Antibiotics meant to heal are leaving a quiet trace in rivers, sediments, and even the fish people eat. A new study from researchers at the Center for Nuclear Energy in Agriculture at the University of São Paulo reveals how deep that trace runs, and how difficult it may be to erase. The research focused on the Piracicaba River, a major waterway in São Paulo state. The team tracked antibiotic residues across water, sediment, and fish. They also tested whether a floating plant, Salvinia auriculata, could help reduce contamination. The findings show a system under pressure. Antibiotics appear across the ecosystem, shift with the seasons, and move into living organisms in ways that are not always predictable. Percentages of EFX and CAP in water throughout the experiment. (CREDIT: Environmental Sciences Europe) Tracing Pollution Through a River System The researchers collected samples near the Santa Maria da Serra dam, close to the Barra Bonita reservoir. This area gathers pollutants from across the river basin. Sources include treated sewage, household waste, aquaculture, pig farming, and agricultural runoff. They …