Influence of Water Hardness on Accumulation and Elimination of Cadmium in Two Aquatic Mosses Under Laboratory Conditions

Abstract

This study investigated the effect of water hardness on the accumulation and elimination of cadmium (Cd) by two aquatic mosses, Fontinalis dalecarlica and Platyhypnidium riparioides, under laboratory conditions. The two mosses were exposed to nominal Cd concentrations of 0, 0.8, 2, and 10 microg . L-1, which includes the concentration range generally found in nature. The influence of three levels of water hardness (very soft: 11.7 mg . L-1; soft: 44.2 mg . L-1; and hard water: 92.3 mg . L-1 as CaCO3) was measured while maintaining the alkalinity and pH constant during the 28-day exposure. The Cd accumulation by the aquatic mosses was rapid, showing the potential of accumulation and the sensitivity of this biomonitor. Even if the actual Cd concentration in the water was low (concentration <0.15 microg . L-1 to 6.82 microg . L-1 of Cd), the uptake of Cd was very fast and mostly linear. This study was conducted in water hardness comparable to that found in the Canadian shield (hardness was <100 mg . L-1 as CaCO3). When the actual Cd concentration in the water was as high as 6.82 microg . L-1, the uptake of Cd was mostly linear and the steady state condition was not reach. Accumulation rates of Cd were significantly different when the mosses were in very soft (11.7 mg . L-1) as compared to hard water (92.3 mg . L-1 as CaCO3). The elimination of Cd followed a very slow process for the two species studied. The elimination rates of Cd from the mosses were not influenced by water hardness.

Effects of nanomolar copper on water plants—Comparison of biochemical and biophysical mechanisms of deficiency and sublethal toxicity under environmentally relevant conditions

“…High concentrations of Ca reduce heavy metal toxicity by preventing entrance into the cell just by competing for uptake. Consistently, aquatic moss species accumulated less Cd in harder water (applied as CaCO 3 , Gagnon et al, 1998). On the other hand, green unicellular microalgae were protected against Ni toxicity solely by Mg, not Ca ions (Deleebeeck et al, 2009a (Markich et al, 2006, and citations within).…”

“…Ca 2+ -ATPase, Markich and Jeffree, 1994). During heavy metal toxicity, high Ca concentrations by competing for uptake into the cell, prevent the entrance of the heavy metals as observed in the Cd accumulation studies in aquatic moss in hard water (applied as CaCO 3 , Gagnon et al, 1998). While in green unicellular microalgae the protective mechanism from Ni toxicity by competition was solely by Mg (Deleebeeck et al, 2009a).…”

Development of a standard protocol for monitoring trace elements in continental waters with moss bags: inter- and intraspecific differences

“…However, it is known that some environmental factors negatively influence trace element uptake in transplants, i.e. increasing water acidity (Fernandez et al 2006), water hardness (Ferreira et al 2009;Gagnon et al 1998;Wehr et al 1987) and antagonistic interactions among cations on binding sites (Cesa et al 2008).…”

Physiological Responses of Non-Vascular Plants to Heavy Metals

“…calcium, magnesium and carbonate ions, reduce the toxicity of metal ions. Gagnon et al (1998) reported a reduced uptake of Cd with increasing water hardness in aquatic mosses. The presence of suspended solids, sulphur-containing amino acids and organic materials influence metal toxicity negatively.…”