Variance in heavy metal leachability of Pb-, Ni-, and Cr-contaminated soils through red brick sintering procedure.

The technology for remediating heavy metal-contaminated soil is considerably limited because heavy metals do not undergo decomposition. Off-site reuse has emerged as the main technique for treating heavy metal-contaminated soil. Soil is the primary material in red brick making; and in the sintering procedure, heavy metals could solidify and stabilize within bricks. In this study, lead-, nickel-, and chromium-contaminated soils were collected from multiple agricultural fields. The sintering process was performed using a kiln that was for making red bricks. The sintering temperature was approximately 1000 °C. Soil and brick samples, before and after sintering, were analyzed for metal extraction concentration and binding form distribution. After sintering, the concentrations of Pb, Ni, and Cr determined through X-ray fluorescence approximated the concentrations in the soil. However, in the bricks, the bioavailability concentration of Pb, Ni, and Cr is less than 1% of that in the soil; the toxicity characteristic leaching procedure (TCLP) leaching concentration of Pb in the bricks was only 4% of that in the soil, and the leaching concentrations of Ni and Cr were lower than the detectable concentration. For the aqua regia extraction method, in the bricks, the Pb, Ni, and Cr were extracted and the concentrations accounted for 4.6%, 8.8%, and 9.4% of the concentrations in the soil, respectively. After sintering, more than 95% of Ni and Cr in the bricks were in residual fractions. The sintering process has the ability to stabilize the heavy metals in the contaminated soil.

Phytoremediation of lead using corn in contaminated agricultural land­an in situ study and benefit assessment.

Phytoremediation is an environmentally friendly and economically feasible remediation technology for mitigating soil contamination in agricultural lands. However, phytoremediation can be a slow process, and for highly contaminated soils this approach would require hundreds to thousands of years to meet soil environmental quality standards. Such a long period of phytoremediation is relatively unfeasible without economic revenue from crop production. This study involves growth of corn in plots of lead-contaminated agricultural land with Pb concentrations of about 6000 mg/kg. Our results showed that Bright Jean No. 7 corn was highly tolerant to lead, as evidenced by minimal effects on its growth and biomass production. Annually, each hectare of corn could produce up to 93.4 tons of dry matter and removed up to 7.2 kg of lead. The corn biomass grown on such contaminated fields could be used as a bioenergy fuel, and each hectare of corn biomass could produce 1545 GJ of thermal energy every year, which is equivalent to the heat from combustion of 57 tons of hard coal. The lead content in the corn kernel was less than the EU standard limit for animal consumption. Each hectare could produce approximately 25 tons of corn grains for animal feed per year, and the remaining parts of the plant could be used as the bioenergy fuel to generate heat energy equivalent to 40 tons of hard coal.

Exploring the benefits of growing bioenergy crops to activate lead-contaminated agricultural land: a case study on sweet potatoes.

Phytoremediation is the most environmentally friendly remediation technology for heavy metal contaminated soil. However, the phytoremediation approach requires a long time to yield results, and the plants used must be economically profitable to maintain the sustainability of the process. Because high levels of bioethanol can be produced from sweet potatoes, an experiment was conducted by planting sweet potatoes in a lead-contaminated site to observe their growth and lead-uptake capacity, thereby enabling the evaluation of the phytoremediation efficiency of sweet potatoes. The lead content in the soil was approximately 6000 mg kg(-1), and the phytoavailable Pb content was 1766 mg kg(-1). Three starch-rich sweet potato varieties, Tainung No. 10 (TNG-10), Tainung No. 31 (TNG-31), and Tainung No. 57 (TNG-57), were used in the experiment. The results indicated that TNG-10, TNG-31, and TNG-57 had fresh root tuber yields of 94.5, 133.0, and 47.5 ton ha(-1) year(-1), produced 9450, 13,297, and 4748 L ha(-1) year(-1) of bioethanol, and removed 2.68, 7.73, and 3.22 kg ha(-1) year(-1) of lead, respectively. TNG-31 yielded the highest bioethanol production and the highest lead removal in the lead-contaminated site. Therefore, implementing phytoremediation by planting TNG-31 would decrease lead content and generate income, thereby rendering the sustainable and applicable activation of contaminated soil possible.

