Active Mine Sites Research Articles

Assessing environmental impacts of inland sand mining in parts of Ogun State, Nigeria

Sand is a valuable resource for construction and other purposes, however sand mining often result in serious environmental problems such as land degradation, loss of agricultural lands and biodiversity, as well increased poverty among people. This study assessed the environmental impacts of inland sand mining in six selected local government areas of Ogun state, Nigeria. Twenty-seven (27) inland sand mining sites were identified, fourteen (14) of which are currently active mining site s while thirteen (13) are abandoned. The geographic location and attributes sites were captured for a spatial analysis using Geographic Information System (GIS). The sites were mapped and classified based on the severity of the damage to the ecological system. The study revealed that three of the local governments areas i.e. Abeokuta South, Ifo, Obafemi/Owode and Ado-Odo/Ota have inland sand mining sites with severe degradation, while Sagamu and Ewekoro local governments areas have inland sand mining sites that can be regarded as moderately and less degraded respectively. The intensive urban and industrial developments around these areas contributed enormously to the increased demand of sand for building and construction. Natural resources particularly, land, water quality and quantity, air quality, are the most significant impacts. Other impacts include loss of farmland, depreciation of land value, and destruction of infrastructural facilities. The study concluded that sand mining should be subject to planning and other controls in order to curtail its negative impacts. Keywords: Urbanization, Ho using, GIS, Land degradation, Sand mining, Pollution

Morphologic Response of a Stream Channel to Extensive Sand Mining

This study assesses the impact of sand mining on the morphology of Kano River channel. The river channel was divided into three sites consisting of site upstream of active mining site, active mining site and downstream of active mining. The upstream site was assumed to be unaffected by the mining activity. The mining site was an area of current active mining. The downstream area is downstream of mining site but with no mining activity. A morphometric assessment of 50 sample points in each of the three sites from a cross section was made where width of the channel was measured from one end of the channel to the other horizontally on transect; depth was measured from the lowest point in the flood plain to the top of the bank; channel slope was determined following standard survey technique from points located from the top of one riffle to the top of another within the entire cross section. One-way ANOVA between groups was employed to test the differences between the measured mophometric variables in the three sites. The results revealed that mining activities has resulted in modification of the channel with great variations in depth between the sites (p<0.01) with the mining site having 7.5 m the upstream site 2.3 m and downstream 2.5 m deeper than the average channel depth; width also vary between the sites (p<0.01); mining site has a mean width of 110 m, downstream site, 75 m and 50 m in the upstream site. Field observation indicate that downstream pools are longer but upstream pools are deeper, expected spacing of riffles given as five to seven stream widths was not observed but riffle interval was however as expected in the mining site.

Erodibility of low‐compaction steep‐sloped reclaimed surface mine lands in the southern Appalachian region, USA

AbstractThe use of loose spoils on steep slopes for surface coal mining reclamation sites has been promoted by the US Department of Interior, Office of Surface Mining for the establishment of native forest, as prescribed by the Forest Reclamation Approach (FRA). Although low‐compaction spoils improve tree survival and growth, erodibility on steep slopes was suspected to increase. This study quantified a combined KC factor (combining the effects of the soil erodibility K factor and cover management C) for low compaction, steep‐sloped (&gt;20°) reclaimed mine lands in the Appalachian region, USA. The combined KC factor was used because standard Unit Plot conditions required to separate these factors, per Revised Universal Soil Loss Equation (RUSLE) experimental protocols, were not followed explicitly. Three active coal mining sites in the Appalachian region of East Tennessee, each containing four replicate field plots, were monitored for rainfall and sediment yields during a 14‐month period beginning June 2009. Average cumulative erosivity for the study sites during the monitoring period was measured as 5248.9 MJ·mm·ha−1·h−1. The KC ranged between 0.001 and 0.05 t·ha·h·ha−1·MJ−1·mm−1, with the highest values occurring immediately following reclamation site construction as rills developed (June – August 2009). The KC for two study sites with about an 18–20 mm spoil D84 were above 0.01 t·ha·h·ha−1·MJ−1·mm−1 during rill development, and below 0.003 t·ha·h·ha−1·MJ−1·mm−1 after August 2009 for the post‐rill development period. The KC values for one site with a 40 mm spoil D84 were never above 0.008 t·ha·h·ha−1·MJ−1·mm−1 and also on average were lower, being more similar to the other two sites after the rill development period. Based on an initial KC factor (Ke) measured during the first few storm events, the average C factor (Ce) was estimated as 0.58 for the rill development period and 0.13 for the post‐rill development period. It appears that larger size fractions of spoils influence KC and Ce factors on low‐compaction steep slopes reclamation sites. Copyright © 2013 John Wiley &amp; Sons, Ltd.

