Part 3-Restoration: Ilorrocks and Ohms-Lint and Dust 351 Section C-Restoring Cave Passages Cave Lint and Dust Removal Projects Rodney D. Horrocks and Marc Ohms The cumulative nature and impact of lint and dust problems in caves has only recently been recognized, researched, and addressed. Originally noticed in show caves, lint and dust accumulations have also been observed Lint is not merely a in heavily used wild caves. Lint is not merely a benign aesthetic nuisance in caves. Lint and dust benign aesthetic removal projects benefit caves in several ways: nuisance in caves. Lint and dust Restore natural conditions. remoyal projects Prevent unnatural speleothem dissolution. benefit caves in Remove artificial food sources. • Eliminate unnatural odors. several ways . Restore visual scenes. Lint consists of foreign materials shed from human visitors-fibers, hair, dander, and other debris that accumulates along heavily used routes (Figure I). Dust originates from trail construction projects, trampling of unpaved trails, and material brought into the cave by visitors. Lint and dust accumulations can be removed with hand-held brushes, vacuums, or washing, depending on the substrates involved. Not only have methods been developed to restore natural conditions in caves, but tech- niques have also been developed to slow the accumulation and facilitate cleaning of these unnatural deposits. Attempts to restore the aesthetic appeal of developed caves occurred as early as 1960 in Jenolan Caves in Australia (Newbould 1976). Lint was recognized as an unsightly foreign material as early as 1969 at Timpanogos Cave (Horrocks 2000). However, it was not until 1977 that lint was Figure I. Close-up of specifically targeted as a detrimental foreign substance in caves and was collected lint and hair identified as a major component of the dirty-appearing passages in many in Timpanogos Cave developed caves (Roth 1987). Test cleaning was conducted at Carlsbad National Monument, Caverns in 1977 and 1986, and the first "cave lint camps" were organized Utah. in 1988 (Jablonsky 1992a). This chapter empha- sizes lint and dust removal in developed caves. However, the same techniques can be used in wild caves. Reasons for Conducting Lint and Dust Removal Projects Developed caves can only be partially restored to ~ natural conditions. Cave managers must com pro- ~ mise between restoring caves to pristine states and ~ causing additional negative impact. Good cave :g managers must recognize when restoration and ~ z 352 Cave Conservation and Restoration cleaning projects need to be halted. Cave managers or project leaders should stop the work, rethink the situation, and possibly retrain the restoration team before additional damage is caused. Because the impacts from lint and dust are cumulative, periodic restora- tion efforts are usually effective toward maintaining natural conditions in show caves. Removing unnatural lint and dust can prevent foreign materials from being cemented onto the surfaces of actively growing speleothems. The incorporation of introduced materials into secondary deposits can cause permanent discoloration and unnatural textures. In fact, accumulations of lint and dust may partially or completely obscure the natural coloration and sheen of cave surfaces. Lint has been shown to cause the dissolution of some speleothems (Jablonsky and others 1994). Lint may act as a condensation site for undersaturated cave water, and can trap carbon dioxide in or underneath the lint. Lint may also attract bacteria, yeast, molds, or algae that secrete or excrete acids that can dissolve the rock substrate (Crowle 1993a, 1993b). The accumulation of lint in humid cave environments may also result in unnatural musty odors (Moore 1993). Many caves are extremely low-energy environments with limited food sources. Natural fiber lint, hair, and skin (dander) can represent a signifi- cant artificial food source and may provide a nutrient base for microbial life (Moore and Jesser 1995). These food sources can shift the balance of Figure 2. This nutrients that sustain cave-adapted microorganisms (Michie 1997). Biota, collection of lint, trash, such as microbes, mites, beetles, and spiders have been observed in lint and chunks of blond accumulations (Jablonsky 1992a, I992b). Whether the organisms are native boot sole was gathered to the cave or accidentals carried into the cave by humans, populations may in the Chandelier artificially balloon as a result of artificial food sources. (See cave microbi- Maze, Lechuguilla ology, page 61). Cave, Carlsbad Caverns National Park, Nature of Lint and Dust New Mexico. Developed caves may have a dusty and dirty appearance caused by a combination of factors. In order of importance, they are listed here: Construction-generated