ZONES OF NITRIFICATION1

ABSTRACT: This paper advances the hypothesis that nitrification exists in shallow streams as a result of surface activity and in estuaries due to growth in the water phase. Between these zones no significant levels of nitrification occur. Field measurements of ammonia, nitrite and nitrate nitrogen, enumerations of Nitrosomonas and Nitrobacter, and respirometry on two small streams and two moderately large rivers are presented. The appropriate mathematical models to describe nitrification must be based on the mechanisms involved - bacterial growth kinetics for estuaries and zero kinetics for the surface activity in shallow streams.     

Results of the European Commission Marina II study: part II--effects of discharges of naturally occurring radioactive material

Enhanced levels of naturally occurring radioactive materials (NORM) are produced through various industrial operations and may lead to discharges to the marine environment. A recent study, called MARINA II, carried out for the European Commission considered discharges of radionuclides from the NORM industries to north European marine waters and their consequences. There are two main sources that were considered in the study. The use of phosphogypsum during the production of phosphoric acid by the fertiliser industry and the pumping of oil and gas from the continental shelf in the North Sea which produces large quantities of water contaminated with enhanced levels of naturally occurring radionuclides. Discharges of alpha emitting radionuclides from these two industries have contributed significantly to the total input of alpha emitters to north European waters over the period 1981-2000 (data were not available prior to 1981). Discharges due to the use of phosphogypsum have declined since the early 1990s and are now very low. Discharges from the oil and gas industries stabilised in the second half of the 1990s and are now the major contributor to alpha discharges to the region. As most European countries do not report discharges of radioactivity with the water produced during extraction, there is considerable uncertainty in the discharges used in the study. The impact of the discharges has been estimated both in terms of the effect on non-human biota and the radiological impact for people. In the 1980s the radiation dose rates to marine biota in the region around a phosphate plant on the north-west coast of England were as high due to the discharges from the phosphate plant as those near to the Sellafield reprocessing plant due to its discharges. In recent years the additional dose to marine biota in this region due to the past NORM discharges is of the same order of magnitude as the natural background. The collective dose rate was estimated to determine the radiological impact on people. The peak collective dose rate from the NORM industries occurred in 1984 and was just over 600 manSv y(-1). The collective dose rate fell with time as discharges from the phosphate industry reduced and was estimated as under 200 manSv y(-1) in 2000.     

Use of agricultural land evaluation and site assessment in Whitman County,Washington, USA

Whitman County, Washington, USA, one of the largest wheat producing counties in the country, developed a land evaluation and site assessment system for evaluating proposed conversions of agricultural land to heavy commercial uses. The system uses soil potential indices to determine a land evaluation score and a nine-factor site assessment system to weigh suitability for development. Details on each of these are provided along with results for four sample sites.Scientific Paper no. 7165, College of Argiculture and Home Economics Research Paper, Washington State University, Pullman, Washington, project no. 0010.     

Stainless Steel Anti-Smog Mufflers—Cut Air Pollution

An automatic process gas chromatograph has been developed for use on the recovery furnace stack of a Kraft pulp mill. The instrument analyzes for widely varying concentrations of H₂S, SO₂, CH₃SH and higher order sulfur compounds. It is insensitive to the fixed gases and water vapor, and performs its analysis in approximately ten minutes. The instrument features a microcoulometric detector giving it sensitivity to H₂S as low as 0.1 ppm, and SO₂ and CH₃SH as low as 0.5 ppm. The major limit to even higher sensitivity at this stage of development lies with two problems: the background noise level in the detector and the sulfur compound absorption in the Porapak Q chromatograph column. At the reported sensitivity, a 40-ml gas sample was used. The instrument also contains a data analysis system supplementary to the usual strip chart recorder. This system is made up of a digital voltmeter, a digital translator, and a teletype and hence allows the transfer of the output data to a digital computer for processing. The processed data are usually presented in the form of ppm quantities of the component gases in the stack gas. The instrument has worked successfully on small furnace effluent for periods of 25 hr but has not been tried on recovery furnace stacks. It has also run on prepared samples for periods of up to seven days with no maintenance or attendance necessary.     

High Volume Air Sampler: An Orifice Meter as a Substitute for the Rotameter

Abstract

NOX control employing several combustion modification techniques is studied in batch annealing furnaces and ammonia combustion ovens in steel plants. The fuels of the annealing furnace and ammonia oven are by-product fuel gases and ammonia vapor, respectively, which are generated in the same steelworks. Study of the emission characteristics of the annealing furnace show that delayed combustion can effectively reduce NOX emissions. Delayed combustion is accomplished by air-staging in burners, off-symmetric mixing of fuel and air, and air-biasing in the furnace, and these modification can operations achieve 60%, 40%, and 26% of NOX reductions, respectively. For the ammonia oven, NOX emission from combustion of ammonia vapor is remarkably reduced by staging the air injected into the oven, adjusting the total air rate, and adding by-product fuel gases to the combustion system.     

