Electricity planning and environmental issues in selected Asian countries

This paper discusses the key issues related to the supply- and demand-side options for the improvement of the environmental performance of the electricity sector in 10 countries of Asia. It also discusses the growth of the electricity sector and its contribution in the total emission of pollutants from the use of commercial energy in the selected countries.     

Allelopathic response of <Emphasis Type="Italic">Vetiveria zizanioides</Emphasis> (L.) Nash on members of the family Enterobacteriaceae and <Emphasis Type="Italic">Pseudomonas</Emphasis> spp.

The biological removal of phosphates was carried as a part of treatment strategy. Vetiveria zizanioides (L.) Nash belonging to the family Poaceae was used for biological removal of biostimulants. Vetiver reportedly has mycorrhizal association; besides having potential for removal of PO₄ ⁻³ also showed allelopathic affect on the microorganisms present in the water. In fact after a period of 96 h old roots of this plant have been found to have killing effects on the E. coli, Enterobacter spp. Pseudomonas spp. belonging to the family Enterobacteriaceae. The paper is opening a new face of study.     

A study of the workload of underground trammers in the Ranigang coal field area of West Bengal, India.

Thirty healthy trammers were examined in underground haulage mines during their normal activity. Physiological strain in terms of heart rate (HR) varied between 101.6 and 104.7 beats/min with mean net cardiac cost of 33.06 and 34.06 beats/min for younger and older groups respectively. The average relative cardiac cost was lower for younger subjects than for older ones. Oxygen consumption (VO2) was measured with an Oxylog-II machine (UK); subsequently values were estimated. Maximum aerobic capacity was estimated with an indirect method following a standard step test protocol. The responses revealed that the average VO2 during the activity was 0.75 and 0.8 L/min, which corresponded to energy expenditure (EE) of 3.8 and 3.97 Kcal/min for younger and older subjects respectively. The workload in terms of HR and EE was moderate, whereas the aerobic strain experienced by aged workers was above the acceptable level.     

The Potential of Soil Carbon Sequestration Through Improved Management Practices in Norway

The study was conducted to assess the potential of Norwegian agricultural ecosystems to sequester carbon (C) based on the data from some long-term agronomic and land use experiments. The total emission of CO₂ in Norway in 1998 was 41.4 million metric ton (MMT), of which agriculture contributed only 0.157 MMT, or <0.4% of the total emissions. With regards to methane (CH₄) and nitrous oxide (N₂O) gases, however, agricultural activities contributed 32.5% and 51.3% of their respective emissions in Norway. The soil organic carbon (SOC) losses associated with accelerated soil erosion in Norway are estimated at 0.475 MMTC yr^–1. Land use changes and soil/crop management practices with potential for SOC sequestration include conservation tillage methods, judicious use of fertilizers and manures, use of crop residues, diverse crop rotations, and erosion control measures. The potential for SOC sequestration is 0.146 MMTC yr^–1 for adopting conservation tillage, 0.011–0.035 MMTC yr^–1 for crop residue management, 0.026 MMTC yr^–1 for judicious use of mineral fertilizer, 0.016–0.135 MMTC yr^–1 for manure application, and 0.036 MMTC yr^–1 for adopting crop rotations. The overall potential of these practices for SOC sequestration ranges from 0.591 to 1.022 MMTC yr^–1 with an average value of 0.806 MMTC yr^–1. Of the total potential, 59% is due to adoption of erosion control measures, 5.8% to restoration of peat lands, 21% to conversion to conservation tillage and residue management, and 14% to adoption of improved cropping systems. Enhancing SOC sequestration and improving soil quality, through adoption of judicious land use and improved system of soil and crop management, are prudent strategies for sustainable management of soil, water and environment resources.Readers should send their comments on this paper to: bhaskarn ath@aol.com within 3 months of publication of this issue.     

