A study of surface water quality using organic pollution indices: Comparative characteristics and educational opportunities
Open accessAbstract
ABSTRACT This study sets out to examine a variety of approaches to the assessment of organic pollution, and to consider the potential application of the results in the educational process of students specializing in the environment. Water samples from the Styr River were collected and analyzed for physicochemical parameters such as nitrogen, phosphorus, carbon components, and dissolved oxygen from 2018 to 2022. Four equations were used to calculate the Organic Pollution Index (OPI). Statistical analyses included Pearson correlation, multiple linear regression, principal component analysis (PCA), and network analysis (NA). Results indicated variations in OPI levels depending on the methodology, with pollution classifications ranging from ‘pure’ to ‘moderate’. Seasonal trends were observed, with higher pollution levels in summer and lower levels in winter. PCA and NA identified key variables contributing to pollution. Some methods showed stable OPI levels, while others exhibited periodic fluctuations. This study provides a comprehensive comparison of OPI calculation methods and integrates statistical techniques for river water quality assessment. It offers a valuable framework for environmental education, enhancing students' understanding of water quality assessment, data analysis, and statistical applications in environmental science.
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Written from the paper’s full text.
TL;DR
The study compares four organic pollution index (OPI) methods on Styr River water near the Rivne Nuclear Power Plant (2018–2022) and integrates statistical analyses for environmental education. It finds method-dependent classifications from “pure” to “moderate”/“none”/“weak,” seasonal patterns, and strong correlations between upstream and downstream OPI values.
Key findings
- Four OPI methods produced different pollution classifications: Equations (1) and (2) were mostly “pure” with occasional “contaminated” periods; Equation (3) was “none” or “weak”; Equation (4) was mainly “good” in spring/autumn and “lightly polluted”/“moderately polluted” in autumn/winter. Reported OPI ranges included 2.45–3.32 for I-A-OPI-H, 1.85–3.52 for II-A-OPI-H, 4.71–22.25 for III-A-OPI-H, and 1.04–3.97 for IV-A-OPI-H.
- Seasonal trends: BOD and COD maxima occurred in summer (June–August) and minima in winter; NO₃ maxima in winter and minima in spring/early summer; PO₄ maxima in summer/autumn and minima in winter; DIN, N-NH₃, and DO maxima in winter and minima in summer.
- PCA showed strong positive loadings on PC1 for BOD and COD, while DO typically had strong negative loadings; NA showed strong connections for OPIs calculated by the same method at sites before (A) and after (B) the RNPP discharge.
- Correlation analysis found statistically significant relationships between OPI values before water intake (A) and after discharge (B), with r > 0.9 or r = 0.8–0.9 at p < 0.001; regression coefficients of determination were medium (R² = 70–85%) to high (R² = 85–100%).
Methods
- Water samples were collected weekly from 2018 to 2022 along the Styr River (Ukraine) upstream (A) and downstream (B) of the Rivne NPP water discharge, using subsurface dark glass vessels per ISO 5667-6:2014 and stored at +4 °C per ISO 5667-3:2018.
- Measured parameters included NO₃, N-NH₃, PO₄³⁻, COD, BOD, DO, water temperature, and water flow; OPI values were calculated using four equations from Chen et al. (2023), Anny et al. (2017), Makki et al. (2023), and Son et al. (2020), compared against maximum permissible concentration standards H (drinking/domestic) and F (fisheries).
- Statistical analysis used Pearson correlation, multiple linear regression, PCA, and network analysis (NA), with Minitab 21.4.1 and JASP 0.14.3; the paper frames these calculations as an educational framework for environmental students.
Limitations
- The paper does not state an explicit limitations section.
- Evident from the text: the study is limited to one river system (Styr River) and one discharge context (Rivne NPP) over 2018–2022, so broader generalizability is not established.
- Evident from the text: the four OPI methods use different parameters and standards, producing divergent classifications; the educational benefits are proposed but no formal assessment of student learning outcomes is reported.
Model-written summary. Check it against the paper before relying on it.
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Cites
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Claims the paper makes
5 of 26 cited sources checked · 0 supported · 0 flagged · accuracy not yet measured
- Interpretationcitation§ 4. DISCUSSION · p. 12
The spring peak in NO3 concentrations is likely due to agricultural runoff.
“likely due to agricultural runoff”
Quote in the paperNot a substantial claim1 of 1 sources checked- cites Saavedra et al. 2024 source
The Introduction says agricultural nitrate can reach streams through runoff-related pathways, supporting the proposed mechanism. It describes high concentrations in winter and low concentrations in summer, but does not identify a spring peak or attribute one to agricultural runoff. The Results (section 3.1) instead report lower spring concentrations during drought and post-drought periods than under non-drought conditions. (LLM, conf=0.82)
Experimental — accuracy not yet measured
- Interpretationcitation§ 4. DISCUSSION · p. 12
The winter maxima of N-NH3 and DIN indicate possible decreased microbial activity and slower nitrification processes.
“indicating possible decreased microbial activity and slower nitri fi cation processes (Klymenko et al. 2018; Böllmann & Martienssen 2024).”
Quote in the paperNot a substantial claim2 of 2 sources checked- cites Klymenko et al. 2018 source
Materials and Methods describes water-quality measurements, including ammonia, nitrate and nitrite nitrogen, during low summer flows in 2013–2015. The Results discusses nitrogenous pollution, but no passage found addresses winter nitrogen maxima, decreased microbial activity or slower nitrification (searched for those terms and seasonal ammonia patterns). (LLM, conf=0.76)
Experimental — accuracy not yet measured - cites Böllmann & Martienssen 2024 source
Section 2.1 reports a winter maximum for nitrate, and Discussion §4.2 reports fewer cultivable nitrate-reducing bacteria in the cold epilimnion. The paper does not establish winter maxima for N-NH3 or DIN, or link those maxima to slower nitrification; it studies nitrate reducers and denitrifiers rather than measuring seasonal nitrification rates. Page numbers were not supplied in our copy. (LLM, conf=0.83)
Experimental — accuracy not yet measured
- Findingown data§ ABSTRACT · p. 1
PCA and NA identified key variables contributing to pollution.
“PCA and NA identi fi ed key variables contributing to pollution.”
Quote in the paperSubstantial claim - Findingown data§ 3.2. Analysis of the OPI levels · p. 8
The OPI levels show different patterns for the different methods from 2018 to 2022.
“The density plots provide a comprehensive view of the changes in the OPI from 2018 to 2022, and the OPI levels show different patterns for the different methods (Figure 5).”
