Selenium (Se), iron (Fe), and free sulfides contents in pore waters were measured to study the liberation of soluble Se in suboxic conditions. The sediment core was collected in a salt marsh in Patos Lagoon estuary (southern Brazil), and it was obtained during a brackish water period, in a low intertidal stand vegetated by Spartina alterniflora. The redox potential (Eh), pH, andacid volatile sulfides (AVS) content were also investigated. Pore water results sustained the idea that S. alterniflora roots promote oxygen penetration to depths of ca. 10 cm below the salt marsh surface, increasing Eh and lowering the pH in this interval. High Se concentrations (e.g., 16.9 µg L⁻¹), that are above US. EPA environmental criteria, were observed in the pore water to depths between 10 and 20 cm and are associated to low AVS contents and high concentrations of free sulfides. In the first 10 cm the lowering of Se contents probably happens due the low pH and biological volatilization of the metalloid.

测量了孔隙水中硒（Se），铁（Fe）和游离硫化物的含量，以研究在低氧条件下可溶性硒的释放。沉积物芯收集在Patos Lagoon河口（巴西南部）的盐沼中，在咸淡水时期，由互花米草（Spartina alterniflora）在低潮间带生长。还研究了氧化还原电势（Eh），pH和酸挥发性硫化物（AVS）含量。孔隙水的结果支持了S的观点。互生菌根促进氧气渗透到大约ca.的深度。在盐沼表面以下10厘米处，在此间隔内增加Eh并降低pH。高硒浓度（例如16.9 µg L ^-1），即高于美国。在孔隙水中观察到的EPA环境标准深度在10到20 cm之间，并且与低AVS含量和高浓度的游离硫化物有关。在最初的10 cm中，Se含量的降低可能是由于低pH值和准金属的生物挥发引起的。