Combination of lanthanum-modified attapulgite and Vallisneria natans for immobilization of phosphorus in various types of sediments

Abstract

As a kind of phosphorus (P) inactivating agent, lanthanum-modified attapulgite (LMA) has effectively been used for controlling the release of P from sediments. However, the effects of LMA on sediments from different types of ecological environments, especially in the rhizosphere of macrophyte, have not yet been studied. In this study, sediments from black-odor rivers (Black-S), cyanobacteria blooms-dominated lake (Algal-S) and macrophyte-dominated lake (Phytic-S) were collected for laboratory-scale microcosmic experiments. The results indicated that LMA had a good inactivation effect on mobile P (sum of Labile-P, Fe-P and organic-P) in three types of sediments, and significantly reduced soluble and labile P in pore water. The rates of reduction of mobile P in Black-S and Algal-S were much higher than that in Phytic-S. LMA capping generated a new sediment water interface, which significantly promoted the growth of roots, the release of oxygen from Vallisneria natans, and the secretion of organic acids to improve the rate of utilization of P in sediments. Meanwhile, the addition of LMA increased the relative abundance of Sideroxydans in the rhizosphere of Vallisneria natans. The study provides a new insight into the applications of LMA capping combined with macrophyte in the restoration of sediments obtained from different ecological settings.