Efficacy of Biosolids in Assisted Phytostabilization of Metalliferous Acidic Sandy Soils with Five Grass Species

The role of sewage sludge as an immobilising agent in the phytostabilization of metal-contaminated soil was evaluated using five grass species viz., Dactylis glomerata L., Festuca arundinacea Schreb., F. rubra L., Lolium perenne L., L. westerwoldicum L. The function of metal immobilization was investigated by monitoring pH, Eh and Cd, Pb, and Zn levels in column experiment over a period of 5-months. Grasses grown on sewage sludge-amendments produced high biomass in comparison to controls. A significant reduction in metal uptake by plants was also observed as a result of sewage sludge application, which was attributed to decreased bioavailability through soil stabilisation. We have observed that the sludge amendment decreased metal bioavailability and concentrations in soil at a depth of 25 cm, in contrast to untreated columns, where metal concentrations in the soil solution were very high.     

Risk assessment of population exposure to toxic trace elements via consumption of vegetables and fruits grown in some mining areas of Armenia

Consumption of unsafe food is one of the most important public health concerns. Trace elements’ contamination caused by direct or indirect activities of mining industries is of importance in this respect. The present study was conducted to assess the chronic dietary exposure and related health risks of trace elements through the intake of selected vegetables and fruits grown under the impact of mining industry in Syunik region (Armenia). Consumption data were obtained via food frequency questionnaire and the concentrations of Cu, Mo, Ni, Cr, Pb, Zn, Hg, and Cd in different fruits and vegetables were determined. Moreover, by combining concentration data with consumption data, estimated daily intake, and target hazard quotient were assessed for each element. The results obtained showed that mean concentrations for Pb and Hg in some vegetables exceeded maximum acceptable levels set by international organizations. Hazard indexes > 1 have been obtained in some cases indicating that for some vegetables (particularly for potato, carrot, maize, onion leaf, grape, bean, beet, sweet pepper, eggplant, and tomato) habitual consumption has a potential to pose adverse health effect to the local population.     

Four Factor Balanced Optimal Designs of Resolution V in Terms of a Modified Trace Criterion

Balanced optimal two level fractional factorial designs of resolution V have been reported in series of papers by SRIVASTAVA and CHOPRA (1971a, 1971b, 1974) and CHOPRA and SRIVASTAVA (1973a, 1973b). The optimality criterion considered by them is the trace optimality which implies minimisation of the average variance of the estimated effects which include the general mean μ, main effects, A_i, and first order interactions, A_ij. In the present work some new optimal designs have been obtained on the basis of a modified criterion of trace optimality. The criterion requires minimisation of the average variance of each of the main effects, two factor interactions, etc. separately instead of minimising average variance of all the estimated effects.     

Morphology and ethology of the Late Devonian trace fossil Rhizocorallium from the Xichuan section of Central China

The trace fossil Rhizocorallium is abundant in the shallow-marine settings of the Upper Devonian Wangguangou Formation in Xichuan, Henan Province, northern margin of the South China block. Based on its morphological characteristics, the studied Rhizocorallium is attributed to Rhizocorallium commune var. auriforme. There is a significant compositional difference between the fillings of the marginal tube and the spreite. The fillings in the marginal tube are similar to the surrounding rock, with abundant bioclasts. The fillings in the spreite are relatively fine-grained and obviously affected by biological activities. Four types of pyrite framboids (pyritohedral, octahedron, cube and spherical) have been found within the Rhizocorallium. Moreover, the ratio of pyrite framboids diameter (D) to submicron crystal diameter (d) is <10, suggesting that they were formed by microbial activities. Relatively large pyrite framboids with smooth surface mainly occur in the marginal tube, while small pyrite framboids with sheath are abundant in the spreite. Energy spectrometer (EDS) analysis showed that the S/Fe ratio in the pyrite increased with decreasing crystal diameter, indicating different redox conditions in the marginal tube and the spreite. These features indicate that Rhizocorallium from the Xichuan section is not simply a foraging trace, but is probably a multi-functional, complex burrow system utilized for living, caching and farming microorganisms.     

