Spatial patterns of soil attributes and components in a mangrove system in Southeast Brazil (São Paulo)

• Published in: Journal of soils and sediments Vol. 10; no. 6; pp. 995 - 1006
• Main Authors: Ferreira, Tiago Osório, Otero, Xosé L, de Souza Junior, Valdomiro S, Vidal-Torrado, Pablo, Macías, Felipe, Firme, Lilian P
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Berlin/Heidelberg : Springer-Verlag 01-09-2010; Springer-Verlag; Springer Nature B.V
• Subjects: Brackish; Cause-effect relationships; Clay minerals; Earth and Environmental Science; Environment; Environmental factors; Environmental Physics; Estuaries; Estuarine environments; Estuarine positions; Forests; Geochemistry; Kaolinite; mangrove soils; Mineralogy; Organic carbon; Organic matter; Physicochemical properties; Pyrite; Sec 1 • Soil Organic Matter Dynamics and Nutrient Cycling • Research Article; Soil attributes; Soil classification; Soil formation; Soil mineralogy; Soil profiles; Soil salinity; Soil Science & Conservation; Soil sciences; Soils; spatial distribution; Sulfate reduction; X-ray diffraction; Brazil; Sao Paulo Brazil; ASW, Brazil, Sao Paulo, Guaruja; ASW, Brazil, Sao Paulo; ASW, Brazil; Estuarine positions; Clay minerals; Soil attributes; Spatial distribution; Mangrove soils
• ISSN: 1439-0108; 1614-7480
• DOI: 10.1007/s11368-010-0224-4

Purpose Among environmental factors governing innumerous processes that are active in estuarine environments, those of edaphic character have received special attention in recent studies. With the objectives of determining the spatial patterns of soil attributes and components across different mangrove forest landscapes and obtaining additional information on the cause-effect relationships between these variables and position within the estuary, we analyzed several soil attributes in 31 mangrove soil profiles from the state of São Paulo (Guarujá, Brazil). Materials and methods Soil samples were collected at low tide along two transects within the Crumahú mangrove forest. Samples were analyzed to determine pH, Eh, salinity, and the percentages of sand, silt, clay, total organic carbon (TOC), and total S. Mineralogy of the clay fraction (<2 mm) was also studied by X-ray diffraction analysis, and partitioning of solid-phase Fe was performed by sequential extraction. Results and discussion The results obtained indicate important differences in soil composition at different depths and landscape positions, causing variations in physicochemical parameters, clay mineralogy, TOC contents, and iron geochemistry. The results also indicate that physicochemical conditions may vary in terms of different local microtopographies. Soil salinity was determined by relative position in relation to flood tide and transition areas with highlands. The proportions of TOC and total S are conditioned by the sedimentation of organic matter derived from vegetation and by the prevailing redox conditions, which clearly favored intense sulfate reduction in the soils (∼80% of the total Fe is Fe-pyrite). Particle-size distribution is conditioned by erosive/deposition processes (present and past) and probably by the positioning of ancient and reworked sandy ridges. The existing physicochemical conditions appear to contribute to the synthesis (smectite) and transformation (kaolinite) of clay minerals. Conclusions The results demonstrate that the position of soils in the estuary greatly affects soil attributes. Differences occur even at small scales (meters), indicating that both edaphic (soil classification, soil mineralogy, and soil genesis) and environmental (contamination and carbon stock) studies should take such variability into account.