Large Smelter Research Articles

Seagrass soils sequester up to half the metal emissions of one of the world's largest smelters

One of the world's largest smelters has been operating in South Australia since 1889, affecting environment and human health. Here we quantified the magnitude of Pb, Zn and Cd emissions from the smelter sequestered in the soil of an adjacent 110 km2Posidonia australis seagrass meadows. Seagrass core records show that the smelter contaminated the entire area with decreasing sequestration with increasing distance from contamination points. The soil accumulated ~1300 t of Pb, ~3450 t of Zn, and ~ 90 t of Cd since 1889, and sequestered the equivalent of ~20 % of Pb, and ~50 % of Zn and Cd cumulative smelter emissions since 1999, showing that seagrass can be significant, long-term sinks of metal pollution in highly contaminated environments. Conservation efforts should prioritize these seagrass meadows to avoid the potential release of pollutants from their soils following habitat loss, which could turn seagrasses from a sink to a source of pollution.

Long-Term and Multipoint Observations of Atmospheric Heavy Metal (Cu and Cd) Deposition and Accumulation in Soil–Crop System and Human Health Risk Evaluation Around a Large Smelter

Long-Term and Multipoint Observations of Atmospheric Heavy Metal (Cu and Cd) Deposition and Accumulation in Soil–Crop System and Human Health Risk Evaluation Around a Large Smelter

Impacts of atmospheric copper and cadmium deposition on the metal accumulation of camphor leaves and rings around a large smelter.

The atmospheric deposition of copper (Cu) and cadmium (Cd) was monitored in eight sites around a Cu smelter with similar distance to verify whether tree leaf and ring can be used as bio-indicators to track spatial pollution record. Results showed that total atmospheric deposition of Cu (103-1215 mg/m2/year) and Cd (3.57-11.2 mg/m2/year) were 4.73-66.6 and 3.15-12.2 times higher than those in background site (164 mg/m2/year and 0.93 mg/m2/year). The frequencies of wind directions significantly influenced the atmospheric deposition of Cu and Cd, and the highest atmospheric deposition of Cu and Cd were at the prevalent northeastern wind (JN), and low frequency south (WJ) and north (SW) winds for the lowest deposition fluxes. Since the bioavailability of Cd was higher than that of Cu, the atmospheric deposition of Cd was more easily adsorbed by tree leaf and ring, resulting in only significant relation between atmospheric Cd deposition and Cinnamomum camphora leaves and tree ring Cd. Although tree rings cannot correctly record the atmospheric Cu and Cd deposition, higher concentrations in the indigenous tree rings than the transplanted tree rings suggested that tree rings can reflect to some extent the variations of atmospheric deposition. Generally, spatial pollution of atmospheric deposition of heavy metals cannot reflect the distribution of soil total and available metals around the smelter, and only camphor leaf and tree ring can bio-indicate Cd deposition. A major implication of these findings is that leaf and tree ring can serve for biomonitoring purposes to assess the spatial distribution of atmospheric deposition metal with high bioavailability around a pollution source with similar distance.

Ecological-health risks assessment and source apportionment of heavy metals in agricultural soils around a super-sized lead-zinc smelter with a long production history, in China

Smelting activities are considered as the primary cause of heavy metal (HM) accumulation in soils, and the human health around the smelter has been a great concern worldwide. In this study, a total of 242 agricultural soil samples were collected around a large scale Pb/Zn smelter in China, and eight HMs (As, Cd, Cr, Cu, Hg, Ni, Pb and Zn) were analyzed to assess HMs status, ecological -health risks, and identify source. Monte Carlo simulation was utilized to evaluate the probabilistic health risks, and positive matrix factorization (PMF) was employed to identify sources. The results revealed the average contents of five heavy metals (Cd 5.28 mg/kg, Pb 203.36 mg/kg, Hg 0.39 mg/kg, Zn 293.45 mg/kg, Cu 37.14 mg/kg) are higher than their background values in Hunan province. Cd had the highest mean pollution index (PI) of 41.8 and the greatest average ecological risk index (Er) of 1256.34, indicating that Cd was the primary enriched pollutant and had a higher ecological risk than other HMs. The mean hazard index (HI) through exposure to eight HMs was 2.95E-01 and 9.74E-01 for adults and children, respectively, with 35.94% of HI values for children exceeding the risk threshold of 1. Moreover, the mean total cancer risks (TCR) were 2.75E-05 and 2.37E-04 for adults and children, respectively, with 75.48% of TCR values for children exceeding the guideline value of 1E-04. In addition, the positive matrix factorization results showed smelting activities, natural sources, agricultural activities and atmospheric deposition were the three sources in soils, with the contribution rate of 48.62%, 22.35%, and 29.03%, respectively. The uncertainty analysis of the PMF indicated that the three-factor solution is reliable. This work will provide scientific reference for the comprehensive prevention of soil HM pollution adjacent to the large smelter.

