Experimental studies of the dilution of vehicle exhaust pollutants by environment-protecting pervious pavement

This study determines whether environment-protecting pervious pavement can dilute pollutants immediately after emissions from vehicle. The turbulence-driven dry-deposition process is too slow to be considered in this aspect. The pavement used is the JW pavement (according to its inventors name), a high-load-bearing water-permeable pavement with patents in over 100 countries, which has already been used for more than 8 years in Taiwan and is well suited to replacing conventional road pavement, making the potential implementation of the study results feasible. The design of this study included two sets of experiments. Variation of the air pollutant concentrations within a fenced area over the JW pavement with one vehicle discharging emissions into was monitored and compared with results over a non-JW pavement. The ambient wind speed was low during the first experiment, and the results obtained were highly credible. It was found that the JW pavement diluted vehicle pollutant emissions near the ground surface by 40%-87% within 5 min of emission; whereas the data at 2 m height suggested that about 58%-97% of pollutants were trapped underneath the pavement 20 min after emission. Those quantitative estimations may be off by +/- 10%, if errors in emissions and measurements were considered. SO2 and CO2 underwent the most significant reduction. Very likely, pollutants were forced to move underneath due to the special design of the pavement. During the second experiment, ambient wind speeds were high and the results obtained had less credibility, but they did not disprove the pollutant dilution capacity of the JW pavement. In order to track the fate of pollutants, parts of the pavement were removed to reveal a micro version of wetland underneath, which could possibly hold the responsibility of absorbing and decomposing pollutants to forms harmless to the environment and human health.     

Detection and quantification of major toxigenic Microcystis genotypes in Moo-Tan reservoir and associated water treatment plant

Two molecular methods, denaturing gradient gel electrophoresis (DGGE) and quantitative real-time polymerase chain reaction (qPCR) with the Universal ProbeLibrary (UPL) probe, were developed and used for the characterization and quantification of several microcystin producers in Moo-Tan Reservoir (MTR), Taiwan and its associated water treatment plant (Shih-Men Water Treatment Plant, SMWTP). Internal transcribed spacer (ITS) sequence, a highly diversified region between the 16S rRNA and 23S rRNA genes, was used to further identify the isolated strains from MTR and also used in DGGE for the detection of the specific DNA fragments and biomarkers for 11 strains observed in MTR. These ITS-DGGE biomarkers were successfully applied to monitor the community changes of potential toxigenic Microcystis sp. over a period of five years. Two highly specific primers were combined with UPL probes to measure microcystins synthesis gene (mcyB) and phycocyanin intergenic spacer region (cpcB) concentrations in water samples. The copy concentrations of UPL-mcyB and UPL-cpcB correlated well with MC-RR concentrations/water temperature and Microcystis sp. cell numbers in the water samples, respectively. For SMWTP, toxin concentrations were low, but the DGGE bands clearly demonstrated the presence of potential microcystin producers in both water treatment plants and finished water samples. It was demonstrated that toxigenic Microcystis sp. may penetrate through the treatment processes and pose a potential risk to human health in the drinking water systems.     

Encapsulation of lead from hazardous CRT glass wastes using biopolymer cross-linked concrete systems

Discarded computer monitors and television sets are identified as hazardous materials due to the high content of lead in their cathode ray tubes (CRTs). Over 98% of lead is found in CRT glass. More than 75% of obsolete electronics including TV and CRT monitors are in storage because appropriate e-waste management and remediation technologies are insufficient. Already an e-waste tsunami is starting to roll across the US and the whole world. Thus, a new technology was developed as an alternative to current disposal methods; this method uses a concrete composite crosslinked with minute amounts of biopolymers and a crosslinking agent. Commercially available microbial biopolymers of xanthan gum and guar gum were used to encapsulate CRT wastes, reducing Pb leachability as measured by standard USEPA methods. In this investigation, the synergistic effect of the crosslinking reaction was observed through blending two different biopolymers or adding a crosslinking agent in biopolymer solution. This CRT-biopolymer-concrete (CBC) composite showed higher compressive strength than the standard concrete and a considerable decrease in lead leachability.     

