toxic, and their ignorant use might lead to numerous health hazards. The significant presence of nitrites in water has proven to have a deadly effect on human life. There is an emergent need to develop a platform for the detection of nitrite in water. In this paper, we have adopted the optical detection readout method for this purpose. By testing and analyzing three different experimental arrangements, we have proposed and identified the most preferable one for the effective implementation of water quality monitoring. Colorimetric analysis using the Griess reagent has been opted for in this work. With the use of a Light-Emitting Diode (LED) as a light source and three types of photodetectors, nitrite is detected in water samples thereby computing its absorbance with correspondence to the color change observed. The comparative study concludes that the LED-phototransistor pair has the best linearity and sensitivity among the three. With context to the results, a platform has been developed to measure the concentration of nitrite in water using phototransistors. This platform encourages the use of a microfluidics-based approach as it grants us benefits of minimal reagent consumption, size reduction, and precise control of the flow of liquids. The microfluidic chip is fabricated by incorporating soft lithography using Polydimethylsiloxane (PDMS) polymer. A Raspberry Pi board along with an Arduino board is interfaced with the microchannel to aid automation. By changing the parameter set for detection along with the necessary changes, fluid analysis of any parameter can be carried out with this platform.

Effects of chronic sub‐lethal nitrite exposure at high water chloride concentration on Atlantic salmon ( Salmo salar, Linnaeus 1758) parr

The present study examined the protective effects of water chloride (Cl−) towards nitrite toxicity in Atlantic salmon parr during 84-day long nitrite exposure. Effects on growth, histology, blood indices and gene expression were studied at a fixed nominal Cl− concentration of 200 mg/L and at several water nitrite concentrations (0, 0.5, 2, 5 and 10 mg/L NO2−–N). The specific growth rate was significantly reduced during the first three weeks at a Cl:NO2−–N ratio of 21:1, suggesting the activation of coping mechanisms at the later stages of the experiment. No significant effect of nitrite on gill histology and mortality was found. Nitrite accumulated in plasma; however, a Cl:NO2−–N ratio of 104:1 or higher prevented nitrite entry. The concentration of NO2−–N in plasma was significantly reduced at the end of the study, supporting the hypothesis of coping mechanisms. Cystic fibrosis transmembrane conductance regulator (cftr)-1 showed a significant up-regulation at highest nitrite concentration on day 22, and in three of the highest exposure groups at the end of the experiment. Our findings suggest that a Cl:NO2−–N ratio above 104:1 should be maintained through episodes of nitrite accumulation in water during the production of Atlantic salmon parr.

<b>Partial replacement of artificial diets by wet bioflocs biomass in Nile tilapia culture tanks

The present work aimed to assess the partial replacement of artificial diets by wet bioflocs biomass in the culture of Nile tilapia juveniles. Fish were fed on different combinations of commercial dry diets (CD) and wet bioflocs biomass (BF), as it follows: 75% CD + 25% BF, 50% CD + 50% BF, and 25% CD + 75% BF, dry matter basis. There were also positive control tanks in which the fish received only commercial diet (100% CD), and three negative control tanks where the reductions of dry diets were not compensated by wet bioflocs biomass (75% CD, 50% CD, and 25% CD). Bioflocs were produced in one 500-L outdoor tank, which did not belong to the culture system, and it was called “separate BFT tank”, in which there was a daily adjustment of the C: N ratio of water to 15: 1, by the application of dry molasses to the water. There were no significant differences between the treatments for water pH, O2, TAN and NH3. Except by 25% CD, nitrite concentrations in water were lower in bioflocs tanks than in the artificial diet tanks. The final body weight of fish was significantly higher in tanks that received only dry diets (21.9 ± 6.4 g) than in tanks with a combination of 50% dry diet and 50% wet bioflocs biomass (10.4 ± 2.5 g; p < 0.05). It can be concluded that the impairment on the growth performance of tilapia submitted to feeding restriction is lessened if wet bioflocs biomass is provided to the animals. Besides, the total substitution of artificial diets for wet bioflocs biomass in clear-water tanks is unfeasible because it leads to higher rates of mortality of tilapia in a relatively short period.

