Dataset on contaminants in water, sediment, and fish from Lake Chapala, Mexico (2024–2025)

This dataset contains environmental monitoring results from Lake Chapala, Mexico, collected across four seasons between 2024 and 2025. It includes concentrations of pesticides, herbicides, heavy metals, and physicochemical parameters in water (superficial and interstitial), sediment, and fish tissue (tilapia, bass, catfish, and carp), covering eight sampling sites with provided spatial coordinates. On each campaign, samples were collected from all eight stations for water (surface and interstitial), sediment, and fish (as available), totaling 64 water samples (8 sites × 2 depths × 4 periods), 32 sediment samples, and a representative set of fish specimens. At each site and during each sampling event, on-site measurements of key water quality parameters were carried out using a calibrated multi-parameter water quality probe (EXO2 YSI® by Xylem, United States). The probe was deployed at both surface and near-bottom (interstitial) depths to measure: water temperature (°C), pH (standard units), dissolved oxygen (DO; mg/L), electrical conductivity (EC, µS/cm), and oxidation-reduction potential (ORP; mV). Additionally, water transparency was estimated with a Secchi disk at each site (Secchi depth in cm). Water samples were analyzed in an accredited laboratory for a suite of chemical parameters following standard methods, largely based on Mexican Norms (NOM) for water quality. Pesticides and herbicides were detected and quantified using Ultra-High Performance Liquid Chromatography coupled with Tandem Mass Spectrometry (UHPLC-MS/MS), while heavy metals were analyzed using Inductively Coupled Plasma Atomic Emission Spectroscopy (ICP-AES). The dataset is structured in an Excel file with five sheets: README Sampling site locations. Water quality data. Sediment contaminant levels. Fish tissue contaminant levels.