Major and minor elemental compositions of streambed biofilms and its implications of riverine biogeochemical cycles. (December 2018)

• Record Type: Journal Article
• Authors: Mori, Naoki; Sugitani, Kenichiro; Yamamoto, Mariko; Tomioka, Rie; Sato, Miyako; Harada, Naomi
• Is Part Of: Environmental pollution. Volume 243(2018)Part A
• Page Start: 308
• Page End: 317
• Publication Date: 2018-12
• Subjects: Streambed biofilm -- Chemical compositions -- Dam reservoir -- Heavy metals; Pollution -- Periodicals; Pollution -- Environmental aspects -- Periodicals; Environmental Pollution -- Periodicals; Pollution -- Périodiques; Pollution -- Aspect de l'environnement -- Périodiques; Pollution -- Effets physiologiques -- Périodiques; Pollution; Pollution -- Environmental aspects; Periodicals; Electronic journals; 363.73
• DOI: 10.1016/j.envpol.2018.08.007
• Languages: English
• ISSNs: 0269-7491

Abstract

Abstract: Chemical compositions of streambed biofilms from a major river of central Japan (the Kushida River) were obtained, with data of associated sediments (fine-grained fractions < 63 μm) and dissolved components of waters, in order to provide preliminary information about biogeochemical significance of streambed biofilms. During the sampling period (July 31st to August 3rd, 2013), dissolved components of the river waters were influenced by the dam reservoir. Concentrations of NO3 −, silica (as Si), SO4 2−, PO4 3− and Ca 2+ decreased across the dam, whereas Fe and Mn increased across the dam, and then decreased downstream rapidly. Streambed biofilms contain significant amount of non-nutrient elements such as Al (up to 21% as Al2 O3 on water and others-free basis), indicating that they are contaminated as siliciclatic (silt and clay) materials. Siliciclastic materials in the biofilms are basically compositionally similar to fine-grained (<63 μm) fractions of streambed sediments. However, some elements such as Ca, P, Mn, and Zn are markedly enriched in the biofilms. Particularly, Mn concentrations in the biofilm samples collected just below the dam reservoir are very high (∼4.0 wt %), probably due to accumulation from the discharged water. Concentrations of trace elements such as P, Cr, Cu, Zn and V appear to be controlled by amounts of Fe-oxides and/or Mn-oxides in biofilms. Numbers of factors are involved in controlling chemical compositions of streambed biofilms, including amount of contaminated siliciclastics, authigenic mineral formation, adsorption of dissolved materials and microbial metabolisms. As demonstrated by this study, systematic analyses including major elements and comparison with associated sediments and waters could reveal biogeochemistry of this complex system. Graphical abstract: Image 1 Highlights: Streambed biofilms are enriched significantly in Ca, P, Mn and Zn, compared with fine fractions of sediments. Mn concentrations of biofilms at the downstream of dam can be very high (∼4%), due to precipitation from outflow enriched in dissolved Mn. Accumulation of trace metals in biofilms appears to be controlled by by Fe- and Mn-oxides. Abstract : Chemical compositions of streambed biofilms can be interpreted by contaminated silts and clays, bioaccumulation and adsorption onto Fe- and Mn- oxides.