A Highly Sensitive Nonenzymatic Sensor Based on Fe2O3 Nanoparticle Coated ZnO Nanorods for Electrochemical Detection of Nitrite

AbstractMonitoring of nitrite is needed for the management of nitrite contamination and to ensure the welfare of environment and human health. Hence, it is important to develop high‐performance sensors that precisely measure nitrite concentration. Herein, the fabrication of a highly sensitive nonenzymatic nitrite sensor based on Fe2O3 nanoparticle coated ZnO nanorods (Fe2O3 NP coated ZnO NRs) is demonstrated. The ZnO NRs are grown on a seeded silver electrode by a hydrothermal method and then coated under optimized conditions with Fe2O3 NPs using a dip‐coating method. Detailed material characterizations and sensor fabrication process are reported. The electrochemical properties of a fabricated nonenzymatic nitrite sensor are tested with different concentrations of nitrite, which indicates that the coating of ZnO NRs with Fe2O3 NPs significantly enhances the electrocatalytic activity. The sensor responds linearly with increasing concentration of nitrite from 1 to 1250 × 10−6m with a high sensitivity (131.2 µA µM−1 cm−2) and low detection limit (0.015 × 10−6m). Moreover, excellent selectivity, stability, and reproducibility allow using these sensors for the determination of nitrite concentration in water with satisfactory results.

<b>Feeding Nile tilapia with artificial diets and dried bioflocs biomass

The effects of supplying dried bioflocs biomass to Nile tilapia juveniles were investigated in the present work. Fish were stocked in experimental rearing tanks for eight weeks. Selected variables of water quality, growth performance and effluent quality were evaluated. Fish were given different combinations of artificial diets and biofloc biomass, in wet (in natura) or dry form. As the supply of artificial diet decreased, the allowance of biofloc biomass increased in the same proportion. Biofloc biomass was produced in two 500-L tanks that received daily applications of dry molasses to adjust the C: N ratio of the water to 15: 1. The concentration of nitrite in water was only reduced in the tanks receiving wet bioflocs. The fish growth performance was poorer in the tanks that received dried biofloc biomass than in the tanks with wet biofloc biomass. Given the lack of positive results, there is no justification to dry the biofloc biomass aiming at delivering it as a dry biomass to reared fish.

Growth Performance, Body Lipid, Brood Amount, and Rearing Environment Response to Supplemental Neutral Phytase in Zebrafish (Danio Rerio) Diet

The present study was to evaluate the effects of neutral phytase supplementation on growth performance, survival ratio (SR), body lipid, brood amount, and rearing environment in zebrafish. The control diet was not supplemented phytase, and three levels of phytase (500, 1000, or 1500 U kg(-1)) was added to the three other diets (named as PP500, PP1000, and PP1500). Triplicate groups (twelve 100-L tanks) of zebrafish (initial mean weight, 0.284±0.012 g) were fed twice daily (08:00 and 16:00 h) to satiation for 12 weeks. The results showed that supplemental phytase in the diet improved weight gain (60.49%, 86.63%, 99.06%, and 111.88% in control, PP500, PP1000, and PP1500) and the specific growth ratio of zebrafish (p<0.05). Dietary phytase addition increased the whole body lipid content of zebrafish. The brood amounts (116, 123, and 124 eggs in PP500, PP1000, and PP1500) of fish fed with phytase-supplemented diets were little higher than the control (mean egg was 112). The ammonia-nitrogen concentration in water of fish fed with phytase-supplemented diet was significantly lower than the control. The nitrite concentration in water was also decreased in water of fish fed with phytase-supplemented diet. The SR was increased with the increasing of dietary phytase despite no significant difference was observed among each group. The present study first suggested that neutral phytase could be applied in the zebrafish diet. Furthermore, phytase addition increased the growth, body lipid, brood amount, and SR of zebrafish, and meanwhile decreased the ammonia-nitrogen and nitrite concentrations in rearing water.

New detector tube for the detection of nitrite in water

Abstract A new colorimetric detector tube for the detection of trace concentrations of nitrite in water was developed. The detector tube is based on a diazo coupling reaction of nitrite with dapsone and N-(1-naphthyl) ethylenediamine dihydrochloride during the formation of red-violet azo dye. Spherical granules (pellets) made from the composite material were used as the carrier of chemical reagents. They were prepared by pelletizing the mixture of microcrystalline cellulose, lactose, kaolin and polyvinylpyrrolidone. Colouring is done on a layer of silica gel impregnated with citric acid. The detector tube is highly sensitive, selective and stable when stored. The detection limit is 0.1 μg.ml-1, i.e. 0.03 μg.ml-1 N(NO2 -). The optimal measuring range of nitrite concentration in the analyzed sample ranges from 0.5 to 80 μg.ml-1, i.e. 0.15-24.36 μg.ml-1 N(NO2 -). The detector tube can easily be structurally modified for analysis of nitrates with a detection limit of 1 μg/ml-1, i.e. 0.23 μg.ml-1 N(NO3 -).

