Conductivity Research Articles

Data-driven water quality prediction for wastewater treatment plants

Monitoring and managing wastewater treatment plants (WWTPs) is crucial for environmental protection. The presection of the quality of treated water is essential for energy efficient operation. The current research presents a comprehensive comparison of machine learning models for water quality parameter prediction in WWTPs. Four machine learning models presented in MLP, GFFR, MLP-PCA, and RBF were employed in this study. The primary notion of this study is to apply the proposed models using two distinct modeling scenarios. The first scenario represents a straightforward approach by utilizing the inputs and outputs of WWTPs; meanwhile, the second scenario involves using multi-step modeling techniques, which incorporate intermediate outputs induced by primary and secondary settlers. The study also investigates the potential of the adopted models to handle high dimensional data as a result of the multi-step modeling since more data points and outputs are progressively integrated at each step. The results show that the GFFR model outperforms the other models across both scenarios, specifically in the second scenario in predicting conductivity (COND) by providing higher correlation accuracy (R = 0.893) and lower prediction deviations (NRMSE = 0.091 and NMAE = 0.071). However, all models across both scenarios struggle to predict the other water quality parameters, generating significantly lower prediction correlations and higher prediction deviations. Nonetheless, the innovative multi-step technique in scenario two has significantly boosted the prediction capacity of all models, with improvement ranging from 0.2 % to 157 % and an average of 60 %. The implementation of AI models has proven its ability to accomplish high accuracy for WQ parameter prediction, highlighting the impact of leveraging intermediate process data.

Remote Sensing Analysis for Vegetation Assessment of a Large-Scale Constructed Wetland Treating Produced Water Polluted with Oil Hydrocarbons

The identification and assessment of plant stress using wetland satellite images is a major task in remote sensing. In this study, one of the largest constructed wetlands (CWs) in the world, located in the Sultanate of Oman, was examined, assessed, and evaluated using remote sensor data from Sentinel-2. This CW system treats produced water generated during oil exploration activities in a desert environment; thus, CW vegetation is subjected to stress induced by oil hydrocarbons and water salinity. This study examined the plant stress and detected changes between the years of 2017 and 2019. Sentinel satellite images were evaluated for vegetation status extraction. The Normalized Difference Vegetation Index (NDVI), Modified Soil-Adjusted Vegetation Index (MSAVI), and Normalized Difference Salinity Index (NDSI) were used to evaluate the vegetation change. The results showed a comprehensive mapping identification of the plant stress and water flow parameter factors including oil in water contamination (OIW), dissolved oxygen (DO), water temperature (WT), and water conductivity (COND). Among the three indices, it was found that the NDVI showed a very good correlation with all parameters in both years with average R2 = 0.78, 0.67, 0.75, and 0.60 for OIW, DO, WT, and COND, respectively. The same trend was found for MSAVI but with R2 = 0.59, 0.48, 0.55, and 0.56 for OIW, DO, WT, and COND, respectively. This shows that the NDVI performed better than the MSAVI in evaluating the water flow parameters. On the other hand, the NDSI showed a strong correlation with one flow parameter, that is, water conductivity, especially at the outlet cells of the CW with R2 = 0.86 and 0.82 for winter time and summer time, respectively. The synchronization and correlation between the water flow parameters and remote sensing vegetation indices in this study lead to a new approach to large-scale landscape wetland monitoring that improves and helps predict any degradation or stress on vegetation growth. Furthermore, the results of this work can help decision makers potentially modify the wetland design and water flow path to improve future expansion phases. The mapping of such a critical and massive industrial CW should consider the use of high spatial resolution sensors where identifications and classifications are further improved. In summary, this research demonstrates that it is feasible to estimate vegetation stress within the constructed wetland using remote sensing techniques across extensive regions when an ample dataset comprising field data, satellite imagery, and supporting information is accessible.

