Evaluation Of The Usefulness Of Spider Webs As An Air Quality Monitoring Tool For Heavy Metals

The study aims at evaluating whether webs reflect the level of air pollution measured with conventional methods. Webs of species Malthonica silvestris (l. KOCH, 1872) (Araneae: Agelenidae) were sampled. Samples were analyzed for heavy metals (Pb, Zn) content. According webs analyses and classic measurements three traffic-oriented sites in Wroclaw (South-West Poland) showed significantly higher mean concentrations of heavy metals than two other sites situated in quieter, low traffic areas. A very strong significant positive correlation was revealed among average concentrations of Zn and Pb associated with fine particulate matter of atmospheric aerosol (PM₁) and webs. We also observed a very strong significant positive correlation among Zn and Pb concentrations on webs and PM_2.5. Any significant correlation among PM-emission fractions 2.5 and 10 and associated heavy metals and dust deposited on spider webs was not observed. Although spider webs proved useful indicators of environmental pollution the obtained results suggest that this tool should be used to evaluate the emission of heavy metals in the similar way as other bioindicators such as mosses and lichens are commonly used. The measured concentrations on webs do not reflect results obtained with classic methods. We conclude that spider webs are good for bioindication of road traffic emissions, they could be even more reliable compared to use of some other bioindicators whose activity is often limited by the lack of water and sun.