Scientists Find Digestive Solubilization of Particle-Associated Arsenate by Deposit-Feeders
Food safety is one of the hottest public issues in China. Arsenic (As) is a notorious toxin. Bioaccumulation of arsenic by aquatic organisms has been an important concern because of possible human health effects associated with seafood consumption. In aquatic ecosystems, benthic organisms usually serve as an important link in As transfer up the aquatic food chain. Since many benthic organisms are harvested for human consumption, they are also a major contributor to human dietary intake of As from seafood consumption.
Dietary uptake is an important pathway for arsenic accumulation in benthic organisms. Solubilization of metals in the gut of benthic organisms is considered to be the key process in dietary uptake of metals.
However, little is known about the digestive solubilization process of arsenate (As(V)) in the gut of these deposit-feeders and the role of digestive surfactant in this process. Scientists from Institute of Applied Ecology, CAS, employed in vitro extraction to investigate the effects of proteins, free amino acids and digestive surfactants on the release of sedimentary As(V) during the digestive solubilization process. Molecular weight fractions of the released As(V) was determined with the adsorption of the extracting agents to shed light on the mechanism of As(V) mobilization in the digestive solubilization process.
They found that both the digestive surfactants and the proteinaceous materials increased As(V) mobilization. Compared to the proteinaceous materials alone, the surfactants could enhance the effects of the proteinaceous materials in As(V) mobilization. Arsenate reduction was not observed during the extracting process, showing that redox reactions were not the reason for As mobilization. Only a minor fration of the released As (< 30%) was distributed in the > 10kDa fraction of the digestive agents, showing that the As mobilization was also not caused by complexation with proteins in the digestive agents.
In contrast, adsorption of the digestive agents occurred along with the release of arsenate from the arsenate-rich substrates, suggesting that competitive adsorption was the mechanism by which the digestive agents mobilized sedimentary arsenate.
The researchers highlighted that digestive surfactants could mobilize sedimentary As during gut passage in deposit feeders. This surfactant should be included in extracting agents used for evaluating the bioavailability and environmental risk of sediment-bound arsenate to deposit feeders.
The research was financially supported by National Key R&D Pro-gram of China, National Natural Science Foundation of China, and the Strategic Priority Research Program of the Chinese Academy of Sciences.
The study entitled “Digestive Solubilization of Particle-Associated Arsenate by Deposit-Feeders: The Roles of Proteinaceous and Surfactant Materials”, has been published in Environmental Pollution.
Publication Name: Wu Xing et al.