Camphor Leaves Can Better Bio-Monitor the Spatial Distribution of Atmospheric Copper and Cadmium Deposition than Tree Rings Around a Large Smelter

Camphor Leaves Can Better Bio-Monitor the Spatial Distribution of Atmospheric Copper and Cadmium Deposition than Tree Rings Around a Large Smelter

The Force Analysis of Landing Stage and Transportation Terminal of Large Module with SPMT Trolley

Nickel ore project is the first main part construct project of modular and integrate large smelter. This project includes fifteen modules and its total weight is nearly forty thousand ton and the biggest module is five thousand ton. Use trolley to lade the nickel ore module. Use interim landing stage and shipboard method to land the nickel ore module because of the depth of water. Calculating the three operating modes in the lading process, design the landing stage construct. Thereby lay the foundation to lade the module safely and smoothly.

Potentially toxic element distribution in soils from the Ag-smelting slag of Kutná Hora (Czech Republic): Descriptive and prediction analyses

The distribution and environmental hazard of potentially toxic elements in the vicinity of a large smelter heap located in the traditional mining town of Kutná Hora, Czech Republic were studied. To understand their occurrence and to predict their mobility and deposition, trends and patterns in PTE distribution were related to soil properties and environmental variables. Slag samples and slag impacted soils were characterized by high 2M HNO3 extractable PTE contents which generally increased with depth, but relatively low plant available fractions; Cd and Mn were the most available elements. Manganese availability was significantly higher in soils under vegetation canopy whereas availability of Cu decreased. Organic matter and pH were identified as significant variables controlling availability of Mn, As and Mn, Zn respectively. Availability of Pb and Cu had significant negative correlation with soil clay content. Mean values of Pb, Mn, Cu, Zn and As from sediment samples exceeded the background value for non-polluted alluvial sediment by 1.8, 1.5, 3.4, 9.8 and 1.3 times respectively. Despite the elevated presence of PTE in river sediments, only Mn and Zn were detected in water samples, but at levels which are not considered hazardous. Included in the paper is a method proposal for quickly and easily identifying threshold values of a chosen soil property which control accumulation of PTE in soil respective of their source. The slag heap at Kutná Hora is a proven source of PTE with evidence of their mobility/transport into the surrounding environment. Although the environment is highly heterogeneous, and the mobility of PTE can be dependent upon pedogenic, geologic, ecological, hydrological and climatic variables, overall the study area was characterized by relatively low availability of PTE, with a limited threat to healthy plant development in the immediate surroundings of the smelter slag heap.

Laboratory Toxicity and Benthic Invertebrate Field Colonization of Upper Columbia River Sediments: Finding Adverse Effects Using Multiple Lines of Evidence

