Assessing water quality is necessary to ascertain its viability for domestic, industrial, and agricultural purposes. A total of 48 water samples were, respectively, drawn from the Rivers Karawa and Iyiaji located in Ezeagu and Uzo-uwani which are typical rural areas in Enugu State, Nigeria. These samples were taken in two seasons (early rainy season and late dry season). Physicochemical properties were determined using standard methods. The scaling and corrosivity potentials of the water were evaluated using the Larson-Skold index, aggressive index, Puckorius scaling index, and Ryznar stability index models. Additionally, seven irrigation evaluation criteria, as well as spatial distribution maps, were used to determine the suitability of the river waters for irrigation purposes and to interpolate the spatial distribution of the river water quality parameters. Major ion chemistry was used in the assessments. The physicochemical properties of river waters fell within the recommended standard values. However, NO₃⁻ greatly exceeded the recommended range in both rivers. The cations and anions from River Karawa were Ca²⁺ > Mg²⁺ > K⁺ > Na⁺ and NO₃⁻ > Cl⁻ > SO₄²⁻ > HCO₃⁻ > CO₃⁻ > PO₄⁻, while those from River Iyiaji were Ca²⁺ > Mg²⁺ > Na⁺ > K⁺ and Cl⁻ > SO₄²⁻ >NO₃⁻ > PO₄⁻ > HCO₃⁻ > CO₃⁻. A piper plot showed the predominance of Ca²⁺ and Mg⁺, as well as SO₄²⁻ and Cl⁻, in both rivers. The seven irrigation assessment indices indicated that the water of the Rivers Karawa and Iyiaji is suitable for irrigation purposes. In addition, the scaling and corrosivity models predicted that the river waters have high scaling and corrosivity potentials. Specifically, while the aggressive index suggested that it is severely corrosive, the Langelier saturation index suggested that the water from both rivers is supersaturated and, thus, has potential to scale.

Polycyclic aromatic hydrocarbons (PAHs) are contaminants of interest in the ecosystem due to associated health risks. Therefore, their detection in the environment is important. In this regard, the risk assessment of PAHs in borehole water near the unlined dumpsite in Anambra State was investigated. Samples of borehole water (16 each) were collected from the study and control areas during both seasons. The PAH concentrations in the borehole water samples were analyzed using gas chromatography. The mean PAH concentration in the study and control samples for the wet season varied from BL–7.65 µg/L to BL–2.98 µg/L, respectively. The study samples' dry season values ranged from BL to 3.33 µg/L, while control samples ranged from BL to 1.87 µg/L. $$\sum$$∑ PAHs for the wet and dry seasons varied from 5.8 to 13.94 µg/L and 4.25 to 10.09 µg/L for study and control samples, respectively. The four and five rings PAH were the most dominant group in the $$\sum$$∑ PAHs for the study and control samples, respectively. Diagnostic ratios suggested pyrolytic and petrogenic sources for both locations. The cluster analysis showed different sources of the congeners in the samples. The non-carcinogenic risk showed no possibility of risks via dermal and ingestion routes. In addition, the possibility of cancer risks via ingestion routes was doubtful. The carcinogenic risk index through dermal contact exceeded the acceptable limit for adults and is at a tolerable limit for children, indicating potential threats to humans, with adults more susceptible to cancer risks. Therefore, this study recommends that sanitary dumpsites be constructed for waste disposal and implementation of environmental laws to prevent underground water pollution and the environment.

Gongronema latifoliumwas used as a low-cost green inhibitor for mild steel by applying the weight loss method at 303–323 K. There was a decrease in percentage inhibition with temperature increase and a rise in inhibition efficiency with an increase in the concentration of inhibitor. The obtained results showed thatGongronema latifoliumextract of methanol had percentage inhibition efficiencies in the range of 59.06–81.69%. Corrosion inhibition of mild steel showed a good fit to the Langmuir model compared to the Freundlich and El-Awardy adsorption models. Thermodynamics parameters, such as $$ E_{\text{a}} $$Ea , $$ Q_{\text{ads}} $$Qads and $$ \Delta G_{\text{ads}} $$ΔGads were evaluated and showed that the mechanism of corrosion inhibition of mild steel by methanol extract ofGongronema latifoliumwas physisorption. The results of this work indicated efficient potentials of the methanol extract ofGongronema latifoliumas a low-cost corrosion inhibitor in acidic media for mild steel, which could be applied to reduce corrosion of metals in industries.