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<p>Human activities have caused acidification of freshwater systems on a large scale resulting in reduced species diversity and ecological functioning in many lakes and streams. However, many naturally acidic freshwater systems have also been found, for instance in northern Sweden. In regions where such naturally acidic aquatic ecosystems have prevailed over evolutionary periods, species diversity and ecological functioning are not automatically impaired due to possible adaptation to the putatively adverse environmental conditions. I studied species diversity patterns and ecological functioning in anthropogenically acidified, naturally acidic, circumneutral, and limed streams to test the adaptation hypothesis and examine the ecological effects of variation in naturally acidic water chemistry. Species diversity was studied using benthic macroinvertebrates, while functioning was modelled using the decomposition rates of leaf litter. In accordance with the evolutionary species pool hypothesis, species richness was reduced more strongly in regions with anthropogenic than natural acidity when compared to circumneutral streams, supporting the adaptation hypothesis. In contrast, the patterns in ecological functioning along the pH-gradients did not differ between regions with anthropogenic and natural acidity, likely resulting from compensation: the biomass of tolerant taxa probably increased which thus rescued the loss in functioning otherwise mediated by the more sensitive taxa. Furthermore, the naturally variable acidic water chemistry clearly supported distinct macroinvertebrate assemblages, as was reflected in differing patterns of species diversity and ecological functioning. Such naturally acidic waters that were rich in dissolved organic carbon supported higher ecosystem process rates and lower species diversity than waters that contained little dissolved organic carbon. Upon liming naturally acidic streams microbial leaf decomposition increased, whereas shredding decreased along with changes in shredder abundances. The abundance of large caddisflies decreased, while the abundance of small stoneflies increased. The results suggest that various types of benthic macroinvertebrates with varying levels of adaptation and tolerance inhabited the hydrochemically variable naturally acidic streams. The distributions of macroinvertebrates in response to different pH levels and differences in acid quality and how these distributions translate into varying patterns of species diversity and ecological functioning are worthy of further investigation. This will likely improve our understanding of how such naturally acidic streams and their biota can be successfully managed.</p>

An acid rain simulation was created under laboratory conditions to study the effects of mortality rates and developmental time of Aedes triseriatus (Say) mosquito larvae. Two hundred-forty instar 1 mosquitoes were placed into separate 120 ml glass jars containing rain water adjusted to pH 2, 3, 4, 5, 6, and 7 with a nitric acid solution. A second part of the experiment was set up like the first except a 70 percent to 30 percent sulfuric-nitric acid solution was used to adjust pH levels. Mortality and developmental time was observed until the insects reached maturity or died.No significant differences at the .05 level in mortality rates were observed between larvae raised in nitric acid solution as compared to sulfuric acid solution. However, exposures to 70 to 30% sulfuric-nitric solution resulted in a significantly (0.05) higher mortality at pH levels 4, 5, and 6 than the sulfuric acid or nitric acid exposures.Developmental time did not vary more the 0.5 days between the sulfuric acid exposure group and the nitric acid group except at pH 4.Ball State UniversityMuncie, IN 47306