From 1930 to 1995, the Upper Columbia River (UCR) of northeast Washington State received approximately 12 million metric tons of smelter slag and associated effluents from a large smelter facility located in Trail, British Columbia, approximately 10 km north of the United States-Canadian border. Studies conducted during the past two decades have demonstrated the presence of toxic concentrations of heavy metals in slag-based sandy sediments, including cadmium, copper, zinc, and lead in the UCR area as well as the downstream reservoir portion of Lake Roosevelt. We conducted standardized whole-sediment toxicity tests with the amphipod Hyalella azteca (28-day) and the midge Chironomus dilutus (10-day) on 11 samples, including both UCR and study-specific reference sediments. Metal concentrations in sediments were modeled for potential toxicity using three approaches: (1) probable effects quotients (PEQs) based on total recoverable metals (TRMs) and simultaneously extracted metals (SEMs); (2) SEMs corrected for acid-volatile sulfides (AVS; i.e., ∑SEM - AVS); and (3) ∑SEM - AVS normalized to the fractional organic carbon (f(oc)) (i.e., ∑SEM - AVS/f(oc)). The most highly metal-contaminated sample (∑PEQ(TRM) = 132; ∑PEQ(SEM) = 54; ∑SEM - AVS = 323; and ∑SEM - AVS/(foc) = 64,600 umol/g) from the UCR was dominated by weathered slag sediment particles and resulted in 80% mortality and 94% decrease in biomass of amphipods; in addition, this sample significantly decreased growth of midge by 10%. The traditional ∑AVS - SEM, uncorrected for organic carbon, was the most accurate approach for estimating the effects of metals in the UCR. Treatment of the toxic slag sediment with 20% Resinex SIR-300 metal-chelating resin significantly decreased the toxicity of the sample. Samples ∑SEM - AVS > 244 was not toxic to amphipods or midge in laboratory testing, indicating that this value may be an approximate threshold for effects in the UCR. In situ benthic invertebrate colonization studies in an experimental pond (8-week duration) indicated that two of the most metal-contaminated UCR sediments (dominated by high levels of sand-sized slag particles) exhibited decreased invertebrate colonization compared with sand-based reference sediments. Field-exposed SIR-300 resin samples also exhibited decreased invertebrate colonization numbers compared with reference materials, which may indicate behavioral avoidance of this material under field conditions. Multiple lines of evidence (analytical chemistry, laboratory toxicity, and field colonization results), along with findings from previous studies, indicate that high metal concentrations associated with slag-enriched sediments in the UCR are likely to adversely impact the growth and survival of native benthic invertebrate communities. Additional laboratory toxicity testing, refinement of the applications of sediment benchmarks for metal toxicity, and in situ benthic invertebrate studies will assist in better defining the spatial extent, temporal variations, and ecological impacts of metal-contaminated sediments in the UCR system.

Automated Metal Siphoning and Cast House Energy Consumption

The transfer of molten aluminium from the potline crucible to the holding furnace is receiving renewed attention as pressure to reduce energy wastage in the form of dross is heightened by the prospect of Emissions Trading. Siphoning has long been recognised as the most loss efficient method of metal transfer and now with the availability of fully engineered, automated systems which are safe and reliable in addition to reducing melt loss by 75%; this method is set to become the industry standard. This paper presents some examples of automated siphon transfer systems and demonstrates the benefits of siphoning in applications ranging from the largest smelters to the smallest of foundry applications.

Characterizing spatial distribution and sources of heavy metals in the soils from mining-smelting activities in Shuikoushan, Hunan Province, China

The spatial variation of heavy metals in the soils in Shuikoushan mining-smelting area, Hunan Province, China, was investigated using multivariate and geo-statistic analysis. A total of 106 composite soil samples were collected in an area of about 100 km2. Concentrations of total As, Cd, Pb, Zn, Cu and Cr were measured using inductively coupled plasma mass spectrometry (ICP-MS). Arsenic and Pb were found to have a common source, indicating the same sources and spreading processes, such as aerosols and airborne particulates from smelting chimneys. Airborne sources from smelting chimneys contributed greatly to Cd in the area, which demonstrated the same dispersion pattern as As and Pb. However, two hot spots of Cd around smelters were possibly enlarged by wastewaters, demonstrating another important source of Cd in Shuikouhsan. Geo-statistic interpolated mapping demonstrated that hot-spots of Zn were only found proximal to the large smelters, suggesting that Zn primarily came from the chimneys of larger smelters. The major Cu hot-spots appeared closely to the tailing dam, indicating that weathering and leaching of tailings were the major sources of Cu contamination in Shuikoushan. Our findings indicated that airborne volatile particles and aerosols contributed the most to As, Cd, Pb, Zn and Cu contamination, while Cd and Cu may also derive from the discharge of wastewater from smelters and the leaching of tailings, respectively.

