澳门特别行政区土壤自然消减能力与污染背景

澳门是我国人口密度最大的城市.选择澳门特别行政区不同功能区绿地土壤为研究对象,首先,通过野外布点采样,调查分析了表层土壤中9种重金属元素(Cr、Ni、Cu、Cd、Pb、Cr、Zn、As、Hg)和16种优先控制多环芳烃(PAHs)的分布特征;其次,利用累积频率分布曲线法估算了土壤重金属和PAHs的土壤污染背景;最后,基于...     

Measurements of the streaming potential of clay soils from tropical and subtropical regions using self-made apparatus

The streaming potential has been wildly used in charged parallel plates, capillaries, and porous media. However, there have been few studies involving the ζ potential of clay soils based on streaming potential measurements. A laboratory apparatus was developed in this study to measure the streaming potential (ΔE) of bulk clay soils’ coupling coefficient (C) and cell resistance (R) of saturated granular soil samples. Excellent linearity of ΔE versus liquid pressure (ΔP) ensured the validity of measurements. The obtained parameters of C and R can be used to calculate the ζ potential of bulk soils. The results indicated that the ζ potentials measured by streaming potential method were significantly correlated with the ζ potentials of soil colloids determined by electrophoresis (r ²?=?0.960**). Therefore, the streaming potential method can be used to study the ζ potentials of bulk clay soils. The absolute values of the ζ potentials of four soils followed the order: Ultisol from Jiangxi?>?Ultisol from Anhui?>?Oxisol from Guangdong?>?Oxisol from Hainan, and this was consistent with the cation exchange capacities of these soils. The type and concentration of electrolytes affected soil ζ potentials. The ζ potential became less negative with increased electrolyte concentration. The ζ potentials were more negative in monovalent than in divalent cationic electrolyte solutions because more divalent cations were distributed in the shear plane of the diffuse layer as counter-cations on the soil surfaces than monovalent cations at the same electrolyte concentration.     

Reduction of Fusarium rot and maintenance of fruit quality in melon using eco-friendly hot water treatment

Significant losses in harvested fruit can be directly attributable to decay fungi and quality deterioration. Hot water treatment (HWT) has been demonstrated to be an effective and economic environment-friendly approach for managing postharvest decay and maintaining fruit quality. In this study, the effects of HWT (45 °C for 10, 15, 20, and 25 min) on in vitro growth of Fusarium oxysporum, in vivo Fusarium rot, and natural decay of melon were investigated. HWT inhibited spore germination and germ tube elongation of F. oxysporum. Protein impairment and ATP consumption triggered by HWT contributed to the inhibitory effect. Results of in vivo studies showed that HWT effectively controlled Fusarium rot and natural decay of melon. Correspondingly, HWT induced a significant increase in content of total phenolic compounds and lignin of melon. These findings indicate that the effects of HWT on Fusarium rot may be associated with the direct fungal inhibition and the elicitation of defense responses in fruit. Importantly, HWT used in this study had beneficial effects on fruit quality as well. HWT may represent an effective non-chemical approach for management of postharvest Fusarium rot.     

Nitrogen critical loads and management alternatives for N-impacted ecosystems in California

Empirical critical loads for N deposition effects and maps showing areas projected to be in exceedance of the critical load (CL) are given for seven major vegetation types in California. Thirty-five percent of the land area for these vegetation types (99,639 km²) is estimated to be in excess of the N CL. Low CL values (3–8 kg N ha^?1 yr^?1) were determined for mixed conifer forests, chaparral and oak woodlands due to highly N-sensitive biota (lichens) and N-poor or low biomass vegetation in the case of coastal sage scrub (CSS), annual grassland, and desert scrub vegetation. At these N deposition critical loads the latter three ecosystem types are at risk of major vegetation type change because N enrichment favors invasion by exotic annual grasses. Fifty-four and forty-four percent of the area for CSS and grasslands are in exceedance of the CL for invasive grasses, while 53 and 41% of the chaparral and oak woodland areas are in exceedance of the CL for impacts on epiphytic lichen communities. Approximately 30% of the desert (based on invasive grasses and increased fire risk) and mixed conifer forest (based on lichen community changes) areas are in exceedance of the CL. These ecosystems are generally located further from emissions sources than many grasslands or CSS areas. By comparison, only 3–15% of the forested and chaparral land areas are estimated to be in exceedance of the NO₃^? leaching CL. The CL for incipient N saturation in mixed conifer forest catchments was 17 kg N ha^?1 yr^?1. In 10% of the CL exceedance areas for all seven vegetation types combined, the CL is exceeded by at least 10 kg N ha^?1 yr^?1, and in 27% of the exceedance areas the CL is exceeded by at least 5 kg N ha^?1 yr^?1. Management strategies for mitigating the effects of excess N are based on reducing N emissions and reducing site N capital through approaches such as biomass removal and prescribed fire or control of invasive grasses by mowing, selective herbicides, weeding or domestic animal grazing. Ultimately, decreases in N deposition are needed for long-term ecosystem protection and sustainability, and this is the only strategy that will protect epiphytic lichen communities.     

Aquatic photolysis of hydroxylated polybromodiphenyl ethers under direct UV irradiation: a case study of 2′-HO-BDE-68

Environmental Science and Pollution Research - Hydroxylated polyhalodiphenyl ethers (HO-PXDEs) have attracted considerable scientific interest as examples of emerging aquatic pollutants. However, a...     

水资源研究中几个问题的探讨

本文讨论了区域水资源的评价问题.无论是地表水、地下水,还是土壤水都是来源于大气降水,降水资源才是区域总水资源;同时讨论了区域水资源的平衡原理.降水资源转化了截留水、地表水、土壤水和地下水4项水资源.该文对这2种不同的水体进行了深入讨论,着重论述了土壤水资源的概念及其特征.并对潜水蒸发和水资源的价值问题提出了看法.     

南京理工大学高压实验室及其研制高压水射流切割机

南京理工大学高压实验室自８０年代初建立以来，在高压容器及武器发射管的自紧理论和工程应用、高压零部件研制、高压传感器和信号放大显示系统、高压介质等方面做了大量的工作。９３年以来，进行了水射流切割机的研制工作，解决了超高压缸体的动态密封、高压缸体的自增强、无触点式换向传感器、内衬不锈钢组合型高压容器等诸多问题，试制成功了水射流切割机样机。     

大空间室内火灾早期自动探测与定位研究

本文在深入研究早期火灾一般燃烧火焰在彩色影像上所呈现的光谱及运动特性基础上，首次提出利用彩色影像实时探测室内火灾的新方法，通过物方坐标与像方坐标的直接线性变换，实现了早期火灾的自动探测与空间定位，实验证明了该方法的有效性与稳健性，且具有巨大的应用前景。     

山东省生物多样性及其保护与开发利用

山东省自然条件优越，生态环境多样，因而具有极其丰富的生物多样性，本文初步研究了山东省生物多样性现状，保护与经济协调发展对策。     

我国环保产业技术现状与发展方向

本文对我国环保产业技术现状进行了全面分析，并指出我国环保产业技术与国外的差距和不足，同时针对环保产业技术落后的各种因素和实际需要，提出了我国环保产业技术的发展方向。