Abstract
PurposeThe Limoncocha lagoon, inside a Ramsar site in the Ecuadorian Amazon, increasingly hosts ecotourism and energy development activities. This work estimates the local sediments’ baseline of As, Ba, Cd, Co, Cr, Cu, Mo, Ni, Pb, V and Zn using four methods. This makes it possible to apply single and integrated pollution indices to estimate the contamination level and the ecological risk of the sediments.MethodsSeven sites were analysed for metal(oid)s by ICP-MS. The local baseline was estimated using the relative cumulative frequency method, the iterative 2σ- and 4σ-outlier-techniques and the normalisation method to a “conservative” element. Combinations of single Cf and Ef and integrated indices (NPI, mNPI, mCd, MEQ, RI, mPELq, mERMq and TRI) were applied.ResultsThe relative cumulative frequency method had the best performance for the geochemical baselines. Cf and Ef indices classify sediments from a “low contamination” remote site to the “moderate contamination” and “minor enrichment” of the remaining sites due to As, Cd and Zn concentrations. The overall analysis of the integrated indices results in Ni, Zn and Cu being identified as priority pollutants because they have occasionally been associated with adverse biological effects in the centre of the lagoon and in the most anthropised areas. These are classified as moderately polluted with a medium–low priority risk level.ConclusionsThis work provides sediment baseline and contamination indicators for pollutants, which could be incorporated into the sediment quality assessment and monitoring programme of the Limoncocha lagoon. Ni, Cd and Cr due to the high baseline values in comparison with SQGs, and Cu and Zn due to their potential risk, should be of special attention.Graphical abstract
Highlights
Wetlands are recognised as some of the most valuable green spaces due to their rich biodiversity and the high number of ecosystem services they provide as the essential building blocks for nature conservation (Dudley 2008; HernandezGonzalez et al 2019)
From the numerous available indices for the classification of sediments site (j) concerning potentially toxic elements pollution (i), a combination of single and integrated risk assessment indices was used in the present study, to determine the state of contamination in the Limoncocha lagoon and tributaries
The contamination factor ( Cfi,j ) and the enrichment factor ( Efi,j ) are used as individual indices to calculate the degree of contamination of each potentially toxic element at a given site
Summary
Wetlands are recognised as some of the most valuable green spaces due to their rich biodiversity and the high number of ecosystem services they provide as the essential building blocks for nature conservation (Dudley 2008; HernandezGonzalez et al 2019). Wetlands contribute to climate regulation and to climate change mitigation as they are responsible for carbon sequestration, improving water quality, flood control, aquifer loading and unloading, food supply, biodiversity maintenance and pollution control (Millennium Ecosystem Assessment 2005) Such complex environmental systems are supported on the equilibrium among environmental compartments such as water bodies, sediments, soils, air and biota, which are regulated by several controlling factors. Bed sediments are formed by the deposition of organic and inorganic particles that accumulate on the bottom of water bodies such as lakes and lagoons This environmental compartment plays an important role in aquatic ecosystems, influencing biogeochemical cycles and reflecting the current quality of the entire ecosystem (de Andrade et al 2018). Their occurrence in the environment results from natural and anthropogenic activities and can be associated with sediments
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