Emissions from burning biofuels in metal cookstoves

Promoting stoves that burn wood and other biofuels more efficiently is one of the means to reduce fuel consumption, but such efficient stoves may also emit more carbon monoxide and total suspended particulates. In an earlier study, a standard chamber method was proposed to estimate emission factors from burning fuelwood (Acacia nilotica). Here that methodology is extended to measure emission factors from burning of dungcakes and crop residues (Brassica or mustard stalks)—common fuels in many developing countries. The amounts of carbon monoxide (CO) and total suspended particulates (TSP) emitted by four different models of stoves, when using each of the three biofuels, are measured.The CO emission factors range from 13–68 (g/kg) for fuelwood to 26–67 g/kg for dungcakes and 20–114 g/kg for crop residues, for particulates they range from 1.1–3.8 to 4.1–7.8 and 2.1–12.0 g/kg for the three fuels, respectively. On a per unit heat delivered basis, the emissions of CO and TSP from both dungcakes and crop residues are two to three times higher compared to those from fuelwood. While for some improved stove-fuel combinations, the increase in emission factors was offset by the increase in thermal efficiency, this was not always so and causes a dilemma. The more efficient stoves are found to have higher emission factors of both CO and TSP for all three fuels. Emissions per standard task (i.e, on a unit heat delivered basis) is proposed as a criterion to evaluate cookstoves.     

Environmental significance of nitrogenous organic compounds in aquatic sources

The presence of nitrogenous organic compounds in raw water sources for municipal supplies is of environmental concern because many of them exert significant chlorine demand, while some produce complex stable mutagenic products upon chlorination or are precursors to haloform formation. Seven N-organic compounds have been identified in municipal water concentrates (adenine, 5-chlorouracil, cytosine, guanine, purine, thymine, and uracil) at concentrations ranging from 20 to 860 μg/L. Eight compounds (adenine, cytosine, purine, pyrrole, thymine, tryptophan, tyrosine, and uracil) have been found in filtrates from cultures of either Anabaena flos aquae or Oscillatoria tenuis. Calculated CHCl₃ levels which might have formed at pH 7 in the water supplies were well below the maximum contaminant level (MCL) of 0.1 mg/L proposed by the U.S. Environmental Protection Agency (USEPA) for total trihalogenated methanes. Calculated levels of CHCl₃ which might have been formed under more alkaline conditions, however, were more than 10% of the MCL and were therefore significant. Calculated levels of combined forms of chlorine yielding falsely positive tests for free chlorine in some samples were slightly less or exceeded the 0.5 mg/L free chlorine residual generally taken as an acceptable level of disinfection. The demonstration of a parallel increase in organic nitrogen content with population density in two laboratory grown blue-green algal cultures, and the finding of elevated organic nitrogen values in a water supply sample collected during the occurrence of a blue-green algal bloom, suggested that summer algal bloom occurrence can add considerably to the organic nitrogen content and the trihalomethane potential of water supplies.     

Sequence-based source tracking of Escherichia coli based on genetic diversity of beta-glucuronidase

High levels of fecal bacteria are a concern for recreational waters; however, the source of contamination is often unknown. This study investigated whether direct sequencing of a bacterial gene could be utilized for detecting genetic differences between bacterial strains for microbial source tracking. A 525-nucleotide segment of the gene for beta-glucuronidase (uidA) was sequenced in 941 Escherichia coli isolates from the Clinton River-Lake St. Clair watershed, 182 E. coli isolates from human and animal feces, and 34 E. coli isolates from a combined sewer. Environmental isolates exhibited 114 alleles in 11 groups on a genetic tree. Frequency of strains from different genetic groups differed significantly (p < 0.03) between upstream reaches (Bear Creek-Red Run), downstream reaches, and Lake St. Clair beaches. Fecal E. coli uidA sequences exhibited 81 alleles that overlapped with the environmental set. An algorithm to assign alleles to different host sources averaged approximately 75% correct classification with the fecal data set. Using the same algorithm, the percent of environmental isolates assignable to humans decreased significantly between Bear Creek-Red Run (30 +/- 3%) and the beaches (17 +/- 2%) (p < 0.05). Birds accounted for approximately 50% of assignable environmental isolates. For combined sewer isolates, the same algorithm assigned 51% to humans. These experiments demonstrate differences in the frequency of different E. coli strains at different locations in a watershed, and provide a "proof in principle" that sequence-based data can be used for microbial source tracking.