Social dimensions of mining: Research,policy and practice challenges for the minerals industry in Australia

The social dimensions of the mining industry are increasingly acknowledged as critical to business success, yet remain the least understood aspect of the business concept of sustainable development—the ‘triple bottom line’ of economy, environment and society.     

Complete degradation of di-n-octyl phthalate by Gordonia sp. strain Dop5

The present study describes the assimilation of di-n-octyl phthalate by an aerobic bacterium, isolated from municipal waste-contaminated soil sample utilizing di-n-octyl phthalate as the sole source of carbon and energy. The isolate was identified as Gordonia sp. based on the morphological, nutritional and biochemical characteristics as well as 16S rRNA gene sequence analysis. A combination of chromatographic and spectrometric analyses revealed a complete di-n-octyl assimilation pathway. In the degradation process, mono-n-octyl phthalate, phthalic acid, protocatechuic acid and 1-octanol were identified as the degradation products of di-n-octyl phthalate. Furthermore, phthalic acid was metabolized via protocatechuic acid involving protocatechuate 3,4-dioxygenase while 1-octanol was metabolized by NAD⁺-dependent dehydrogenases to 1-octanoic acid, which was subsequently degraded via β-oxidation, ultimately, leading to tricarboxylic acid cycle intermediates. Apart from phthalic acid and 1-octanol metabolizing pathway enzymes, two esterases, di-n-octyl phthalate hydrolase and mono-n-octyl phthalate hydrolase involved in di-n-octyl phthalate degradation were found to be inducible in nature. This is the first report on the metabolic pathway involved in the complete degradation of di-n-octyl phthalate by a single bacterial isolate, which is also capable of efficiently degrading other phthalate esters of environmental concern having either shorter or longer alkyl chains.     

Underwater treatment of lead-contaminated sediment

The sediment associated with the reconstruction of a bridge pier was classifiable as hazardous by the Toxicity Characteristic Leaching Procedure (TCLP), due to elevated concentrations of lead. However, RCRA regulations do not classify the sediment as hazardous unless it is moved. RMT designed an in-situ, underwater treatment process to render the sediment nonhazardous, using phosphate-based chemistry before dredging. Subsequent sediment management was conducted without the additional regulatory requirements and costs associated with managing hazardous waste.     

Herbicide loading to shallow ground water beneath Nebraska's Management Systems Evaluation Area

Better management practices can counter deterioration of ground water quality. From 1991 through 1996 the influence of improved irrigation practices on ground water pesticide contamination was assessed at the Nebraska Management Systems Evaluation Area. Three 13.4-ha corn (Zea mays L.) fields were studied: a conventional furrow-irrigated field, a surge-irrigated field and a center pivot-irrigated field, and a center pivot-irrigated alfalfa (Medicago sativa L.) field. The corn fields received one identical banded application of Bicep (atrazine [6-chloro-N-ethyl-N'-(1-methylethyl)-1,3,5-triazine-2,4,-diamine] + metolachlor [2-chloro-N-(2-ethyl-6-methylphenyl)-N-(2-methoxy-1-methylethyl) acetamidel) annually; the alfalfa field was untreated. Ground water samples were collected three times annually from 16 depths of 31 multilevel samplers. Six years of sample data indicated that a greater than 50% reduction in irrigation water on the corn management fields lowered average atrazine concentrations in the upper 1.5 m of the aquifer downgradient of the corn fields from approximately 5.5 to <0.5 microg L(-1). Increases in deethylatrazine (DEA; 2-chloro-4-amino-6-isopropylamino-s-triazine) to atrazine molar ratios indicated that reducing water applications enhanced microbial degradation of atrazine in soil zones. The occurrence of peak herbicide loading in ground water was unpredictable but usually was associated with heavy precipitation within days of herbicide application. Focused recharge of storm runoff that ponded in the surge-irrigated field drainage ditch, in the upgradient road ditch, and at the downgradient end of the conventionally irrigated field was a major mechanism for vertical transport. Sprinkler irrigation technology limited areas for focused recharge and promoted significantly more soil microbial degradation of atrazine than furrow irrigation techniques and, thereby, improved ground water quality.     

