Chemometric analysis and risk assessment indices to evaluate water and sediment contamination of a tropical mangrove forest

Abstract

BackgroundMangroves are among the utmost productive forest residing at the interface amid terrestrial and marine environments. They play an essential role in carbon storage, nutrient cycling, and the marine food web's sustenance. Rapid land use and land cover changes have severely affected these ecosystems worldwide. Material and methodsThe present study was carried out in the mangrove forest of Kachchh district in Gujarat. This area is one of India's most swiftly growing industrialized coastal regions, embracing several ports, thermal power plants, salt production units, textile, petrochemical, cement, and fertilizer manufacturing industries. Therefore, this study aims to investigate nutrients and trace metal contamination status in mangroves. A total of 25 physicochemical parameters for water and 16 parameters for surface sediment were analysed using standard protocols. Trace metals were determined using Flame Atomic Absorption Spectrophotometry. Results and discussionImmensely higher chloride (20,116 ± 1929 mg L −1) and sulfate (2315 ± 679 mg L −1) concentrations were observed, suggesting high seawater and saltpan brine mixing in this coastal region. High tidal influx and arid-climate of the area are responsible for higher salinity (52.7 ± 5.0 PSU) in water. Cluster analysis depicts that sites M2, M3, M5, and M6 incorporate higher nutrient levels, indicating the anthropogenic origin of nutrients. The results depict the role of granulometric composition in controlling carbon, nitrogen, sulfur, and metal biogeochemistry in sediments. Results showed that mean trace metal (Fe, Cu, and Ni) content in sediment was higher than the world average shale value, indicating anthropogenic sources. Geo-accumulation index (Igeo) and Enrichment factor (EF) indicates sediment samples were moderately polluted with Cu, Zn, and Ni. ConclusionThe findings revealed that anthropogenic activities have affected the hydrogeochemistry of mangroves in the studied region, which will eventually impact flora and fauna. Therefore, there is a pressing necessity to implement pollution control, mitigation, and restoration policies for the endurable management of the mangroves.