Sulphate toxicity to the aquatic moss, Fontinalis antipyretica

The aquatic moss, Fontinalis antipyretica was exposed to elevated sulphate concentrations for 21-days. Gametophores were sectioned to 2 cm lengths and exposed to sulphate concentrations up to 1500 mg/l, in waters of different water hardness. Significant reductions in shoot length, dry weight, and chlorophyll a and b concentrations (per gram dry weight) were observed in soft water (19 mg/l as CaCO 3); however, effects were significantly reduced in waters of increasing hardness (up to 105 mg/l as CaCO 3). The substantial reduction of sulphate toxicity in waters of increasing hardness suggests water chemistry plays a significant role in affecting sulphate toxicity and should be considered when setting sulphate discharge limits.