Simulating dairy liquid waste management options as a nitrogen source for crops

Large scale dairy operations are common. In many cases the manure is deposited on a paved surface and then removed with a flushing system, after which the solids are separated, the liquid stored in ponds, and eventually the liquid applied on adjacent crop land. Management of liquid manure to maximize the fertilizer value and minimize water quality degradation requires knowledge of the interactive effects of mineralization of organic N (ON) to NH₄⁺, crop uptake of mineral N, and leaching of NO₃⁻ on a temporal basis. The purpose of the research was to use the ENVIRO-GRO model to simulate how the amount of applied N, timing of N application, ON mineralization rates, chemical form of N applied, and irrigation uniformity affected (1) yields of corn (Zea mays) in summer and a forage grass in winter in a Mediterranean climate and (2) the amount of NO₃⁻ leached below the root zone. This management practice is typical for dairies in the San Joaquin Valley of California. The simulations were conducted for a 10-year period. Steady state conditions, whereby an equivalent amount of N applied in the organic form will be mineralized in a given year, are achieved more rapidly for materials with high mineralization rates. Both timing and total quantity of N application are important in affecting crop yield and potential N leaching. Major conclusions from the simulations are as follows. Frequent low applications are preferred to less frequent higher applications. Increasing the amount of N application increased both the crop yield and the amount of NO₃⁻ leached. Increasing irrigation uniformity increased crop yields but had variable effects on the amount of NO₃⁻ leached. A winter forage crop following a summer corn crop effectively reduced the leaching of residual soil N following the corn crop.     

外控电势对Ch-1菌株生长及Cr(Ⅵ)还原的影响

为进一步优化Ch-1菌株对碱性含铬废水的处理及铬渣的解毒效果,以细菌总数和6价铬的还原率为指标,详细考察了外控电位对Ch-1菌株生长及Cr(Ⅵ)还原的影响.结果表明,电极材料对细菌生长及其活性有一定的影响,不锈钢电极和铂电极体系对细菌生长及活性的影响基本相同,而采用石墨电极细菌的培养效果欠佳.静态培养和动态培养Ch-1菌株时,Cr(Ⅵ)的最终还原率与初始Cr(Ⅵ)浓度无关,24h时Cr(Ⅵ)的还原率均达到了100%;但就还原过程而言,动态培养对Cr(Ⅵ)的还原速率明显优于静态培养,外控电势能够增强或抑制Ch-1菌株的生长及活性,0～-900 mV的负电位可以促进细菌的生长,而400 mV以上的正电势对Ch-1菌株的生长有抑制作用.在-800～ 200 mV的电势范围内,Ch-1菌株还原6价铬的能力得到增强,在此范围外其还原能力受到抑制.     

关于畜禽养殖业环境管理的思考

介绍了畜禽养殖业对环境的污染现状及存在的问题,提出了强化环境管理的对策和措施.     

矿区复合生态系统中土壤演替和植被演替的相互影响

在讨论矿区复合生态系统涵义的基础上，以平朔安太堡露天煤矿为例，探讨了大型露天矿区复合生态系统演替与原生态系统演替的不同，即露天矿区复合生态系统演替极大地受着社会--经济--自然三方面的控制，在演替过程中土壤演替与植被演替相互影响、相互协调，共同作用了矿区复合生态系统。同时，还阐述了进行矿区生态重建的两大关键措施：生态环境建设和群落建设。     

Inter and intra-population variation in shoaling and boldness in the zebrafish (<Emphasis Type="Italic">Danio rerio</Emphasis>)

Population differences in anti-predator behaviour have been demonstrated in several species, although less is known about the genetic basis of these traits. To determine the extent of genetic differences in boldness (defined as exploration of a novel object) and shoaling within and between zebrafish (Danio rerio) populations, and to examine the genetic basis of shoaling behaviour in general, we carried out a study that involved laboratory-raised fish derived from four wild-caught populations. Controlling for differences in rearing environment, significant inter-population differences were found in boldness but not shoaling. A larger shoaling experiment was also performed using one of the populations as the basis of a North Carolina type II breeding design (174 fish in total) to estimate heritability of shoaling tendency. A narrow-sense heritability estimate of 0.40 was obtained, with no apparent dominance effects.     

Egyptian blue — Cuprorivaite a window to ancient Egyptian technology

Egyptian Blue, a multicomponent synthetic blue pigment has been recorded in ancient Egypt since the Fourth Dynasty of the Old Kingdom (2600–2480 B.C.). The pigment consisting of cuprorivaite (CaCuSi₄O₁₀) with variable amounts of wollastonite (CaSiO₃), Cu-rich glass and cuprite (Cu₃O) or tenorite (CuO) was prepared by melting the copper-rich ingredient with lime and desert sand. Low melting temperatures (below 742 °C) were achieved by addition of flux-like plant ashes. The high quality of the pigments collected from monuments of the Fifth Dynasty (2480–2320 B.C.) may indicate that the first manufacture was in early dynastic or perhaps predynastic eras. During the reign of Thutmosis III (18th Dynasty, 1490–1436 B.C.) probably bronze filings were first applied as starting material, thus indicating a technological innovation. This new method was employed till the Roman times.