Field distribution characteristics and influencing factors of crayfish in rice-crayfish integrative system

Transformation of food systems will be required to feed the burgeoning global population in the coming decades. Co-culture systems enable production of multiple types of food within the same land area. One such co-culture production system - rice-crayfish integrative system (RCIS) - has seen recent emergence and rapid growth in Asian countries. As yet, however, there remains a paucity of information on how crayfish distribute across paddy fields, even though such information is key in management of crayfish feeding, rice planting and environmental protection. Here, we conducted a 2-year field experiment to gain insight into the spatial distribution of crayfish using cage trapping and LED tracking. We had four key observations: (1) spatial distributions of crayfish across fields were heterogenous, (2) the individual weight of crayfish per ground cage was normally distributed and there was a linear relationship between the number and weight of crayfish captured in different ground cages, (3) distribution characteristics of crayfish altered diurnally, with night capture of the mid columns being higher than that of the side columns, and with day capture being less than that measured at night (rows 1, 2, 14 and 15 near the short inner ridge was always higher than that of other rows) and (4) cumulative capture in each ground cage was linear with water depth (P<0.001) but there was no significant correlation with other environmental indicators, including temperature, pH, dissolved oxygen (DO), salt, total dissolved solids (TDS), conductivity (CON), turbidity and fresh weight of aquatic plants. We conclude that spatial distributions of crayfish in RCIS were closely related to water depth and field topography, with the highest densities realized in gullies within 6–7 m of the short ridge of rectangular farmland. Co-culture farmers can adjust their feeding and capturing strategies based on the distribution characteristics reported here, thereby reducing feeding costs, improving labor efficiency and mitigating detrimental environmental impacts.

EFFECT OF ABATTOIR EFFLUENT ON SOME HEAVY METALS AND PHYSICO-CHEMICAL PARAMETERS OF TA’JAN WATER IN OGBAGI AKOKO, ONDO STATE

The study examined the effect of abattoir effluent on some physico-chemical parameters and heavy metal content of Ta’jan River in Ogbagi Akoko, Ondo State. Water samples were taken once in October and November at seven different locations along the receiving water body at sampling points:S1, S0, S2, S3, S4, S5 and S6; S1 (10meters upstream of the point at which effluents enter the stream),S0 (point at which effluents enter the stream) S2 (10 meters downstream of the point of effluent discharge), S3 (20meters downstream of the point of effluent discharge), S3 (30meters downstream of the point of effluent discharge), S4 (40meters downstream of the point of effluent discharge), S5 (50meters downstream of the point of effluent discharge) and S6 (60meters downstream of the point of effluent discharge) along Ta’jan stream. The time of taking the samples were in the morning during slaughter hours.The samples were collected, preserved, and analysed in the laboratory using standard methods. Wastewater parameters analysed were dissolved oxygen, Temperature (TEMPT), conductivity (COND), salinity, turbidity, nitrate, sulphate, phosphate, pH, total suspended solid (TSS), total dissolved solid (TDS), and heavy metals, such as iron, lead, copper, and zinc. The downstream levels of most of the parameters were significantly (p&lt;0.05) better than the discharge point. This suggests river Ta’jan has good recovery capacity.The findings can be useful in identifying the water quality problems and how to improve the water body when been diverted into fishponds or used for all other industrial or agricultural purposes in the community.

The properties of electric double layer at activated carbon surface and their effect on gold and silver adsorption from cyanide solutions

This paper looks at the properties of electric double layer (EDL) found at the surface of activated carbons. The study relied on the electrical conductivity method, which is based on simultaneous use of polarization dependences at direct current and conductometric measurements at alternating current. It was found that the adsorption of gold and silver intensifies in the anode region of carbon surface polarization. Two regions with peak adsorption were identified in the following ranges of potentials: +0.2&divide;+0.25 and +0.6&divide;+0.8 V. EDL diffusion helps improve the environment for the adsorption of cyanide complexes of gold and silver by active centres of the adsorbent surface. The authors believe that an increased mass transfer in the first range of potentials can be attributed to a decreased diffusion resistance caused by changed zero charge polarity, while in the second range of potentials it can be attributed to the cyan-ion oxidation reaction and an easier access of the negatively charged cyanide complexes of gold and silver to the positively charged surface of the carbon adsorbent. The polarization dependences by direct current in the anode region tend to monotonously rise, which is indicative of a lower EDL density, an increased conductivity at the adsorbent surface/solution boundary and improved adsorption conditions. Graphs showing a relationship between alternating current and carbon adsorbent potential helped determine maximum conducti vity values, which almost match the peak values of gold and silver adsorption. The authors established that the adsorbent&rsquo;s potential has a significant effect on the activated carbon adsorption of cyanide complexes of gold and silver. The use of the electrical conductivity method for examining the EDL helps explain certain features typical of the activated carbon adsorption of gold and silver from cyanide solutions.

