Strip Mine Sites Research Articles

An acellular assay to assess the genotoxicity of complex mixtures of organic pollutants bound on size segregated aerosol. Part I: DNA adducts

An acellular assay consisting of calf thymus DNA with/without rat liver microsomal S9 fraction was used to study the genotoxicity of complex mixtures of organic air pollutants bound to size segregated aerosols by means of DNA adduct analysis. We compared the genotoxicity of the organic extracts (EOMs) from three size fractions of aerosol ranging from 0.17 μm to 10 μm that were collected by high volume cascade impactors in four localities of the Czech Republic differing in the extent of the environmental pollution: (1) small village in proximity of a strip mine, (2) highway, (3) city center of Prague and (4) background station. The total DNA adduct levels induced by 100 μg/ml of EOMs were analyzed by 32P-postlabelling analysis with a nuclease P1 method for adduct enrichment. The main finding of the study was most of the observed genotoxicity was connected with a fine particulate matter fraction (<1 μm). The concentrations of carcinogenic polycyclic aromatic hydrocarbons (c-PAHs) in EOMs indicate that fine fractions (0.5–1 μm) bound the highest amount of c-PAHs in all aerosol sampling sites, which might be related to the higher specific surface of this fraction as compared with a course fraction (1–10 μm) and higher mass as compared with a condensational fraction (0.17–0.5 μm). As for aerosol mass, both fine and condensational fractions are effective carriers of c-PAHs. Similarly, the DNA adduct levels per m 3 of air were highest for the fine fraction, while the condensational fraction (strip mine site and city center) revealed the highest DNA adduct levels in cases where aerosol mass is taken into consideration. A strong correlation was found between the c-PAHs and DNA adduct levels induced by EOMs in all the localities and for various size fractions ( R 2 = 0.98, p < 0.001). It may be concluded that the analysis of total DNA adducts induced in an acellular assay with/without metabolic activation represents a relatively simple method to assess the genotoxic potential of various complex mixtures.

Photosynthetic rates and vegetative production of Sorghastrum nutans in response to competition at two strip mines and a railroad prairie

The effect of differing environmental conditions on competition for resources was investigated by a comparison of net photosynthetic rate (PN) and vegetative production of Indiangrass [Sorghastrum nutans (L.) Nash.] at two strip mine sites with differing reclamation histories, and a railroad prairie site where this species occurs naturally. The treatment for a competition experiment consisted of tying back all species of neighboring plants around a target plant, and measuring its PN and vegetative performance during the growing season. Environmental variables at each site were also measured during the growing season. Soil bulk density and pH were higher at the two mine sites than at the prairie site, and soil texture, nutrients, and water potential were different at each of the three sites. PN of target plants compared closely among the three sites, and were lowest for plants at the railroad prairie. The competition experiment indicated that lower canopy leaves were most affected by competition for photosynthetically active radiation (PAR) at all sites. Significant differences in PN of upper canopy leaves were found between treatment and control plants at one of the mine sites. This site had higher soil water potentials and higher soil levels of P and K than the other mine site or the railroad prairie. Target plants at the other mine site experienced a low competition for PAR, likely due to lower soil moisture availability and therefore lower aboveground productivity. The largest differences in PN and irradiances between upper and lower canopy leaves occurred in target plants with neighbors at the railroad prairie, likely due to inter-specific competition. Vegetative production of the target plants also reflected the environment at each site, but did not reflect PN differences between treatments. S. nutans is well adapted to the varying environment at these three sites, and aboveground competition for radiant energy was probably not as limiting for this C4 grass as belowground competition.

Physiological Performance of Andropogon gerardii, Panicum virgatum, and Sorghastrum nutans on Reclaimed Mine Spoil

AbstractPhysiological and vegetative performances of three prairie grasses were investigated to assess their adaptation to soil conditions at two strip mine sites and a nearby railroad prairie. Additionally, rhizomes of the species were transplanted to a pot experiment and grown in both field soil and greenhouse potting medium to investigate the extent to which plants are limited under field conditions. Field measurements of photosynthetic rate and stomatal conductance to water vapor were made on the three species monthly from May to late August. Gas exchange measurements on potted plants were made biweekly from early May to mid‐July. In September, vegetative and flowering characteristics were measured on both field and potted plants. Field gas exchange rates were highest at one of the mines. Sorghastrum nutans had the highest rates at the mine sites, whereas Panicum virgatum had the highest rates at the prairie site. Potted plants from the prairie site usually exhibited the highest gas exchange rates, and Sorghastrum nutans had higher rates than Panicum virgatum and Andropogon gerardii. Potted plants in field soil generally had higher gas‐exchange rates than plants growing in greenhouse potting medium, and potted plants had higher gas‐exchange rates than field‐grown plants. Vegetative and reproductive performance of field plants was highest at one of the mine sites. Potted plants in greenhouse medium had up to twice the vegetative and reproductive output as potted plants in field soil or plants growing in the field. The physiological and vegetative performance of these species indicates that they are well adapted to the soil conditions at these strip mine sites, and that they are a viable alternative to nonnative plantings for restoration.

