Cadmium fractions in an acid sandy soil and Cd in soil solution as affected by plant growth          下载免费PDF全文

Christos Stritsis  Bernd Steingrobe  Norbert Claassen 《植物养料与土壤学杂志》2014,177(3):431-437

In a previous experiment, plants were able to immobilize or solubilize Cadmium (Cd) in a sandy acid soil enriched with 40 μmol Cd kg^–1, because Cd solution concentration was decreased by maize (Zea mays) and sunflower (Helianthus annuus), and increased by flax (Linum usitatissimum L. ssp. usitatissimum) and spinach (Spinacia oleracea). It is assumed that the equilibrium with Cd fractions in the soil solid phase and the chemical form of Cd in the soil solution were affected. In the present study, the effect of the four plant species mentioned above on Cd binding in soil was investigated by means of a fractionation of soil Cd with a sequential extraction of seven steps. The seven fractions of Cd are operationally defined by the extraction sequence that follows the order of increasing acidity with extractants of different complexing and redox properties. In the unplanted soil, Cd was predominantly present in the exchangeable Fraction I (F. I) and easily mobilizable Fraction II (F. II) (64%). Significant concentrations of Cd were found in F. III (occluded in Mn oxides; 22%) and F. IV (organically bound; 10%). Fractions V (occluded in poorly crystalline Fe oxides), F. VI (occluded in well crystallized Fe oxides), and F. VII (residual fraction) amounted to less than 5% of the total soil Cd concentration. The plants changed the binding of Cd in soil in a different manner. All plants decreased F. I, but F. II was increased by maize and spinach, decreased by flax or remained unaffected by sunflower. Fraction III was not affected by maize and flax, but decreased by sunflower and spinach, and F. IV was not affected by sunflower and spinach, but was increased by maize and flax. These changes of Cd fractions were not related to the changes the plants had caused in total Cd or Cd²⁺ concentration of the soil solution. These results show that plant species differ in how they affect Cd binding to the soil solid phase, but this effect is not related to how they affect Cd in soil solution. The mechanisms by which plants affect the relationship between the soil solid and liquid phase are still unclear.  相似文献   

Would you be happier if you were richer? A focusing illusion   总被引：1，自引：0，他引：1  

Kahneman D  Krueger AB  Schkade D  Schwarz N  Stone AA 《Science (New York, N.Y.)》2006,312(5782):1908-1910

The belief that high income is associated with good mood is widespread but mostly illusory. People with above-average income are relatively satisfied with their lives but are barely happier than others in moment-to-moment experience, tend to be more tense, and do not spend more time in particularly enjoyable activities. Moreover, the effect of income on life satisfaction seems to be transient. We argue that people exaggerate the contribution of income to happiness because they focus, in part, on conventional achievements when evaluating their life or the lives of others.  相似文献   

Spatial and temporal characteristics of the damage caused by wild ungulates in maize (Zea mays L.) crops     

Norbert Bleier  Imre Kovács  Gergely Schally  László Szemethy  Sándor Csányi 《国际虫害防治杂志》2017,63(1):92-100

Agricultural damage caused by wild ungulates can be economically very important worldwide. In Europe, the impact of wild ungulates causes significant losses to crops, mainly to maize, where it exceeds billions of US dollars annually. The objective of this study was to explore the spatial and temporal characteristics of damage caused by wild boar and red deer to maize, in order to propose efficient prevention and mitigation of losses to agricultural producers worldwide. The study was carried out in three forests neighbouring maize fields in two different areas. We recorded data on the proportion, type and the location of the damage by ungulates within the fields. According to our results the damage varied greatly along the vegetation growth period (from green plant to corncob), likely due to the changes in the food supply provided by maize. The proportion of damaged plants increased through the growing season and was probably affected by the appearance of corncobs. Seventy to 90% of the total damage occurred within a 300 m distance to the forest edge. Considering these findings, we propose to arrange a protocol for damage prevention based on damage risk maps.  相似文献