Smoke Wars: Anaconda Copper, Montana Air Pollution, and the Courts, 1890-1920

Review: Smoke Wars: Anaconda Copper, Montana Air Pollution, and Courts, 1890-1920 By Donald MacMillan Donald MacMillan. Smoke Wars: Anaconda Copper, Montana Air Pollution, and Courts, 1890-1920. Helena, MT: Montana Historical Society Press, 2000. 296 pp. ISBN 0-917298-65-9 (paper). US$18.95 Donald Macmillan's doctoral dissertation History of Struggle to Abate Air Pollution from Copper Smelters of Far West, 1885-1993, was edited posthumously and published in 2000 as Smoke Wars. book begins with a lengthy introductory chapter by William L. Lang that reviews genesis of dissertation. In addition, Lang writes about milieu of environmental history and Macmillan's place among other environmental historians and his work among other environmental histories. According to MacMillan, struggle to abate copper smelter air pollution consisted of three distinct phases. Phase one, war between citizens of Butte and smelter owners, concerned issues of public health and well being. Phase two, construction of world's largest smelter in Deer Lodge Valley in 1902, concerned issues of property destruction. Phase three; confrontation between federal government and most powerful of mining and smelting trusts, concerned issues of land conservation. Chapter 1, A Struggle for Property, and Conservation, provides a very brief introduction to book and presents a central thesis and themethat the current conflict over air pollution in smelting industry is not a mutation springing from an unknown parent. It is not a case of society suddenly changing rules. present conflict is legacy of those earlier battles (p. 21). Chapter 2, The Humblest Citizen of Butte is Entitled at Least to Fresh Air, chapter 3, Bluffs Don't go in Smoke Wars, and chapter 4, The War of Wealth Against Health, examine environmental and public health issues related to smelter smoke in Butte and surrounding communities between 1885 and 1900. MacMillan describes physical setting and early history of smelting and smelters. He also details reported ill effects of smelter smoke on environment, humans, and animals. Of special interest are attempts by several so-called experts to abate smelter smoke using untested and suspect technologies. Some of these have corollaries in today's many remediation technologies-for right price or potential profit there is always someone willing to invent a cleanup technology. In addition, these chapters bring into focus burgeoning battle between those seeking to provide healthy living conditions versus those seeking to press on with bountiful smelting economy. media's increasing role in supporting smelting industry is examined as well. Chapter 5, Progress and Pollution Come to Valley, chapter 6, The Farmers Versus Trust, and chapter 7, The Struggle Outside Court, recount epic struggle between economic interests of Trust and environmental and public health concerns of public. …

Lead Exposure in Children Living in a Smelter Community in Region Lagunera, Mexico

Industrial growth has created the potential for environmental problems in Mexico, since attention to environmental controls and urban planning has lagged behind the pace of industrialization. The aim of this cross-sectional study was to assess lead exposure in children aged 6-9 yr attending 3 primary schools and living in the vicinity of the largest smelter complex in Mexico. One of the schools is located 650 m distant from a smelter complex that includes a lead smelter (close school); the second is located 1750 m away from the complex and at the side of a heavy traffic road (intermediate school) in Torreón, Coahuila. The third school is located in Gómez Palacio, Durango, 8100 m away from the smelter complex and distant from heavy vehicular traffic or industrial areas (remote school). Lead was measured in air, soil, dust, and well water. Lead in blood (PbB) was determined in 394 children attending the above mentioned schools. Determinations were performed by atomic absorption spectrometry. Diet, socioeconomic status, hygienic habits, and other variables were assessed by questionnaire. Median (range) PbB values were 7.8 µg/dl (3.54-29.61) in the remote school, 21.8 µg/dl (8.37-52.08) in the intermediate school and 27.6 µg/dl (7.37-58.53) in children attending the close school. The percentage of children with PbB >15 µg/dl was 6.8%, 84.9%, and 92.1% respectively. In this order, the geometric means (range) of Pb concentrations in air were 2.5 µg/m3 (1.1-7.5), 5.8 µg/m3 (4.3-8.5), and 6.1 µg/m3 (1.6-14.9). The Pb concentrations in dust from playgrounds areas in the intermediate and close school settings ranged from 1457 to 4162.5 mg/kg. Pb concentrations in drinking water were less than 5 µg/L. Soil and dust ingestion and inhalation appear to be the main routes of exposure. Our results indicate that environmental contamination has resulted in an increased body burden of Pb, suggesting that children living in the vicinity of the smelter complex are at high risk for adverse effects of lead.

