Assessment of water quality in eutrophized water bodies through the application of indexes and toxicity

Carolina Acuña-Alonso; Xana Álvarez; Olalla Lorenzo; Ángeles Cancela; Enrique Valero; Ángel Sánchez

doi:10.1016/j.scitotenv.2020.138775

Assessment of water quality in eutrophized water bodies through the application of indexes and toxicity

Sci Total Environ. 2020 Aug 1:728:138775. doi: 10.1016/j.scitotenv.2020.138775. Epub 2020 Apr 19.

Authors

Carolina Acuña-Alonso¹, Xana Álvarez², Olalla Lorenzo³, Ángeles Cancela⁴, Enrique Valero⁵, Ángel Sánchez⁶

Affiliations

¹ Department of Natural Resources Engineering and the Environment, School of Forestry Engineering, University of Vigo, Campus A Xunqueira s/n., 36005, Pontevedra, Spain. Electronic address: carolina.alonso@uvigo.es.
² Department of Natural Resources Engineering and the Environment, School of Forestry Engineering, University of Vigo, Campus A Xunqueira s/n., 36005, Pontevedra, Spain. Electronic address: xaalvarez@uvigo.es.
³ School of Forestry Engineering, University of Vigo, Campus A Xunqueira s/n, 36005, Pontevedra, Spain.
⁴ Chemical Engineering Department, School of Forestry Engineering, University of Vigo, Campus Campus A Xunqueira s/n., 36005, Pontevedra, Spain. Electronic address: chiqui@uvigo.es.of.
⁵ Department of Natural Resources Engineering and the Environment, School of Forestry Engineering, University of Vigo, Campus A Xunqueira s/n., 36005, Pontevedra, Spain. Electronic address: evalero@uvigo.es.
⁶ Chemical Engineering Department, Industrial Engineering College, University of Vigo, Campus Lagoas-Marcosende s/n, 36310 Vigo, Pontevedra, Spain. Electronic address: asanchez@uvigo.es.

PMID: 32339839
DOI: 10.1016/j.scitotenv.2020.138775

Abstract

It is essential to have tools that can be used to diagnose water resources. For this reason, this study sets out on the one hand to assess water quality in three reservoirs in Spain (Salas, A Baxe and Conchas) with Cyano-Habs problems through the application of water quality indexes: The National Sanitation Foundation Water Quality Index (NFSWQI), the General Quality Index (GQI), the Trophic State Index (TSI), and the Trophic Contamination Index (ICOTRO). On the other hand, it seeks to learn how parameters such as nitrogen and phosphorus influence the presence of cyanotoxin, specifically Microcystis aeruginosa. To that end, samples from the three reservoirs are cultured and physical-chemical parameters and the toxicity of the water are measured. The results show that Salas reservoir has the worst water quality rating (GQI is bad and NFSWQI medium), while As Conchas and A Baxe obtain very good figures for NFSWQI. This contrasts with the data obtained via the TSI of moderately eutrophic conditions for all three reservoirs, and hypereutrophic levels for As Conchas and A Baxe downstream. On the other hand, the toxicity analysis shows levels of 1.12 ± 0.06 μg/l microcystin-LR (MC-LR) for As Conchas, 0.64 ± 0.04 μg/l MC-LR for Salas, and 1.24 ± 0.05 μg/l MC-LR for A Baxe, of which 20% corresponds to free MC-LR. This study finds that nitrogen is the parameter that most favors the production of MC-LR. We conclude that the eutrophication indexes are more reliable when studying the presence of cyanobacteria. Furthermore, nitrogen and phosphorous are the most significant parameters in this regard. They are taken into account in the quality indices (GQI, NFSWI), but they are not sufficiently representative. It is recommended as a future line of research that water quality indices be adapted or designed to incorporate eutrophication levels and even water toxicity.

Keywords: Cyanobacteria; Microcystin; Microcystis sp; Nitrogen; Water quality index.

MeSH terms

Cyanobacteria*
Eutrophication
Microcystins / analysis
Microcystis*
Spain
Water Quality

Substances

Microcystins