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A large complex water quality data set of a polluted river, the Tay Ninh River, was evaluated to identify its water quality problems, to assess spatial variation, to determine the main pollution sources, and to detect relationships between parameters. This river is highly polluted with organic substances, nutrients, and total iron. An important problem of the river is the inhibition of the nitrification. For the evaluation, different statistical techniques including cluster analysis (CA), discriminant analysis (DA), and principal component analysis (PCA) were applied. CA clustered 10 water quality stations into three groups corresponding to extreme, high, and moderate pollution. DA used only seven parameters to differentiate the defined clusters. The PCA resulted in four principal components. The first PC is related to conductivity, NH4-N, PO4-P, and TP and determines nutrient pollution. The second PC represents the organic pollution. The iron pollution is illustrated in the third PC having strong positive loadings for TSS and total Fe. The fourth PC explains the dependence of DO on the nitrate production. The nitrification inhibition was further investigated by PCA. The results showed a clear negative correlation between DO and NH4-N and a positive correlation between DO and NO3-N. The influence of pH on the NH4-N oxidation could not be detected by PCA because of the very low nitrification rate due to the constantly low pH of the river and because of the effect of wastewater discharge with very high NH4-N concentrations. The results are deepening the understanding of the governing water quality processes and hence to manage the river basins sustainably.

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In linguistics, adversative conjunctions are linking words that connect different parts of language to produce a cohesive message. They are studied for their formation, functions, and relation to content words. "Nhưng" is an example of an adversative conjunction in Vietnamese, which functions as a syntactic and textual cohesive marker. This article explores the patterns of "nhưng" usage in terms of sentence and utterance cohesion, highlighting structural differences that affect meaning and reflect the speaker's communicative intent. The authors investigate the structural differences that affect meaning and reflect the speaker's communicative intent. Through analysis, the author highlights the ways that "nhưng" can be used to connect contrasting ideas or expressing opposition. The author also examines the role of context and intonation in shaping the meaning of this conjunction. The findings of this study have implications for understanding of language use and communication. By shedding light on the patterns of adversative conjunctions in Vietnamese, this research contributes to the broader field of linguistics and provides insights for language learners and teachers.

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