Eroded Aggregate Size Distributions from Disturbed Lands

A characterization of eroded soil properties, especially size, is required for proper usage of modern process-based soil erosion models. In a study addressing reclaimed mine land erodibility, over 350 measured eroded aggregate size distributions were collected from erosion plots created on reclaimed and nearby unmined soils at three separate strip mine sites. The experimental design allowed for a comparison of eroded aggregate size distributions as a function of land slope, run sequence, and reclamation treatment. No influence of slope was apparent, as distributions collected from plots constructed at 6% slope were coarser than those collected from 18% slope, but finer than those collected from 12%. Samples collected during extra inflow runs, in which runoff rates, flow velocity, and rill erosion were greatest, had coarser distributions than samples collected during rainfall only runs, which tended to have similar distributions. Distributions from reclaimed topsoil treatments were similar to nearby unmined soils and were distinct from subsoil reclamation treatments. At two sites, topsoil treatments had coarser distributions, while the converse was true at the third.

A Geotechnical Investigation of Abandoned Strip Mines for Sanitary Landfill Purposes

Five strip mine sites in northeastern Ohio were selected to investigate their suitability as sanitary landfills. Engineering properties of the mine spoil from each site were studied for possible utilization as a cover and as liner material. Detailed investigations were conducted to evaluate the geologic and hydro-geologic conditions at each site. The mine spoil can be generally classified as a well-graded sand with fines of low plasticity. Laboratory density values range from 99 to 124 pcf (1.59 to 1.99 Mg/m 3 ) whereas in-situ density values of end-dumped, uncompacted, spoil range from 75 to 118.5 pcf (1.20 to 1.90 Mg/m 3 ). Density vs. permeability curves indicate that the required permeability of a cover material (1 × 10 −5 cm/sec) can be obtained at approximately 90 percent relative compaction while some spoil material can meet liner specifications (1 × 10 −7 cm/sec) at a relative compaction of 95 percent or more. Permeability values of spoil compacted at maximum dry density and slightly wet of optimum moisture content range from 2.5 × 10 −7 to 5.6 × 10 −8 cm/sec whereas field infiltration tests yield permeability values ranging from 5 × 10 −3 to 5 × 10 −7 cm/sec. The in-situ values of moisture content generally fall on the wet side of the optimum. Slake durability indices range from 54.6 to 97.7 suggesting that shales in the mine spoil have medium to very high resistance to slaking. The engineering properties of the mine spoil indicate that it is highly suitable for use as a cover material but only marginally suitable for use as a liner material. Shale is the predominant rock type underlying the sites. Underclay, which greatly increases the suitability of a site as a landfill, is present at three of the five sites. Generally, no significant aquifers were found immediately below the sites. Most water supplies are obtained well below the land surface and would be hydrologically separated from surface operations by the intervening clay and shale. These investigations indicate that properly engineered abandoned strip mines can be environmentally sound for sanitary landfill purposes.

Backfill settlement of restored strip mine sites - case histories. Short communication: Reed, S M; Hughes, D B; Singh, R N Int J Min Geol EngngV5, N2, July 1987, P161–169

Backfill settlement of restored strip mine sites - case histories. Short communication: Reed, S M; Hughes, D B; Singh, R N Int J Min Geol EngngV5, N2, July 1987, P161–169

Municipal Sludge for Minespoil Reclamation: II. Effects on Organic Matter

AbstractA field study of five coal stripmine sites reclaimed with sewage sludge and one site reclaimed with chemical fertilizer was conducted to determine the effects of sludge amendments and time on dry matter yields, detritus accumulation, root growth, organic matter content, and soil organic C and N content. The reclaimed sites ranged in age from 1 to 5 yr following reclamation with sludge at rates of 120 to 134 Mg ha−1 (dry wt. basis). The fertilizer‐amended site was 5 yr old. All sites were planted in grass and legume cover. On the sludge‐amended sites, yield, detritus, root growth, and organic matter were positively correlated with site age, increasing from the 1‐yr‐old to the 3‐yr‐old site. On the 4‐yr‐old and 5‐yr‐old sites values were greater than or equal to the 2‐yr‐old site, and no indication of site deterioration was evident. Organic C significantly increased from the 1‐yr‐old to the 2‐yr‐old site, and was highest on the 5‐yr‐old site. Total N remained constant on all sites. On the three older sites detritus accumulation and root growth surpassed that of the 5‐yr‐old fertilizer‐amended site. Yield and organic matter content on the four oldest sludge sites surpassed that of the fertilizer‐amended site, and organic C and N content on all sludge sites surpassed that of the fertilizer‐amended site. As measured by these parameters, eventual soil development and ecosystem recovery appear to be accelerated on the sites reclaimed with sludge compared to the fertilizer‐amended site.