dust Dust from tours traveling over unpaved trails Dust tracked into caves on shoes or brought in on clothes • Lint accumulations • Other materials shed from humans • Natural dust Human visitors shed a plethora of other materials into caves (Jablonsky 1995). Lint and dust removal efforts should address most of these foreign materials: Hair Dander Skin flakes and debris Mites Microbes Shoe rubber Pet animal fur Part 3-Restoration: Lint and Dust-Horrocks and Ohms 353 Lint is composed primarily of fibers from natural and synthetic fabrics. Natural cellulose-based fibers include cotton, hemp, and linen. Natural protein-based fibers include keratin, wool, alpaca, mohair, silk, and cashmere. Synthetic fibers include oil-based synthetic polymers (Michie 1997). Both natural and synthetic fibers are usually present. Old deposits of lint in caves may be almost entirely synthetic fibers. Natural libers are morc brittle and tend to shed more over time but they are often eliminated by deterioration or consumed by molds, fungi, or bacteria, resulting in concentrations of synthetic fiber lint (Jablonsky 1995). Dust is composed of silica and fine clay mineral particles ranging from 0.1 micron to 100 microns In sIze. Recognizing Lint and Dust Accumulations Due to the gradual accumulations oflint and dust Q; in show caves, long-term employees may not ~ recognize the subtle color changes and worsening ~ l' conditions associated with these deposits. These :g conditions are noticeable only when the walls near ~ trails are viewed close-up with a bright flashlight. ~ Older deposits appear as a grayish mass made up nf finely ground lint and Figure 3. This strand dust. Black lights are useful in locating lint concentrations because many of hairy lint was found natural fibers are treated with optical brighteners that reflect long-wave ofTtrai I near Lake ultraviolet (UV) light. When viewed under a black light, these fibers Chandalar, Lechu- appear bluish-white against dark cave surfaces. guilla Cave, Carlsbad Caverns National Accumulation of Lint Park, New Mexico. Lint accumulation is influenced by many different factors: Number of cave visitors Gravity A if movement Cave wall contours and textures Trail design Heat Humidity Generally, more visitors lead to greater deposits of lint. Mammoth Cave, Kentucky, and Carlsbad Cavern, New Mexico, generate tremendous accumulations oflint in short periods of time. Observations in Lehman Caves, Nevada, showed noticeable lint accumulating one year after cleaning (Horrocks and Green 2000). Lint accumulates faster at interpretive stops, especially those where visitors sit down. More lint is produced by a combination of longer times spent at sit-down spots and the abrasive nature of clothes rubbing against benches. Lint fibers also get caught in shoe soles and are tracked through- out tour routes. Most lint initially falls directly to the floor and is then moved laterally to the edge of the trail by foot traffic. Lint also tends to concentrate on the lower portion of walls immediately adjacent to trails. Trail design and construction materials can influence how and where lint accumulates. 354 Cave Conservation and Restoration • Trails with curbs 20- to 60-centimeters (8- to 24- inches) high, capture a large percentage of lint falling from visitors' clothes (Jablonsky 1995). • Trails with grates and underlying tarps capture a larger percentage of lint. Grated trail surfaccs must be periodically cleaned because the open sp.aces become i chokcd with lint, dust, and other debris. "i ~ Airflow determines where lint accumulates. Over l time, trampled fibers on the trail become airborne ~ and are carried by air movement and redeposited Z on cave surfaces away from the Figure 4. Along trails. Large quantities of lint may be deposited on ledges high above a trail developed cave lour or on ceiling formations (Figure 4). Fibers less than 3 microns in size will routes, lint is carried become suspended immediately, without falling to the trail. These fibcrs on air currents and will dcsccndcd at a rate of 1 meter (3 feet) every 9 minutes in laboratory collect and mass along conditions (Moser 1988). certain ledges. This Manmade entrances and tunnels may artificially increase cave airflow example from and compound lint problems. Lint accumulations lend to concentrate on Timpano-gos Cave flat or sloping shelves. Lint also accumulates on any rough surface, National Monument especially on stalactites, popcorn, helictites, spiked frostwork, or on shows thick lint low ceilings. [n dryer areas, accumulations will often ball up into "lint deposits on a ledge. bunnies." Heat generated from lights and visitors can cause distribution, or redistribution, of lint near trails. Movement of people also causes airflow disturbances