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51.
Long-term effects of fertilization on the forms and availability of soil phosphorus in rice paddy 总被引:4,自引:0,他引:4
The changes in total P accumulation and P compounds with time in the plough layer in a paddy soil in southern Korea were investigated in relation to the continuous application of chemical fertilizers (NPK), straw based compost (Compost), combination these two (NPK+Compost) for 31 years. Continuous fertilization increased the total and inorganic P contents in plough layers. In NPK, inorganic P fraction did not change with time, but organic P content increased significantly. Long-term application of chemical fertilizer together with compost accelerated the decrease in the organic P fraction, presumably due to promoting microbial activity in the plow layer, and then increased significantly inorganic P fraction. Compost application decreased the residual P and Fe-P fractions and then increased inorganic P fraction, in spite of continuous compost application. Increase in total, inorganic and extractable P with time may be closely related to the increase in the availability of accumulated P for rice growth. 相似文献
52.
Pablo D. Ribeiro John H. Christy Rebecca J. Rissanen Tae Won Kim 《Behavioral ecology and sociobiology》2006,61(1):81-89
Courting male fiddler crabs Uca terpsichores (1 cm carapace width) sometimes build mounds of sand called hoods at the entrances to their burrows. Males wave their single
enlarged claws to attract females to their burrows for mating. It was shown previously that burrows with hoods are more attractive
to females and that females visually orient to these structures. In this study, we test whether males also use their hoods
to find their burrows. We first determined the maximum distance that males can see and find a burrow opening without a hood.
Males were removed from their burrows and placed on the sand at a range of distances from a burrow opening. If they were more
than about 8 cm (seven units of eye-height) away, they were unable find the burrow. In contrast, males that were burrow residents
used a non-visual path map to return to their burrows from much greater distances. To determine if hoods help males find their
burrows when there are errors in their path maps, we moved residents 1–49 cm on sliding platforms producing errors equal to
the distances they were moved. Males with self-made hoods or hood models at their burrows relocated their burrows at significantly
greater distances than did males with unadorned burrows. Hood builders also relocated their burrows faster. Hence, hoods have
two functions: they attract females and they provide a visual cue that males use to find their burrows quickly and reliably
when their path maps fail.
An erratum to this article can be found at 相似文献
53.
54.
Mercury contamination in agricultural soils from abandoned metal mines classified by geology and mineralization 总被引:1,自引:0,他引:1
The concentrations and loadings of major and trace elements in coal mine drainage (CMD) from 49 abandoned mines located in
the coal fields of the Brazilian state of Santa Catarina were determined. The CMD sites typically displayed a wide spatial
and temporal variability in physical and geochemical conditions. The results of our CMD analyses in Santa Catarina State were
used to illustrate that the geochemical processes in the rock piles can be deduced from multiple data sets. The observed relationship
between the pH and constituent concentrations were attributed to (1) dilution of acidic water by near-neutral or alkaline
groundwater and (2) solubility control of Al, Fe, Mn, Ba and Sr by hydroxide, sulfate, and/or carbonate minerals. The preliminary
results of the CMD analyses and environmental health in the Santa Catarina region, Brazil, are discussed. 相似文献
55.
Kyu Sik Kwon 《International journal of occupational safety and ergonomics》2013,19(3):212-217
This study deals with designing robot teach pendants for industrial robots. The emergency stop button on robot teach pendants is the primary safety device for industrial robots. Recommendations for the design of the emergency stop button were proposed based on experimental evaluations. Human performance was measured by the reaction time necessary to press the button on a pendant. The variation factors were randomly combined by seven button locations and three different button sizes. The results indicated that the shortest reaction time was obtained for the 38-mm button located on the left and left-down of the seven button positions on the pendant. 相似文献
56.
57.