Spatial Distribution of As, Cr, Pb, Cd, Cu, and Zn in the Water and Sediment of a River Impacted by Gold Mining

Historical and active mining has adversely affected the geochemistry of the Jiehe River in the Jiaodong Peninsula, which has the largest gold ore reserves in China. Water and sediment samples were collected along the 37.8 km long river during the critical low flow season. Samples were analyzed for their geochemical properties, total concentrations of As, Cr, Pb, Cd, Cu, and Zn in the sediment, and dissolved/particulate concentrations of trace elements in filtered/unfiltered water samples. Our results demonstrate that substantial amount of these elements have been released into the Jiehe River during the processes of extracting, selecting, processing, and smelting at the many historical and active gold mining sites in the watershed. High concentrations of potentially toxic elements (1.9–1,004 μg L−1 As, 4.2–210 μg L−1 Cr, 7.9–9,529 μg L−1 Pb, 2.0–855 μg L−1 Cd, 47.4–8,494 μg L−1 Cu, and 105–11,336 μg L−1 Zn) have seriously affected water quality in the region. In addition, these contaminants have accumulated in the bed sediment (7.7–181 mg kg−1 As, 24.1–726 mg kg−1 Cr, 9.9–1,100 mg kg−1 Pb, 0.1–51.8 mg kg−1 Cd, 22.1–1,524 mg kg−1 Cu, and 53.5–5,484 mg kg−1 Zn). Spatial distribution of these contaminants in water and sediment is controlled by the discharge from point and non-point sources as well as the reactive transport processes. Spatial analysis conducted on the sediment and stream concentration of As, Pb, Cd, and Zn suggests that two mining-related sources, at 4.3 and 17.6 km downstream of the headwaters, contributed most of the As, Pb, Cd, and Zn load as particulates. In contrast, high levels of Cr and Cu in the sediment are not related to the current loading pattern and may be due to historical sources. As the first comprehensive study on the pollution caused by intensive gold mining in this area, this research has provided much needed information to establish effective management and remediation strategies.

Effect of Gangue Minerals on Hydrophobic Recovery of Gold

In this paper, the effect of gangue minerals on the hydrophobic recovery of gold is being investigated using ores obtained from the active small scale gold mining sites in Tanzania. Gold ores of different gangue contents were tested. The effects of silica gangue and high sulphide gangue on gold attachment were examined including the effect of surface activators (potassium amyl xanthate) and the possibility of depressing the effects of gangue using reagents. The results were evaluated in terms of gold recovery, volumes and grade of concentrates formed. There was no change in gold recoveries when the amount of oxide gangue (quartz) in the ore was increased, indicating absence of competition between gold and quartz gangue. High sulphide contents in the ore above 6% reduced gold recoveries considerably. It was noted that potassium amyl xanthate surfactants increased the attachment of both gold and the sulphide gangue. Using lime at pH 10 it was possible to depress the sulphide gangue which is mainly pyrite and hence increased gold recoveries considerably.

Speciation of mercury in mine waste: case study of abandoned and active gold mine sites at the Bibiani–Anwiaso–Bekwai area of South Western Ghana

Speciation determines toxicity, transport pathways and residence time of a metal in different compartments of the environment. This study investigated the speciation of mercury in soils, derived from sites known for dumping of mine wastes in the Bibiani-Anwiaso-Bekwai district, a gold mining community of the Western Region of Ghana. Soil samples were taken from the surface; depths of 20, 40 and 60 cm from mine waste at both abandoned and active mine sites. Each sample was analysed for total mercury, organic mercury and elemental mercury. After sample treatment, digestion and reduction with stannous chloride (SnCl(2)), total mercury content was determined using the Inductively Coupled Plasma-Optical Emissions Spectrometer (ICP-OES). Organic mercury content was determined employing a differential technique after disposing of elemental mercury by heating. Total mercury content in samples ranged from 0.067 to 0.876 mg/kg for surface soils. The same soil of depths 20, 40 and 60 cm had total mercury from 0.102 to 1.066, 0.037 to 4.037 and 0.191 to 4.998 mg/kg, respectively. For organic mercury, concentrations range from 0.012 to 0.260 mg/kg for surface soil. Soil depths of 20, 40 and 60 cm had organic mercury concentrations from 0.016 to 0.653, 0.041 to 1.093 and 0.101 to 2.546 mg/kg respectively. Elemental mercury concentrations in surface soils, soils at depths of 20, 40 and 60 cm ranged from 0.043 to 0.780; 0.017 to 0.749; 0.014 to 2.944 and 0.009 to 2.452 mg/kg respectively. Among the sites studied, only galamsey tailings (GM) showed a trend of increasing total mercury level with increasing depth. For the other sites, trends were not defined. There has been no defined trend for elemental mercury with depth at any of the sampling sites. Just as with total mercury, it was only GM that showed an increasing trend of organic mercury concentration with depth.