Effect of Acidity on Germination and Seedling Growth of Paulownia tomentosa

(1) Seed germination and seedling growth of Paulownia tomentosa were evaluated over a pH range of 1 5-7 0 to determine the species' suitability for use in the reclamation of acidic strip-mine environments. (2) No seed germination occurred below pH 40, and seedling emergence was significantly reduced in soil of pH 4 5. Further, seedling growth was depressed in soil of pH 4 5, with significantly lower root length, leaf number and root and shoot dry mass, when compared with seedlings grown on soils of pH 5-5 and 6 5. (3) Although P. tomentosa invades strip-mine sites, measurements of the effect of acidity on seed germination and seedling growth suggest that only less acidic microsites may be habitable.

Backfill settlement of restored strip mine sites — case histories

Backfill settlement of restored strip mine sites — case histories

Soil compaction in topsoil replacement during mining reclamation

Current U.S. mining regulations require revegetation in reclaiming surface mines. Excessive soil compaction can be an impediment to successful revegetation in poor soil conditions common to Eastern U.S. coal mine sites. A field study was performed to determine the bulk densities of soils that had been spread by either bulldozers or scrapers at a strip mine site. Moisture-density relationships for the soils were determined from the field samples. These were compared with samples compacted by the Standard Proctor compaction test. The results of the study indicate that the degree of compaction, could be lessened through proper soil handling procedures.

Survival and growth of conservation shrubs and trees, with thin-cover reclamation on acid substrate, Iowa, USA

Many abandoned strip-mine sites in midwestern USA are highly acidic and require a separate layer of low-acidity cover materials for successful revegetation. Economics and logistics often constrain this reclamation to a very thin cover. Twenty-two species of shrubs and trees were tested for 6 years of survival and growth on a thin wedge of silt loess (up to 0.75m thick) emplaced over highly acid spoils, in south-central Iowa. No weed control or maintenance was provided. The performance of 21 of the species could be categorized into 3 groups: Group 1-consistent survival (10 species); Group 2-irregular survival and growth (6 species); Group 3-little suitability for survival (5 species). Mouldy nursery stock precluded evaluation of 1 species.For most species, the most favourable survival and growth was not on the thickest loess cover (0.75 meters) because weeds became too well established. In general, the shrubs survived severe weed competition in dwarfed form until they could break through the weed canopy. But the tree species had to penetrate the weed canopy within their first few years of growth or perish. There is evidence that if weed competition were reduced or eliminated, the species in Group 2 would probably have survival and growth equivalent to those in Group 1. The use of "tubelings" for establishing shrubs and trees on thincover reclamation sites is suggested.

Relationship between the ectomycorrhizal fungus Pisolithus tinctorius associated with loblolly pine and acid-generating Thiobacillus spp. on an acidic strip mine site

Loblolly pine seedlings were transplanted onto a pyritic coal mine site in a commercial reclamation effort. After 5 years, trees which became naturally infected with Pisolithus tinctorius, or other ectomycorrhizal fungi which produced sporocarps, were twice the height and stem diameter of trees not associated with sporocarps. The hypothesis that P. tinctorius promotes superior growth of its host by inhibiting the growth or activity of Thiobacillus ferrooxidans and T. thiooxidans, which catalyze production of sulfuric acid from pyrite, was examined. Soil pH was lower in the root zones of trees associated with P. tinctorius than with trees not associated with P. tinctorius, and sulfate was higher. Differences were not found in ferric or ferrous ions or in populations of the two bacterial species. Apparently P. tinctorius benefits its hosts by mechanisms other than inhibition of Thiobacillus spp.

Results of a Tree Species Trial on a Recontoured Surface Mine in Southwestern Virginia

Abstract Fifteen tree species, five pine and ten hardwood, were planted on a reclaimed, return-to-contour, strip-mine site in Wise County, Virginia. A systemic herbicide was sprayed on half of each of four experimental blocks prior to the second growing season. After three growing seasons, this treatment resulted in increased survival of five species. Black locust (Robina pseudoacacia) performed best with 90% survival and a tenfold increase in height. Other hardwoods that showed promise were black alder (Alnus glutinosa), sycamore (Platanus occidentalis), and cottonwood (Populus deltoides). As a group, the pines outperformed the hardwoods. Loblolly (Pinus taeda) and Virginia pine (Pinus Virginiana) were the fastest growing, and survival of each was signifcantly higher on the sprayed plots.

