Biomonitoring heavy metal contaminations by moss visible parameters

Traditional sampling for heavy metal monitoring is a time-consuming and inconvenient method, which also does not indicate contaminants non-invasively and instantaneously. Moss is sensitive to heavy metals and is therefore considered a pollution indicator. However, it is unknown what kind physiological parameters can indicate metal contaminations quickly and non-invasively. Here, we systematically examined the effects of six heavy metals on physiological parameters and photosynthetic activities of two moss species grown in aquatic media or moist soil surface. We suggest that a phenotype with anthocyanin accumulation pattern and chlorosis pattern and two chlorophyll fluorescence parameters with their images can roughly reflect metal species groups, concentrations and differences between the two moss species. In other words, metal contaminations could be roughly estimated visually using the naked eye. Enzymatic and non-enzymatic anti-oxidative abilities and photosynthetic protein contents of Eurhynchium eustegium were higher than those of Taxiphyllum taxirameum, indicating their differential metal tolerance. Neither anti-oxidative abilities nor photosynthetic proteins were found to be ideal indicators. This study provides new ideas to monitor heavy metals rapidly and non-invasively in water or on wetland and moist soil surface.