Ambient Air Quality Surveillance and Indexing in and around Mining Clusters in Western Kachchh Region, Gujarat, India

Generation of baseline information about ambient air quality of any given region assumes significance, when the area is 1) an active mine site, 2) proposed to be mined out in future, and 3) industrialization in the area is in fast pace. Ambient air quality monitoring (with respect to SPM, RPM, SO2, NOx and CO) was carried out in and around two mining complexes in western parts of Kachchh district in Gujarat to generate baseline air quality status of the area. This area has two major mine complexes and various large scale industrial projects (thermal power plants, cement plants and several ports and jetties) are also in pipeline. Ambient air sampling was carried out in eight locations within five km radial distance from two major mine sites, i.e. Panandhro and Mata-na-Madh, with four locations for each mine site. Air Quality Indexing was done for all the locations, since it is a simplest way for the prediction of ambient air quality status of any region with respect to industrial, residential and rural areas. Of the eight locations studied the air quality for six locations fell under fairly clean (Light Air Pollution, AQI 25-50) category, while the rest (rural areas in the region), had relatively better air quality and fell under clean (Clean Air, AQI 10-25) category.

Mobility of trace and potentially harmful elements in the environment from high sulfur Indian coal mines

Abstract Coal mine rejects and sulfide bearing coals are prone to acid mine drainage (AMD) formation due to aqueous weathering. These acidic effluents contain dissolved trace and potentially harmful elements (PHEs) that have considerable impact on the environment. The behavior of these elements in AMD is mainly controlled by pH. The focus of the present study is to investigate aqueous leaching of mine rejects for prediction of acid producing potential, rates of weathering, and release of PHEs in mine drainage. Mine reject (MR) and coal samples from the active mine sites of Meghalaya, India typically have high S contents (1.8–5.7% in MR and 1.7–4.7% in coals) with 75–90% of the S in organic form and enrichment of most of the PHEs in rejects. Aqueous kinetic leaching experiments on mine rejects showed high acid producing potential and release of trace and potentially harmful elements. The elements (Sb, As, Cd, Cr, Co, Cu, Pb, Mn, Ni, V and Zn) in mine sample leachates are compared with those in mine waters. The concentrations of Al, Si, P, K, Ti, Mn, Fe, Co, Ni, Cu, Zn and Pb are found to increase with leaching time and are negatively correlated with pH of the solution. The processes controlling the release of these elements are acid leaching, precipitation and adsorption. The critical loads of PHEs in water affected by AMD are calculated by comparing their concentrations with those of regulatory levels. The Enrichment Factors (EFs) and soil pollution indices (SPIs) for the elements have shown that PHEs from coal and mine reject samples are mobilized into the nearby environment and are enriched in the associated soil and sediment.

Distribution and mobility of heavy metals in paddy soils of the Kočani Field in Macedonia

Contamination of soils with heavy metals is widespread and poses a long-term risk to ecosystem health. Abandoned and active mining sites contain residues from ore-processing operations that are characterised by high concentrations of heavy metals. The distribution and mobility characteristics of heavy metals (As, Cd, Cu, Pb, and Zn) in paddy soil samples from Kočani Field (Macedonia) using ICP-EAS and a sequential extraction procedure was evaluated. The results indicate that highly elevated concentrations of As, Cd, Cu, Pb, and Zn were detected in the paddy soil sample from location VII-2 in the vicinity of Zletovo mine and Zletovska river in the western part of Kočani Field, which drains the untreated acid mine waters and mine wastes from the active Zletovo mine. The degree of contamination based on index of geoaccumulation (I geo) from strong to weak in the paddy soils samples is Pb > As > Cd > Zn > Cu. The mobility potential of heavy metals in all paddy soil samples increases in the order As < Cu < Pb < Zn < Cd. According to the results of the anthropogenic impact on the paddy soils, a further study on the heavy metal concentrations in rice and other edible crops, the remediation process of the paddy soils and a dietary study of the local population are needed.

