Contributions of humic substances to the dissolved organic carbon pool in wetlands from different climates

Wetlands are an important source of DOM. However, the quantity and quality of wetlands' DOM from various climatic regions have not been studied comprehensively. The relationship between the concentrations of DOM (DOC), humic substances (HS) and non-humic substances (NHS) in wetland associated sloughs, streams and rivers, in cool temperate (Hokkaido, Japan), sub-tropical (Florida, USA), and tropical (Sarawak, Malaysia) regions was investigated. The DOC ranged from 1.0 to 15.6 mg CL(-1) in Hokkaido, 6.0-24.4 mg CL(-1) in Florida, and 18.9-75.3 mg CL(-1) in Sarawak, respectively. The relationship between DOC and HS concentrations for the whole sample set was regressed to a primary function with y-intercept of zero (P<0.005) and a slope value of 0.841. A similar correlation was observed between DOC and NHS concentrations, with a smaller slope value of 0.159. However, the correlation coefficient of the latter was much larger when the data was regressed to a logarithmic curve. These observations suggest the presence of a general tendency that the increased DOC in the river waters was mainly due to the increased supply of HS from wetland soils, whereas the rate of the increase in the NHS supply has an upper limit which may be controlled by primary productivity.     

Hybrid-Type Electrostatic Precipitator

Three experiments were designed to determine the effects of SO₂ concentration on two Southeastern oat varieties—Caroiee and Coker 227. The plants were grown under uniform conditions prior to and after the experimental growth period. During the 7 to 14 day experimental growth period the plants were subjected to four growth temperatures (18/14, 22/18, 26/22 and 30/26° C day/night temperatures) and exposed 2 or 4 times to specific concentrations of SO₂ (from 0 to 4 ppm) for 1.5 or 3.0 hr periods. In the first two experiments, the exposure temperatures were varied (18° to 30° C). In the third design, the exposure temperatures remained constant and two exposure relative humidities (55 and 80%) were used. Injury and growth reductions were more severe in Coker 227 than in Caroiee. Root dry weight (RDW) was affected more than top dry weight (TDW). Plants were more sensitive at the higher growth temperatures. Exposure temperatures had little to variable effects. Plants were more sensitive at 80% than at 55% relative humidity. Biomass was reduced at 0.4 ppm SO₂ after four 3 hr exposures and at 0.75 ppm after two 1.5 hr exposures, but growth was also increased as often. These concentrations approached the accepted threshold for adverse effects to sensitive vegetation. Foliar injury was highly correlated with growth reductions.     

Regulatory Off-Gas Analysis from the Evaporation of Hanford Simulated Waste Spiked with Organic Compounds

Abstract

After strontium/transuranics removal by precipitation followed by cesium/technetium removal by ion exchange, the remaining low-activity waste in the Hanford River Protection Project Waste Treatment Plant is to be concentrated by evaporation before being mixed with glass formers and vitrified. To provide a technical basis to permit the waste treatment facility, a relatively organic-rich Hanford Tank 241-AN-107 waste simulant was spiked with 14 target volatile, semi-volatile, and pesticide compounds and evaporated under vacuum in a bench-scale natural circulation evaporator fitted with an industrial stack off-gas sampler at the Savannah River National Laboratory. An evaporator material balance for the target organics was calculated by combining liquid stream mass and analytical data with off-gas emissions estimates obtained using U.S. Environmental Protection Agency (EPA) SW-846 Methods. Volatile and light semi-volatile organic compounds (<220 °C BP, >1 mm Hg vapor pressure) in the waste simulant were found to largely exit through the condenser vent, while heavier semi-volatiles and pesticides generally remain in the evaporator concentrate. An OLI Environmental Simulation Program (licensed by OLI Systems, Inc.) evaporator model successfully predicted operating conditions and the experimental distribution of the fed target organics exiting in the concentrate, condensate, and off-gas streams, with the exception of a few semi-volatile and pesticide compounds. Comparison with Henry's Law predictions suggests the OLI Environmental Simulation Program model is constrained by available literature data.     

Study on chlorine removal from mixture of waste plastics

The recycling of waste plastics that include plastics that contain chlorine, such as polyvinyl chloride, is difficult because the chlorine leads to the corrosion of equipment. Then, the dechlorination method of waste plastics containing chlorine (CCWP) that consists of a series of melt process and hot water process was examined. CCWP was put into the melt process with coal tar (HOB) and converter dust (CD) to inhibit the diffusion of the chlorine-containing gas. The results indicated that iron oxide of the principal element of CD combines with chlorine eliminated from CCWP, and forms water-soluble iron chloride on the melt process. HOB dissolves or adsorbs a part of the chlorine during the melt process, and inhibits the diffusion of the chlorine-containing gas. Approximately 98% of the chlorine in the CCWP reacts with CD and forms iron chloride, which can be extracted on the hot water process.     