Soil trace element changes during a phytoremediation trial with willows in southern Québec,Canada

This study determined the changes in trace elements (TE) (As, Cd, Cu, Ni, Pb, Zn) chemistry in the soils of a willow (“Fish Creek” – Salix purpurea, SV1 – Salix x dasyclados and SX67 – Salix miyabeana) plantation growing under a cold climate during a three-year trial. The soil HNO₃-extractable and H₂O-soluble TE concentrations and pools significantly decreased under most cultivars (Fish, SX67). Yet, TE changes showed inconsistent patterns and localized soil TE increases (Ni, Pb) were measured. Temporal changes in soil TE were also detected in control plots and sometimes exceeded changes in planted plots. Discrepancies existed between the amount of soil TE change and the amount of TE uptake by willows, except for Cd and Zn. Phytoremediation with willows could reduce soil Cd and Zn within a decadal timeframe indicating that they can be remediated by willows in moderately contaminated soils. However, the time needed to reduce soil As, Cu, Ni and Pb was too long to be efficient. We submit that soil leaching contributed to the TE decrease in controls and the TE discrepancies, and that the plantation could have secondary effects such as the accelerated leaching of soil TE.     

城市景观复写——从空间分析到设计途径

当代景观设计中价值取向的转变，包括设计行为从创造画面转向塑造场所，从创造新事物转向重现场地本质与原貌。依据景观设计中的空间特征和规划设计应用价值，将文本视角下的当代景观空间特征“复写”（palimpsest）定义为场地中各历史层次与当代层次的结合与共同显现。复写空间利用场地的潜力，实现了景观意义的传达，具有二元性、互文性及透明性的特点。复写既可以作为分析工具，也可以作为设计手段，其核心价值在于：多层空间结构得以平等呈现；历史信息积累而显现场地特质；设计创造诱发新的发展空间与场地产生关联。结合案例论述，研究与复写相关的分析方法与设计路径：呈现自治或在场地介入过程中建立互设关系，相关设计思想可回溯到埃森曼“人工开挖”（artificial excavation）的设计理念，以及文化景观及遗产保护中的“踪迹”（trace）概念。以场地空间特征出发，选择合适的设计方法，进而提出复写空间的多层建构是设计过程的关键部分。     

Evaluation of trace element status of organic dairy cattle

The present study aimed to evaluate trace mineral status of organic dairy herds in northern Spain and the sources of minerals in different types of feed. Blood samples from organic and conventional dairy cattle and feed samples from the respective farms were analysed by inductively coupled plasma mass spectrometry to determine the concentrations of the essential trace elements (cobalt (Co), chromium (Cr), copper (Cu), iron (Fe), iodine (I), manganese (Mn), molybdenum (Mo), nickel (Ni), selenium (Se) and zinc (Zn)) and toxic trace elements (arsenic (As), cadmium (Cd), mercury (Hg) and lead (Pb)). Overall, no differences between organic and conventional farms were detected in serum concentrations of essential and toxic trace elements (except for higher concentrations of Cd on the organic farms), although a high level of inter-farm variation was detected in the organic systems, indicating that organic production greatly depends on the specific local conditions. The dietary concentrations of the essential trace elements I, Cu, Se and Zn were significantly higher in the conventional than in the organic systems, which can be attributed to the high concentration of these minerals in the concentrate feed. No differences in the concentrations of trace minerals were found in the other types of feed. Multivariate chemometric analysis was conducted to determine the contribution of different feed sources to the trace element status of the cattle. Concentrate samples were mainly associated with Co, Cu, I, Se and Zn (i.e. with the elements supplemented in this type of feed). However, pasture and grass silage were associated with soil-derived elements (As, Cr, Fe and Pb) which cattle may thus ingest during grazing.