The amorphous mackinawite produced during the blackening of hypoxic waters: determination methods, generation process, and existing patterns

Abstract

Due to pollution discharge and climate change, hypoxia is becoming more prevalent in water bodies such as lakes, rivers, and oceans. It leads to black blooms in lakes, black and odors in rivers, and dead zones in the oceans. Iron sulfide, especially amorphous mackinawite, is the main blackening substance. In this paper, the physical characteristics and detection methods of mackinawite were used to determine how to detect it in hypoxic water bodies. The population and metabolism of key microorganisms during mackinawite generation were analyzed to provide a reference for studying related microorganisms during the blackening process. Finally, the influence of macromolecular organic matter and microorganisms on the stable suspension of mackinawite was determined, and the existing patterns of mackinawite during the blackening process of hypoxic waters were illustrated. The generation of amorphous mackinawite and its stable suspension in a supernatant are two indispensable factors during the blackening process. The clarification of substance characteristics and key action processes are conducive to the accurate and targeted control of the blackening process and promote the restoration of the sustainable self-purification ability of water bodies.