Delta-Aminolevulinate Dehydratase Polymorphism and Blood Lead Levels in Chinese Children

This study investigated the relationship between the delta-aminolevulinate dehydratase (ALAD) isozymes and the blood lead levels of Chinese children. The purpose of this study was to determine the precise ALAD genotyping in Chinese children and identify the contribution of the ALAD genotype to the body lead burden. Blood samples were obtained from 109 boys and 120 girls. These children were 6–10 years old and from a single primary school. Both the school and their homes were within a community in which a large smelter was located. An environmental questionnaire was obtained for each subject, and blood lead levels and ALAD isozyme phenotype were analyzed in a double-blinded fashion. The blood lead levels of 229 children ranged from 4.5 to 26.4 μg/dl; the mean was 10.3 μg/dl and the standard deviation was 3.3 μg/dl. The gene distribution of the ALAD isozyme phenotypes in these environmentally exposed children was ALAD 1-1 (92%), ALAD 1-2, (8%), and ALAD 2-2 (0%). The mean blood level of the environmentally exposed children, who were homozygous for the ALAD1 allele, was 9.7 μg/dl; the mean for those who were heterozygous for the ALAD2 allele was 11.7 μg/dl. Using the t test, the means of the groups were different at the level of t=2.2058, P<0.05. Step-wise regression and multiple analyses of covariance were employed to control the confounders to measuring the independent contribution of the ALAD genotype on blood lead levels. After controlling the confounders, the contribution of the ALAD genotype to the blood lead level was greater and still statistically significant (F=7.3201, P<0.01). These results indicate that individuals carrying the ALAD2 allele are more likely to have sustained increases in blood lead levels when exposed to a lead-contaminated environment.

Spent Potlining – A Hazardous Waste Made Safe

The electrolytic production of aluminium is undertaken in large smelters containing carbon-lined pots in which carbon acts as the cathode, the pots having a life typically of 2 to 6 years. Eventually the potlining is incapable of performing electrically and a toxic waste product of enormous tonnage is created. The potlining is heavily contaminated with metals, fluorides, cyanide and other compounds. The carbon content is reduced to less than 50%. Spent potlining (SPL) has been dumped in rivers, at sea and on land, creating major environmental problems. Today most spent potlining is stored at great expense awaiting a safe treatment process. The paper describes a low temperature chemical extraction process which has been demonstrated to recover valuable by-products from the SPL, leaving an environmentally acceptable landfill solid product. A demonstration plant has been built and plant trials have been performed. Cyanide is adequately removed in the water wash stage and fluoride is recovered as CaF 2 . The acid washes remove the rest of the fluoride and a significant quantity of this is recovered as AlF 3 .

Multivariate modelling of soil microbial variables in forest soil contaminated by heavy metals using wet chemical analyses and pyrolysis GC/MS

Microbial activity, biomass and community patterns were measured in the forest soils surrounding a large smelter emitting heavy metals and sulphur in northern Sweden. The chemical background to the high variation of the microbial variables in mor samples with a content of Cu+Zn between 100 and 1000 μgg −1 organic matter was investigated. Soil respiration rate was modelled using different combinations of wet chemistry data and pyrolysis. A combination of carbohydrate data, humus fractionation data and physicochemical data explained 86% of the variance in soil respiration rate. Pyrolysis data explained less variance and was more difficult to interpret. Phospholipid fatty acid (PLFA) patterns in the soils were also analysed. A multivariate (MVP-PLS) model of basal respiration rate, substrate induced respiration (SIR), lag time after glucose addition and the scores from the first component of a principal components analysis (PCA) of 33 phospholipid fatty acids (PLFAcomp1) was made. The explained variance for basal respiration rate was 75%, for SIR 85%, for lag time 52% and for PLFAcomp1 82%. Respiration rate and SIR were negatively correlated to the amount of soil organic matter in the mor layer (SOM m −2), nitrogen content and humic acids and positively correlated to glucans and humins. The content of base cations and pH were positively correlated to respiration rate and SIR and negatively correlated to lag time. The phospholipid fatty acid patterns (PLFAcomp1) showed that fungal fatty acid patterns dominated in shallow mor layers with higher cellulose content, while gram-positive bacteria were more abundant in thicker mor layers with more humic acids and a higher nitrogen content. The variation in the microbial variables was partitioned into a heavy metal dependent and an organic matter quality dependent part, which increased the correlation between heavy metals and the microbial variables.