Effect of air-drying and oven-drying treatment on Cr(VI) content and Cr bond forms in soil.

Air-drying and oven-drying are pretreatment processes often used before testing and analyzing various soil characteristics in the laboratory. This study selected three kinds of soil, including red soil, entisol, and alluvial soil, and examined the variation of the Cr(VI) content and Cr bond forms in these soils during air-drying and oven-drying. The results show that when the soil is air-dried in natural environment, the Cr(VI) content decreases with air-drying time. On day 10 of air-drying, the Cr(VI) content in these soils is 22.8∼47.9 % of the initial value. When the soil is oven-dried, the Cr(VI) concentration decays faster; on day 8, the Cr(VI) is no longer detected in these soil samples. When the Cr(VI)-contaminated soil is treated by air-drying and oven-drying, the Cr bond form converts into a more stable form. After oven-drying, the Cr mainly exists in Fe-Mn oxide form, organic bond form, and residual form. The air-drying and oven-drying pretreatment processes of soil reduce the Cr(VI) content and stabilize the Cr bond form. If the laboratory analytic results are applied to risk analysis or remediation strategy planning for chromium-contaminated soil, the toxicity, bioavailability, and mobility of Cr in soil may be underrated.

Remediation of soils contaminated with chromium using citric and hydrochloric acids: the role of chromium fractionation in chromium leaching.

Acid washing is a common method for soil remediation, but is not always efficient for chromium-contaminated soil. Both soil particle size and the forms of chromium existing in the soil affect the efficiency of soil washing. Laboratory batch and column dissolution experiments were conducted to determine the efficiencies of citric and hydrochloric acids as agents to extract chromium from soils contaminated with chromium. The effects of soil particle size and chromium fractionation on Cr leaching were also investigated. About 90% of chromium in the studied soil existed either in residual form or bound to iron and manganese oxides, and Cr fraction distributions were similar for all soil particle sizes. Almost all exchangeable and carbonate-bound chromium was removed by washing once with 0.5 M HCl, whereas organic chromium was more effectively removed by washing with citric acid rather than with HCl solution of the same concentration. For chromium fractions that were either bound to Fe-Mn oxides or existed as residual forms, the efficiencies of acid washing were usually 20% or less, except for 0.5 M HCl solution, which had much higher efficiencies. Separation of the soil sample by particle size before the separate washing of the soil fractions had little improvement on the chromium removal.

Investigating the technical adequacy of curriculum-based measurement in written expression for students who are deaf or hard of hearing.

This study investigated the technical adequacy of curriculum-based measures of written expression (CBM-W) in terms of writing prompts and scoring methods for deaf and hard-of-hearing students. Twenty-two students at the secondary school-level completed 3-min essays within two weeks, which were scored for nine existing and alternative curriculum-based measurement (CBM) scoring methods. The technical features of the nine scoring methods were examined for interrater reliability, alternate-form reliability, and criterion-related validity. The existing CBM scoring method--number of correct minus incorrect word sequences--yielded the highest reliability and validity coefficients. The findings from this study support the use of the CBM-W as a reliable and valid tool for assessing general writing proficiency with secondary students who are deaf or hard of hearing. The CBM alternative scoring methods that may serve as additional indicators of written expression include correct subject-verb agreements, correct clauses, and correct morphemes.

The operation characteristics and electrochemical reactions of a specific circulation-enhanced electrokinetics.

For electrokinetics remediation, the acid produced at the anode due to the water electrolysis will cause the soil acidification and destroy the soil constituents. Especially, the contaminated soils in Taiwan are usually agricultural lands; it is necessary to improve the performance of EK system to maintain the soils nature after remediation. In this study, a circulation-enhanced EK system (CEEK) was designed to neutralize the pH of the working solution and soils. Experiments were conducted by the control of different electrolyte species (sodium and potassium salts) and concentrations (10(-3) to 5x10(-2)M), respectively. Experimental results show the operational characteristics include: the CEEK system can effectively stabilize the pH of processing solution at neutral range and the current can be maintained at stable status with carbonate salts; the pH buffering range of working solution in the CEEK system depends on the electrolyte species and their concentration significantly; the water content remains roughly as their original nature in the CEEK system. For consideration of electrochemical reactions, the water electrolysis is the predominating electrochemical reaction in the CEEK system, which not only influences the pH but also the conductivity of the working solution. In the application of practical engineering, there exist linear relationships between the pH, conductivity, current and the electrolyte concentration, respectively, which can serve as a means to assist engineers to select operational parameters of CEEK.