Jang Hyun Lee Kyung Su Kim Jae Beom Lee Yong Sik Yang Mi Ji Yoo 《Journal of Loss Prevention in the Process Industries》2009,22(6):889-896
This paper is concerned with the evaluation of cyclic hardening models within the stress–strain behavior of aluminum alloy AC4C-T6 that can be used to LNG cargo pump operating in cryogenic temperature. To insure the strength assessment of LNG cargo pump, material model of cyclic hardening and plasticity for aluminum alloy AC4C-T6 is investigated through FEA (Finite Element Analysis) with various hardening options including linear and non-linear hardening, isotropic and kinematic hardening, and combined hardening model. Monotonic tensile and cyclic tensile experiments for AC4C-T6 alloy were performed at room temperature and temperature of ?165 °C. Parameters of each hardening model are obtained from the experimental data; thus five hardening models are numerically simulated thereafter. Appropriate hardening models which describe the cyclic stress–strain relationship are investigated through the simulations of cyclic hardening behavior by FEA. In order to verify the predicted behavior of cyclic hardening obtained by FEA, the results of FEA and those measured by experiments are compared. 相似文献
58.
Ok YS Kim SC Kim DK Skousen JG Lee JS Cheong YW Kim SJ Yang JE 《Environmental geochemistry and health》2011,33(Z1):23-30
The cadmium (Cd) content of rice grain grown in metal-contaminated paddy soils near abandoned metal mines in South Korea was found to exceed safety guidelines (0.2 mg Cd kg?1) set by the Korea Food and Drug Administration (KFDA). However, current remediation technologies for heavy metal-contaminated soils have limited application with respect to rice paddy soils. Laboratory and greenhouse experiments were conducted to assess the effects of amending contaminated rice paddy soils with zerovalent iron (ZVI), lime, humus, compost, and combinations of these compounds to immobilize Cd and inhibit Cd translocation to rice grain. Sequential extraction analysis revealed that treatment with the ameliorants induced a 50-90% decrease in the bioavailable Cd fractions when compared to the untreated control soil. When compared to the control, Cd uptake by rice was decreased in response to treatment with ZVI + humus (69%), lime (65%), ZVI + compost (61%), compost (46%), ZVI (42%), and humus (14%). In addition, ameliorants did not influence rice yield when compared to that of the control. Overall, the results of this study indicated that remediation technologies using ameliorants effectively reduce Cd bioavailability and uptake in contaminated rice paddy soils. 相似文献
59.
Application of eggshell waste for the immobilization of cadmium and lead in a contaminated soil 总被引:2,自引:0,他引:2
Ok YS Lee SS Jeon WT Oh SE Usman AR Moon DH 《Environmental geochemistry and health》2011,33(Z1):31-39
Liming materials have been used to immobilize heavy metals in contaminated soils. However, no studies have evaluated the use of eggshell waste as a source of calcium carbonate (CaCO?) to immobilize both cadmium (Cd) and lead (Pb) in soils. This study was conducted to evaluate the effectiveness of eggshell waste on the immobilization of Cd and Pb and to determine the metal availability following various single extraction techniques. Incubation experiments were conducted by mixing 0-5% powdered eggshell waste and curing the soil (1,246 mg Pb kg?1 soil and 17 mg Cd kg?1 soil) for 30 days. Five extractants, 0.01 M calcium chloride (CaCl?), 1 M CaCl?, 0.1 M hydrochloric acid (HCl), 0.43 M acetic acid (CH?COOH), and 0.05 M ethylendiaminetetraacetic acid (EDTA), were used to determine the extractability of Cd and Pb following treatments with CaCO? and eggshell waste. Generally, the extractability of Cd and Pb in the soils decreased in response to treatments with CaCO? and eggshell waste, regardless of extractant. Using CaCl? extraction, the lowest Cd concentration was achieved upon both CaCO? and eggshell waste treatments, while the lowest Pb concentration was observed using HCl extraction. The highest amount of immobilized Cd and Pb was extracted by CH?COOH or EDTA in soils treated with CaCO? and eggshell waste, indicating that remobilization of Cd and Pb may occur under acidic conditions. Based on the findings obtained, eggshell waste can be used as an alternative to CaCO? for the immobilization of heavy metals in soils. 相似文献
60.