Emissions of ammonia (NH3) into the atmosphere, principally from agricultural sources, have been implicated in the pollution of forests, moorlands and grasslands, through the subsequent deposition of reduced nitrogen (NH,, -N). Consequently, legislation has been implemented to control both the transboundary transport and local environmental impacts of NH,,. This thesis investigates the emission, dispersion and local deposition of N113 from two sources that are major components of national N113 emissions inventories, slurry applied to grassland and naturally ventilated cattle buildings. AN balance method was identified for determining the time-average deposition of N113 downwind of a farm building, whilst an adapted micrometeorological flux-gradient technique was developed for estimating local deposition downwind of slurry spreading. This method used an analytical atmospheric dispersion model to provide advection corrections to the standard flux-gradient method. The UK-ADMS model, which incorporates a reasonably detailed treatment of building effects, was identified for use in determining the near-field dispersion from naturally ventilated farm buildings. Eight field experiments were conducted to determine the emission, dispersion and local deposition of N113 volatilised from slurry applications. Emission fluxes during the initial runs following slurry spreading were found to depend on friction velocity, relative humidity and rainfall. Local deposition, at sufficient rates to affect local deposition budgets, was not found to occur during near-freezing conditions or following the application of fertilisers. Local deposition velocities during other periods were found to depend on the latent heat flux, temperature and the roughness length. During such periods, 14 - 18 % of the emitted NH3 was estimated to deposit within 50 rn of the source. Experiments were also conducted at two naturally ventilated farm buildings, the Silsoe Research Institute Structures Building and a working dairy farm. Ammonia emission factors were determined for the main building and slurry lagoon at the dairy farm. A novel application of a model back-calculation method was applied to determine the emission from the lagoon. Dispersion of NH3 from both sites was found to be adequately modelled using UK-ADMS. Approximately 2% of the emitted NH3 deposited within 100 - 150 rn of each building. Time averaged deposition velocities calculated from the farm building studies confirmed that NH3 was deposited to the leaf surfaces and uptaken across the leaf cuticle. Temperature dependent exchange rates were also indicated by the results of the farm building experiments, With NH3 uptake being regulated by the assimilation potential of the plant. The experimental results demonstrated that deposition around both sources could lead to local critical load exceedancesT. hese were only estimatedt o occur within a few tens of metres downwind of slurry spreading whilst critical load exceedancesw ere predicted at distanceso f up to 100 m or more downwind of the farm building. The temporal variability in local recapture found in these experiments, particularly for farm buildings, suggests that seasonal variability in the treatment of N113 eniission and deposition should be included in atmospheric transport models. Furthermore, it is possible that transboundary transport of NHx may increase during winter periods with peak housing emissions.

This thesis presents data from an integrated study of precip~tation, ground and surface water chemistry from 460 km of the Peak District, between May 1987 and April 1988. All samples have been analysed for a suite of nine major ions. Data have been used to: (1) describe temporal and spatial variability of acid precipitation and deposition; (2); examine the controls on precipitation chemistry; (3) describe the chemistry of sampled waters and elucidate catchment processes; and (4) examine the impact of bulk deposition on ground and surface water chemistry. The dense network of collectors has clearly identified significant small scale variability of precipitation chemistry across the study area. However, temporal variability is consistent with observations of other workers. It has been statistically demonstrated that calcium and non-marine sulphate have a close temporal and spatial association. This is hypothesised as being the result of atmospheric reactions between regional gaseous sulphur dioxide and extractive industry derived calcium. The resultant calcium sulphate is prinCipally removed by below cloud scavenging and dry deposition. All sampled groundwaters bave .a high acid neutralising capacity which illustrates the dominance of limestone solutional processes. Surface waters have relatively high concentrations of base cations indicating some buffering potential. However, high variability of bo~~ hydrogen and aluminium suggests a limited buffering capability during storm events. Advanced statistical techniques have demonstrated a complex association between surface water acidification and the bulk deposition of marine ions. This is consistent with the findings of other researchers. Cross and partial correlation have shown the mobility of aluminium in acid sensitive waters to be related to elevated loadings of hydrogen. This research has demonstrated the importance of finescale resolution in precipitation chemistry monitoring networks. Advanced statistical techniques have identified relationships between precipitation chemistry and ground and surface water quality in a geologically complex ..environment.

This research presents the development and application of generic methodologies for the production of a spatially resolved emissions inventory for the North West region of England. The overall purpose of the estimates is to provide emissions data for use within air quality management applications. The North West region is used as the basis of the work due to being composed of a number of administrative units and providing the regional context for local air quality management in the main urban areas of Greater Manchester and Merseyside. Estimates are made for the key urban pollutants (CO, NOx, VOCs, PM and S02) from anthropogenic sources in 1994 and are shown at a variety of spatial scales. Data are available in terms of a regional 5 x 5 km grid, a sub-regional 1 x 1 km grid or at the scale of the original data source. Source categories, which correspond to broad management groupings, comprise road transport; rail transport; airports; shipping; industry; (Part A and Part B); and other (domestic and commercial) sources. Estimation procedures are developed in relation to readily available data sources and are applied within a GIS environment. The use of GIS has been shown to be an appropriate tool for the development of spatially resolved inventories and has further potential in relation to additional applications of the resultant emissions data. The requirements of producing a generic methodology which uses readily available data sources has been found to limit the degree of detail with which it is possible to develop estimation procedures. One of the principal limitations is the availability of comparable activity data for a number of administrative units. However, the results of the inventory are shown to be useful for a number of air quality management activities, including the identification of patterns of emissions at different scales of investigation and the identification of the location and causality of emission 'hotspots'.