Early monitoring of gas kick in deepwater drilling based on ensemble learning method: A case study at South China Sea

Gas kick monitoring is of great significance for prevention of blow-out accidents, especially in deep drilling and deep-water drilling. In this study, a machine learning (ML) model for early-monitoring of gas kick is developed using the ensemble learning algorithms based on 7363 lines of drilling logging data at South China Sea. The selected input parameters based on mechanism analysis of gas kick are six fast engineering parameters, including hook load (WHO), weight on bit (WOB), torque (TOR), flow rate (FLW), rate of penetration (ROP) and stand-pipe pressure (SPP), and two slow mud property parameters, i.e. electrical conductivity (CON) and mud outlet density (DEN). The model is constructed using RUSboosted, Subspace-KNN and Bagged Trees algorithms, and is compared with the neural network algorithm. We propose a comprehensive error to quantitatively evaluate the performance of the gas kick monitoring models. The models for early-monitoring of gas kick are applied for a single well and multiple wells, respectively. The results indicate that: (i) The optimal combination of input parameters is made up of six fast engineering parameters and two slow mud parameters. When there is a higher requirement on timeliness, only use of the six fast engineering parameters is also acceptable. (ii) The ensemble learning models work well when the input data expand from single well to multiple wells in the same block. For most cases, the prediction error of the optimal model is below 10%. The RUSboosted algorithm performed best in most data sets. (iii) Gas kick identification from lots of drilling logging records is mathematically a small-sample problem. The output labelling of a potential gas kick should be based on the field practical requirement. The recommended positive length of continuous-point labelling method is 5 m for the studied area, which can effectively reduce the average error from 8.02% to 5.48%.

Applying Factor Analysis and the CCME Water Quality Index for Assessing Groundwater Quality of an Aegean Island (Rhodes, Greece)

Globally, water quality indices (WQIs) are beneficial for evaluating groundwater and surface water quality. The Canadian Council of Ministers of Environment Water Quality Index (CCME WQI) was combined with the parametric values given by Directive 98/83/EC to investigate the possible suitability of groundwater resources for human consumption on Rhodes Island. Chloride (Cl−), pH, calcium (Ca2+), electrical conductivity (CND), carbonate (CO32−), bicarbonate (HCO3−), potassium (K+), magnesium (Mg2+), sulfate (SO42−), sodium (Na+),nitrate (NO3−), nitrite (NO2−), ammonium (NH4+), and phosphate (PO43−) were included in the dataset applied in this study. Statistical analysis, GIS database, and WQI estimation were successfully used to evaluate the groundwater resources of the study area. All studied groundwater parameters have mean and median values lower than the corresponding parametric values established by Directive 98/83/EC. The high CND values (up to 2730 μs cm−1) in groundwater collected from Rhodes’ coastal aquifers indicate a direct relationship with seawater intrusion. CCME-WQI classifies the groundwater samples for most monitoring stations on Rhodes aquifers as “excellent”, Class 5, for 2019 and 2020. The findings of this study may be helpful for scientists and stakeholders monitoring the study area and applying measures to protect the groundwater resources.