Herbicides in ground water beneath Nebraska's Management Systems Evaluation Area

Profiles of ground water pesticide concentrations beneath the Nebraska Management Systems Evaluation Area (MSEA) describe the effect of 20 yr of pesticide usage on ground water in the central Platte Valley of Nebraska. During the 6-yr (1991-1996) study, 14 pesticides and their transformation products were detected in 7848 ground water samples from the unconfined water table aquifer. Triazine and acetamide herbicides applied on the site and their transformation products had the highest frequencies of detection. Atrazine [6-chloro-N-ethyl-N'-(1-methylethyl)-1,3,5-triazine-2,4,-diamine] concentrations decreased with depth and ground water age determined with 3H/3He dating techniques. Assuming equivalent atrazine input during the past 20 yr, the measured average changes in concentration with depth (age) suggest an estimated half-life of >10 yr. Hydrolysis of atrazine and deethylatrazine (DEA; 2-chloro-4-amino-6-isopropylamino-s-triazine) to hydroxyatrazine [6-hydroxy-N-ethyl-N'-(1-methylethyl)-1,3,5-triazine-2,4-diamine] appeared to be the major degradation route. Aqueous hydroxyatrazine concentrations are governed by sorption on the saturated sediments. Atrazine was detected in the confined Ogallala aquifer in ultra-trace concentrations (0.003 microg L(-1)); however, the possibility of introduction during reverse circulation drilling of these deep wells cannot be eliminated. In fall 1997 sampling, metolachlor [2-chloro-N-(2-ethyl-6-methylphenyl)-N-(2-methoxy-1-methylethyl) acetamide] was detected in 57% of the 230 samples. Metolachlor oxanilic acid [(2-ethyl-6-methylphenyl)(2-methoxy-1-methylethyl) amino]oxo-acetic acid] was detected in most samples. In ground water profiles, concentrations of metolachlor ethane sulfonic acid [2-[(ethyl-6-methylphenyl)(2-methoxy-1-methylethyl)amino]-2-oxo-ethanesulfonic acid] exceeded those of deethylatrazine. Alachlor [2-chloro-N-(2,6-diethylphenyl)-N-(methoxymethyl)acetamide] was detected in <1% of the samples; however, alachlor ethane sulfonic acid [2-[(2,6-diethylphenyl)(methoxymethyl)amino]-2-oxoethanesulfonic acid] was present in most samples (63%) and was an indicator of past alachlor use.     

GEOMORPHIC AND PEDOLOGIC INFLUENCE ON SMALL-SCALE EPHEMERAL CHANNEL DIMENSION IN RANGELANDS1

ABSTRACT: Geomorphic processes may partly determine channel geometry. Soil particle uplift during freezing and thawing cycles and bank sloughing during wetting and drying periods were observed. Soil properties and channel dimension were measured to determine the dominant processes controlling channel geometry in eight small (mean area 0.096 km²) drainages in Logan Canyon, Utah. Soil cohesion was low (plasticity index > 15) for all but one of the drainages sampled. Basin scale geomorphic variables were examined to determine if they control channel dimension. Bankfull width was highly correlated to channel length and valley length with r² values of 0.85 and 0.84, respectively. A strong canonical correlation (0.64) showed that distance from the watershed divide, bank liquid limit, and bank sand content were effective predictor variables of bankfull width and depth. The interrelations between geomorphic and pedogenic processes were the strongest determinants of ephemeral channel dimension in this study.     

COMPARING SOME METHODS OF ESTIMATING MEAN AREAL RAINFALL1

ABSTRACT: A comparison of 13 different methods of estimating mean areal rainfall was made on two areas in New Mexico, U.S.A., and one area in Great Britain. Daily, monthly and yearly rainfall data were utilized. All methods, in general, yielded comparable estimates, especially for yearly values. This suggested that a simpler method would be preferable for estimating mean areal rainfall in these areas.     

External threats: the dilemma of resource management on the Colorado River in Grand Canyon National park,USA

The United States Congress established Grand Canyon National Park in 1919 to preserve for posterity the outstanding natural attributes of the canyon cut by the Colorado River. In some cases National Park Service attempts to maintain Grand Canyon's natural environment have been thwarted by activities outside the park. One of the most obvious external threats is Glen Canyon Dam, only 26 km upstream from the park boundary. Constructed in 1963, this gigantic dam has greatly altered the physicochemical and biological characteristics of 446 km of the Colorado River in Grand Canyon National Park. The river's aquatic ecosystem has been greatly modified through the loss of indigenous species and the addition of numerous exotics. We consider this anexotic ecosystem. The riparian ecosystem has been less modified, with addition of a few exotics and no loss of natives—this we consider anaturalized ecosystem.The great dilemma now faced by park managers is that, after 20 years of managing resources along a river controlled by Glen Canyon Dam, the Bureau of Reclamation has proposed major changes in operational procedures for the dam. Scientists and managers from the National Park Service, Bureau of Reclamation, and cooperating federal and state resource management agencies are using a systems analysis approach to examine the impacts of various Colorado River flow regimes on aquatic, riparian, and recreational parameters in the park. This approach will help in the development of management alternatives designed to permit the most efficient use of that river's natural resources without their destruction.     

Development of a Quality-Assessed Agrichemical Database For Monitoring Anthropogenic Impacts on Ground-Water Quality

The Quality–Assessed Agrichemical Contaminant Database for Nebraska Ground Water is a unique repository of nitrate and pesticide data collected by federal, state, and local agencies. Each contaminant concentration in the database has been evaluated based upon well–defined criteria that address completeness of the well–attribute data, analytical method and field and laboratory quality control practices and assigned to one of five quality levels. The quality assessment level always accompanies the contaminant concentration so that the end–user knows the quality assurance effort expended in the acquisition of the data, can select comparable data, and choose data whose quality assurance effort is commensurate with project objectives. The database can be viewed and queried on–line; downloaded in its entirety; or imported to a spreadsheet or a geographic information system. Setting criteria for data quality and assessing the level of quality have resulted in significant increases in the percentages of high quality (Levels 3–5) nitrate and pesticide data. These high quality data presently constitute 52% of the nitrate and 55% of the pesticide data.