Quote in the paperNot a substantial claim- Rests on an assumption: Organic pollution of surface waters can be monitored using the organic pollution index (OPI).
- Findingown data§ ABSTRACT · p. 1
Seasonal trends in OPI levels were observed, with higher pollution levels in summer and lower levels in winter.
“Seasonal trends were observed, with higher pollution levels in summer and lower levels in winter.”
Quote in the paperNot a substantial claim- Rests on an assumption: Organic pollution of surface waters can be monitored using the organic pollution index (OPI).
- Findingreasoning§ 3.2. Analysis of the OPI levels · p. 9
Maximum values of nitrogen group substances did not result in maximum OPIs.
“Notably, the maximum values of nitrogen group substances did not result in the maximum OPIs.”
Quote in the paperSubstantial claim- Rests on an assumption: Organic pollution of surface waters can be monitored using the organic pollution index (OPI).
- Findingown data§ 4. DISCUSSION · p. 12
PCA revealed distinct patterns in OPI levels of variation before and after the water discharge.
“PCA revealed distinct patterns in OPI levels of variation (Figure 6)”
- Also stated in: § 5. CONCLUSION · p. 12 · plain
“revealing distinct patterns in OPI levels before and after the water discharge.”
Quote in the paperSubstantial claim - Also stated in: § 5. CONCLUSION · p. 12 · plain
- Findingown data§ 3.3. Estimation of the numerical levels and distribution of the OPIs · p. 11
The results of the numerical calculations of the OPIs showed a positive correlation characterized by very strong, functional (r > 0.9) and strong (r = 0.7-0.9) relationships.
“The results of the numerical calculations of the OPIs showed a positive correlation characterized by very strong, functional ( r . 0.9) and strong ( r ¼ 0.7 -0.9) relationships.”
Quote in the paperSubstantial claim - Findingnone given§ 3.3. Estimation of the numerical levels and distribution of the OPIs · p. 10
Water temperature (t) often significantly contributed to PC3, with varying signs across categories H and F.
“Moreover, parameters t (water temperature) often signi fi cantly contributed to the PC3, albeit with varying signs across different categories (H and F).”
Quote in the paperNot a substantial claim - Findingown data§ 4. DISCUSSION · p. 12
Seasonal variations in water quality parameters from 2018 to 2022 revealed distinct patterns.
“The seasonal variations in water quality parameters from 2018 to 2022 revealed distinct patterns (Figure 3).”
Quote in the paperSubstantial claim - Findingreasoning§ 4. DISCUSSION · p. 12
NO3 concentrations peak in spring.
“NO 3 concentrations peak in spring”
Quote in the paperNot a substantial claim - Findingown data§ 3.3. Estimation of the numerical levels and distribution of the OPIs · p. 11
These correlation coefficients are comparable for the OPIs calculated according to the MPCs for both F and H standards and for different sampling sites before water intake (A) and after water discharge (B) from the RNPP.
“These correlation coef fi cients are comparable for the OPIs calculated according to the MPCs for both F and H standards and for different sampling sites before water intake (A) and after water discharge (B) from a point anthropogenic source, in this case, the RNPP water discharge (Figure 8).”
- Also stated in: § 4. DISCUSSION · p. 12 · plain
“The obtained r levels are comparable for the OPIs, both for those calculated according to the MPCsfor the F and H and for different sampling sites before water intake (A) and after discharge (B) with return water from a point anthropogenic source, in this case, the RNPP water discharge (Figure 8).”
Quote in the paperSubstantial claim - Also stated in: § 4. DISCUSSION · p. 12 · plain
- Findingreasoning§ 4. DISCUSSION · p. 12
Phosphate levels are highest in autumn and winter.
“while phosphate levels are highest in autumn and winter”
Quote in the paperNot a substantial claim - Findingown data§ 3.3. Estimation of the numerical levels and distribution of the OPIs · p. 10
Strong connections are observed for OPIs calculated using the same methods for different sites before (A) and after (B) the water discharge from the RNPP.
“Strong connections are observed for OPIs calculated using the same methods for different sites before (A) and after (B) (Figure 1) the water discharge from the RNPP.”
Quote in the paperNot a substantial claim - Findingown data§ 3.1. Analysis of water quality parameters · p. 6
The data on monitoring of chemical parameters of the Styr River in the area influenced by RNPP water discharge show a wide range of fluctuations in concentrations of controlled parameters.
“The data on the monitoring of chemical parameters of the Styr River in the area in fl uenced by the RNPP water discharge show a wide range of fl uctuations in the concentrations of controlled parameters (Table 2).”
Quote in the paperNot a substantial claim - Findingreasoning§ 4. DISCUSSION · p. 12
DO peaks in winter when temperatures are lower and solubility is higher.
“DO shows an inverse relationship, peaking in winter when temperatures are lower and solubility is higher.”
Quote in the paperNot a substantial claim - Findingown data§ 3.3. Estimation of the numerical levels and distribution of the OPIs · p. 10
D, t, PO4^3-, NO3 and N-NH3 were identified as PC4 and PC5.
“Additionally, D , t , PO 3 4 , NO 3 and N-NH3 were identi fi ed as PC4 and PC5 (Figure 6).”
Quote in the paperNot a substantial claim - Findingown data§ 3.3. Estimation of the numerical levels and distribution of the OPIs · p. 10
Several weak connections are observed for OPI levels within the same category across different monitoring points (H or F).
“Notably, several weak connections are observed for OPI levels within the same category across different monitoring points (H or F).”
Quote in the paperNot a substantial claim - Findingown data§ 3.3. Estimation of the numerical levels and distribution of the OPIs · p. 11
There is a statistically significant direct relationship between the values of the OPI at sampling sites before water intake (A) and after water discharge (B) from the RNPP, with correlation coefficients very strong to functional (r > 0.9) and strong (r = 0.8-0.9) at p < 0.001.
“The correlation analysis revealed a statistically signi fi cant direct relationship between the values of the OPI at the sampling sites before water intake (A) and after water discharge (B) from the RNPP, as depicted in Figure 8.”
- Also stated in: § 3.3. Estimation of the numerical levels and distribution of the OPIs · p. 11 · plain
“The correlation coef fi cients were very strong to functional ( r . 0.9) and strong ( r ¼ 0.8 -0.9) with a signi fi cance level of p , 0.001”
- Also stated in: § 5. CONCLUSION · p. 12 · plain
“Correlation analysis revealed a statistically signi fi cant relationship between OPI levels at sampling sites before water intake (A) and after discharge (B) of water discharge from the RNPP, with correlations ranging from very strong ( r . 0.9) to strong ( r ¼ 0.8 -0.9) at the signi fi cance level of p , 0.001.”
