Water quality changes of a closed underground coal mine in Korea

The objective of this study was to assess the changes in mine water quality as an underground mine flooded from July 2005 to October 2008. The effect of air injection with a blower into the water was used to evaluate the potential to convert ferrous to ferric iron and to provide in situ treatment and precipitation. Mine flooding averaged 31 cm/day with a linear shape until November 2007, when it flattened out due to outflow. During flooding, mine water pH remained around 6, but Eh shifted from 200 to −150 mV. After the mine water level stabilized, contents of elements such as Fe and SO₄ tended to decrease as time passed. Air was injected by diffusers (150 L/min/each) at three different depths of 2, 3, and 5 m below the water level in the shaft. Dissolved oxygen eventually increased to 4 or 5 mg/L depending on the depth of the diffusers. Aeration caused conversion of ferrous iron to ferric iron and about 30 mg/l of iron was removed from the mine water. Therefore, air injection shows potential as a semi-active treatment or part of conventional treatment to precipitate iron in the mine pool.     

PUBLIC EXPENDITURE PROGRAMS IN APPALACHIA AND THEIR IMPACT ON REGIONAL EMPLOYMENT1

ABSTRACT: The reduction of regional unemployment requires a sufficient demand for regional labor and the demand pattern must parallel that of supply. Due to the interdependency of Appalachian economy with the rest of the Nation, the leakage of the final demand imposed on a subregion of Appalachia is substantial. The more capital intensive the investment the higher the leakage which will lead to less demand for labor in Appalachia. While water resource projects are generally longterm projects which aim at structural changes in a regional economy, consumption expenditures induced by welfare payments or public employment programs are basically temporary measures for the rescue of unemployment. Average consumption and private investment programs may impose on Appalachia a larger material demand but the demand for the total regional labor, off-site and on-site combined, is estimated to be less than that from water resource investments. The public expenditure program for combating regional unemployment must be discretionary based on its purpose and its potential to generate optimum demand for labor which will be created by the pattern of regional resource distribution and interindustrial and interregional interactions. An interregional I/O model is best suited for analysis of this type.     

The amplification refractory mutation system (ARMS): A rapid and direct prenatal diagnostic technique for β-thalassaemia in Singapore

β-Thalassaemia major patients have chronic anaemia and since 3–4 per cent of Singaporeans carry the β-gene, prenatal diagnosis is essential. We evaluated the amplification refractory mutation system (ARMS) technique as a routine test for prenatal diagnosis of β-major. Six mutations along the β-gene were studied—41–42 (-TCTT), IVSII #654 (C-T), 17β (A-T), – 28 TATA (A-G), IVSI #5 (G-C), and IVSI #1 (G-T). Our results indicate that prenatal diagnosis using these mutations can be offered to 90 per cent (35/39) of our Chinese couples and 54·6 per cent (12/22) of our Malay couples at risk. Confirmation of ARMS results was carried out using allele-specific oligonucleotide hybridization. Prenatal diagnosis using ARMS was successfully carried out in nine cases which included a set of triplets and twins. The triplets were diagnosed with the β-trait carrying the 41–42 mutation. The couple with twins possessed the #654 mutation and one twin was diagnosed with the β-trait and the other with #654 homozygosity. Genomic sequencing of the undefined mutations in the Chinese couples revealed rarer mutations at − 29 and an ATG-AGG base substitution at the initiation codon for translation. In the Malay couples, genomic sequencing detected mutations at codon 15 (TGG-TAG) and codon 26 (GAG-AAG). We conclude that ARMS with its direct detection of amplified products by gel electrophoresis provides an accurate, rapid, and simpler method for our β-thalassaemia prenatal diagnosis programme in Singapore.     

Industrial processes and waste characterization

Specific industrial processes and its waste characteristics should be known for proper management and control of the wastes produced from industries. Some industrial processes and waste characteristics are introduced to explain how to deal with the wastes for waste characterization. Evaluation methods of biodegradability of industrial wastewater were introduced in order for environmental engineers to be able to decide the proper treatment method of the industrial wastewaters. Industrial processes and characterization discussed in this section might be useful for the selection of suitable methods to prevent pollutant discharge from industrial processes.     

