Woody plant roots fail to penetrate a clay-lined landfill: Managment implications

In many locations, regulatory agencies do not permit tree planting above landfills that are sealed with a capping clay, because roots might penetrate the clay barrier and expose landfill contents to leaching. We find, however, no empirical or theoretical basis for this restriction, and instead hypothesize that plant roots of any kind are incapable of penetrating the dense clays used to seal landfills. As a test, we excavated 30 trees and shrubs, of 12 species, growing over a clay-lined municipal sanitary landfill on Staten Island, New York. The landfill had been closed for seven years, and featured a very shallow (10 to 30-cm) soil layer over a 45-cm layer of compacted grey marl (Woodbury series) clay. The test plants had invaded naturally from nearby forests. All plants examined—including trees as tall as 6 m—had extremely shallow root plates, with deformed tap roots that grew entirely above and parallel to the clay layer. Only occasional stubby feeder roots were found in the top 1 cm of clay, and in clay cracks at depths to 6 cm, indicating that the primary impediment to root growth was physical, although both clay and the overlying soil were highly acidic. These results, if confirmed by experimental research should lead to increased options for the end use of many closed sanitary landfills.     

Developing of a pricing model for Turkish lignite used in thermal plants

The objective of this paper is to develop a general pricing model for Turkish Lignite, which is mainly sold to thermal plants. This model will contribute to the development of coal mining within the scope of privatization efforts of the Turkish energy market. The paper consists of two stages. First, data of 10 thermal plants have been evaluated by using hedonic pricing analysis to determine influential price parameters. The results of hedonic regression analysis indicate the effect and importance of calorific value and electricity price on lignite prices. Second, a general coal-pricing model has been developed by taking into account the results of hedonic analysis. Comparison of the coal prices estimated by the developed pricing model and the coal prices obtained from thermal plants indicates an acceptable relation.     

Biological Pollutants: Alien Fishes in Mountain Lakes

Many lakes in the national parks of the Canadian Rockies were stocked with alien fish species in the early to mid 20th century. Changes to Parks Canada's mandate require the original communities of these lakes to be restored. We document the changes to invertebrate communities caused by the stocking of alien fishes into three fishless alpine lakes, and describe the results of two restoration experiments, one the reintroduction of Hesperodiaptomus arcticus, a planktonic predator that had been eliminated from Snowflake Lake by stocked fish, and the other the removal of brook trout (Salvelinus fontinalis) from Bighorn Lake. In both cases, there were great changes to the zooplankton communities, which required several years to complete, probably because of the cold water and unproductive nature of the lakes. Many of the invertebrate species extirpated by stocked alien fishes co-exist with native fish species in nearby lakes. Possible reasons are discussed.     

POTENTIALS FOR REUSE OF WASTEWATER IN NORTH CENTRAL TEXAS1

ABSTRACT There are several possible ways in which wastewater from municipalities may be reclaimed and reused so as to minimize the need for imported water in North Central Texas. The rationale for reuse is enhanced by the fact that new water quality requirements in the Trinity River system will necessitate a very high degree of treatment at municipal sewage plants, just for discharge to surface streams. The largest potential market for municipal effluent is the steam-electric power industry. Within the next decade the generating capacity for electric power in North Central Texas will have to be more than doubled to meet increasing demand. Adequate supplies of condenser cooling water for such expansion will be difficult to obtain and assure. New large power stations might advantageously be located adjacent to municipal wastewater treatment plants, to utilize effluent as make-up water for cooling towers. Experience elsewhere has shown that well-treated wastewater can be used for cooling tower make-up with a minimum of trouble, with a considerable saving in overall cost, and with conservation of pristine water for other uses.     

DESIGN OF DESALTING PLANTS FOR CONJUNCTIVE OPERATION1

ABSTRACT The selection of an evaporator design must reflect the balancing of captial cost (primarily in heat exchanger surface and vessels) against operating cost (primarily steam cost) to achieve minimum cost. In a conjunctive plant the tendency is to select a low-capital cost, high-operating cost plant. In addition, it is advantageous to use a high-capacity plant which needs to be operated much less of the time than a plant which is sized just at the needed rate. For example, in the study of a possible system to satisfy a future increase of 450 MGD in water supply to New York Qty, a plant of 750 MGD capacity was selected as optimum. This plant, of the advanced VTE-MSF process type, would have a performance ratio of 9 lb product/1000 Btu as compared to 10-13 normally used for base-loaded plants. Steam would be supplied by a multi-unit dual-purpose nuclear power plant. The most economical type of energy supply would be “interruptible”; the steam would be used by a low pressure turbine to generate electricity during periods of peak electrical demand but would be available to the desalting plant at other times. The low pressure turbine would be available as spinning reserve during desalting plant operation. It is estimated that the desalting plant would have a load factor of 27 per cent over its life.     

