Ecological risk of mercury in bottom sediments and spatial correlation with land use in Neotropical savanna floodplain lakes, Araguaia River, Central Brazil

Lucas Cabrera Monteiro; Ludgero Cardoso Galli Vieira; José Vicente Elias Bernardi; Lilian de Castro Moraes; Ygor Oliveira Sarmento Rodrigues; João Pedro Rudrigues de Souza; Jurandir Rodrigues de Souza; Wanderley Rodrigues Bastos; Carlos José Sousa Passos; José G Dórea

doi:10.1016/j.envres.2023.117231

Ecological risk of mercury in bottom sediments and spatial correlation with land use in Neotropical savanna floodplain lakes, Araguaia River, Central Brazil

Environ Res. 2023 Dec 1;238(Pt 2):117231. doi: 10.1016/j.envres.2023.117231. Epub 2023 Oct 2.

Affiliations

¹ Programa de Pós-Graduação em Ecologia, Instituto de Ciências Biológicas, Universidade de Brasília, Brasília, DF, 70910-900, Brazil; Núcleo de Estudos e Pesquisas Ambientais e Limnológicas, Faculdade UnB Planaltina, Universidade de Brasília, Planaltina, DF, 73345-010, Brazil; Laboratório de Geoestatística e Geodésia, Faculdade UnB Planaltina, Universidade de Brasília, Planaltina, DF, 73345-010, Brazil. Electronic address: lcabreramonteiro@gmail.com.
² Núcleo de Estudos e Pesquisas Ambientais e Limnológicas, Faculdade UnB Planaltina, Universidade de Brasília, Planaltina, DF, 73345-010, Brazil. Electronic address: ludgero@unb.br.
³ Laboratório de Geoestatística e Geodésia, Faculdade UnB Planaltina, Universidade de Brasília, Planaltina, DF, 73345-010, Brazil. Electronic address: bernardi@unb.br.
⁴ Laboratório de Geoestatística e Geodésia, Faculdade UnB Planaltina, Universidade de Brasília, Planaltina, DF, 73345-010, Brazil; Programa de Pós-Graduação em Ciências Ambientais, Faculdade UnB Planaltina, Universidade de Brasília, Planaltina, DF, 73345-010, Brazil. Electronic address: lilian.moraes@gmail.com.
⁵ Laboratório de Geoestatística e Geodésia, Faculdade UnB Planaltina, Universidade de Brasília, Planaltina, DF, 73345-010, Brazil; Programa de Pós-Graduação em Ciências Ambientais, Faculdade UnB Planaltina, Universidade de Brasília, Planaltina, DF, 73345-010, Brazil. Electronic address: ygorsarmento@gmail.com.
⁶ Laboratório de Química Analítica e Ambiental, Instituto de Química, Universidade de Brasília, Brasília, DF, 70919-970, Brazil. Electronic address: joaoprsouza@outlook.com.
⁷ Laboratório de Química Analítica e Ambiental, Instituto de Química, Universidade de Brasília, Brasília, DF, 70919-970, Brazil. Electronic address: rodsouza@unb.br.
⁸ Laboratório de Biogeoquímica Ambiental, Universidade Federal de Rondônia, Porto Velho, RO, 76901-000, Brazil. Electronic address: bastoswr@unir.br.
⁹ Faculdade UnB Planaltina, Universidade de Brasília, Brasília, DF, 73345-010, Brazil. Electronic address: cjpassos@unb.br.
¹⁰ Faculdade de Ciências da Saúde, Universidade de Brasília, Brasília, DF, 70910-900, Brazil. Electronic address: jdorea@unb.br.

PMID: 37793585
DOI: 10.1016/j.envres.2023.117231

Abstract

The Araguaia River floodplain is an important biogeographic boundary between the two largest South American biomes: the Cerrado (Brazilian Savanna) and the Amazon rainforest. The large-scale degradation due to land use conversion experienced in the Araguaia River watershed represents a potential source of mercury (Hg) transport to aquatic ecosystems. However, more information is needed about the dynamics of Hg distribution in savanna floodplains, including the Araguaia River floodplain. We analyzed total mercury (THg) concentrations in the bottom sediments of 30 lakes connected to the Araguaia River and four tributaries, aiming to evaluate the environment's integrity based on the geoaccumulation index (I_geo) and the ecological risk index (ERI). The principal component analysis was applied to examine associations between Hg concentrations, environmental conditions, and land use intensity among lakes associated with different river systems. We used indicator cokriging to identify areas with a greater probability of Hg pollution and ecological risk associated with land use intensity. The land use data showed the predominance of areas used for pasture in the Araguaia River basin. THg concentrations in the sediments varied between 22.6 and 81.9 ng g^-1 (mean: 46.5 ± 17.7 ng g^-1). Sediments showed no significant pollution (I_geo: 1.35 - 0.50; Classes 1 and 2) and low to considerable ecological risks (ERI: 23.5-85.1; Classes 1 to 3). THg in bottom sediments was associated with land use, water turbidity and electrical conductivity, and sediment organic matter. The indicator cokriging indicates a moderate to strong spatial dependence between land use intensity and Hg, confirming the contribution of anthropic sources to the increment of ecological risk but also the influence of extrinsic factors (such as environmental conditions, geology, and hydrology). Integrating sediment assessment and land use indices with geostatistical methods proved a valuable tool for identifying priority areas for Hg accumulation at a regional scale.

Keywords: Ecological risk index; Geoaccumulation index; Indicator CoKriging; Land use; Mercury; Savanna Floodplain.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Brazil
Ecosystem
Environmental Monitoring
Geologic Sediments / analysis
Grassland
Lakes
Mercury* / analysis
Rivers
Water Pollutants, Chemical* / analysis

Substances

Mercury
Water Pollutants, Chemical