Enumeration and characterization of nitrogen-fixing bacteria in a stripmine site

Nitrogen-fixing heterotrophic bacteria were isolated from a stripmine reclamation site in western North Dakota. Of 232 isolates, 164 wereBacillus spp., 38 were members of the Enterobacteriaceae, and 21 wereClostridium spp. Single isolates ofAzotobacter chroococcum andAzospirillum lipoferum were identified, as were several isolates considered to beXanthobacter autotrophicum. Fewer nitrogen-fixing bacteria adhered to the root system of crested wheatgrass (Agropyrum desertorum) in sites with replaced topsoil than in sites with no topsoil. Several media and techniques were compared in enumeration of nitrogen fixers by most probable numbers.

Growth and fungal persistence by Quercus rubra inoculated with ectomycorrhizal fungi and planted on a clear-cutting and strip mine

Quercus rubra seedlings were grown in a greenhouse in media inoculated with and without vegetative hyphae of the ectomycorrhizal fungi Pisolithus tinctorius, Cenococcum geophilum, Scleroderma auranteum, and Rhizopogon nigrescens. Some seedlings were also inoculated with basidiospores of P. tinctorius and S. auranteum in the greenhouse. Rhizopogon nigrescens did not infect the seedlings during greenhouse production. Seedlings were planted and grown for two seasons on clear-cut and strip-mine sites. Some nonmycorrhizal seedlings were inoculated with basidiospores at planting. Seedling growth after one season on the clear-cut site was positive for all P. tinctorius, C. geophilum, and vegetative S. auranteum inoculations and significant differences in growth occurred among inoculation treatments. Root-core samples after one season showed that 80–100% of the seedlings on the clear-cut site had fungal persistence of assigned fungal species from all fungal inoculations except that no ectomycorrhizae were evident with seedlings field inoculated with basidiospores. Growth after two seasons on the clear-cut site was significantly different among treatments but not significantly different on the strip-mine site. Excavated root systems after two seasons showed that 0–100% of the seedlings on the clear-cut and strip-mine sites had fungal retention of assigned fungal species and ectomycorrhizae from basidiospore chip inoculations.

Endomycorrhizal fungi occurring on orphan strip mines in Kentucky

Abandoned strip-mine sites in Kentucky which were mostly naturally revegetated were examined for the presence of endomycorrhizal fungi in the rhizospheres of established trees and other plants. Soil pH ranged from 3.2 to 7.1. Sixty-five percent of root samples examined were found to be mycorrhizal. Eight Glomus, three Gigaspora, and two Acaulospora species were positively identified. Plants sampled had one to eight different mycorrhizal species associated with them. The mean number of species per plant was 3.2. Spore numbers ranged from 0.4 to 53.0 spores per gram soil, with a mean value of 12.3 spores per gram. Strip-mine sites such as these may be a good source of ecologically adapted endomycorrhizal fungi for use in strip-mine reclamation.

Fertilizer-induced pathogenicity of mycorrhizal fungi to sweetgum seedlings

One isolate of Glomus clarus, two of G. etunicatus, and one of G. claroideum, obtained from plants growing on abandoned stripmine sites in Kentucky, and an isolate of G. fascicutatus known to stimulate growth of various woody plants, were evaluated for their influence on growth of sweetgum seedlings in a mixture of sand and stripmine soil. Soils were supplemented with various rates of a complete slow-release fertilizer. Throughout the growth period, G. fasciculatus, and most of the stripmine isolates, stimulated growth at low fertilizer rates. At higher fertilizer rates, including the level optimum for non-mycorrhizal plants, the stripmine isolates inhibited plant growth. After 14 weeks, plants inoculated with one of the four stripmine isolates overcame the early growth depression, and those inoculated with a second isolate appeared to be overcoming the growth depression. G. fasciculatus was not inhibitory at any fertilizer rate. Root colonization by all three isolates evaluated was inhibited by the highest fertilizer rate, but this effect was not related to growth inhibition of plants. The other two isolates colonized roots at an extremely low rate (< 1%). Sporulation of all the stripmine isolates, but not G. fasciculatus, was also inhibited by the highest fertilizer rate. The G. fasciculalus isolate used in this study may be atypical of mycorrhizal fungi occurring randomly in nature in its mutualistic or neutral effect on plants under a wide range of growth conditions.