231 Electrical Conductivity, Color, and Tenderness Values of Fresh and/or Cooked Beef

Abstract A study with fresh and cooked beef loins, beef jerky, and water types was conducted to evaluate electrical conductivity (EC) measurements as a procedure in quality appraisal. Six full strip loins x 6 steaks per loin x 2 types provided 72 electrical conductivity (CV) observations, and 72 measurements of color variables (chroma, hue, L*, a* b*) of loins. Six core samples per cooked steaks provided 216 Warner-Bratzler shear force (WBSF) values. EC was also measured on three water types and saline (n=20), and commercial beef jerky samples (n=72). Procedures used for EC were developed in our lab and consisted of using emulsified samples enclosed in a silicon vessel with copper electrodes connected to a digital multimeter. Microsiemens (µS) were measured over 60 s with a sampling rate of two per s. Color variables were measured using a Varian Cary 50 Series Spectrophotometer. Data were analyzed using ANOVA and Pearson correlation coefficients. EC means (µS) were 14.4, 42.5, 34.9, 22.9, 16.1 and 24.7 for fresh steaks (P= .07); and 7.8, 16.5, 6.4, 10.7, 5.2, and 8.0 for cooked steaks (P=.36). Means for all color variables were different (P&amp;lt; 0.05) across fresh steaks. Correlation of EC to each color variable was negative: chroma -0.013, hue -0.050, L*-0.009, a*-0.131, b*-0.110. Only a* was significantly correlated (P&amp;lt; 0.05) to EC. WBSF tenderness (kg/f) means were not different (P &amp;gt; 0.05) across steaks but did differ (P&amp;lt; 0.05) within steaks. Correlations of EC to tenderness was not significant (P &amp;gt; 0.05). EC mean of beef jerky was 106.9 (SEM 5.05). EC of water types differed (P&amp;lt; 0.05) - deionized 0.40, purified 1.56, tap 1.30. EC for saline was 0.04. These data indicate that EC of beef can be effectively measured, but high variations across EC, color, and tenderness values decreased the overall probability of finding relationships.

Impact of abiotic factors and road networks on the freshwater turtle Emys orbicularis (Linnaeus, 1758) (Reptilia: Emydidae) in northern Iran.

Emys orbicularis is one of the freshwater turtles occurring in Europe, Middle East and Western Asia, but also occur in Caucasus region as Georgia, Armenia, Azerbaijan and Southern Caspian Sea region (northern Iran provinces as Guilan, Mazandaran, Golestan). In this study, seventeen localities in three Iranian provinces were investigated to study the response of this species to abiotic factors (water quality parameters) and road mortality. To test for differences in occurrence of E. orbicularis between sites that could be explained by variation in abiotic factors, one-way ANOVA test and Tukey's HSD post hoc tests were conducted. These showed significant differences in conductivity (CON) and Total Dissolved Solids (TDS) between locations in the three provinces of Golestan, Mazandaran and Gilan [CON: (F (2, 13) = 9.824, p = 0.003); TDS: (F (2, 13) = 13.957, p = 0.001)]. Differences in four other abiotic variables-water temperature, pH, salinity and dissolved oxygen (DO)-were not significant between provinces, although there were differences. These findings suggested that the species can occur in ponds with the following features: temperature 21-28°C; pH 7-8; salinity > 750mg/L; DO > 30%. Road mortality might be another factor that could contribute to the decline of this turtle's population in northern Iran, noting that the roads were created by human within the species' habitat and increased the mortality rate. Roads should be monitored in order to evaluate their effect on freshwater turtle mortality. Overall, our results demonstrated the advantage of using analysis of abiotic variables as a valid approach for defining species-responses to abiotic factors in E. orbicularis and recommended monitoring roads to find high-risk mortality of this species and create under road tunnels for moving turtles without any risk to reduce high rate of mortality.

Multivariate relations of river habitat to water–sediment indexes in the Yangtze Estuary

River habitat varies with water–sediment. The relations of river habitat to water–sediment are significant in river ecosystems and water environment management but rarely studied. An index system regarding to river habitat and water–sediment was proposed, in which 14 parameters were monthly monitored at Xuliujing hydrological station of the Yangtze Estuary during 2015 to 2018. The relations of river habitat indexes to water temperature (T), discharge (Q) and suspended sediment concentration (SS) were investigated by using principal component analysis/factor analysis (PCA/FA), discriminant analysis (DA), artificial neural networks (ANNs) and multivariate regression (MR). The correlation coefficient matrix for 14 parameters indicated which indexes were well related to a specific index. Five principal components from PCA contributed to 70.2% of the total variance of all variables so that data dimension reduction was realized. Then five independent factors were obtained through FA, in which river habitat and water–sediment indexes were interrelated. The seasonal relations of river habitat to water–sediment were further developed after DA. Dissolved oxygen (DO), chloride (Cl), conductivity (COND), total nitrogen (TN), total phosphorus (TP), SS, T and Q were the most significant parameters for discriminating differences between the wet season and dry season, which could be applied to explain most of the expected temporal variations in river habitat and water–sediment. SS, T and Q was selected as input variables in the ANNs and MR models for predicting river habitat indexes. The predicted values of river habitat indexes DO, TN, TP, COND and Cl agreed well with the measured based on ANNs and MR models, which have high correlation coefficients ranged from 0.64 to 0.96. The results indicated that river habitat management policies should also consider the hydrological processes.

