TY - JOUR

T1 - Spatial and seasonal dynamics of the methane cycle in a tropical coastal lagoon and its tributary river

AU - Aguirrezabala-Cámpano, T.

AU - Gonzalez-Valencia, R.

AU - García-Pérez, V.

AU - Torres-Alvarado, R.

AU - Pangala, S.R.

AU - Thalasso, F.

PY - 2022/6/15

Y1 - 2022/6/15

N2 - Coastal aquatic ecosystems such as estuaries and coastal lagoons are important atmospheric methane sources that must be better constrained. This work presents a detailed characterization of the methane cycle in a tropical coastal lagoon (La Mancha, Veracruz, Mexico) and its tributary river over three distinct seasons, along a transect from the river to the sea connection. In addition to several physicochemical parameters, the dissolved methane, carbon dioxide, and oxygen concentrations were measured with high resolution in the sediments and the water column, combined with production/uptake rates. Methane and carbon dioxide cycles were further constrained by determining atmospheric flux over the entire river and lagoon sections. The results indicate that La Mancha is a highly contrasted ecosystem. The river section is characterized by a strong pycnocline, relatively high methane concentration, and active methanogenesis and methanotrophy, discharging into a relatively homogeneous lagoon section where the methane and carbon cycles are less active. Overall, both the river and the lagoon were a net source of methane and carbon dioxide, with an annual emission of 2.9 metric tons of methane and 2757 metric tons of carbon dioxide. The spatial structure of the main components of the methane, carbon dioxide, and oxygen cycles was established, and it was observed that depthwise heterogeneities predominated in the river section. In contrast, lengthwise heterogeneities dominated in the lagoon section.

AB - Coastal aquatic ecosystems such as estuaries and coastal lagoons are important atmospheric methane sources that must be better constrained. This work presents a detailed characterization of the methane cycle in a tropical coastal lagoon (La Mancha, Veracruz, Mexico) and its tributary river over three distinct seasons, along a transect from the river to the sea connection. In addition to several physicochemical parameters, the dissolved methane, carbon dioxide, and oxygen concentrations were measured with high resolution in the sediments and the water column, combined with production/uptake rates. Methane and carbon dioxide cycles were further constrained by determining atmospheric flux over the entire river and lagoon sections. The results indicate that La Mancha is a highly contrasted ecosystem. The river section is characterized by a strong pycnocline, relatively high methane concentration, and active methanogenesis and methanotrophy, discharging into a relatively homogeneous lagoon section where the methane and carbon cycles are less active. Overall, both the river and the lagoon were a net source of methane and carbon dioxide, with an annual emission of 2.9 metric tons of methane and 2757 metric tons of carbon dioxide. The spatial structure of the main components of the methane, carbon dioxide, and oxygen cycles was established, and it was observed that depthwise heterogeneities predominated in the river section. In contrast, lengthwise heterogeneities dominated in the lagoon section.

KW - Carbon budget

KW - Carbon dioxide

KW - Dissolved oxygen

KW - Homogeneity model

KW - Aquatic ecosystems

KW - Atmospheric chemistry

KW - Budget control

KW - Lakes

KW - Methane

KW - Rivers

KW - Tropics

KW - Atmospheric methanes

KW - Carbon budgets

KW - Coastal lagoons

KW - La Mancha

KW - Me-xico

KW - River section

KW - Seasonal dynamics

KW - Spatial dynamics

KW - Veracruz

U2 - 10.1016/j.scitotenv.2022.154074

DO - 10.1016/j.scitotenv.2022.154074

M3 - Journal article

VL - 825

JO - Science of the Total Environment

JF - Science of the Total Environment

SN - 0048-9697

M1 - 154074

ER -