Quote in the paperSubstantial claim - Also stated in: § 3.3. Estimation of the numerical levels and distribution of the OPIs · p. 11 · plain
- Findingown data§ 3.3. Estimation of the numerical levels and distribution of the OPIs · p. 11
The lines obtained by plotting two OPI calculations at an upstream and downstream site exhibited medium (R2 = 70-85%) to high (R2 = 85-100%) coefficients of determination.
“The lines obtained by plotting two OPI calculations at an upstream and downstream site exhibited medium ( R 2 ¼ 70 -85%) to high ( R 2 ¼ 85 -100%) coef fi cients of determination”
Quote in the paperSubstantial claim - Findingreasoning§ 3.3. Estimation of the numerical levels and distribution of the OPIs · p. 10
For II-A(B)-OPI-H(F), DO had strong negative loading on PC1.
“A strong negative loading on PC1 for DO and II-A(B)-OPI-H(F) indicates an inverse relationship between these parameters.”
Quote in the paperNot a substantial claim - Findingreasoning§ 4. DISCUSSION · p. 12
Higher BOD and COD values are associated with warmer summer months.
“Higher BOD and COD values are associated with warmer summer months”
Quote in the paperNot a substantial claim - Findingown data§ 3.3. Estimation of the numerical levels and distribution of the OPIs · p. 10
For I-A(B)-OPI-H(F), BOD and COD had strong positive loading on PC1.
“For I-A(B)-OPI-H(F), there was a strong positive loading on PC1 for BOD and COD”
Quote in the paperNot a substantial claim - Findingown data§ 3.1. Analysis of water quality parameters · p. 6
Among annual variations, maximum concentrations of DIN, N-NH3 and NO3 occurred in 2020.
“Among the annual variations, the maximum concentrations of DIN, N-NH3 and NO 3 were occurred in 2020.”
Quote in the paperNot a substantial claim - Findingown data§ 5. CONCLUSION · p. 12
These indices indicate periods of 'pure' water with occasional 'contaminated' episodes.
“These indices indicate periods of ' pure ' water with occasional ' contaminated ' episodes.”
Quote in the paperSubstantial claim - Findingown data§ 5. CONCLUSION · p. 12
Over the period 2018-2022, the water quality parameters in the Styr River demonstrated significant fluctuations.
“Over the period of 2018 -2022, the water quality parameters in the Styr River demonstrated signi fi cant fl uctuations”
Quote in the paperSubstantial claim - Findingown data§ 3.3. Estimation of the numerical levels and distribution of the OPIs · p. 11
Equations were derived to characterize the relationship between the OPI levels at different control locations.
“equations were derived to characterize the relationship between the OPI levels at different control locations (Figure 8).”
Quote in the paperSubstantial claim - Findingown data§ 5. CONCLUSION · p. 12
Different OPI calculation methods yielded varying levels of organic pollution.
“with different OPI calculation methods yielding varying levels of organic pollution.”
Quote in the paperSubstantial claim - Findingown data§ 3.3. Estimation of the numerical levels and distribution of the OPIs · p. 10
For II-A(B)-OPI-H(F), COD had strong positive loading on PC1.
“while for II-A(B)-OPI-H(F), there was a strong positive loading on PC1 for COD.”
Quote in the paperNot a substantial claim - Findingcitation§ 4. DISCUSSION · p. 12
N-NH3 and DIN values are highest in winter.
“N-NH3 and DIN values are highest in winter”
Quote in the paperNot a substantial claim - Interpretationown data§ 3.2. Analysis of the OPI levels · p. 9
The annual distribution of OPIs calculated using different methods is determined by the weight of water quality parameters utilized for calculations.
“The annual distribution of OPIs, calculated using different methods, is determined by the weight of water quality parameters (Figure 5), which are utilized for calculations.”
Quote in the paperSubstantial claim - Premisecitation§ 1. INTRODUCTION · p. 2
The generation of organic pollution can, to a large extent, be predicted by the content of biogenic elements of nitrogen, carbon, phosphorus and oxygen and the corresponding chemical indicators.
“The generation of organic pollution can, to a large extent, be predicted by the content of biogenic elements of nitrogen, carbon, phosphorus and oxygen (Hoque et al. 2023) and the corresponding chemical indicators of nitrate ions (NO 3 ), ammonium nitrogen (N-NH3), phosphate ions (PO 3 4 ), dissolved inorganic nitrogen (DIN), the rate of chemical oxygen demand (COD), the rate of biochemical oxygen”
Quote in the paperSubstantial claim0 of 1 sources checked- cites Hoque et al. 2023 source
- Interpretationown data§ 3.3. Estimation of the numerical levels and distribution of the OPIs · p. 11
The correlation coefficients indicate the adequacy of the selected study assessment approach.
“indicating the adequacy of the selected study assessment approach.”
Quote in the paperSubstantial claim - Interpretationreasoning§ 5. CONCLUSION · p. 12
The discharge from the RNPP influenced the OPI levels.
“The discharge from the RNPP in fl uenced the OPI levels.”
Quote in the paperSubstantial claim - Interpretationown data§ 3.3. Estimation of the numerical levels and distribution of the OPIs · p. 10
The strong negative loading of DO on PC1 for II-A(B)-OPI-H(F) indicates an inverse relationship between these parameters.
“A strong negative loading on PC1 for DO and II-A(B)-OPI-H(F) indicates an inverse relationship between these parameters.”
Quote in the paperNot a substantial claim - Interpretationown data§ 4. DISCUSSION · p. 12
The strong connections between certain indices imply that the methods used for these indices capture similar aspects of water quality.
“and imply that the methods used for these indices capture similar aspects of water quality.”
Quote in the paperNot a substantial claim - Interpretationown data§ 3.3. Estimation of the numerical levels and distribution of the OPIs · p. 11
The lines can be used to predict the OPI after water discharge from the RNPP.
“which can be used to predict the OPI after water discharge from the RNPP.”
Quote in the paperSubstantial claim - Interpretationown data§ 5. CONCLUSION · p. 12
The strong negative loadings of DO suggest its inverse relationship with pollution levels.
“suggesting its inverse relationship with pollution levels.”
Quote in the paperSubstantial claim - Interpretationown data§ 4. DISCUSSION · p. 12
The strong connections between certain indices suggest that they share similar underlying factors or conditions affecting organic pollution.
