Can Chitin and Chitosan Replace the Lichen Evernia prunastri for Environmental Biomonitoring of Cu and Zn Air Contamination?

Abstract

This study compared the ability of the lichen Evernia prunastri, chitin and chitosan to take up Cu2+ and Zn2+. It was hypothesized that chitin and chitosan have an accumulation capacity comparable to the lichen, so that these biopolymers could replace the use of E. prunastri for effective biomonitoring of Cu and Zn air pollution. Samples of the lichen E. prunastri, as well as chitin (from shrimps) and chitosan (from crabs), were incubated with Cu and Zn solutions at concentrations of 0 (control), 10, 25, 50, 75, and 100 µM and analyzed by Inductively Coupled Plasma Mass Spectrometry (ICP-MS). Metal concentrations accumulated by lichen, chitin and chitosan samples were strongly and linearly correlated with the concentrations in the treatment solutions. The lichen always showed significantly higher accumulation values compared to chitin and chitosan, which showed similar accumulation features. The outcomes of this study confirmed the great effectiveness of the lichen Evernia prunastri for environmental biomonitoring and showed that chitin and chitosan have a lower accumulation capacity, thus suggesting that although these biopolymers have the potential for replacing E. prunastri in polluted areas, their suitability may be limited in areas with intermediate or low pollution levels.

Chitin as a Sorbent Superior to Other Biopolymers: Features and Applications in Environmental Research, Energy Conversion, and Understanding Evolution of Animals

“…This transition is located at −1.50 V vs. SCE which translates into −1.07 V vs. NHE in DMF (the larger difference vs. SCE owing to the higher proton affinity of this solvent) and thus pK a(M x+ -OH); dmf ≈ 18, comparable to anion acids (HSO 4 − , HC 2 O 4 − ) [43] or glycine (own measurements) in this solvent. Using the equations pK a(dmf) = 23.48 − 22.91 σ para (10) pK a(dmf) = 10.82 − 9.12 σ R for RCOOH (11) derived by us for acidities of oxoacid solutions in DMF, one can estimate σ para for the metal-loaded OH groups to be + 0.24 (comparing to metal-free OH = −0.37). By now, there are no σ para -based regressions for all the metals studied concerning their interactions with chitin, but there is a focus on those which are most important in our own work.…”

“…Sampling was conducted by either grafted chitin [14] and/or collecting arthropods [17,22], lichens [10]. The former method is preferred for reasons of both (a) protection of possibly endangered species and (b) full control of exposition times while…”

“…(parameters calculated by SF [36]) depend on denticity d and charge of ligand. Thus, a couple of parameters is required rather than a single set, given in the following Table 3: The advantage of ( 1) is that many more Hammett constants σ are available (e.g., [28]) than electrochemical ligand parameters [10,29,31].…”

“…There are no indications for isotopic fractionation of multi-isotopic elements during chitin adsorption; for example, determinations of Sm content on chitin surfaces using isotopes 147 Sm, 149 Sm, and 152 Sm, respectively, provide the same result assuming the normal isotopic composition of samarium [18]; (this does likely permit to reconstruct the whereabouts of chitin-covered organisms by means of Pb [41] isotopic signature). Solvent impact may alter chitin structure [42]; acidity values of potential ligands (protonated forms thereof) in DMF are given in [43] and were used besides own measurements to derive Equations ( 9) and (10).…”

“…Thus, chitin is the material of choice if one wants to study sorbent properties concerning, e.g., trace metals in environmental analytics. Moreover, many different organisms, including such of meaningful operative surface sizes such as spiders [9], lichens [3,10] or many insects, crabs, and crayfish are fully or partially covered by chitin which can in turn be sampled without necessarily killing the animals or lichens. The surface of grafted chitin surface used for adsorbing metal ions has a diameter of 1 cm and thus an active surface of some 0.78 cm 2 .…”