Facile and green synthesis cobalt embedded in N-doped porous carbon under zeo-waste conditions as an efficient oxygen evolution reduction catalyst

A facile and green method is developed to synthesize cobalt species embedded in a nitrogen-doped carbon matrix (P–Co@NCs). The materials are synthesized using hard template precursors via single-step in-situ thermal treatment under free solvent conditions. The optimal P–Co@NC composite prepared through rational synthesis and synergic composition shows an efficient electrocatalytic performance for oxygen evolution reduction (OER). The P–Co@NC exhibits the OER overpotential of 350 mv at 10 mA cm −2 and low Tafel 73 mv·dec −1 in 0.1 M KOH electrolyte. The advantage of catalyst is the dispersion of Co species, which are in close interaction with nitrogen-doped carbon matrix. The Co-Nx plays a dominating role among Co species in P–Co@NC and is well protected by the nitrogen-doped carbon matrix layer. That resulted in efficient electron transport on CNTs (high conductivity) that improves the OER performance of P–Co@NC compared to the reference catalysts (IrO 2 and B–Co@NC). The P–Co@NC also showed excellent cycling performance from long-term chronoamperometry testing. Interestingly, the P–Co@NC catalyst could be synthesized straightforward via a short solvent-free single-step process that introduced it as a green and environmental friendly method, which can be potential to develop catalyst based on metal embedded N-doped carbon. • The single-step, rapid and effective “green” route of the IST method to synthesize cobalt species embedded in nitrogen-doped carbon (P–Co@NC). • The advantages of economic practicability, minimization of synthesis period, energy consumption without any waste formation could outweigh the catalyst for OER performance. • The advantage of Co dispersion and close interaction with nitrogen-doped carbon matrix showed efficient catalytic performance. • The efficient electron transport on CNTs (high conductivity) improved the OER performance of P–Co@NC over the reference catalysts (IrO 2 and B–Co@NC).

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Single-phased samples of the medium-entropy BiSbTe1.5Se1.5 (low-temperature thermoelectric with electron con- ductivity) and PbSnTeSe (mid-temperature thermoelectric with hole conductivity) compounds have been prepared by reactive spark plasma sintering of powder mixtures consisting of relevant elemental metals. The samples prepared are grained. Plate- like grains with average grain size of ∼ 3.3 μm are observed in BiSbTe1.5Se1.5, whereas irregularly-shaped grains with average grain size of ∼ 18.9 μm are typical for PbSnTeSe. Highest value of the thermoelectric figure-of-merit of the samples is equal to ∼ 0.43 (at 500 K for BiSbTe1.5Se1.5) and ∼ 0.35 (at 725 K for PbSnTeSe).

