Phosphorus concentrations into a subtropical lake strongly influence nitrogen accumulation, nitrogen export, and Chl a concentrations

We measured water quality monthly for 22 years in water entering, within, and exiting a 65 km2 shallow polymictic and eutrophic freshwater lake in the northern Gulf of Mexico. Fertilizer use in the watershed is the dominate source of phosphorous (P) going into the lake and controls the lake’s P concentrations, but nitrogen (N) fertilizer use was not related to total nitrogen concentration in the lake. Half of the particulate P entering the lake is trapped within it and there is a net accumulation of N that appears to be from the stimulation of nitrogen fixation. The lake’s concentration of Chlorophyll a (µg Chl a l−1) and increase in N in the lake was directly related to the concentration of P in water entering the lake. Variations in the Chl a concentration within a freshwater lake downstream are also directly related to the annual use of P fertilizer, but not to N fertilizer use. Reducing agriculture-sourced P runoff will lower (but not eliminate) both the frequency of algal blooms within Lac des Allemands and the amount of N delivered to the estuary.

Dataset on the Effects of Anti-Insect Nets of Different Porosity on Mineral and Organic Acids Profile of Cucurbita pepo L. Fruits and Leaves

The growing interest in healthy foods has driven the agricultural sector towards eco-friendly implementation to manage biotic and abiotic factors in protected environments. In this perspective, anti-insect nets are an effective tool for controlling harmful insect populations concomitantly with reducing chemicals’ interference. However, the low porosity of nets necessary to ensure high exclusion efficiency for a designated insect leads to reduced airflow, impacting the productivity and quality attributes of vegetables. The evidence presented in this dataset pertains to the content of total nitrogen, minerals (i.e., NO3, K, PO4, SO4, Ca, Mg, Cl, and Na), and organic acids (i.e., malate and citrate) of zucchini squash (Cucurbita pepo L. cv. Zufolo F1) in leaves and fruits grown with two anti-insect nets with different porosities (Biorete® 50 mesh and Biorete® 50 mesh AirPlus), is and analyzed by the Kjeldahl method and ion chromatography (ICS3000), respectively. Data of total nitrogen concentration, macronutrients, and organic acids provide in-depth information about plants’ physiological response to microclimate changes induced by anti-insect nets.

Case Study Regarding the Variation of the Qualitative Parameters of Wastewater

Romania is making efforts in order to enforce the Directive concerning urban waste water treatment and was left behind by other member states. Starting from the premise that the lack of a proper treatment of wastewater can negatively influence the quality of the emissary in which they are discharged., we proposed that in this paper we analyze the main indicators of wastewater quality, identifying also the causes of water pollution. For this purpose, we followed the variation of five representative indicators of wastewater from Calarasi Wastewater Treatment Plan: chemical oxygen consumption, biochemical oxygen consumption, total nitrogen, total phosphorus, suspended solids. The best results in purification were observed regarding the biochemical oxygen consumption (over 95%). The low temperature of wastewater at the entrance to the Wastewater Treatment Plant during winter leads to a difficult exploitation of the biological step and implicitly to the increase of the phosphorus and total nitrogen concentration in the effluent, which means a weak process of eutrophication in the emissary.

Features of hospital wastewater treatment

При высоких концентрациях азотных соединений и низком содержании органических веществ в сточных водах денитрификация протекает не в полной мере, что приводит к высокому содержанию нитратов в очищенной воде. Описан опыт применения дополнительного субстрата для обеспечения денитрифицируемого азота нитратов требуемым органическим веществом. Выявлено глубокое угнетение биоценоза при высоких концентрациях хлорпроизводных в поступающих на очистку сточных водах. При концентрации общего хлора 5,4–6,8 мг/л процессы биологической очистки практически не протекали, а биопленка на поверхности загрузки не формировалась. Отмечено, что состав сточных вод больничного комплекса отличается низким содержанием органических веществ (БПК5 в среднем 42,3 мг/л, ХПК в среднем 128,9 мг/л) при концентрации общего азота 43,4 мг/л. Экспериментально подтверждена эффективность применения сахарозы в качестве субстрата для денитрификации сточных вод больничного комплекса. Расход сахара составил 0,17 кг/м3 при соотношении БПК5/азот общий 0,95 в поступающих на очистку сточных водах. At high concentrations of nitrogen compounds and low concentrations of organic substances in wastewater, the process of denitrification does not proceed in full, resulting in a high concentration of nitrates in the effluent. The experience of using an extra substrate to supply the denitrified nitrate nitrogen with the required organic matter is described. Deep suppression of biocenosis at high concentrations of chlorine derivatives in raw wastewater was revealed. At a total chlorine concentration of 5.4–6.8 mg/l, neither biological treatment processes proceeded, nor a biofilm formed on the media surface. It is noted that the composition of the hospital wastewater is characterized by a low concentration of organic matter (BOD5 was on average 42.3 mg/l, COD – on average 128.9 mg/l) with a total nitrogen concentration of 43.4 mg/l. The effectiveness of using sucrose as a substrate for the denitrification of hospital wastewater has been experimentally confirmed. The sugar consumption was 0.17 kg/m3 at the ratio of BOD5/total nitrogen of 0.95 in the incoming wastewater.

Characterization of Anaerobic Effluent: Seasonal Influence and use of Anammox Process as Post-Treatment

This study aimed to verify if subtropical annual seasonality variation of organic matter and nitrogen ratio facilitates the use of anammox process as a post – treatment of anaerobic effluent. We characterized the anaerobic effluent from a wastewater treatment plant (WWTP) located in Campinas/SP, Brazil. The collected composed samples were from an UASB reactor in different days, hours and months during one year. We concluded subtropical annual seasonality of COD/N ratio range (2.2 to 3.1) from anaerobic effluent indicates that the use of anammox process is appropriate as post-treatment of anaerobic effluent in subtropical areas. However, as Total COD degrades over time and as total nitrogen concentration is influenced by seasons, these factors need to be taken into account in the project and operation of the reactor over the year.

Measurement of Total Nitrogen Concentration in Surface Water Using Hyperspectral Band Observation Method

Nitrogen overload is one of the main reasons for the deterioration of surface water quality. Hence, monitoring nitrogen loadings is vital in maintaining good surface water quality. Increasingly, the use of spectral reflectance to monitor nitrogen concentration in water has shown potentials, but it poses some problems. Therefore, it is necessary to explore new methods of quantitative monitoring of nitrogen concentration in surface water. In this paper, hyperspectral data from surface water in the Ebinur Lake watershed are used to select sensitive bands using spectral transformation, the spectral index, and a coupling of these two methods. The particle swarm optimization support vector machine (PSO-SVM) model, constructed on the basis of sensitive bands, is used quantitatively to estimate the total nitrogen concentration in surface water and subsequently to verify its accuracy. The results show that the bands near 680, 850, and 940 nm can be used as sensitive bands for estimation of the total nitrogen concentration of surface water in arid regions. Compared with the best estimation models constructed by sensitive bands selected using the spectral transformation or the spectral index alone, the best model based on the coupling of these two measures is more accurate (R2 = 0.604, Root Mean Square Error (RMSE) = 1.61 mg/L, Residual Prediction Deviation (RPD) = 2.002). This coupling method leads to a robust, accurate, and strong predictability model, and can contribute to improved quantitative estimation of water quality indexes of rivers in arid regions.