On the use of micro-electrodes in fish pond sediments

Abstract The surface layer of fish pond sediments is characterized by very high microbial activity. Oxygen uptake by the microbes at the sediment surface leaves little oxygen to penetrate the sediment. In marine and freshwater lake sediments, oxygen only penetrated a few millimeters. In this study, oxygen penetration into the sediment layer in fish ponds and simulated fish ponds was measured with an oxygen micro-electrode. Oxygen profiles determined with micro-electrodes showed that oxygen does not penetrate deeper than 1 mm under quiescent conditions in intensive and semi-intensive fish pond sediments. Sediment oxygen consumption (SOD) at approximately 25°C, calculated from measured oxygen profiles, ranged from 45 to 50 mg O 2 /m 2 per h. Change in water temperature and the addition of formaldehyde showed that most of the oxygen consumption in the sediment surface layer is related to biological activity. Redox potential profiles of fish pond sediments measured with a microplatinum electrode, showed reducing conditions conducive to sulfide formation at 2 -4 mm below the sediment surface. Nitrate addition to the overlying water poised redox potential above 300 mV to a sediment depth of about 15 mm. Nitrate thus buffered the sediment -water interface against reducing conditions in the sediment and the possible diffusion of toxic reduced end products to the water. © 1999 Elsevier Science B.V. All rights reserved

Application of a comparative multidimensional life cycle analysis in solid waste management policy: the case of soft drink containers

Abstract The paper describes the application of a multidimensional life cycle analysis (LCA) for packaging soft drinks in Israel. The suggested approach combines the conventional product LCA, vertical summation of all environmental burdens along the chain of production, use and disposal activities, and horizontal comparison of dierent products and disposal options, such as recycling, incineration or land®lling. The paper attempts to show that the most eective, as well as transparent, means of comparing packaging alternatives, is to place them on a commensurate basis, the most appropriate one being a monetary basis. Taking into account limitations and drawbacks of monetary valuation of non-market assets (namely, environmental assets), the study derived estimates of environmental bene®ts and damages associated with each alternative. The production of soft drinks containers in Israel, used here as an example for the above mentioned considerations, is based mainly on imported materials, since natural resources such as oil or bauxite do not exist in Israel. Locally, only direct production and pollution abatement costs are incorporated in the ®nal bill, while global environmental burdens are excluded. Countries extracting and producing raw material for the packaging industry, in eect, grant an environmental subsidy to the ®nal users, in this case Ð the Israeli user. The paper suggests that only by globalization of externalities and fully internalizing environmental costs into the price of the ®nal product (the packaging material or the packaged product), an equitable full environmental accounting can be designed. This mechanism can be even accompanied by global trading in the relevant environmental credits. Decisions will, consequently, follow a sustainable path, in both importing and exporting countries.

Policy Paper 14: Promoting Regional Cooperation in the Middle East

Since the inception of the Middle East Peace Process in 1991, arms control and regional security issues have been one of the most difficult areas to address. The establishment and functioning of the official multilateral Arms Control and Regional Security (ACRS) Working Group in the multilateral process has had to overcome at best lack of knowledge and at worst deep skepticism on the part of Arab and Israeli officials and onlookers about arms control. In that regard, the parallel process of so-called “track-two” non-official discussions has helped to increase understanding and build support for the concept of a regional arms control and confidence-building component in the overall Middle East Peace Process

Policy Paper 14: Promoting Regional Cooperation in the Middle East

Since the inception of the Middle East Peace Process in 1991, arms control and regional security issues have been one of the most difficult areas to address. The establishment and functioning of the official multilateral Arms Control and Regional Security (ACRS) Working Group in the multilateral process has had to overcome at best lack of knowledge and at worst deep skepticism on the part of Arab and Israeli officials and onlookers about arms control. In that regard, the parallel process of so-called “track-two” non-official discussions has helped to increase understanding and build support for the concept of a regional arms control and confidence-building component in the overall Middle East Peace Process

Nitrogen removal techniques in aquaculture for a sustainable production

As the aquaculture industry intensively develops, its environmental impact increases. Discharges from aquaculture deteriorate the receiving environment and the need for fishmeal and fish oil for fish feed production increases. Rotating biological contactors, trickling filters, bead filters and fluidized sand biofilters are conventionally used in intensive aquaculture systems to remove nitrogen from culture water. Besides these conventional water treatment systems, there are other possible modi operandi to recycle aquaculture water and simultaneously produce fish feed. These double-purpose techniques are the periphyton treatment technique, which is applicable to extensive systems, and the proteinaceous bio-flocs technology, which can be used in extensive as well as in intensive systems. In addition to maintenance of good water quality, both techniques provide an inexpensive feed source and a higher efficiency of nutrient conversion of feed. The bio-flocs technology has the advantage over the other techniques that it is relatively inexpensive; this makes it an economically viable approach for sustainable aquaculture