The behaviour of giant clams (Bivalvia: Cardiidae: Tridacninae)

Giant clams, the largest living bivalves, live in close association with coral reefs throughout the Indo-Pacific. These iconic invertebrates perform numerous important ecological roles as well as serve as flagship species—drawing attention to the ongoing destruction of coral reefs and their associated biodiversity. To date, no review of giant clams has focussed on their behaviour, yet this component of their autecology is critical to their life history and hence conservation. Almost 100 articles published between 1865 and 2014 include behavioural observations, and these have been collated and synthesised into five sections: spawning, locomotion, feeding, anti-predation, and stress responses. Even though the exact cues for spawning in the wild have yet to be elucidated, giant clams appear to display diel and lunar periodicities in reproduction, and for some species, peak breeding seasons have been established. Perhaps surprisingly, giant clams have considerable mobility, ranging from swimming and gliding as larvae to crawling in juveniles and adults. Chemotaxis and geotaxis have been established, but giant clams are not phototactic. At least one species exhibits clumping behaviour, which may enhance physical stabilisation, facilitate reproduction, or provide protection from predators. Giant clams undergo several shifts in their mode of acquiring nutrition; starting with a lecithotrophic and planktotrophic diet as larvae, switching to pedal feeding after metamorphosis followed by the transition to a dual mode of filter feeding and phototrophy once symbiosis with zooxanthellae (Symbiodinium spp.) is established. Because of their shell weight and/or byssal attachment, adult giant clams are unable to escape rapidly from threats using locomotion. Instead, they exhibit a suite of visually mediated anti-predation behaviours that include sudden contraction of the mantle, valve adduction, and squirting of water. Knowledge on the behaviour of giant clams will benefit conservation and restocking efforts and help fine-tune mariculture techniques. Understanding the repertoire of giant clam behaviours will also facilitate the prediction of threshold levels for sustainable exploitation as well as recovery rates of depleted clam populations.     

Natural and synthesised iron-rich amendments for As and Pb immobilisation in agricultural soil

The immobilisation of heavy metals in contaminated soils is a promising alternative to conventional remediation techniques. Very few studies have focused on the use of iron-rich nanomaterials and natural materials for the adsorption of toxic metals in soils. Synthesised iron-rich nanomaterials (Fe and Zr–Fe oxides) and natural iron-rich materials (natural red earth; NRE) were used to immobilise As and Pb in contaminated agricultural soil. Total concentrations of As and Pb in the initial soil (as control) were 170.76 and 1945.11 mg kg^?1, respectively. Amendments were applied into the soil at 1, 2.5 and 5% (w/w) in triplicate and incubated for 150 days. Except for the NRE-amended soil, soil pH decreased from 5.6 to 4.9 with increasing application rates of Fe and Zr–Fe oxides. With addition of Fe and Zr–Fe oxides at 5%, the ammonium acetate (NHO₄Ac)-extractable Pb was greatly decreased by 83 and 65% compared with NRE addition (43%). All subjected amendments also led to a decrease in NHO₄Ac-extractable As in the soils, indicating the high capacity of As immobilisation. Soil amended with NRE showed a lower ratio of cy19:0 to 18:1ω7c, indicating decreased microbial stress. The toxicity characteristic leaching procedure produced results similar to the NHO₄Ac extraction for As and Pb. The NRE addition is recommended for immobilising heavy metals and maintaining biological soil properties.     

Settling and dewatering characteristics of granulated methane-oxidizing bacteria

We evaluated the settling ability and dewaterability of granulated methane-oxidizing bacteria (GMOB) after granulation using a continuous-flow reactor. A comparative analysis on settling and dewatering characteristics due to changes in sludge retention time (SRT, 10, 15 and 20 days) during cultivation of GMOB was conducted. In assessing dewaterability, the specific resistance to filtration (SRF) of activated sludge and GMOB was found to be 8.21×1013-2.38×1014 and 4.88 × 1012-1.98×1013 m/kg, respectively. It was confirmed that as SRT decreased, SRF of GMOB increased. In the case of bound extracellular polymeric substance (EPS), activated sludge registered 147.5 mg/g-VSS while GMOB exhibited 171-177.2 mg/g-VSS. In the case of extracellular polymeric substance soluble EPS in effluent, activated sludge measured 62 mg/L and GMOB had 17.4-21.4 mg/L. The particle size analysis showed that mean particle diameters of GMOB were 402, 369, and 350 μm, respectively, at SRTs of 20, 15 and 10 days. In addition, it was found that GMOB had a larger mean particle diameter and exhibited much better settleability and dewaterability than activated sludge did.     

Kinetic modeling of fenton oxidation of phenol and monochlorophenols

A kinetic model, consisting of 28 reactions, was proposed to understand the key mechanism of the Fenton oxidation of phenol and o-, m-, and p-chlorophenols. Particular attention is paid to the interactions of the organic intermediates with the Fe species. The proposed model reasonably predicts the decomposition kinetics and by-product formation for the different phenols at widely varying levels of Fe2+, H2O2, and the phenols. For the phenols and intermediates, change in concentrations with time was predicted within 20-30% deviation from the measured data. The single model predicts the overall kinetics of Fenton oxidation of all the tested phenols by adjusting the rate constant of hydroxyl radical for each phenol. Sensitivity analysis indicates that the key reactions are those that directly govern the levels of OH radical and Fe2+. Both the model prediction and the experimental results show that the decomposition rate could be complicated particularly by the availability of Fe2+. Understanding the interactions of the organic intermediates with Fe2+ is thus of critical importance to improve the decomposition performance.