Concentrations of various elements and inorganic ions in rice straw and ash

Various elements and inorganic ions in rice straw and ash samples were analyzed by using inductively coupled plasma atomic emission spectrometry (ICP‐AES) and ion chromatography (IC). Five major elements: Mg, Mn, Al, Ca, and Fe and eight minor and trace elements: Cr, Cu, Ti, Zn, La, Sr, Ba, and Hg were detected in these samples, at more than ppm‐level. In ash samples the trace elements such as Y, As, V, Se, and Sc were also identified. The concentrations of SO₄, PO₄, Cl, Na, and K ions in these samples were higher than those of other ions measured. These elements and inorganic ion concentrations were approximately one order of magnitude higher in the ash than in the straw samples. Gas chromatography/mass spectrometry (GC/MS) and library search showed the presence of fatty‐, carboxylic‐ and nicotinic acids, and their derivatives in small quantities in the straw samples.     

Concentrations and compositions of organochlorine contaminants in sediments, soils, crustaceans, fishes and birds collected from Lake Tai, Hangzhou Bay and Shanghai city region, China

Contamination by persistent organochlorines (OCs), such as DDTs, hexachlorocyclohexane isomers (HCHs), chlordane compounds (CHLs), hexachlorobenzene (HCB) and polychlorinated biphenyls (PCBs) were examined in sediments, soils, fishes, crustaceans, birds, and aquaculture feed from Lake Tai, Hangzhou Bay, and in the vicinity of Shanghai city in China during 2000 and 2001. OCs were detected in all samples analyzed, and DDT and its metabolites were the predominant contaminants in most sediments, soils and biota. Concentrations of p,p'-DDT and ratio of p,p'-DDT to SigmaDDTs were significantly higher in marine fishes than those in freshwater fishes. While the use of DDTs has been officially banned in China since 1983, these results indicate a recent input of technical DDTs into the marine environment around Hangzhou Bay. Comparison of organochlorine concentrations in fishes collected from Lake Tai and Hangzhou Bay suggests the presence of local sources of HCHs, chlordanes and PCBs at Lake Tai. Higher proportions of penta- and hexa-PCB congeners in fishes at Lake Tai may suggest the use of highly chlorinated PCB product, such as PCB(5), around this lake. To our knowledge, this is a first comprehensive study to examine the present status of organochlorine contamination in various environmental media, such as sediments, soils and wildlife, in China.     

Time-trend (1973-2000) of polybrominated diphenyl ethers in Japanese mother's milk

The time-trend and recent concentrations of polybrominated diphenyl ethers (PBDEs) in Japanese mother's milk were investigated. The time-trend of 16 PBDEs (BDE-28, 37, 47, 66, 71, 75, 77, 85, 99, 100, 119, 153, 154, 138, 183, and 190) in pooled milk samples from mothers living in Osaka between 1973 and 2000 was analyzed. Additionally, PBDE concentrations in individual milk samples collected from 13 mothers living in Kanagawa and Okayama in 1999 were measured. The total concentration of all PBDE congeners (SigmaPBDEs) measured in the pooled samples increased during the period between 1973 (<0.01 ng/g lipid) and 1988 (1.64 ng/g lipid), and remained low afterwards while showing remarkable changes in PBDE congener profiles. The SigmaPBDEs in the 1999 individual milk samples were also low (0.56-3.97 ng/g lipid), except for a single sample (291 ng/g lipid). The source of this exposure could not be identified.     

Influence of mixed molten carbonate composition on hydrogen formation by steam gasification

Steam gasification in the presence of carbonate compounds is an effective method to recover useful materials from electronic waste streams by converting plastics into gaseous products that can be used for energy production and avoiding the expensive manual disassembly process. We investigated steam gasification of activated carbon in the presence of various mixtures of lithium carbonate, sodium carbonate, and potassium carbonate. The activated carbon was almost completely converted into hydrogen and carbon dioxide at 700°C under 0.1 MPa pressure in the presence of carbonate mixtures. Carbon dioxide was also derived from partial decomposition of lithium carbonate. Steam gasification was accelerated in the presence of various carbonate mixtures and at increasing steam partial pressures. These experimental results show that fluidity of carbonates, the potassium content of the carbonate, and the steam partial pressure are important factors in accelerating steam gasification.     