Acid mine drainage and heavy metals contamination at abandoned and active mine sites in Pahang

Active and abandoned mine sites in Pahang have been investigated recently to find out the occurrence of acid mine drainage and heavy metals contamination. Acid mine drainage (or also popularly known as AMD), which is a product of weathering (oxidation and hydrolysis) on sulphide minerals has been a major concern in mining industry. Seven mine and quarry sites in Pahang were visited, namely Bukit Botol, Bukit Ibam, Panching quarry, Sg Lembing, Kota Gelanggi, Padang Piol and Kg Awah. In-situ water quality parameters such as pH, dissolved oxygen and electrical conductivity were measured. Some surface water samples were also collected and analysed for heavy metals. After the first screening test on these sites, the abandoned tin mine of Sg. Lembing (underground mining) was chosen for further examination. Detailed study at Sg. Lembing involved sampling of surface water and mine tailings. The study has revealed that arsenic (As) concentrations in surface water ranges from 0.003-16.20 mg/L and in mine tailings 755-74475 mg/kg. The arsenic level measured in surface water and mine tailings at Sg Lembing Mine are higher than the environmental standard for effluents (Standard A) in Environmental Quality Act (1974) and contaminated soil standard by ICRCL (1987). The concentrations of other heavy metals such as Cu, Fe, Mn, Pb, and Zn are also exceeding the limit allowed by EQA (1974) and ICRCL (1987). The study concludes that there is an urgency to regulate the better closure of abandoned mine sites. Pulverised mine tailings which is very rich in sulphide minerals must be kept away from contact with water and oxygen to avoid reactions that will produce acidic water and harmful chemicals.

Acid rock drainage and climate change

Rainfall events cause both increases and decreases in acid and metals concentrations and their loadings from mine wastes, and unmined mineralized areas, into receiving streams based on data from 3 mines sites in the United States and other sites outside the US. Gradual increases in concentrations occur during long dry spells and sudden large increases are observed during the rising limb of the discharge following dry spells (first flush). By the time the discharge peak has occurred, concentrations are usually decreased, often to levels below those of pre-storm conditions and then they slowly rise again during the next dry spell. These dynamic changes in concentrations and loadings are related to the dissolution of soluble salts and the flushing out of waters that were concentrated by evaporation. The underlying processes, pyrite oxidation and host rock dissolution, do not end until the pyrite is fully weathered, which can take hundreds to thousands of years. These observations can be generalized to predict future conditions caused by droughts related to El Niño and climate change associated with global warming. Already, the time period for dry summers is lengthening in the western US and rainstorms are further apart and more intense when they happen. Consequently, flushing of inactive or active mine sites and mineralized but unmined sites will cause larger sudden increases in concentrations that will be an ever increasing danger to aquatic life with climate change. Higher average concentrations will be observed during longer low-flow periods. Remediation efforts will have to increase the capacity of engineered designs to deal with more extreme conditions, not average conditions of previous years.

English

UAbstract:U Water treatment is often required at active and inactive mine sites to remove heavy metals and other contaminants of concern (COCs) prior to discharging water. Traditional water treatment can be expensive and impractical at some sites due to excessive energy, manual labor, and operations and maintenance (O&M) requirements. Passive treatment has emerged as a way to treat such waters inexpensively by requiring minimal amounts of O&M and little to no external energy. One form of passive treatment technology that has been developed over the last twenty years is the biochemical reactor (BCR), also known as a sulfate reducing bioreactor (SRBR). As its name would suggest, a BCR treats water by way of biological and chemical reactions. A BCR uses a combination of organic substrate materials and microbial activity to remove heavy metals, remove other COCs, and stabilize pH in mining influenced water (MIW). Additionally, a BCR adds hardness, alkalinity, and organic matter to the MIW, all of which are beneficial to overall water quality and aquatic life.