ОСОБЕННОСТИ РЕАЛИЗАЦИИ ТЕМПЕРАТУРНОГО РЕЖИМА В УСТАНОВКЕ КОНТАКТНОГО ТИПА ПРИ СУШКЕ МЕЛКОСЕМЕННЫХ КУЛЬТУР

When creati ng modern eff ecti ve complex technical systems that realize the processes of thermal impact on bulk agricultural materials with the required quality and at a high energy level, it is important to know the conditi ons of heat and moisture transfer. The target functi on of our research was scienti fi c substanti ati on of the main thermophysical parameters of the studied process of thermal eff ect on the drying product as a whole, as well as identi fi cati on of the eff ect of the created temperature regime of the drying unit on the temperature gradient when heati ng the treated seeds, and, ulti mately, on the effi ciency of the enti re process. In case of contact drying of small-seeded crops, both external heat and moisture exchange processes are carried out - from the surface of the treated seeds to the external environment, and internal - the migrati on of heat and moisture inside the seeds. The main quanti tati ve factor that most fully describes the mechanism of moisture transfer is the Bio criterion (Bim). This criterion establishes a relati on between such parameters of the contact drying process as the intensity of moisture exchange on the surface of the processed grain and its moisture conducti vity. The descripti on of the process is reduced to solving an internal problem for the moisture contained in the processed grain, when considering the latt er as a colloidal body, Bim = 0.16. In this case, the removal of moisture with its transformati on into steam directly depends on the energy consumpti on for the heat treatment process. The driving force of this process is the temperature gradient arising from thermal acti on. Studies have established that the kineti c coeffi cient, which most fully describes this phenomenon, is the thermal and moisture conducti vity coeffi cient or the thermal gradient coeffi cient δ. This parameter characterizes the moisture content change in the processed grain at a temperature gradient equal to one degree Celsius. In order to confi rm the above theoreti cal dependencies, experimental studies were carried out to identi fy the features of contact thermal eff ects on various small-seed crops. Based on the results of the studies, it was revealed that the following operati ng parameters have the greatest infl uence on temperature regime during grain drying in the developed contact type grain dryer: the temperature of the heati ng surface and the rotati on frequency of the transporti ng working body. In this study, the rotati on frequency of the transporti ng working body was changed from 30 min-1 to 110 min-1, and the temperature of the heati ng surface - in the range from 40 ºС to 100 ºС. It was revealed that the temperature gradient of grain heati ng in the developed installati on for grain drying at appropriate drying modes is 9 ... 12 ºС and does not signifi cantly depend on the type of processed seeds. When improving the operati ng parameters of the drying process of seeds of one crop, it is possible to operate the developed grain dryer without loss of quality during heat treatment of small seeds of other crops.

Patterns of yeast diversity distribution and its drivers in rhizosphere soil of Hami melon orchards in different regions of Xinjiang

BackgroundThe unique climatic conditions of the Xinjiang region nurture rich melon and fruit resources, the melon and fruit sugar sources provide sufficient nutrients for the survival of yeast, and the diverse habitats accompanied by extreme climatic conditions promote the production of yeast diversity and strain resources. However, the relationship between yeast species and their relationship with environmental factors in the soil of Xinjiang specialty cash crop Hami melon is not clear. Here, we aimed to characterize the diversity, community structure, and relationship between yeast species and environmental factors in Hami melon orchards soils in different regions of Xinjiang, China.ResultsBased on Illumina MiSeq high-throughput sequencing analysis of the D1 domain of the LSU rRNA genes, the community richness of yeast in the soil of Northern Xinjiang was higher than in the Southern and Eastern Xinjiang, but the community diversity was significantly lower in the Northern Xinjiang than in the Southern and Eastern Xinjiang. A total of 86 OTUs were classified into 59 genera and 86 species. Most OTUs (90.4%) belonged to the Basidiomycota; only a few (9.6%) belonged to Ascomycota. The most dominant species in the Southern, Eastern and Northern Xinjiang were Filobasidium magnum (17.90%), Solicoccozyma aeria (35.83%) and Filobasidium magnum (75.36%), respectively. Principal coordinates analysis (PCoA) showed that the yeast community composition in the soils of the three regions were obviously different, with the Southern and Eastern Xinjiang having more similar yeast community. Redundancy analysis (RDA) showed that soil factors such as conductivity (CO), total phosphorus (TP) and Total potassium (TK) and climate factors such as average annual precipitation (PRCP), relative humidity (RH) and net solar radiation intensity (SWGNT) were significantly correlated with yeast communities (P < 0.05).ConclusionThere are abundant yeast resources in the rhizosphere soil of Hami melon orchard in Xinjiang, and there are obvious differences in the diversity and community structure of yeast in the three regions of Xinjiang. Differences in climatic factors related to precipitation, humidity and solar radiation intensity and soil factors related to conductivity, total phosphorus and total potassium are key factors driving yeast diversity and community structure.