“The strong connections between certain indices suggest that they share similar underlying factors or conditions affecting organic pollution”
Quote in the paperNot a substantial claim - Interpretationreasoning§ 3.3. Estimation of the numerical levels and distribution of the OPIs · p. 10
For OPI calculated according to Equation (3), PC2 comprises a physical water discharge parameter (D) due to the limited number of water quality parameters used.
“It is important to note that due to the limited number of water quality parameters used for calculating OPI according to Equation (3), PC2 comprises a physical water discharge parameter ( D ).”
Quote in the paperNot a substantial claim - Interpretationnone given§ 5. CONCLUSION · p. 12
Integrating PCA with NA provided a more comprehensive understanding of the interrelationships among water quality parameters.
“Moreover, integrating PCA with NA provided a more comprehensive understanding of the interrelationships among water quality parameters.”
Quote in the paperSubstantial claim - Interpretationcitation§ 4. DISCUSSION · p. 12
The distribution of OPIs by year, as calculated using different methods, is determined by the weight of water quality parameters.
“The distribution of OPIs by year, as calculated using different methods (Figure 5), is determined by the weight of water quality parameters (Chen et al. 2022).”
Quote in the paperNot a substantial claim0 of 1 sources checked- cites Chen et al. 2022 source
- Classified as probably not a substantial claim. 20
- May combine two claims. 30
- The quote only partly states this claim. 1
Probably not a substantial claim: may not pass S3 (load-bearing).
Premisecitation§ 1. INTRODUCTION · p. 2Different calculation methods are known as OPIs.
“Different calculation methods are known as OPIs (Anny et al. 2017; Son et al. 2020; Chen et al. 2023; Makki et al. 2023).”
Quote in the paperNot a substantial claim1 of 3 sources checked- cites Anny et al. 2017
Couldn’t be matched to a paper in Crossref, so it can’t be checked.
- cites Son et al. 2020 source
- cites Chen et al. 2023 source
The copy’s Section 3.1 discusses calculating a saturation index (SI) using different equations, but does not call those methods OPIs. Searches for “OPIs different calculation methods” and “organic pollution indices OPI calculation methods” found no passage defining OPIs or supporting the attributed statement. (LLM, conf=0.72)
Experimental — accuracy not yet measured
Probably not a substantial claim: may not pass S3 (load-bearing).
Interpretationcitation§ 4. DISCUSSION · p. 12The autumn and winter phosphate peaks are possibly due to runoff and reduced uptake by aquatic plants.
“possibly due to runoff and reduced uptake by aquatic plants (Saavedra et al. 2024).”
Quote in the paperNot a substantial claim1 of 1 sources checked- cites Saavedra et al. 2024 source
The Introduction and section 4.2 discuss runoff-driven transport of nitrate, while the Introduction describes reduced nitrogen uptake by water-stressed vegetation. Neither the supplied passages nor searches for phosphate peaks and aquatic-plant uptake address the proposed explanation for autumn and winter phosphate peaks. (LLM, conf=0.76)
Experimental — accuracy not yet measured
May combine two claims.
Findingreasoning§ 3.2. Analysis of the OPI levels · p. 7The range (min-max) and mean index were almost comparable for I-A(B)-OPI-H(F) and II-A(B)-OPI-H(F) and identical for III-A(B)-OPI-H(F).
“The range (min -max) and M index were almost comparable for I-A(B)-OPI-H(F) and II-A(B)-OPI-H(F) and identical for III-A(B)-OPI-H(F).”
Quote in the paperNot a substantial claim- Rests on an assumption: Organic pollution of surface waters can be monitored using the organic pollution index (OPI).
May combine two claims.
Findingown data§ 3.2. Analysis of the OPI levels · p. 9The year 2022 frequently exhibits the highest density around moderate to high OPI levels, suggesting a potential increase in OPI levels compared with previous years.
“The year 2022 frequently exhibits the highest density around moderate to high OPI levels, suggesting a potential increase in OPI levels compared with previous years.”
Quote in the paperNot a substantial claim- Rests on an assumption: Organic pollution of surface waters can be monitored using the organic pollution index (OPI).
May combine two claims.
Findingown data§ 3.2. Analysis of the OPI levels · p. 6The I-A(B)-OPI-H(F) levels calculated by Equation (1) were characterized as 'pure', with insignificant periods characterized as 'contaminated'.
“The І -А ( В )-OPI-H(F) levels, calculated according to Equation (1), were characterized as ' pure ' , and there were insigni fi cant periods characterized as ' contaminated ' (Figure 4(a)).”
Quote in the paperNot a substantial claim- Rests on an assumption: Organic pollution of surface waters can be monitored using the organic pollution index (OPI).
- Rests on an assumption: The upstream (A) and downstream (B) sampling points are representative of the Styr River before and after the RNPP water discharge.
May combine two claims.
Findingown data§ 3.2. Analysis of the OPI levels · p. 8Minimal levels for I-A(B)-OPI-H(F) and II-A(B)-OPI-H(F) occurred in 2021, and maximal levels for III-A(B)-OPI-H(F) occurred in 2022.
“The temporal dynamics of changes in their permit the identi fi cation of minimal levels for I-A(B)-OPI-H(F) (Figure 5(a)) and II-A(B)-OPI-H(F) (Figure 5(b)) in 2021, and maximal levels in 2022 for III-A(B)-OPI-H(F) (Figure 5(c)).”
Quote in the paperNot a substantial claim- Rests on an assumption: Organic pollution of surface waters can be monitored using the organic pollution index (OPI).
- Rests on an assumption: The upstream (A) and downstream (B) sampling points are representative of the Styr River before and after the RNPP water discharge.
May combine two claims.
Findingown data§ 3.2. Analysis of the OPI levels · p. 9Methods represented by Equations (1) and (2) exhibit greater variability and bimodal distributions, whereas Equations (3) and (4) demonstrate greater stability with pronounced peaks.
“The methods represented by Equations (1) and (2) exhibit greater variability and bimodal distributions, whereas Equations (3) and (4) demonstrate greater stability with pronounced peaks.”
Quote in the paperNot a substantial claim- Rests on an assumption: Organic pollution of surface waters can be monitored using the organic pollution index (OPI).
May combine two claims.
Findingown data§ 3.2. Analysis of the OPI levels · p. 7The III-A(B)-OPI-H(F) levels calculated by Equation (3) were characterized as 'none' or 'weak', and did not characterize the water as polluted with organic matter during the period of the year.