Using Landscape Context to Guide Ecological Restoration: An Approach for Pits and Quarries in Ontario

Robert C. Corry, Raffaele Lafortezza, Robert D. Brown, Natasha Kenny and P. Jill Robertson

Biomarkers of metals exposure in fish from lead-zinc mining areas of Southeastern Missouri, USA

The potential effects of proposed lead-zinc mining in an ecologically sensitive area were assessed by studying a nearby mining district that has been exploited for about 30 y under contemporary environmental regulations and with modern technology. Blood and liver samples representing fish of three species (largescale stoneroller, Campostoma oligolepis, n=91; longear sunfish , Lepomis megalotis, n=105; and northern hog sucker, Hypentelium nigricans, n=20) from 16 sites representing a range of conditions relative to mining activities were collected. Samples were analyzed for metals (also reported in a companion paper) and for biomarkers of metals exposure [erythrocyte δ-aminolevulinic acid dehydratase (ALA-D) activity; concentrations of zinc protoporphyrin (ZPP), iron, and hemoglobin (Hb) in blood; and hepatic metallothionein (MT) gene expression and lipid peroxidation]. Blood lead concentrations were significantly higher and ALA-D activity significantly lower in all species at sites nearest to active lead-zinc mines and in a stream contaminated by historical mining than at reference or downstream sites. ALA-D activity was also negatively correlated with blood lead concentrations in all three species but not with other metals. Iron and Hb concentrations were positively correlated in all three species, but were not correlated with any other metals in blood or liver in any species. MT gene expression was positively correlated with liver zinc concentrations, but neither MT nor lipid peroxidase differences among fish grouped according to lead concentrations were statistically significant. ZPP was not detected by hematofluorometry in most fish, but fish with detectable ZPP were from sites affected by mining. Collectively, these results confirm that metals are released to streams from active lead-zinc mining sites and are accumulated by fish.

Microbial studies of a selenium-contaminated mine site and potential for on-site remediation

Surface water Selenium (Se) concentrations are above regulatory standards at several active and inactive phosphate mine sites in the US Western Phosphate Resource Area. The focus of the present study was to examine the impacts of the microbial communities on the oxidation state of Se in overburden waste from the Smoky Canyon phosphate mine in Idaho, USA. Microbial populations were found that reduce soluble selenate (SeO (4) (2-) ) to insoluble elemental Se. Microcosm experiments were conducted for molecular genetic analysis of this microbial community by rRNA gene profiling. An acetone pretreatment step was developed to remove interfering pre-petroleum hydrocarbons from the samples prior to extraction. PCR was used to amplify 16S and 18S rRNA genes present in the microbial community DNA. The amplified products were subjected to denaturing gradient gel electrophoresis (DGGE). Isolates and excised DGGE bands were amplified and sequenced for identification to determine the relative importance of culturable isolates to the total microbial population. Analysis of samples from different sites at the mine showed how Se contamination and previous remediation treatments changed the microbial populations across the site. Members of the family Enterobacteriaceae were dominant among the selenate reducing isolates from the site containing high Se levels. In particular, Serratia fonticola was isolated repeatedly from contaminated Smoky Canyon Mine site samples. Packed column studies were performed with seleniferous waste rock fractions from Smoky Canyon Mine. Column amendments consisted of combinations of iron, compost, and whey. Eh, pH, and extractable Se measurements were taken. Tests with infiltrated water showed columns containing an organic amendment combined with iron metal were the most resistant to Se leaching. Iron-based compounds from the corroding metal are thought to strongly bind the Se reduced by microbial activity, thereby stabilizing the Se in an insoluble form. We conclude that long-term stabilization of selenium at contaminated mine sites may require reductive microbial processes combined with abiotic immobilization by iron, either natural or engineered, to stabilize the Se and retard re-oxidation and release. Iron-selenide or iron-selenite compounds are more stable and resistant to leaching, especially when removed from active weathering.

Studies on reaction mechanism of bioleaching of manganese ore

A systematic study has been made to establish the reaction mechanism of bioleaching of manganese ore with the manganese reducing fungi, Penicillium citrinum, isolated from the top soil of an active manganese ore mine site. The fungi was utilised for dissolution of manganese from the low grade manganiferous ore. Leaching with the biomass free culture filtrate and with various acids such as oxalic, citric and sulphuric acid, provide a better insight to the process. On the basis of these studies, kinetic equations as a function of time is plotted to obtain appropriate conversion-time equation for leaching of manganese ore with bioacid and organic acid. The experimental values showed that the reaction is controlled by diffusion of the reactants through the permeable product layer.