СВОЙСТВА МЕМБРАН НА ОСНОВЕ 1-ВИНИЛ-1,2,4-ТРИАЗОЛА И НАТРИЕВОЙ СОЛИ ВИНИЛСУЛЬФОНОВОЙ КИСЛОТЫ

The composition and structure of the membrane based on the acid-base method of &#x0D; elemental analysis, IR and NMR spectroscopy were studied. The ion-exchange capacity, proton con ductivity, activation energy, and thermogravimetric analysis of the resulting membranes were studied

A 3D-printed robotic system for fully automated multiparameter analysis of drinkable water samples

This work describes a 3D-printed robotic system named RSAWA (robotic system for automatic water analysis) for fully automated water analysis. RSAWA consists of a robotic arm coupled to a syringe pump, temperature and conductivity sensors, a low-cost webcam as colorimetric detector, and a 96-well microplate placed on a 3D-printed platform. The robotic system is controlled by software and it performs all analytical procedures. RSAWA was applied to measure conductivity (CDT), pH, total alkalinity (TA), total hardness (TH), chloride (Cl−), nitrite (NO2−), total dissolved phosphorus (TP), and total iron (TI) in drinkable water samples. A simple circuit was designed for conductivity determinations, while colorimetric pH determinations were carried out using Hue values extracted from digital images and a pH universal indicator. HSV histograms were used to calculate Pearson's correlation coefficients, allowing the construction of accurate titration curves. In addition to achieving sample throughputs of 112 h−1 for TA and TH determinations and 92 h−1 for Cl− determinations, RSAWA produced 99.5% less waste than the corresponding reference methods during titrations. Colorimetric measurements were performed through RGB vector norms calculated from digital images were used as analytical signals. Limits of quantification (μg L−1) were 6.83, 13.0 and 1.5 mg L−1 for NO2−, TP, and TI determinations, respectively. Sample throughputs (samples h−1) were 83 for NO2− and TP and 72 for TI with a 98.5% reduction in waste generation. Thus, RSAWA is a low-cost, feasible, and environmentally friendly alternative to quickly and accurately determine several chemical and physicochemical parameters in aqueous samples.

Carcass decay deteriorates water quality and modifies the nirS denitrifying communities in different degradation stages

Corpse degradation may release amounts of hazardous materials (e.g., cadaverine, putrescine and ammonia) into surrounding areas, which deteriorate environments and result in nitrogen contamination. Nitrate or nitrite can be reduced to nitrogen gas by denitrifying bacteria, thus alleviating nitrogen contamination and purifying aquatic environments. However, the reaction of nirS-encoding denitrifiers to carcass degradation is less studied. Therefore, water physiochemical analysis and high-throughput sequencing were applied to explore the successional pattern of nirS denitrifying communities in the Yellow River water and tap water during three stages of animal cadaver decay (submerged fresh, advanced floating decay as well as sunken remains) and relevant control group. Nitrate nitrogen (NO3-N) and ammonia nitrogen (NH4+-N) concentration in corpse groups were highly elevated compared with control groups. The dominant phylum for nirS denitrifying communities was Proteobacteria. Abundant denitrifying genera Paracoccus, Alicycliphilus and Diaphorobacter were detected, and these genera have been reported to participate in the degradation of organic pollutants. Particularly, nirS-type community structures were remarkably influenced by corpse decay and became similar with succession. Water total dissolved solids (TDS), salinity, conductivity (CON) and phosphate were primary impacting factors driving the community structures, but the effect of water type was almost negligible. Notably, denitrifying community assembly was dominated by deterministic processes rather than stochastic processes, and the relative importance of deterministic processes among most corpse groups was higher than that in control groups, indicating that environmental filtering regulates the denitrifying communities. Our results provide new insight into environmental purification for hazardous materials produced by corpse degradation, thereby providing valuable advice to environmental administration.