Characterization of eco-cement paste produced from waste sludges

In this study, marble sludge, sewage sludge, drinking water treatment plant sludge, and basic oxygen furnace sludge were used as replacements for limestone, sand, clay, and iron slag, respectively, as the raw materials for the production of cement in order to produce eco-cement. It was found that it is feasible to use marble sludge to replace up to 50% of the limestone and also that other materials can serve as total replacements for the raw materials typically used in the production of cement. The major components of Portland cement were all found in eco-cement clinkers. The eco-cement was confirmed to produce calcium hydroxide and calcium silicate hydrates during the hydration process, increasing densification with the curing age. The compressive strength (S_c) and microstructural evaluations conducted at 28 d revealed the usefulness of eco-cement. It was observed that the S_c data correlated linearly with the pore volume (P) data at 28 d. The proposed model equation could be represented as S_c = 178-461P (correlation coefficient, R² = 0.96). Two parameters, the large capillary pore volume and the medium capillary pore volume, were evaluated using multiple regression analysis.     

Distribution of Selected Soil and Water Conservation Practices in the U.S. as Identified with Google Earth

The proper representation of conservation practices on agricultural lands is an important factor in large‐scale assessments of water quality in the United States. Unfortunately, there are few publicly available data sources at the local level and even fewer at the national scale. In this research, randomly selected points within agricultural lands were examined for selected conservation practices using Google Earth aerial imagery by a team of interpreters. In total, 13,530 points had field boundaries digitized, and were subsequently examined and classified. The presence of terraces, grassed waterways, contour farming, center pivot irrigation, strip cropping, ponds, riparian vegetation, filter strips, and land cover were noted. Subjectivity among interpreters was evaluated using duplicate samples and was found to be similar to image misclassification rates in other research. Conservation practice adoption rates for selected major river basins compared favorably with data collected by the Conservation Effects Assessment Project. The frequency of occurrence of each conservation practice was summarized and presented by ecoregion. To facilitate future research, point level data and software source code developed in this research are available via the web at http://nlet.brc.tamus.edu/Conservation . Aerial imagery was found to be a powerful, inexpensive, and easily accessible tool to assess large‐scale conservation practice implementation for certain conservation practices.     

Development of a Cropland Management Dataset to Support U.S. Swat Assessments

The Soil and Water Assessment Tool (SWAT) is widely used in the United States (U.S.) to simulate hydrology and water quality simulation. Process‐based models like SWAT require a great deal of data to accurately represent the natural world, including topography, land use, soils, weather, and management. With the exception of management, all these data are available nationally from multiple sources. To date, credible SWAT studies in the U.S. have assembled suitable management data (operation scheduling, fertilization application rates, and plant growth parameterization). In this research, we develop a national management database for SWAT using existing U.S. Department of Agriculture data sources. These data are compatible with existing SWAT interfaces and are relatively easy to use. Although management data from local sources is preferred, these data are not always available. This work is intended to fill this void with more reasonable management data than the existing defaults. This national database covers all major cultivated crops and should facilitate improved SWAT applications in the U.S. These data were tested in two case studies and found to produce satisfactory SWAT predictions. The database developed in this research is freely available on the web.     

Effect of octylphenol on physiologic features during growth in Arabidopsis thaliana

Alkylphenol ethoxylates are widely used as detergents, emulsifiers, solubilizers, wetting agents and dispersants. Octylphenol (OP) ethoxylates, one of alkylphenol ethoxylates, represent 15–20% of the market, and their metabolic residues may be discharged to surface waters, sediments and soils as a persistent and ubiquitous pollutant. We tested the response of Arabidopsis thaliana to different concentrations of OP. OP affected the germination percentage and mean germination period. 10 d treatment with OP, especially high concentration (10 and 50 mg L⁻¹), decreased shoot and root biomass and root length of 30 d-old A. thaliana. Content of chlorophyll was decreased but that of proline was increased in leaves with OP treatment. OP caused oxidative stress in leaves; malondialdehyde content was increased, and the activities of ascorbate peroxidase, catalase and superoxide dismutase were induced. OP affects the physiologic and morphologic features of A. thaliana during growth. Because plants might be exposed to OP for a long time in the surroundings, more attention needs to be paid to the effect of OP on plants.     

