Costa L, Mirlean N, Garcia F
Oceanography Institute, Federal University of Rio Grande, Av. Itália km 08 Campus Carreiros, Rio Grande, RS, 96201-900, Brazil.
Bull Environ Contam Toxicol. 2017 Apr;98(4):521-524. doi: 10.1007/s00128-016-2024-z. Epub 2017 Jan 13.
We investigate the distributions of the metalloid arsenic (As) and metals iron (Fe) and manganese (Mn) in the sediments of two pristine areas of a biological reserve in the Patos Lagoon Estuary. This area is occupied by Spartina alterniflora and by Neohelice granulata crab colonies and low concentrations of As are expected. The bioturbation/bioirrigation of sediments by crabs and the roots of plants lead to the penetration of oxygen below the oxic/suboxix division and the subsequent precipitation of Fe-Mn hydroxides. Ferruginous incrustations and nodules along roots and crab channels propagate to depths of over 35 cm and sediment contains up to 33 mg kg of As. The metalloid distribution in sediments is strongly correlated with that of Fe but not with Mn. This study revealed that areas with biologically disturbed sediments could demonstrate contamination in As, which is not anthropogenic in origin.
我们研究了帕托斯泻湖河口生物保护区两个原始区域沉积物中类金属砷（As）、金属铁（Fe）和锰（Mn）的分布情况。该区域生长着互花米草和颗粒新海伦蟹群落，预计砷含量较低。螃蟹和植物根系对沉积物的生物扰动/生物灌溉作用导致氧气渗透到有氧/亚有氧分界以下，进而促使铁锰氢氧化物沉淀。沿着根系和螃蟹洞穴形成的铁锈质结壳和结核延伸至超过35厘米的深度，沉积物中砷含量高达33毫克/千克。沉积物中类金属的分布与铁的分布密切相关，但与锰无关。这项研究表明，沉积物受到生物扰动的区域可能存在并非人为来源的砷污染。