“The IIIА ( В )-OPI-H(F) levels, calculated according to Equation (3), were characterized as ' none ' or ' weak ' (Figure 4(c)), and the results obtained by Equation (3) did not characterize the water as polluted with organic matter during the period of the year.”
Quote in the paperNot a substantial claim- Rests on an assumption: Organic pollution of surface waters can be monitored using the organic pollution index (OPI).
- Rests on an assumption: The upstream (A) and downstream (B) sampling points are representative of the Styr River before and after the RNPP water discharge.
May combine two claims.
Findingown data§ 3.1. Analysis of water quality parameters · p. 6Maximum BOD and COD concentrations were observed in summer months (June-August), especially in 2018, 2019 and 2020 for BOD and in 2018 and 2019 for COD, and minimum concentrations were observed in winter months (December-February) in all years.
“Thus, the maximum BOD and С OD concentrations were observed in the summer months (June -August), especially in 2018, 2019 and 2020 for BOD and in 2018 and 2019 for COD, and the minimum concentration was observed in the winter months (December -February) in all years.”
Quote in the paperNot a substantial claimMay combine two claims.
Findingown data§ 3.2. Analysis of the OPI levels · p. 7The IV-A(B)-OPI-H(F) levels calculated by Equation (4) were characterized as 'good' mainly in spring and autumn and 'lightly polluted' and 'moderately polluted' in autumn and winter.
“The І VА ( В )-OPI-H(F) levels, calculated according to Equation (4), were characterized as ' good ' mainly in spring and autumn and ' lightly polluted ' and ' moderately polluted ' in autumn and winter (Figure 4(d)).”
Quote in the paperNot a substantial claim- Rests on an assumption: Organic pollution of surface waters can be monitored using the organic pollution index (OPI).
- Rests on an assumption: The upstream (A) and downstream (B) sampling points are representative of the Styr River before and after the RNPP water discharge.
May combine two claims.
Findingown data§ ABSTRACT · p. 1Some OPI calculation methods showed stable OPI levels, while others exhibited periodic fluctuations.
“Some methods showed stable OPI levels, while others exhibited periodic fl uctuations.”
- Also stated in: § 3.2. Analysis of the OPI levels · p. 9 · hedged
“Overall, the data suggest that some methods show stable pollution levels, while others show periodic fl uctuations or shifts in OPI levels.”
Quote in the paperSubstantial claim- Rests on an assumption: Organic pollution of surface waters can be monitored using the organic pollution index (OPI).
- Also stated in: § 3.2. Analysis of the OPI levels · p. 9 · hedged
May combine two claims.
Findingown data§ 3.2. Analysis of the OPI levels · p. 6The II-A(B)-OPI-H(F) levels calculated by Equation (2) were characterized as 'pure', with insignificant periods characterized as 'contaminated'.
“The ІІ -А ( В )-OPI-H(F) levels, calculated according to Equation (2), were characterized as ' pure ' , and there were insigni fi cant periods characterized as ' contaminated ' (Figure 4(b)).”
Quote in the paperNot a substantial claim- Rests on an assumption: Organic pollution of surface waters can be monitored using the organic pollution index (OPI).
- Rests on an assumption: The upstream (A) and downstream (B) sampling points are representative of the Styr River before and after the RNPP water discharge.
May combine two claims.
Findingown data§ ABSTRACT · p. 1OPI levels in the Styr River water varied depending on the calculation method, with pollution classifications ranging from 'pure' to 'moderate'.
“Results indicated variations in OPI levels depending on the methodology, with pollution classi fi cations ranging from ' pure ' to ' moderate ' .”
Quote in the paperSubstantial claim- Rests on an assumption: Organic pollution of surface waters can be monitored using the organic pollution index (OPI).
The quote only partly states this claim.
Findingnone given§ 3.3. Estimation of the numerical levels and distribution of the OPIs · p. 10The III-A(B)-OPI-H(F) levels showed strong positive loadings on PC1 for BOD.
“The I ІІ -A(B)-OPI-H(F) levels showed strong positive loadings on PC1 for BOD.”
Quote in the paperNot a substantial claimMay combine two claims.
Findingown data§ 3.3. Estimation of the numerical levels and distribution of the OPIs · p. 10COD, BOD and DO had the greatest contributions to PC1 and PC2, often exhibiting strong negative and positive loadings, respectively.
“COD, BOD and DO had the greatest contributions to PC1 and PC2, which often exhibited strong negative and positive loadings, respectively (Figure 6).”
Quote in the paperNot a substantial claimMay combine two claims.
Findingown data§ 3.3. Estimation of the numerical levels and distribution of the OPIs · p. 10DO concentration is identified as PC2 for I-A(B)-OPI-H(F) and as PC1 for II-A(B)-OPI-H(F).
“The concentration of DO is identi fi ed as PC2 for I-A(B)-OPI-H(F) and as PC1 for IIA(B)-OPI-H(F)”
Quote in the paperNot a substantial claimProbably not a substantial claim: may not pass S3 (load-bearing).
Findingown data§ 4. DISCUSSION · p. 12The network graph provides a visual and quantitative representation of the relationships between various OPIs calculated using different methods.
“The network graph provides a visual and quantitative representation of the relationships between various OPIs calculated using different methods (Figure 7).”
Quote in the paperNot a substantial claimMay combine two claims.
Findingown data§ 3.1. Analysis of water quality parameters · p. 6Minimum PO4 concentration was generally observed in winter months (September-February) in all years, and maximum concentration was observed in summer months (June-August) and autumn months (September-November), especially in August in 2020, 2021 and 2022.
“The minimum PO 3 4 concentration was generally observed in the winter months (September -February) in all years, and the maximum concentration was observed in the summer months (June -August) and autumn months (September -November), especially in August in 2020, 2021 and 2022.”
Quote in the paperNot a substantial claimMay combine two claims.
Findingreasoning§ 3.3. Estimation of the numerical levels and distribution of the OPIs · p. 10For IV-A(B)-OPI-H(F) levels, discrepancies in the formation of PCs are noted, with a strong negative loading on PC1 for water temperature (t) under standard H and for DO under standard F.
“For IV-A(B)OPI-H(F) levels, discrepancies in the formation of PCs are noted, with a strong negative loading on PC1 for water temperature ( t ) under standard H and for DO under standard F.”
Quote in the paperNot a substantial claimMay combine two claims.
Findingown data§ 3.1. Analysis of water quality parameters · p. 6Maximum DIN, N-NH3 and DO concentrations were observed in winter months (December-February), and minimum concentrations were observed in summer months (June-August).