Carcinogenicity of diesel exhaust as tested in strain a mice

Groups of strain A mice were exposed to diesel exhaust by inhalation and diesel particulate by intraperitoneal injection. The animals were exposed from seven to eight weeks and then sacrificed 26–30 weeks postexposure. Other animals were exposed for up to seven months by the inhalation route. Some animals were promoted using urethane at a dose below which tumors would occur. There was no increase in incidence of pulmonary adenomas in the animals exposed to either diesel exhaust or diesel particulate over the control animals. In the animals which were promoted using urethane at a low dose, there was a significant increase in pulmonary adenomas. Diesel particulate was found in the lungs and bronchial lymph nodes of animals exposed to diesel exhaust 26–30 weeks after cessation of exposure.     

Chlorinated pesticides and PCBs in sediments and molluscs from freshwater canals in the Hanoi region

The concentrations of organochlorine pesticides and PCBs were determined in surface sediments and freshwater molluscs (Angulyagra sp.) from water canals in the region of Hanoi city. Results obtained show that the concentration of sigma DDT compounds in sediments range from 7 to 80 ng/g (dry weight) and from 6 to 864 ng/g (dry weight) in the soft tissues of molluscs. The concentrations of sigma DDTs were higher in populated sites and much lower in rural sites, indicating that the DDT has been used for mosquito control and not as a crop protection chemical. Hexachlocyclohexanes (HCHs) have also been widely used in the region but the current environmental concentrations are much lower than those of DDT's, which is due to the less persistence of those compounds. Polychlorinated biphenyls (PCBs) were measured, for example as aroclor 1254, in concentrations up to 40 ng/g (dry weight) and up to 76 ng/g (dry weight) in sediments and molluscs, respectively. Molluscs from water canals are a very popular food in the region. Taking into consideration the high DDT levels measured in these molluscs their consumption is worrisome and may expose the population to high levels of endocrine disrupting substances. Current PCB levels in sediments are lower than usually measured in industrialized countries. Therefore, PCB concentrations in aquatic molluscs are still also relatively low. These snails do not have enzyme ability to metabolize most of the CB congeners and, thus, are passive accumulators and a significant transfer pathway of CBs to consumers. Therefore, measures to phase out the use of these persistent and bioaccumulable chemicals should be adopted in order to prevent further environmental contamination.     

Dechlorination pathways of ortho-substituted PCBs by UV irradiation in n-hexane and their correlation to the charge distribution on carbon atom

The photodegradations of 22 individual polychlorinated biphenyl (PCB) congeners (including 21 non-coplanar ortho substituted and one non-ortho substituted) by irradiation with ultraviolet lamp in n-hexane solution were studied. Photoproducts were identified by matching their retention times and mass spectra with those of authentic standards. PCB congener with less than two chlorides was photodegraded within half an hour, if more than three chlorine on ring, the photodechlorination time for PCB needs one and half hours or more, sometimes even longer than 15 h. The half-life of PCB degradation by photodechlorination was much shorter than that by anaerobic biological dechlorination. Charge distribution on carbon atom combined with the monitoring products of individual PCB congeners were used to deduce the photodegradation pathways. The higher the charge distribution for carbon to which chlorine is attached, the easier for photodechlorination to occur. A lot of chlorine atoms attached PCB, the dechlorination was found to occur prior to the carbon with higher charge distribution at the benzene ring with more chlorine atoms attached.