Pivotal behavior as the mediator of the relationship between parental responsiveness and children's symbolic behavior.

Previous research with parents and children with developmental disabilities indicated that the relationship between mothers' responsive style of interaction and children's rate of development was mediated by the simultaneous relationship between mothers' responsiveness and children's social engagement, or pivotal behavior. In this study, we attempted to determine whether children's pivotal behavior might also mediate the relationship between responsiveness and child development in a sample of 165 typically developing toddlers and their Taiwanese parents. Child development was assessed with a parent report measure of children's symbolic behavior. Parental responsiveness and children's pivotal behavior were assessed from observations of parent-child play. Results indicated that parental responsiveness was correlated with children's pivotal behavior, and that both of these variables were correlated with children's symbolic behavior. Structural equation models indicated that the relationship between responsiveness and children's symbolic behavior was fully mediated by children's pivotal behavior.

The remediation performance of a specific electrokinetics integrated with zero-valent metals for perchloroethylene contaminated soils.

This research was conducted to evaluate an integrated technique, combination of the electrokinetics (EK) and zero-valent metal (ZVM), for remediation of the perchloroethylene (PCE) contaminated soils. Various experimental conditions were controlled such as different voltage gradients, the position of ZVM, and ZVM species. The appropriate operational parameters are concluded as follows: (1) 0.01 M sodium carbonate serves as the working solution; (2) the voltage gradient is controlled at 1.0 V/cm; (3) ZVM wall is settled close to the anode. Based on the above operation conditions, the pH value of working solution can maintain at neutral range for avoiding the soil acidification. Neutral pH also causes the system to stay at a stable status of electricity consumption. The removal efficiency reaches 99% and 90% for decontaminating the PCE in the pore-water and the soil, respectively, after a 10-day treatment. The zero-valent zinc performs better PCE degradation than zero-valent iron. Moreover, the soils treated by EK+ZVM still possess their original properties.

The preliminary analysis of the reliability and validity of the Chinese Edition of the CSBS DP.

This study marked a preliminary attempt to standardize the Chinese Edition of the Communication and Symbolic Behavior Scales Developmental Profile (Wetherby & Prizant, 2002; CSBS DP) to assist in the early identification of young children with special needs in Taiwan. The study was conducted among 171 infants and toddlers aged 1-2. It also included a follow-up study one year after the initial test. Three domestically developed standardized child development inventories were used to measure the concurrent validity and predictive validity. The Chinese Edition of the CSBS DP demonstrated overall good test-retest and inter-rater reliability. It also showed good concurrent and predictive validity. The current study yields preliminary evidence that the Chinese Edition of the CSBS DP could be a valuable assessment tool worthy of wider distribution. Future research should employ random sampling to establish a true national norm. Additionally, the follow-up study needs to include atypical groups and to expand to children aged 6-12 months to strengthen the applicability of the instrument in Taiwan.

The methanol extract of Euonymus laxiflorus, Rubia lanceolata and Gardenia jasminoides inhibits xanthine oxidase and reduce serum uric acid level in rats.

Chinese herbal medicinal plants, Euonymus laxiflorus (EL), Rubia lanceolata (RL) and Gardenia jasminoides (GJ), have been used wildly to treat arthritis and gout in Taiwan for decades. To understand the beneficial effects of these three plants, their xanthine oxidase (XO) inhibitory activity in vitro and hypouricaemic activity in vivo were investigated. Our results suggested that methanol extracts were better than water extracts for inhibition of XO activity and 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity, except the water extract of GJ, which exhibited the strongest radical scavenging effect. In animal study, the serum urate level was significantly decreased after oral administration of higher dose (0.39g/kg) methanol extract of the mixture of three plants (ERG). In addition, methanol extract of ERG reduced the pain reaction time in the second phase of formalin induced pain. The results provide useful information on the pharmacological activities of these plants for the potential in treating hyperuricemia.