“The maximum DIN, N-NH3 and DO concentrations were observed in the winter months (December -February), and the minimum concentration was observed in the summer months (June -August).”
Quote in the paperNot a substantial claimMay combine two claims.
Findingown data§ 3.1. Analysis of water quality parameters · p. 6Minimum NO3 concentration was preferentially observed in spring months (March-May) and early summer (June), especially in 2018 and 2019, and maximum concentration was observed in winter months.
“The minimum NO 3 concentration was preferentially observed in the spring months (March -May) and early summer (June), especially in 2018 and 2019, and the maximum concentration was observed in the winter months.”
Quote in the paperNot a substantial claimProbably not a substantial claim: may not pass S3 (load-bearing).
Findingnone given§ 3.3. Estimation of the numerical levels and distribution of the OPIs · p. 10Other water quality parameters (DIN, PO4^3-, N-NH3) are defined as PC4 and PC5.
“In addition, other water quality parameters (DIN, PO 3 4 , N-NH3) are de fi ned as PC4 and PC5.”
Quote in the paperNot a substantial claimMay combine two claims.
Findingown data§ 3.3. Estimation of the numerical levels and distribution of the OPIs · p. 10BOD concentration is identified as PC1 for I-A(B)-OPI-H(F) and as PC2 for II-A(B)-OPI-H(F).
“where the concentration of BOD is identi fi ed as PC1 for I-A(B)-OPI-H(F) and as PC2 for II-A(B)-OPI-H(F).”
Quote in the paperNot a substantial claimMay combine two claims.
Findingown data§ 5. CONCLUSION · p. 12BOD and COD had strong positive loadings on the PCs for OPI levels, while DO typically showed strong negative loadings.
“BOD and COD had strong positive loadings on the PCs for OPI levels, while DO typically showed strong negative loadings”
Quote in the paperSubstantial claimMay combine two claims.
Interpretationreasoning§ 3.2. Analysis of the OPI levels · p. 7The comparability/identity of ranges and means is due to different calculations, use of the same MPCs, and for III-A(B)-OPI-H(F) the limited indicators used for calculation.
“This is due to the different calculations used and the use of the same MPCs, and for IIIA(B)-OPI-H(F), the limited indicators used for the calculation (Table 3), as the MPC values are the same for BOD, DO, PO 3 4 and slightly different for NO 3 , С OD and N-NH3 according to the standards (Standard 1990, 2022).”
Quote in the paperNot a substantial claim0 of 1 sources checked- cites Standard 1990, 2022
Couldn’t be matched to a paper in Crossref, so it can’t be checked.
Probably not a substantial claim: may not pass S3 (load-bearing).
Study design and conductcitation§ 2.1. Study location · p. 4The preservation and handling of the samples were carried out in accordance with ISO 5667-3:2018.
“The preservation and handling of the samples were carried out in accordance with ISO 5667-3:2018.”
Quote in the paperNot a substantial claim0 of 1 sources checked- cites ISO 5667-3:2018
Couldn’t be matched to a paper in Crossref, so it can’t be checked.
Probably not a substantial claim: may not pass S3 (load-bearing).
Study design and conductcitation§ 2.1. Study location · p. 4Water samples were collected from the subsurface, with no air bubbles, directly into dark glass vessels according to ISO 5667-6:2014.
“Water samples were collected from the subsurface, with no air bubbles, directly into dark glass vessels according to ISO 5667-6:2014.”
Quote in the paperNot a substantial claim0 of 1 sources checked- cites ISO 5667-6:2014
Couldn’t be matched to a paper in Crossref, so it can’t be checked.
Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.
Premisecitation§ 1. INTRODUCTION · p. 3Chen et al. (2023) calculated OPI using Equation (1), where OPI > 2 indicates river water is contaminated by organic matter.
“Chen et al. (2023) calculated the OPI of water using Equation (1). When ОРІ 2, the river water is contaminated by organic matter.”
Quote in the paperNot a substantial claim0 of 1 sources checked- cites Chen et al. 2023 source
Checked before — its earlier verdict is held back until a new check runs.
Probably not a substantial claim: may not pass S3 (load-bearing).
Study design and conductnone given§ 2.2. Water monitoring and performance · p. 4The concentration parameters were monitored using standard measurement methods recognized in Ukraine and listed in Table 1.
“The concentration parameters were monitored using standard measurement methods recognized in Ukraine and listed in Table 1.”
Quote in the paperNot a substantial claimProbably not a substantial claim: may not pass S3 (load-bearing).
Premisecitation§ 1. INTRODUCTION · p. 3Statistical methods are widely used in studies of the impact of pollution on the environment.
“It is well known that statistical methods are widely used in studies of the impact of pollution on the environment (Kuznietsov et al. 2024).”
Quote in the paperNot a substantial claim0 of 1 sources checked- cites Kuznietsov et al. 2024
Couldn’t be matched to a paper in Crossref, so it can’t be checked.
Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.
Premisecitation§ 4. DISCUSSION · p. 12PCA is frequently used in environmental studies to identify patterns and reduce the dimensionality of data, thereby making it easier to interpret complex data sets.
“PCA is frequently used in environmental studies (Biedunkova & Kuznietsov 2024; Shams et al. 2024) to identify patterns and reduce the dimensionality of data, thereby making it easier to interpret complex data sets.”
Quote in the paperNot a substantial claim0 of 2 sources checked- cites Biedunkova & Kuznietsov 2024
Couldn’t be matched to a paper in Crossref, so it can’t be checked.
- cites Shams et al. 2024
Couldn’t be matched to a paper in Crossref, so it can’t be checked.
Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.
Premisecitation§ 1. INTRODUCTION · p. 3Anny et al. (2017) calculated OPI using Equation (2), where OPI > 2 indicates contamination by organic matter; it uses N-NH3 instead of NO3 and does not take PO4 into account.
“Anny et al. (2017) calculated the OPI of water using Equation (2), where a numerical value of OPI 2 indicates contamination by organic matter. Therefore, instead of the concentration of nitrate ions (NO 3 ) in (1), the concentration of ammonium nitrogen (N-NH3) is used in calculation (2), and the concentration of phosphate PO 3 4 is not taken into account.”
Quote in the paperNot a substantial claim0 of 1 sources checked- cites Anny et al. 2017
Couldn’t be matched to a paper in Crossref, so it can’t be checked.
May combine two claims.
Interpretationown data§ 4. DISCUSSION · p. 12DO shows an inverse relationship with temperature, with higher solubility in winter.
