Magnetic
biomonitoring of mosses and lichens (referred to as cryptogams) is a rather new
approach to air quality studies and assessments. Magnetic biomonitoring is a part
of environmental magnetism. The discipline is based on the fundamental nature
of magnetism and the ubiquitous presence of iron-bearing mineral particles in
the environment. Magnetic mineral particles and air pollutants, such as heavy
metals, originate from the same sources and are subjected to environmental
processes. Heavy metals are bound to magnetic particles. Thus, they are
typically present together in the environment. Information about the
concentration, composition and grain sizes of magnetic mineral particles and
heavy metals are obtained by investigating the magnetic properties of environmental
samples. In enviromagnetic air quality research, cryptogams are applied as
passive in situ biomonitors and as
active transplant biomonitors in urban and industrial areas. The use of the active
moss bag technique is presently hampered by the lack of international
standardisation and guidelines but attempts to establish these have emerged.
Current studies have successfully described the characteristics of magnetic
particles; indicated spatial and temporal differences in the pollution
distribution and levels on different scales; helped to recognise
anthropogenically loaded hot-spots and other contaminated areas; strengthened
the role of existing sources, and revealed unknown or underrated pollution
sources; and advanced the methodology of cryptogam usage in magnetic
biomonitoring by comparing the feasibility of different species. Overall, the
combined use of enviromagnetic methods and traditional cryptogam biomonitoring
has several advantages: the magnetic methods describe in detail the
characteristics of pollutants while easy and cost-effective biomonitoring
yields spatially and temporally representative air quality data. Therefore,
magnetic biomonitoring can produce the data needed for investigating
health-related issues, and for establishing and evaluating the air pollution
levels and limits. Moreover, it has the potential to become a valuable and
officially recognised tool for air quality assessments and monitorings in the
near future.