In Korea, soils adjacent to abandoned mines are commonly contaminated by heavy metals present in mine tailings. Further, the
disposal of oyster shell waste by oyster farm industries has been associated with serious environmental problems. In this
study, we attempted to remediate cadmium (Cd)- and lead (Pb)-contaminated soils typical of those commonly found adjacent to
abandoned mines using oyster shell waste as a soil stabilizer. Natural oyster shell powder (NOSP) and calcined oyster shell
powder (COSP) were applied as soil amendments to immobilize Cd and Pb. The primary components of NOSP and COSP are calcium
carbonate (CaCO3) and calcium oxide (CaO), respectively. X-ray diffraction, X-ray fluorescence and scanning electron microscope analyses conducted
in this study revealed that the calcination of NOSP at 770°C converted the less reactive CaCO3 to the more reactive CaO. The calcination process also decreased the sodium content in COSP, indicating that it was advantageous
to use COSP as a liming material in agricultural soil. After 30 days of incubation, we found that the 0.1 N HCl-extractable
Cd and Pb contents in soil decreased significantly as a result of an increase in the soil pH and the formation of metal hydroxides.
COSP was more effective in immobilizing Cd and Pb in the contaminated soil than NOSP. Overall, the results of this study suggest
that oyster shell waste can be recycled into an effective soil ameliorant. 相似文献
Toxicity of heavy metals adversely affects environment and human health. Organic materials derived from natural matters or wastes have been applied to soils to reduce the mobility of contaminants such as heavy metals. However, the application of cow bone powder (CB), biochar (BC), and eggshell powder (ES) is rarely investigated for the reduction of Pb bioavailability in soils irrigated with saline water. The objective of this study was to assess the effectiveness of CB, BC, and ES additions as immobilizing substances on Pb bioavailability in shooting range soil irrigated with deionized and saline water. Each additive of CB, BC, and ES at 5 % (w/w) was mixed with soils and then the deionized and saline water were irrigated for 21 days. With deionized water irrigation, the soils treated with CB, BC, and ES exhibited higher pH when compared with saline water irrigation. With saline water irrigation, the electrical conductivity, water-soluble anions, and cations were significantly increased in soils treated with CB, BC, and ES. The water-soluble Pb in soils treated with CB, BC, and ES was significantly decreased with saline water irrigation. On the other hand, the water-soluble Pb in soil treated with CB was increased with deionized water irrigation. Only BC with saline water irrigation decreased the Pb concentration in maize shoots. 相似文献
The objective of this study was to assess the lake sediment budget of land use changes using the Universal Soil Loss Equation (USLE), sediment delivery ratio (SDR), and trap efficiency (TE). The geographic information system was combined with the USLE to estimate the soil erosion of the Lake Asan watershed. Spatial data for each of the USLE factors were obtained from the land use, soil, and 1/25,000 scale digital contour maps. Landsat-5 TM images were selected for analyzing soil erosion changes due to land use changes. The sediment yield to Lake Asan was estimated using the SDR and TE. The estimated sediment budget was compared with observed data from the Lake Asan watershed between 1974 and 2003. The total estimated annual mean sediment budgets from Lake Asan in 1986, 1992, and 2000 were 0.267, 0.301, and 0.339 × 106 ton, respectively, with an average of 0.302 × 106 ton. The average measured sediment budget was 3.15 × 106 ton year?1. The average estimated value shows reasonable agreement with the observed sediment balance. The average estimated and measured sediment budgets contain uncertainties due to both the methods and the approach used by the observers. The simulated results indicated that soil erosion in the Lake Asan watershed increased at a rate of approximately 2 % per year from 1986 to 2000 due to land use change. This study may be useful for managers to identify reservoir rehabilitation management methods for stable irrigation water supply. 相似文献
Microbes live throughout the soil profile. Microbial communities in subsurface horizons are impacted by a saltwater–freshwater transition zone formed by seawater intrusion (SWI) in coastal regions. The main purpose of this study is to explore the changes in microbial communities within the soil profile because of SWI. The study characterizes the depth-dependent distributions of bacterial and archaeal communities through high-throughput sequencing of 16S rRNA gene amplicons by collecting surface soil and deep core samples at nine soil depths in Longkou City, China. The results showed that although microbial communities were considerably impacted by SWI in both horizontal and vertical domains, the extent of these effects was variable. The soil depth strongly influenced the microbial communities, and the microbial diversity and community structure were significantly different (p < 0.05) at various depths. Compared with SWI, soil depth was a greater influencing factor for microbial diversity and community structure. Furthermore, soil microbial community structure was closely related to the environmental conditions, among which the most significant environmental factors were soil depth, pH, organic carbon, and total nitrogen.
Geotechnical and Geological Engineering - A shale rock sample was scanned by micro-CT technology, tomographic images of the rock sample were obtained, and the three-dimensional structure was... 相似文献
We have used synthetic spectra to analyze a medium resolution 2.9-4.2 μm spectrum of Saturn's temperate region observed at UKIRT using CGS4. The synthetic spectra include CH4, PH3, and NH3 lines, for which mixing ratios were adopted from recent Cassini results. The observed absorption features in the spectrum are well accounted for by lines of these molecular species formed 22 +/− 8 km above the 1 bar pressure level at ∼610 mbar. The influence of optically thin haze particles at higher altitudes on the spectrum is not pronounced, with higher spectral resolution probably required to constrain the effects of haze in this wavelength region. Fluorescent line emission by CH4 in its ν3 and ν3+ν4−ν4 bands, detected in the 3.2-3.5 μm region, originates between 400 km (∼0.06 mbar) and 800 km (∼0.01 μbar) above the 1 bar level, with peak contributions from the two major contributing bands at 550 km (∼3 μbar) and 700 km (∼0.1 μbar), respectively. 相似文献
Using coral data, sea surface temperature (SST) reanalysis data, and Climate Model Intercomparison Project III (CMIP3) data, we analyze 20th-century and future warm pool and cold tongue SST trends. For the last 100?years, a broad La Nina-like SST trend, in which the warming trend of the warm pool SST is greater than that of the cold tongue SST, has appeared in reanalysis SST data sets, 20C scenario experiments of the CMIP3 data and less significantly in coral records. However, most Coupled General Circulation Models subjected to scenarios of future high greenhouse gas concentrations produce larger SST warming trends in cold tongues than in warm pools, resembling El Nino-like SST patterns. In other words, warmer tropical climate conditions correspond to stronger El Nino-like response. Heat budget analyses further verify that warmer tropical climates diminish the role of the ocean’s dynamic thermostat, which currently regulates cold tongue temperatures. Therefore, the thermodynamic thermostat, whose efficiency depends on the mean temperature, becomes the main regulator (particularly via evaporative cooling) of both warm pool and cold tongue temperatures in future warm climate conditions. Thus, the warming tendency of the cold tongue SST may lead that of the warm pool SST in near future. 相似文献