Groundwater geochemistry in shallow aquifers above longwall mines in Illinois, USA

Aquifers above high-extraction underground coal mines are not affected by mine drainage, but they may still exhibit changes in groundwater chemistry due to alterations in groundwater flow induced by mine subsidence. At two active longwall mine sites in Illinois, USA, glacial-drift aquifers were largely unaffected by mining, but the geochemistry of the bedrock aquifers changed during the post-mining water-level recovery. At the Jefferson site, brackish, high-sulfate water present in the upper bedrock shale briefly had lower values of total dissolved solids (TDS) after mining due to increased recharge from the overlying drift, whereas TDS and sulfate increased in the sodium-bicarbonate water present in the underlying sandstone due to downward leakage from the shale and lateral inflow of water through the sandstone. At the Saline site, sandstones contained water ranging from brackish sodium-chloride to fresh sodium-bicarbonate type. Post-mining recovery of the potentiometric levels was minimal, and the water had minor quality changes. Longwall mining affects geochemistry due to subsidence-related fracturing, which increases downward leakage from overlying units, and due to the temporary potentiometric depression and subsequent recovery, whereby water from surrounding areas of the aquifer recharges the affected zone above and adjacent to the mine.

Revegetation of coarse taconite iron ore tailing using municipal solid waste compost

On Minnesota's Mesabi Iron Range, coarse taconite iron ore tailing is often used as the principal material in the construction of dams for large tailing impoundments. Mineland reclamation rules in Minnesota require that tailing dams be vegetated to control erosion for dam stability and safety. Coarse taconite iron ore tailing is characterized chemically by an alkaline pH, low organic matter content, lack of plant-essential nutrients, and low cation-exchange capacity; physically by its coarse texture, lack of structure, low water-holding capacity, and dark color; and biologically by a lack of microorganisms. To investigate the potential of composted municipal solid waste to ameliorate these conditions and make the material more amenable to plant establishment and growth, the US Bureau of Mines implemented a series of factorial experiments at two active taconite mine sites in northeastern Minnesota. At each experimental site, vegetative cover has improved depending on the type of municipal solid waste compost used and rate of application. At site I, overall plant cover across all treatments has improved from zero prior to experimental manipulation to 72% after four years, with seven treatment combinations exceeding 90% cover. At site II, overall plant cover has improved from zero prior to experimental manipulation to 83% after four years, with 23 treatment combinations exceeding 90% cover. At both sites, total cover has progressively increased over four years and has not reached steady-state conditions. These results suggest a possible new strategy for reclaiming difficult sites through the use of municipal solid waste compost.

Oxygen Diffusion through Soil Covers on Sulphidic Mine Tailings

Engineered soil covers are being evaluated under Canada's Mine Environment Neutral Drainage (MEND) program for their effectiveness in preventing and controlling acid generation in sulphidic mill tailings. A critical parameter for predicting the performance of these covers is the diffusion coefficient of gaseous oxygen in the cover materials. Laboratory experiments conducted to determine the effective diffusion coefficient of a candidate cover material, a glacial till from an active mine site, are described. The diffusion coefficient is determined by fitting a semianalytic solution of the one‐dimensional, transient diffusion equation to experimental gaseous oxygen concentration versus time graphs. Effective diffusion coefficients determined at high water saturations (85%–95%) were of the order of 8×10-8m2/s. The diffusion coefficients decreased with increase in water saturation as a result of the low diffusivity of gaseous oxygen in water relative to that in air and the low solubility of oxygen in water. Placement of soil covers in high saturation conditions would ensure that the flux of oxygen into tailings underneath such covers is low, resulting in low acid flux. This is confirmed by combined laboratory, field, and modeling studies.

Biomonitoring of lead-contaminated Missouri streams with an assay for erythrocyte ?-aminolevulinic acid dehydratase activity in fish blood

The activity of the enzyme δ-aminolevulinic acid dehydratase (ALA-D) in erythrocytes has long been used as a biomarker of lead exposure in humans and waterfowl and, more recently, in fishes. The assay was tested for ALA-D activity in fishes from streams affected by lead in combination with other metals from lead-zinc mining and related activities. Fishes (mostly catostomids) were collected from sites affected by historic and current mining activities, and from sites considered to be unaffected by mining (reference sites). A group of potentially toxic elements was measured in blood and carcass samples of individual fish, as were ALA-D activity, total protein (TP), and hemoglobin (Hb) in blood. Concentrations of mining-related metals (lead, zinc, and cadmium) were significantly greater (P<0.05) in fish blood and carcass at sites affected by historic mining activities than at reference and active mining sites. When analyzed by multiple regression, ALA-D activity, Hb, and TP accounted for 66% of blood-lead and 69% of carcass-lead variability. Differences among species were small. ALA-D activity as a biomarker adequately distinguished sites affected by bioavailable environmental lead. Zinc was the only other metal that affected ALA-D activity; it appeared to ameliorate the inactivation of ALA-D by lead.