Water and sediments pollution from Iza river (Romania): Influence on water quality and metals content

Abstract

The present study introduces a monitoring initiative focused on the quality of surface water quality of the water samples collected from Iza and Tisa rivers, situated in the Sighetu Marmației locality in the Upper Tisa, a Natura 2000 protected area, in the North-West region of Romania. The study assessed the evolution of 15 chemical indicators (electric conductivity, pH, oxide-reduction potential, dissolved oxygen, total hardness, turbidity, fluoride, chloride, ammonium concentration (NH₄⁺), nitrates (NO₃^-), nitrites (NO₂^-), sulphate (SO₄^2-), Total Dissolved Solids, alkalinity (HCO₃^-, CO₃^2-)), and 20 metals (Ag, Al, As, Ba, Ca, Cd, Co, Cr, Cu, Fe, K, Li, Mg, Mn, Na, Ni, Pb, Sb, Sr, Zn) in the water samples, and 12 metals in sediments collected from Isa river (As, Ba, Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb, Sb, Zn), which were monthly measurement in the year of 2024. The objectives of this study were: (1) to assess the quality of Iza and Tisa rivers by measuring and analyzing the chemical load. (2) To identify the extent of the anthropogenic pressures and to elaborate measurements destined for mitigation of negative anthropogenic emission and environmental alterations. (3) To determine the typology of Iza river by applying the Total Ionic Salinity chart based on the major ions, Gibbs Piper and Ficklin-Caboi plots, indicating the precipitation, rock dominance, and silicate weathering, characterizing all studied surface waters. (4) To identify and evaluate the metal pollution in water and sediments, based on metal pollution index (MPI), and the human health risk at metals through variate risk indices (HQ and CDI). (5) To calculate the transfer of metals from Isa River to sediments, and to determine the ecological impact based on the enrichment factor and geoaccumulation index. Piper diagram indicated Ca-Na-HCO₃^- mixed typology, attributed to mineral solubilization or recharge water, and the Ficklin-Caboi chart indicated near-neutral high metal type of waters. According to the metal pollution indices scores, most surface waters (86 %) were characterized by medium pollution with the metals of interest. The mean scores varied between the critical range of 30–15, indicating medium pollution, MPI scores ranged between14.9–22.8 respectively. No human health risk at metals through ingestion for adults and children was determined, based on the hazard quotient scores which were lower than the critical value of one. Generally, the descendent trend associated to the transfer of metals from sediment to water was: Fe>Mn>As>Cu>Pb>Co>Cr>Sb>Ba>Ni>Cd>Zn. Generally, samples had a depletion to minimal enrichment with heavy metals (ER <2.0), especially with Cr, Fe, Ni, and Pb. All samples present significant enrichment (5.00 <EF<20) with Cd, while 70 % of samples present significant enrichment with Mn, and 57 % of sample were characterized by significant enrichment with Zn. Sediments were characterized by heavily contaminated with Cd, indicated by the I_geo scores. All sediments indicated I_geo scores lower than zero (I_geo<0), characterized by lack of contamination with As, Cr, Cu, Fe, Mn, Ni, Pb, and Zn. A comparative analysis of metals in water and sediments revealed notable connections between physico-chemical indicators and metal content. This analysis underscored the necessity for a customized conservation strategy. Correlation analyses revealed both positive and negative relationships between metal pairs. A comprehensive understanding of these parameters is imperative for effective water resource management and the preservation of biodiversity in the region. The findings of this study are advantageous in identifying the level of pollution in the Isa watercourse. They serve as an indicator for local authorities, prompting the implementation of measures to reduce pollution in the surrounding area. This is crucial for enhancing human health and preserving the ecosystems within the protected area.