Flow-injection spectrophotometry of nitrites based on the diazotization reactions of azine dyes

The diazotization reactions of azine dyes (safranin, Neutral Red, ethacridine, and trypaflavine) were studied under flow conditions. These reactions are accompanied by the formation of intensely colored diazo compounds with a high contrast (more than 100 nm). The formation, stability, and optical properties of these compounds in solutions were supported by quantum-chemical calculations. The kinetic stability of diazo compounds was found to be sufficient for the flow-injection detection of an output peak. Trypaflavine was found to be the best and most sensitive reagent; in this case, the diazotization reaction in 0.2 MHCl occurred especially rapidly and almost completely with a degree of conversion of 0.98. A procedure for the determination of nitrite ions based on the reaction with trypaflavine was developed. The combination of on-line preconcentration on an EDE-10P anion-exchange resin and the reaction at the instant of elution in a flow system allowed us to determine selectively low nitrite concentrations in water with the limit of detection equal to 2 ng/mL, as calculated according to Kaiser (3s) or IUPAC. The procedure developed was used for the monitoring of nitrite concentrations in various water samples; the throughput was 100 samples per hour.

Nitrite toxicity to crayfish, Astacus leptodactylus, the effects of sublethal nitrite exposure on hemolymph nitrite, total hemocyte counts, and hemolymph glucose

The 48-h acute toxicity range of nitrite to narrow-clawed crayfish, Astacus leptodactylus was within 22 and 70mgL−1 (mean 29.43mgL−1). Environmental chloride (100mgL−1 chloride) increased the 48-h toxicity of nitrite to a range of 31 and 80mgL−1 (mean 49.20mgL−1). Hemolymph nitrite, total hemocyte counts (THCs), and hemolymph glucose were examined in A. leptodactylus exposed to different sublethal nitrite concentrations. The same parameters were also determined for A. leptodactylus exposed to different sublethal nitrite concentrations with additional environmental chloride. Additionally, hemolymph nitrite and THCs were analyzed for crayfish exposed to nitrite-free water after 24h following a 48-h exposure to nitrite. In the nitrite-exposed tests, hemolymph nitrite increased directly with water nitrite; however, after recovery, nitrite in hemolymph decreased. In the nitrite plus chloride-exposed tests, the accumulation of nitrite in hemolymph was relatively low compared to the nitrite-exposed tests. Thus, hemolymph to environment ratios of nitrite in the nitrite-exposed tests were higher than those of nitrite plus chloride-exposed tests. THCs decreased following nitrite exposure and, in general, increased after recovery. In the nitrite with chloride exposed and recovery from nitrite tests, THCs increased. Hemolymph glucose levels elevated following nitrite exposure, independent of water nitrite concentrations. However, with environmental chloride nitrite exposure did not cause elevation of hemolymph glucose. Hemolymph nitrite accumulation was found to be closely related to the decrease in THCs and increase in hemolymph glucose.

Flow-injection chemiluminescence determination of ultra low concentrations of nitrite in water

A new flow chemiluminescence method for the determination of ultra low concentrations of nitrite in water is presented. Nitrite reacts with H2O2 in acid medium to form peroxynitrous acid that is subsequently detected as peroxynitrite by the chemiluminescence reaction with alkaline solution of luminol. The detection limit of nitrite is 1 × 10−9 mol 1−1 (for 50 μl samples) and the calibration graph is linear up to 1 × 10−5 M NO−2 The relative standard deviations for 1 × 10−6 M and 3 × 10−8 M NO-2 are 1.8% and 5.4%, respectively. The interferences of cations are eliminated by passing the sample through a cation-exchange column. Common anions do not interfere. Analysis time is 3 minutes. The results are in good agreement with a standard spectrophotometric method.

Some initial aquaculture experiments in recirculating water systems

First experiences in the management of different recirculating water systems are described after discussion of design and specification of purification plants for intensive fish farming. The problem of nitrate and nitrite concentrations in water is also analyzed. Further investigations directed at the improvement of environmental factors and economic organization of fish recirculating systems are required.