Current and Future Strategies for Water and Wastewater Management of Istanbul City

Istanbul has experienced rapid increases in population to more than 12 million people, which has created infrastructure problems of water supply and wastewater treatment and disposal. In this article, the achievements and approaches of the Istanbul Water and Sewerage Administration (ISKI) to solve the water shortage problem and to improve services are summarized. Istanbul had a very severe water shortage problem in 1994 because of ignorance of the implementation of the needed projects. After reviewing the reasons and causes of the problem, new priority criteria adopted after 1994 are given. Following the implementation of the projects determined according to the aforementioned criteria, water supplied has exceeded the water demand. The added capacity is equal to one to three times of the capacity built up to 1994 for water treatment, service reservoirs, pumping stations, transmission lines, and the water distribution network; water quality has been improved the meet local and international potable water standards. Unaccounted for water has been reduced from 60% to 27%. The percentage of treated wastewater has been increased from 10% to 90% in 8 years, resulting in drastic improvements and rehabilitation of the Golden Horn and coastal water quality. Through improved customer services, complaints were reduced from 33% in 1994 to 0.3%. Some of the main criteria and the approaches behind this success are summarized. Published online     

A Quantitative Safety Assessment Model For Transgenic Protein Products Produced In Agricultural Crops

Transgenic plants are now being used to develop pharmaceutical and industrial products in addition to their use in crop improvement. Using confinement requirements, these transgenic plants are grown and processed under conditions that prevent intermixing with commodity crops. Regulatory agencies in the United States have provided guidance of zero tolerance of these new industrial crops with commodity crops. While this is a worthy goal, it is theoretically unattainable. In spite of the best containment practices, there is a potential risk using any system of production due to unforeseen incidences including natural disasters or exposure to workers. The precautionary principle has been used for numerous regulated articles in addressing the potential risks of new products and technology based on a risk assessment in similar situations. We present here a risk assessment model that could be used as a start to develop an accepted model for the industry. The model is based on current risk models used for other regulated articles, but adapted for these types of products. This could be used to determine action levels in the event of an unintended exposure or to ensure that detection or confinement methods are adequate to avoid risks. As an example, aprotinin, a therapeutic protein now being produced in maize, was evaluated for potential risk to humans using this model.     

THERMAL GRADIENTS IN RIVERS AND RESERVOIRS DUE TO HEATED PLANT EFFLUENTS1

ABSTRACT The direction of heated effluents from large thermal power plants into streams and lakes has been a matter of public concern for some time, and the collection of prototype data related to the hydraulic aspects has taken on massive proportions. Unfortunately, most of the data are proprietary and not available for public analysis. The authors have endeavored to collect such data as are available to them for the initiation of steps toward generalization and the discussion of some of the more evident hydraulic considerations. The study is primarily concerned with rivers, including estuaries, with some interest in cooling ponds.     

Comparative Evaluation of Biomonitoring Techniques of Tropospheric Ozone

During a survey of tropospheric ozone pollution carried out using tobacco plants (Nicotiana tabacum L.) cv. Bel-W3, ozone- supersensitive, and cv. Bel-B, ozone-resistant, as bioindicators, the effectiveness of the traditional biomonitoring method, based on the use of adult plants, was compared with an innovative miniaturized kit of seedlings. The ratio of foliar and cotyledonar necrosis, respectively, was estimated as ozone injury rate. The miniaturized kit proved to be advantageous, since seedlings need only easy growth procedures and a large number of individuals can be placed in a small space, supplying good data amounts for statistical elaboration. Moreover, correlation studies among cotyledonar and foliar injury index and ozone levels monitored through physico-chemical measurements and results of analysis of variance tests highlighted the high sensitivity of the innovative methodology.