Groundwater-soil-crop relationship with respect to arsenic contamination in farming villages of Bangladesh--a preliminary study

To clarify the groundwater-soil-crop relationship with respect to arsenic (As) contamination, As concentration was measured in tubewell (TW) water, surface soil from farmyards and paddy fields, and fresh taro (Colocasia esculenta) leaves from farmyards in the farming villages of Bangladesh. The As concentration in TW water from farmyards was at least four times higher than the Bangladesh drinking water standard, and the concentration in fresh taro leaves was equal to or higher than those reported previously for leafy vegetables in Bangladesh. As concentration of surface soils in both farmyards and paddy fields was positively correlated with that of the TW water. Further, the concentration in surface soil was positively correlated with levels in fresh taro leaves in the farmyard. This study, therefore, clarified the groundwater-soil-crop relationship in farmyards and the relationship between groundwater-soil in paddy fields to assess the extent of As contamination in Bangladeshi villages.     

Two clinal trends in male-male aggressiveness in a subsocial spider mite (Schizotetranychus miscanthi)

We studied the correlation between male-male aggressive behavior of the spider mite, Schizotetranychus miscanthi and winter coldness, a factor hypothesized to correlate with the degree of relatedness of the interacting males through the frequent occurrence of mother-son mating in the spring. Thirty-one samples from various populations throughout Japan were added to previous data. A cluster analysis revealed two clinal trends for male-male aggression in S. miscanthi in regions of light or no snowfall. The two clines may represent a dimorphism within the species, each having a similar clinal trend within Japan. Further support for the hypothesis that male overwintering survival affects male-male aggressiveness came from a comparison between regions of heavy snowfall and those of light or no snowfall. In regions with heavy snow insulation, overwintering survival may not be as high as in other areas, and there was no correlation between male aggressiveness and the minimum winter temperature. However, there was a significant correlation in regions of light snow. Received: 26 May 1998 / Received in revised form: 16 December 1998 / Accepted: 30 December 1998     

Studies on the pyrolysis behavior of gasification and melting systems for municipal solid waste

 It is important to investigate the pyrolysis processes of municipal solid waste (MSW) in the same way as for any mixture comprised of multiple substances. In this article, a two-reaction model for a variety of MSW mixtures is proposed to predict mass changes due to pyrolysis. In order to formulate the model based on pyrolysis kinetics, we conducted experiments to determine the kinetic model parameters. By thermal analysis of the typical components of MSW, mass changes attributable to the pyrolysis reaction were found at about 350°C for paper, 400°–500°C for plastics, and 200°–400°C for garbage (dry condition). Activation energies were obtained by the Ozawa method based on the mass changes in pyrolysis. Thus, the pyrolysis behavior is formulated as a function of temperature. Then the pyrolysis mass change of the mixture can be predicted by using a weighted sum of the individual components. The model proved useful in experiments with real waste (refuse-derived fuels). Furthermore, the weight yields (pyrolysis gas, tars, solid residues) of the mixture can be calculated by their additive property after measuring the mass balance of each component. Received: May 11, 2001 / Accepted: November 16, 2001     

Three-spined stickleback: an emerging model in environmental endocrine disruption.

The three-spined stickleback, a small teleost species with habitats that range from full marine to fresh water bodies across the whole Northern hemisphere, has a number of advantages for endocrine disruption research. It is the only teleost species with an unambiguous biomarker for androgens, the presence of the glue protein spiggin in the male kidney, which can be measured by enzyme-linked immunosorbent assay (ELISA). The androgen assay has been adopted to detect antiandrogens in two different ways and an homologous ELISA for stickleback vitellogenin is also available. DNA markers for molecular sex determination are available; thus, sex ratios can also be used for in situ biomonitoring. In addition, the critical period of sexual differentiation has been determined and the occurrence of intersex fish has been reported several times. The species full genome sequence is almost complete. All aspects of stickleback biology (ecology, evolution, behavior, physiology, endocrinology) are well documented. In European waters, the stickleback is the only fish that can bring laboratory and field studies together and allow the true impact of endocrine disruptors on fish populations to be evaluated.