CHITIN ADSORPTION IN ENVIRONMENTAL MONITORING: NOT AN ALTERNATIVE TO MOSS MONITORING BUT A METHOD PROVIDING (LOTS OF) BONUS INFORMATION

Although moss-based biomonitoring of environmental pollutants (heavy metals, POPs, reactive nitrogen, and sometimes other items) is well established after 50 years of a history starting in Scandinavia, the method now faces a crisis also in terms of funding. This latter is due to the assumption that precision and reproducibility of this biomonitoring method are too poor to provide information on small recent changes of situation well after the large changes had occurred, that is, around 1990. In addition, moss-monitoring requires that conditions where mosses can live and grow be constantly kept over a longer period of time; measurements in the dark or at sites where there are high levels of herbicides, radioactivity, acids, etc. cannot be accomplished at all; proper identification of used moss species is crucial, too. Hence moss-monitoring should be supplemented by other methods which - unlike passive biological or synthetic filters of atmospheric deposition - can provide information on local transport (both by airborne deposition and underground biological uptake or precipitation, plus reductive dissolution of sulfates) at ecotones such as the water/sediment interface at bottom of water-bodies or at some shore. Studies of adsorption to chitin, which originally had been applied for fractionation of radioactive waste and for withholding trace concentrations of heavy metals from wastewaters, can fill this gap as more robust "dead" (grafted) chitin is used. Adsorption is fast, and even minute traces of analytes can be recovered. Analytics are cheap and straightforward, requiring no digestion of samples. In understanding the data, some calibration line(s) for partition of both di- and trivalent metal ions (best: such which are not involved in biological processes) between water- and sediment-exposed chitin samples are constructed then to identify "deviations" from this expectation. These can be due to biological uptake of trace elements (Ni by methanogenes, plants, Mo, certain more "exotic" bioelements), precipitation (Fe, Mn), reductive dissolution (sulfates of Ba, Pb, Eu exposed to ascending CH4 ) or, of course, atmospheric or aquatic pollution from above. As a rule, chitin-related partition of toxic nonmetals (As, Se) does respond to different environmental conditions, vegetation covers less than metal ions will do. Grafted chitin can be fitted to robots like drones transporting it to hazardous sites where organisms (arthropods, lichens) would not survive. Of course, data of this kind can be combined with pieces of information from biomonitoring (are there organisms controlling transport of certain elements?, is there eutrophication of open waters?) and biogeochemistry.