The velocity of DNAPL fingering in water-saturated porous media: laboratory experiments and a mobile–immobile–zone model

Dense nonaqueous phase liquids (DNAPLs) are immiscible with water and can give rise to highly fingered fluid distributions when infiltrating through water-saturated porous media. In this paper, a conceptual mobile–immobile–zone (MIZ) model is presented to describe the structure of a DNAPL finger in water-saturated porous media and the velocity of finger propagation. A finger is composed of a finger body and a tip. The finger body has a mobile core and an immobile sheath. All the DNAPL within the tip of a finger is mobile. Lab experiments utilizing image analyses of a DNAPL (PCE) penetrating into water-saturated homogeneous glass beads were carried out in a two-dimensional transparent chamber. The results show that the fingers elongated almost linearly with time. The fingers did not grow laterally after the tip of the finger had passed. The average finger diameters were between 3.9 and 5.4 mm for PCE propagation in water-saturated glass bead porous media with mean particle diameters from 0.32 to 1.36 mm. The estimated mobile core diameters were 51–60% of the average finger diameters.     

RecoPhos: Full-scale fertilizer production from sewage sludge ash

The substitution potential of sewage sludge for German primary phosphate imports has been estimated as 40%. Yet, a marketable option for the full scale recovery has been lacking. This study focuses on a full-scale process for the manufacture of a P-fertilizer from sewage sludge ash (SSA) adapted from the production of Triple Superphosphate. Given (i) conformity of the input with phosphate ores mined from sedimentary deposits, (ii) comparability of the product with a commercially available P-fertilizer regarding contaminant levels, P-fractionation and yield effects, and (iii) compliance of the output with the German Fertilizer Ordinance the RecoPhos P 38 fertilizer was discharged from the waste legislation regime. The fertilizer is currently being produced at a rate of 1000 tonnes per month and sold at a competitive price.     

Release of alien populations in Sweden

Introduction of alien species is a major threat to biological diversity. Although public attention typically focuses on the species level, guidelines from the Convention of Biological Diversity define alien species to include entities below species level. This inclusion recognizes that release of nonlocal populations of native species may also result in negative effects on biodiversity. In practice, little is known about the extent, degree of establishment, or the effects on natural gene pools of such releases. Existing information on the releases in Sweden shows that alien populations are spread to a great extent. The most commonly released species include brown trout, Atlantic salmon, Arctic char, common whitefish, Scots pine, Norway spruce, mallard duck, gray partridge, and pheasant. Although millions of forest trees, fish, and birds are released annually, poor documentation makes the geographic and genetic origin of these populations, as well as the sites where they have been released, largely unclear. We provide recommendations for urgently needed first steps relating to the risks and problems associated with release of alien populations.     

Ozone concentrations in the Central Wasatch Mountains of Utah

In the Salt Lake Valley, a June through August SUM60 value (sum of hourly average ozone concentrations > or =60 parts per billion by volume [ppbv]) of 25,000 ppbv-hr was exceeded in 9 yr between 1978 and 1998. Ozone concentrations in the nearby Central Wasatch Mountains were monitored to determine the potential for vegetation injury. The SUM60 value of 19,000 ppbv-hr in these mountains and peak hourly concentrations >100 ppbv suggests that ozone-sensitive species may be injured. Ozone concentrations in the mountains were greatest during periods of strong upslope winds from the Salt Lake Valley. Both SUM60 values and hourly average concentrations in the Central Wasatch Mountains were strongly correlated with those in the Salt Lake Valley, suggesting that data from valley stations could be used to estimate ozone in the mountains.     

Evaluation of surface water quality impacts of hazardous chemical sites

Common deficiencies in the typical evaluation of the surface water quality impacts of hazardous chemical sites are discussed. Particular attention is given to deficiencies in monitoring stormwater runoff, as well as the input of contaminated groundwaters that lead to impairment of the beneficial uses of nearby surface waters because of site-derived hazardous and deleterious chemicals. An alternative approach, Evaluation Monitoring, is presented in this paper. Evaluation Monitoring shifts the monitoring program from periodic sampling and analysis of stormwater runoff and ambient waters for a suite of chemical parameters, to examining the receiving waters to determine what, if any, water quality use impairments are occurring in surface waters due to the runoff-associated constituents and shallow groundwater input.     

Mammalian community characteristics on surface mine lands in Pennsylvania

Mammalian communities were studied on 10 surface mines over a four year period. The size and composition of these communities varied among the different areas. The size, composition, and spatial distribution of these mammalian communities were related to the structure of the plant community, and native plant species were of greater importance in determining size and composition of these communities than were those used in reclamation.     

ENVIRONMENTAL IMPACT OF STREAM CHANNELIZATION1

ABSTRACT Geologic, engineering, and biological investigations of six Pennsylvania coldwater streams were undertaken to determine the impact of channel modifications instituted both prior to and following Hurricane Agnes. The primary focus of the study was on the ecological changes brought about by stream channelization. No long-term deleterious effects on water quality, attached algae, benthic fauna, or forage fish populations were found. Trout, however, were found to be greater in numbers and weight in natural than in channelized stream reaches. Lack of suitable physical habitat appears to be the primary cause of reduced trout populations in stream reaches which have been channelized.