Numerical investigation concerning the impact of CO2 geologic storage on regional groundwater flow

Large-scale storage of carbon dioxide in saline aquifers may cause considerable pressure perturbation and brine migration in deep rock formations, which may have a significant influence on the regional groundwater system. With the help of parallel computing techniques, we conducted a comprehensive, large-scale numerical simulation of CO₂ geologic storage that predicts not only CO₂ migration, but also its impact on regional groundwater flow. As a case study, a hypothetical industrial-scale CO₂ injection in Tokyo Bay, which is surrounded by the most heavily industrialized area in Japan, was considered, and the impact of CO₂ injection on near-surface aquifers was investigated, assuming relatively high seal-layer permeability (higher than 10 microdarcy). A regional hydrogeological model with an area of about 60 km × 70 km around Tokyo Bay was discretized into about 10 million gridblocks. To solve the high-resolution model efficiently, we used a parallelized multiphase flow simulator TOUGH2-MP/ECO2N on a world-class high performance supercomputer in Japan, the Earth Simulator. In this simulation, CO₂ was injected into a storage aquifer at about 1 km depth under Tokyo Bay from 10 wells, at a total rate of 10 million tons/year for 100 years. Through the model, we can examine regional groundwater pressure buildup and groundwater migration to the land surface. The results suggest that even if containment of CO₂ plume is ensured, pressure buildup on the order of a few bars can occur in the shallow confined aquifers over extensive regions, including urban inlands.     

Genetic Engineering of Cyanobacteria to Enhance Biohydrogen Production from Sunlight and Water

To mitigate global warming caused by burning fossil fuels, a renewable energy source available in large quantity is urgently required. We are proposing large-scale photobiological H₂ production by mariculture-raised cyanobacteria where the microbes capture part of the huge amount of solar energy received on earth’s surface and use water as the source of electrons to reduce protons. The H₂ production system is based on photosynthetic and nitrogenase activities of cyanobacteria, using uptake hydrogenase mutants that can accumulate H₂ for extended periods even in the presence of evolved O₂. This review summarizes our efforts to improve the rate of photobiological H₂ production through genetic engineering. The challenges yet to be overcome to further increase the conversion efficiency of solar energy to H₂ also are discussed.     

An Ex Post Cost-Benefit Analysis of the Nitrogen Dioxide Air Pollution Control Program in Tokyo

ABSTRACT

The benefits and costs of past nitrogen dioxide (NO₂) control policies were calculated for Tokyo, Japan, using environmental, economic, political, demographic, and medical data from 1973 to 1994. The benefits of NO₂ control were estimated as medical expenses and lost work time due to hypothetical no-control air concentrations of NO₂. Direct costs were calculated as annualized capital expenditures and 1 year's operating costs for regulated industries plus governmental agency expenses. The major findings were as follows:

(1) Using Tokyo's average medical cost of pollution-related illness, the best net estimate of the avoided medical costs due to incidence of phlegm and sputum in adults was 730 billion yen ($6.08 billion; 1 U.S. dollar = 120 yen).

(2) The best net estimate of the avoided medical costs due to incidence of lower respiratory illness in children was 93 billion yen ($775 million).

(3) Using Tokyo's average duration of pollution-related illness and average wages, the best net estimate of the avoided costs of lost wages in workers was 760 billion yen ($6.33 billion).

(4) The best net estimate of the avoided costs of lost wages in mothers caring for their sick children was 100 billion yen ($833 million).

(5) Using Tokyo-specific data, the best net costs were estimated as 280 billion yen ($2.33 billion).

(6) Using human health and productivity benefits, and annualized capital cost and operating cost estimates, the best net benefits-to-costs ratio was 6:1 (upper limit 44:1; lower limit 0.3:1). Benefit calculations were sensitive to assumptions of mobile source emissions and certain health impacts that were not included. Cost calculations were highly dependent on assumptions of flue gas volume and fuel use. For comparative purposes, we identified other studies for air pollution-related illness. Assumptions that formed the basis for most of the inputs in the present study, such as duration of illness, medical treatment costs, per person illness in children, and lost wages for working mothers, were similar to those recommended in the literature. Lost wages in sick workers and per capita illness incidence in adults were higher than numbers reported elsewhere. Further advances in cost-benefit analysis (CBA) procedures to evaluate the economic effectiveness of NO₂ controls in Tokyo are recommended to estimate impacts and values for additional human health benefits, ecosystem health and productivity effects, and nonliving system effects, as well as benefits of ancillary reductions in other pollutants. The present study suggests that Tokyo's past NO₂ control policies in total were economically quite effective.