“DO shows an inverse relationship, peaking in winter when temperatures are lower and solubility is higher.”
Quote in the paperNot a substantial claimMay combine two claims.
Interpretationreasoning§ 4. DISCUSSION · p. 12The association of higher BOD and COD with warmer summer months reflects increased organic pollution and microbial activity.
“re fl ecting increased organic pollution and microbial activity.”
Quote in the paperNot a substantial claimMay combine two claims.
Interpretationreasoning§ 5. CONCLUSION · p. 12The discharge might have a slight effect on certain pollutants or the river's mitigation processes and dilution are effective in this region.
“This suggests that discharge might have a slight effect on certain pollutants or that the river ' s mitigation processes and dilution are effective in this region.”
Quote in the paperSubstantial claimProbably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.
Premisecitation§ 1. INTRODUCTION · p. 3Son et al. (2020) calculated OPI using Equation (4) based on COD, DO, DIN and PO4, not BOD, with categories: excellent OPI <0, good OPI = 0-1, polluted OPI = 1-4, extremely polluted OPI = 4-5.
“An OPI was calculated by Son et al. (2020) using Equation (4) and the pollution level of a water based on four parameters: COD, DO, the concentration of DIN and PO 3 4 . DIN is the total concentration of N-NH3, NO 3 and nitrite ions (NO 2 ). The BOD values of Son et al. (2020), unlike those of Chen et al. (2022), Anny et al. (2017) and Makki et al. (2023), are not considered. OPIs by Son et al. (”
Quote in the paperNot a substantial claim0 of 1 sources checked- cites Son et al. 2020 source
Classified as probably not a substantial claim. May combine two claims.
Premisereasoning§ 1. INTRODUCTION · p. 2Different MPCs may be applied to different sections of a river, so it is important to assess the ecological status of a water body according to different standards.
“Consequently, different MPCs may be applied to different sections of a river, so it is important to assess the ecological status of a water body according to different standards.”
Quote in the paperSubstantial claimProbably not a substantial claim: may not pass S3 (load-bearing).
Interpretationreasoning§ 3.3. Estimation of the numerical levels and distribution of the OPIs · p. 10The strong negative loading on PC1 for DO under standard F for IV-A(B)-OPI-H(F) may be attributed to the higher MPC value for DO in water bodies designated for fish farming.
“This may be attributed to the higher MPC value for DO in water bodies designated for fi sh farming.”
Quote in the paperNot a substantial claimProbably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.
Premisecitation§ 1. INTRODUCTION · p. 3Makki et al. (2023) calculated OPI using Equation (3), using only BOD, NO3 and PO4, with levels: none <9; weak 10-29; medium 30-39; poor 40-49; deteriorated 50-59; bad 60-69.
“Makki et al. (2023) calculated the OPI of water using Equation (3), а nd the numerical value of the OPI was calculated only by the chemical parameters, namely BOD, NO 3 and PO 3 4 . Thus, the following levels have been established that characterize organic matter pollution: none , 9; weak 10 -29; medium 30 -39; poor 40 -49; deteriorated 50 -59 and bad 60 -69.”
Quote in the paperNot a substantial claim0 of 1 sources checked- cites Makki et al. 2023 source
Probably not a substantial claim: may not pass S3 (load-bearing).
Study design and conductnone given§ 2.2. Water monitoring and performance · p. 4The parameters were monitored by the RNPP certified measuring laboratory.
“The parameters were monitored by the RNPP certi fi ed measuring laboratory.”
Quote in the paperNot a substantial claimProbably not a substantial claim: may not pass S3 (load-bearing).
Premisecitation§ 1. INTRODUCTION · p. 3PCA and NA are effective in elucidating complex relationships in environmental data.
“Principal component analysis (PCA) (Cai et al. 2022; Samuel et al. 2023) and network analysis (NA) (Dsikowitzky et al. 2017; Azli et al. 2022) are effective in elucidating complex relationships in environmental data.”
Quote in the paperNot a substantial claim0 of 3 sources checkedProbably not a substantial claim: may not pass S3 (load-bearing).
Premisecitation§ 1. INTRODUCTION · p. 2The WCU in Ukraine establishes the analogue of the WFD environmental quality standards, the maximum permissible concentration (MPC) of a substance in water, which determines the suitability of water for specific water use purposes.
“The WCU in Ukraine establishes the analogue of the WFD environmental quality standards, the maximum permissible concentration (MPC) of a substance in water, which determines the suitability of water for speci fi c water use purposes.”
Quote in the paperNot a substantial claim0 of 2 sources checked- cites WCU 2002
Couldn’t be matched to a paper in Crossref, so it can’t be checked.
- cites WFD 2000
Couldn’t be matched to a paper in Crossref, so it can’t be checked.
Probably not a substantial claim: may not pass S3 (load-bearing).
Interpretationown data§ 4. DISCUSSION · p. 12The PCA components help in understanding the underlying factors affecting OPIs in different MPCs (H and F), which might represent different habitats or sampling conditions.
“these components help in understanding the underlying factors affecting OPIs in different MPCs (H and F), which might represent different habitats or sampling conditions.”
Quote in the paperNot a substantial claimClassified as probably not a substantial claim. May combine two claims.
Premisecitation§ 1. INTRODUCTION · p. 2The MPCs are divided into two groups: Group H for water used to meet drinking, domestic and other needs of the population, and Group F for water used for fisheries.
“The MPCs are divided into two groups: Group H ' for water used to meet drinking, domestic and other needs of the population ' (Standard 2022) and Group F ' for water used for fi sheries ' (Standard 1990).”
Quote in the paperSubstantial claim0 of 2 sources checked- cites Standard 2022
Couldn’t be matched to a paper in Crossref, so it can’t be checked.
- cites Standard 1990
Couldn’t be matched to a paper in Crossref, so it can’t be checked.
The paper relies on this without support.
Organic pollution of surface waters can be monitored using the organic pollution index (OPI).
“Organic pollution of surface waters can be monitored using the organic pollution index (OPI).”
The paper relies on this without support.
The OPI can be used as an immediate measure of the overall health of a river ecosystem.
“The OPI can be used as an immediate measure of the overall health of a river ecosystem.”
The paper relies on this without support.
The upstream (A) and downstream (B) sampling points are representative of the Styr River before and after the RNPP water discharge.
“The sampling points included, in particular, the upstream (A) and downstream (B) of the RNPP water discharge (Figure 1).”
The paper relies on this without support.
The educational approach described (students calculating OPIs, using PCA/NA, correlation) improves students' analytical and statistical skills and environmental assessment capabilities.