GIS Analysis of Surface Water Chemistry Susceptibility and Response to Industrial Air Pollution in the Kola Peninsula, Northern Russia

The Kola Peninsula (Figure 1) is the most industrially developed and urbanized region in the Russian North. The main pollution sources are the large smelters Severonickel and Pechenganickel, which are responsible for > 80% of SO2 emission and nearly 100% of the Ni and Cu emission in the region. The heterogeneous structure of the hydrologic network and geochemistry across the region cause natural variability in water chemistry. Due to moist and cool climate, large territories on the Kola are sensitive to acid precipitation, but around the smelters, geological peculiarities, erosion and alkaline dust emissions increase buffering capacity of waters to acidification. Lake and river monitoring implemented from 1989–1993 by the laboratory of water ecosystems, Institute of Northern Ecology Problems was a basis for GIS-analysis (ARCNIEW-2.1) of the major constituents of water chemistry attributed to anthropogenic load in the region. After correction for sea salt, acid-neutralizing capacity (ANC) of waters was calculated. The highest concentrations of anthropogenic non-sea sulfates were confined to the districts with high cation concentrations (Na+ + K+ + Ca2+ + Mg2+) that reduced negative effects. The most vulnerable regions were found in the northern tundra and high mountain tundra.

Critical loads of SO4 for surface waters in the Kola region of Russia

Precipitation falling on the Kola North of Russia is severely polluted by strong acids and heavy metals emitted from large local smelters operated by the “Severonickel” and “Pechenganickel” companies. Large areas in the affected region are considered sensitive to acid precipitation due to geological and climatological conditions. Extensive surface water acidification has taken place, particularly, in the mountain and remote tundra regions. Critical loads and their cxceedances have been calculated for 370 lakes sampled in the Kola peninsula. These data indicate that the surface waters in the Kola North are highly sensitive to acidic deposition. Using the minimum values determined for each NILU grid cell, critical loads of less than 20 meq/m2yr occur in about 50 percent of the area.

Aluminium and energy

Aluminium smelters are very large consumers of both electricity and gas, and energy efficiency is absolutely vital. Today a modern smelter occupies a site outside Holyhead, and this factory is one of Europe&apos;s largest smelters. It consumes over 1800 million units of electricity a year which is supplied from a nuclear power plant

Distribution of cadmium, lead and zinc amongst the marine sediments, seagrasses and fauna, and the selection of sentinel accumulators, near a lead smelter in South Australia

The concentrations of Cd, Pb and Zn in 23 species of marine animal and three species of seagrass were determined from samples collected near a large lead smelter. The spatial patterns of metal distribution in sediments, seagrasses, crustaceans and fish could be described in terms of distance from the smelter, although the fit of the mathematical model was often improved by the inclusion of other environmental variables, such as clay content of the sediment or time of sample collection. In the fish and seagrasses, Zn was the most widely dispersed metal, followed by Cd, then Pb, which was least dispersed. In general, organisms at higher trophic levels (fish) had lower metal concentrations than primary producers (seagrass). There was evidence for bioaccumulation of metals in many species, especially in the molluscs, but no biomagnification of any metal could be detected. The strong relationship between distance and metal content of several species of seagrass, fish and crustacean indicates that they are potential sentinel accumulators for monitoring the distribution of Cd, Pb and Zn. Although bivalve molluscs contained high concentrations of Cd, Pb and Zn, their contents did not consistently relate to distance from the smelter, suggesting that, except for Pinna bicolor, they are of little value as sentinel accumulators for these metals. The implications of the results for the design of monitoring programs using sentinel accumulators are discussed.

Economic Effects of Sulfur Dioxide on Forest Growth

The body of information presented in this paper is directed to ecologists concerned with the effects and economic impact of sulfur dioxide on forest growth. Investigations were carried out over a ten-year period, 1953–1963, in the Sud-bury smelter district of Ontario, where three large smelters discharge annually approximately 2,000,000 tons of sulfur dioxide gas into the surrounding atmosphere. The study was designed to determine the long-term chronic effects of sulfur dioxide on yield, growth, and survival of plant life. Since eastern white pine is the most susceptible coniferous tree to sulfur dioxide injury, it was selected as the indicator tree to determine the degree and extent of injury in the Sudbury area. Tree data accumulated from the sample plots were correlated with records of atmospheric sulfur dioxide monitored continuously during the growing season by a network of ten strategically-located Thomas autometers. Based on the degree of injuries exhibited by the trees, and on air sampling records...