Use of standardized methods to improve extinction-risk classification

Standardized classification methods based on quantifiable risk metrics are critical for evaluating extinction threats because they increase objectivity, consistency, and transparency of listing decisions. Yet, in the United States, neither federal nor state agencies use standardized methods for listing species for legal protection, which could put listing decisions at odds with the magnitude of the risk. We used a recently developed set of quantitative risk metrics for California herpetofauna as a case study to highlight discrepancies in listing decisions made without standardized methods. We also combined such quantitative metrics with classification tree analysis to attempt to increase the transparency of previous listing decisions by identifying the criteria that had inherently been given the most weight. Federally listed herpetofauna in California scored significantly higher on the risk-metric spectrum than those not federally listed, whereas state-listed species did not score any higher than species that were not state listed. Based on classification trees, state endemism was the most important predictor of listing status at the state level and distribution trend (decline in a species’ range size) and population trend (decline in a species’ abundance at localized sites) were the most important predictors at the federal level. Our results emphasize the need for governing bodies to adopt standardized methods for assessing conservation risk that are based on quantitative criteria. Such methods allow decision makers to identify criteria inherently given the most weight in determining listing status, thus increasing the transparency of previous listing decisions, and produce an unbiased comparison of conservation threat across all species to promote consistency, efficiency, and effectiveness of the listing process.     

Genetically informed captive breeding of hybrids of an extinct species of Galapagos tortoise

Hybridization poses a major challenge for species conservation because it threatens both genetic integrity and adaptive potential. Yet, hybridization can occasionally offer unprecedented opportunity for species recovery if the genome of an extinct taxon is present among living hybrids such that selective breeding could recapture it. We explored the design elements for establishing a captive-breeding program for Galapagos tortoises (Chelonoidis spp.) built around individuals with admixed ancestry involving an extinct species. The target individuals were hybrids between the extinct species from Floreana Island, C. niger, and an extant species, C. becki, which were recently found in the endemic range of C. becki, from Wolf Volcano on Isabela Island. We combined genotypic data from 35 tortoises with high ancestry from C. niger with forward-in-time simulations to explore captive breeding strategies that maximized overall genetic diversity and ancestry from C. niger while accommodating resource constraints, species biology, and the urgency to return tortoises to Floreana Island for facilitating ecosystem restoration. Overall genetic diversity was maximized when in the simulation tortoises were organized in relatively small breeding groups. Substantial amounts of the C. niger genome were captured despite limited resources available for selectively breeding tortoises in captivity. Genetic diversity was maximized when captive-bred offspring were released to the wild rather than being used as additional breeders. Our results provide genetic-based and practical guidance on the inclusion of hybrids with genomic representation from extinct taxa into species restoration programs and informs the ongoing debate on the value of hybrids in biodiversity conservation.     

Incorporating geodiversity into conservation decisions

In a rapidly changing climate, conservation practitioners could better use geodiversity in a broad range of conservation decisions. We explored selected avenues through which this integration might improve decision making and organized them within the adaptive management cycle of assessment, planning, implementation, and monitoring. Geodiversity is seldom referenced in predominant environmental law and policy. With most natural resource agencies mandated to conserve certain categories of species, agency personnel are challenged to find ways to practically implement new directives aimed at coping with climate change while retaining their species‐centered mandate. Ecoregions and ecological classifications provide clear mechanisms to consider geodiversity in plans or decisions, the inclusion of which will help foster the resilience of conservation to climate change. Methods for biodiversity assessment, such as gap analysis, climate change vulnerability analysis, and ecological process modeling, can readily accommodate inclusion of a geophysical component. We adapted others’ approaches for characterizing landscapes along a continuum of climate change vulnerability for the biota they support from resistant, to resilient, to susceptible, and to sensitive and then summarized options for integrating geodiversity into planning in each landscape type. In landscapes that are relatively resistant to climate change, options exist to fully represent geodiversity while ensuring that dynamic ecological processes can change over time. In more susceptible landscapes, strategies aiming to maintain or restore ecosystem resilience and connectivity are paramount. Implementing actions on the ground requires understanding of geophysical constraints on species and an increasingly nimble approach to establishing management and restoration goals. Because decisions that are implemented today will be revisited and amended into the future, increasingly sophisticated forms of monitoring and adaptation will be required to ensure that conservation efforts fully consider the value of geodiversity for supporting biodiversity in the face of a changing climate.