The spatial and temporal dynamics of phytoplankton community and their correlation with environmental factors in Wuliangsuhai Lake, China

The principal environmental factors influencing the monthly dynamics of phytoplankton were examined from April to October in 2016 in 12 stations of Lake Wuliangsuhai (northwest China). Interestingly, in this lake, nutrient did not exhibit to be limiting for the phytoplankton growth. From April to October, the volume of total nitrogen (TN) range 0.66~22.22 mg/L, maximum volume was in W1 station in October; total phosphorus (TP) range 0.008~0.339 mg/L, maximum volume was in W2 station in April; NH4–N range 0.11~1.74mg/L, maximum volume was in W12 station in October. The most critical forcing factors were water quality physicochemical parameter variables, mainly water temperature (WT), salinity (Sal), conductivity (CON), total dissolved solids (TDS), pondus hydrogenii (pH), and water transparency (SD). The highest phytoplankton density (2.99 × 108 cells/L) was recorded in station W12 in June, and the lowest phytoplankton density (4.84 × 105 cells/L) in station W8 in May, in conditions of increasing water temperature in summer and lower water temperature in spring. Conversely, the highest species number (61 species) exhibited in station W5 in September, and the lowest species number (6 species) exhibited in station W1 in May. The physicochemical parameter variables, mainly WT, Sal, CON, TDS, pH, and SD, had a significant and measurable effect not only on the development of phytoplankton density but also on the monthly dynamics of the phytoplankton community. Our results revealed that the species number and density of the phytoplankton could serve as biological water quality indicators, which would give overall descriptions of water quality in Wuliangsuhai Lake.

Perchlorate Levels in Polish Water Samples of Various Origin

Perchlorate ion (ClO4−) is known as a potent endocrine disruptor and exposure to this compound can result in serious health issues. It has been found in drinking water, swimming pools, and surface water in many countries, however, its occurrence in the environment is still poorly understood. The information on perchlorate contamination of Polish waters is very limited. The primary objective of this study was to assess ClO4− content in bottled, tap, river, and swimming pool water samples from different regions of Poland and provide some data on the presence of perchlorate. We have examined samples of bottled, river, municipal, and swimming pool water using the IC–CD (ion chromatography–conductivity detection) method. Limit of detection and limit of quantification were 0.43 µg/L and 1.42 µg/L, respectively, and they were both above the current health advisory levels in drinking water. The concentration of perchlorate were found to be 3.12 µg/L in one river water sample and from 6.38 to 8.14 µg/L in swimming pool water samples. Importantly, the level of perchlorate was below the limit of detection (LOD) in all bottled water samples. The results have shown that the determined perchlorate contamination in Polish drinking waters seems to be small, nevertheless, further studies are required on surface and river samples. The inexpensive, fast, and sensitive IC–CD method used in this study allowed for a reliable determination of perchlorate in the analyzed samples. To the best of our knowledge, there are no other studies seeking to assess the perchlorate content in Polish waters.

Effect of Power Ultrasound on Wettability and Collector-Less Floatability of Chalcopyrite, Pyrite and Quartz

Numerous studies have addressed the role of ultrasonication on floatability of minerals macroscopically. However, the impact of acoustic waves on the mineral hydrophobicity and its physicochemical aspects were entirely overlooked in the literature. This paper mainly investigates the impact of ultrasonic power and its time on the wettability and floatability of chalcopyrite, pyrite and quartz. For this purpose, contact angle and collectorless microflotation tests were implemented on the ultrasonic-pretreated and non-treated chalcopyrite, pyrite and quartz minerals. The ultrasonic process was carried out by a probe-type ultrasound (Sonopuls, 20 kHz and 60 W) at various ultrasonication time (0.5–30 min) and power (0–180 W) while the dissolved oxygen (DO), liquid temperature, conductivity (CD) and pH were continuously monitored. Comparative assessment of wettabilities in the presence of a constant low-powered (60 W) acoustic pre-treatment uncovered that surface of all three minerals became relatively hydrophilic. Meanwhile, increasing sonication intensity enhanced their hydrophilicities to some extent except for quartz at the highest power-level. This was mainly related to generation of hydroxyl radicals, iron-deficient chalcopyrite and elemental sulfur (for chalcopyrite), formation of OH and H radicals together with H2O2 (for pyrite) and creation of SiOH (silanol) groups and hydrogen bond with water dipoles (for quartz). Finally, it was also found that increasing sonication time led to enhancement of liquid temperature and conductivity but diminished pH and degree of dissolved oxygen, which indirectly influenced the mineral wettabilities and floatabilities. Although quartz and pyrite ultrasound-treated micro-flotation recoveries were lower than that of conventional ones, an optimum power-level of 60–90 W was identified for maximizing chalcopyrite recovery.