“students will deepen their analytical and statistical skills whilst getting hands-on practice in environment assessments and pollution mitigation.”
The paper relies on this without support.
The chemical monitoring data from the Styr River for 2018-2022 are accurate and representative of the river's water quality in the area influenced by the RNPP.
“In this study, the results of chemical monitoring of the Styr River in the area in fl uenced by water discharge from the RNPP for 2018 -2022 are used.”
Self-check
Percentages, sums and reported differences re-computed from the paper’s own numbers.
Each contradiction between two passages listed here was confirmed by an independent check.
Phosphate is described as both lowest and highest in winter
MajorThe results describe winter as a period of generally minimum phosphate concentrations, whereas the discussion says phosphate levels are highest in autumn and winter.
“The minimum PO 3 4 concentration was generally observed in the winter months (September -February) in all years”
“phosphate levels are highest in autumn and winter”
Nitrate peak season changes from winter to spring
MajorThe results say nitrate concentrations were highest in winter and lowest in spring and early summer. The discussion instead says they peaked in spring.
“The minimum NO 3 concentration was preferentially observed in the spring months (March -May) and early summer (June), especially in 2018 and 2019, and the maximum concentration was observed in the winter months.”
“NO 3 concentrations peak in spring, likely due to agricultural runoff”
Reported ammonium-nitrogen minimum falls below its measurement range
MinorTable 1 lists 0.5 mg/dm3 as the lower end of the ammonium-nitrogen measurement range, while Table 2 reports a minimum of 0.25 mg/dm3.
“| Ammonium nitrogen N-NH 3 (mgN/dm 3 ) | 0.5 - 10 |”
“| N-NH 3 | 0.25 - 2.13 |”
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Self-citationOkafor, C. P., Nduka, J. K., Okafor, P. O., & Offor, C. C. (2025) · Cleaner Water · doi:10.1016/j.clwat.2025.100127 · Cited by 10 · see citing works
Which factors and how they determine nitrogen runoff loss in rice agroecosystems across China
Qi, J., Wang, Y., Zhao, Y., Lv, Z., Kan, S. Y., Lv, Y., & Li, Y. (2025) · Agricultural Water Management · doi:10.1016/j.agwat.2025.109778 · Cited by 5 · see citing works
Biedunkova, O., Кузнєцов, П., Martynov, S., Kucherova, A., & Hrytsyna, O. (2025) · Engineering Reports · doi:10.1002/eng2.70473 · Cited by 5 · see citing works
Self-citationKlymenko, M., Romanchuk, L., Biedunkova, O., Vozniuk, N., & Ліхо, О. А. (2025) · Visnyk of V N Karazin Kharkiv National University series Geology Geography Ecology · doi:10.26565/2410-7360-2025-63-42 · Cited by 3 · see citing works
Self-citationNagar, V., Kumari, M., Verma, V. K., Kumari, M., & Garg, M. C. (2026) · Environmental Monitoring and Assessment · doi:10.1007/s10661-026-15446-3 · Cited by 3 · see citing works
Zhao, X., Lihua, W., Wang, F., Dong, Z., Wu, K., Yuan, L., & Liu, J. (2026) · Journal of Mountain Science · doi:10.1007/s11629-025-0110-6 · Cited by 2 · see citing works
Al-Gburi, M. R. G., & Alkhafaji, M. W. (2026) · Physics and Chemistry of the Earth Parts A/B/C · doi:10.1016/j.pce.2026.104637 · Cited by 2 · see citing works
Perumal, G., Krishnamoorthy, V., Elaiyarasan, Mariselvam, A. K., & Santharaman, P. (2026) · Physics and Chemistry of the Earth Parts A/B/C · doi:10.1016/j.pce.2026.104652 · Cited by 1 · see citing works
A machine learning model for real-time total nitrogen monitoring in Tampa Bay
Yang, B., Liu, Y., Tang, W., Law, J. A., Weisberg, R. H., Beck, M. W., Sherwood, E. T., & Frazer, T. K. (2026) · Marine Pollution Bulletin · doi:10.1016/j.marpolbul.2026.120184 · Cited by 1 · see citing works
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Processes Optimisation of Coagulation, Flocculation, and Liming for Power Plant Water Treatment
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Water quality status and pollution indexing of Bharathapuzha River in Malappuram district, India
Kolothumthodi, S. A., Anjudikkal, J., & Pulikkal, A. K. (2026) · Next research. · doi:10.1016/j.nexres.2026.102401
Babošová, M., & Porhajašová, J. I. (2026) · Acta fytotechnica et zootechnica/Acta fytotechnica et zootechnica · doi:10.15414/afz.2026.29.03.304-309
- Authors
- Biedunkova, O., Kuznietsov, P., & Korbutiak, V.
- Affiliations
- National University of Water and Environmental Engineering (UA)
- 1 National University of Water and Environmental Engineering, Soborna St. 11, Rivne 33028, Ukraine
- Venue
- Water Quality Research Journal
- Publisher
- IWA Publishing
- Published
- 2025-03-17
- Volume
- 60
- Issue
- 2
- Pages
- 333-347
- ISSN
- 2709-8044 (ISSN-L)
- 2709-8052
- OpenAlex
- W4408507913
- Semantic Scholar
- 5f8e004652a1dd243778c5586cb8c317c0a41e31
- Cited by
- 22
- References
- 47
- Citations by year
- 2026: 15 · 2025: 7
- FWCI
- 5.18
- Type
- journal article
- Language
- en
- Open access
- hybrid
- doi.org
- Licence
- Locations
- Water Quality Research Journal (publishedVersion, cc-by)
- Research Square (acceptedVersion, cc-by)
- Topics
- Physical Sciences › Environmental Science › Water Science and Technology › Water Quality and Pollution Assessment
- Physical Sciences › Environmental Science › Water Science and Technology › Water Quality and Resources Studies
- Physical Sciences › Environmental Science › Waste Management and Disposal › Water Quality Monitoring and Analysis
- Keywords
- surface water quality, organic pollution index, river pollution, Styr River, nitrogen, phosphorus, dissolved oxygen, seasonal variation, environmental education, principal component analysis, network analysis
About these checks
Registry, retraction, Cites and statistics results are computed, not judged, with one exception: a printed reference that no index lists is read once by a model before it counts as a citation error. Claims are extracted by a model and kept only when their quote appears verbatim in the text; each cited source is then checked, with a model’s help, for whether it says what the claim relies on. Those verdicts can be wrong — read the claim’s quote and the cited source before relying on one.
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