Biotreatability and kinetics of UASB reactor to mixtures of chlorophenol pollutants

In most natural ecosystems heterotrophic microorganisms encountercomplex mixtures of carbon sources, each of which is present at aconcentration of few micrograms per litre. This study examined the biotreatability and kinetics of an upflow anaerobic sludge blanket (UASB) reactor to complex mixtures of chlorophenols encountered in environmental conditions using on-line and off-line experimental studies. Results indicate that (1) steady-state concentration was quite lower (98.3 mg L^-1) with complex mixture of chlorophenols than steady-state concentration achieved when only 2.4 dichlorophenol (124 mg L^-1) was studied alone on the same reactor; (2) that toxiceffects of chlorophenols increase with increasing concentrationsof toxicant. (Onset of the inhibitory effect occurred at a lowerconcentration in multi-substrate than in single substrate utilization); (3) addition of alternative utilizable substrate can mitigate toxic effects and enhance degradation; (4) the relative concentration of substrate was critical in determiningutilization patterns. HPLC analysis of off-line experimental samples resulted in a steady-state treatment efficiency of68% for COD, 36% for 2-hlorophenol, 40.5% for 4-chlorophenol, 70.7% for 2,4-dichlorophenol, 53.2% for 2,4,6-trichlorophenol and 42% for pentachlorophenol in presence of glucose. Kinetic constant in terms of V _max and K _s were determined. K _s for the five chlorophenols ranged between 0.016 and 0.117 kg m^-3 day^-1 while V _max ranged between 0.056 and 0.244 kg m^-3 day^-1.     

IMPACTS OF VISITORS ON SOIL AND VEGETATION OF THE RECREATIONAL AREA “NACIMIENTO DEL RÍO MUNDO” (CASTILLA-LA MANCHA, SPAIN)

This study examines the effects of recreational use on the soil and vegetation at a site of ecological importance (Nacimiento del Río Mundo, Albacete, Spain). The most visited sites showed increased soil compaction of approximately 50%, bare ground increase to 61 ± 10% and a decrease in richness (from 25 ± 2 to 15 ± 2 species), diversity (from 4.0 ± 0.1 to 2.7 ± 0.4) and stratification of plant species (from 80 ± 11 to 21 ± 4%). The most visited sites had 90% less plant species as compared to the least visited. Intense use was associated with the presence of nitrophilous plant and vegetal species with a morphology adapted to heavy trampling. The recreational areas showed a distribution pattern of impact radiating outwards from the most used and degraded point. At the most visited point, Los Chorros (the spring of the river), the impact radiated outwards for about 20 m. A pilot experiment examining the effects of one-year restriction to visitors for access to a formerly impacted area showed a plant cover increase by anthropic and not by native species of 57 percent units.     

Evaluation of interference to conventional and real-time PCR for detection and quantification of fungi in dust

Advances in polymerase chain reaction (PCR) have permitted accurate, rapid and quantitative identification of microorganisms in pure cultures regardless of viability or culturability. In this study, a simple sample processing method was investigated for rapid identification and quantification of fungal spores from dust samples using both conventional and real-time PCR. The proposed method was evaluated for susceptibility to interference from environmental dust samples. Stachybotrys chartarum and Aspergillus fumigatus were used as test organisms. The sensitivity of detection in pure culture was 0.1 spore DNA equivalents per PCR reaction corresponding to 20 spores ml(-1) in the sample. However, 1 spore DNA equivalent per PCR reaction corresponding to 200 spores ml(-1) in the sample was the lowest amount of spores tested without interference in dust samples spiked with spores of either fungal species. The extent of inhibition was calculated using conventional and real-time PCR reactions containing fungal spores, specific primers, specific probes (for real-time PCR) and various amounts of dust. The results indicate that the extent of inhibition by dust on PCR varies with the type and amount of dust, and number of spores. No interference in the analysis of spiked samples was detected from 0.2 mg ml(-1) of four real-life dust samples at p-value >0.05 using 2 x 10(4) spores for conventional PCR and 2 x 10(5) spores for real-time PCR. However, samples containing >0.2 mg ml(-1) real-life dust compromised the PCR assay. These results suggest the potential usefulness of a simple sample processing method in conjunction with PCR for monitoring the fungal content of aerosols collected from indoor environments.     

Land User Participation in Developing a Computerised Decision Support System for Combating Desertification

Combating desertification in natural rangelands has recently become a priority in large parts of southern Africa. Rangeland managers, farmers, scientists, conservationists and land users have been applying a variety of restoration technologies to address this problem. Bush encroachment, as part of the desertification process, involves the natural replacement of the herbaceous plant cover by undesirable problem woody species. The active and passive restoration technologies that are applied, are mainly based on indigenous knowledge and include the chemical, mechanical or manual reclamation of unproductive rangelands, as well as the combating of woody and alien species encroachment. Indigenous practices and knowledge play a major role in the effectiveness and success rate of these technologies. This project faces the challenge of bringing together both local and scientific knowledge in a single user-friendly, computerised Decision Support System (DSS) which is directly accessible by land users to support them in the process of decision making, concerning the combating of desertification. Case studies from central and northern Namibia were used to combine qualitative and quantitative data to develop this Decision Support System. The DSS currently consists of two databases and an expert system, which evaluates the results of land users’ management practices, and provides easily accessible information and advice for participants in the system, based on the incorporated data. The DSS is also linked to national and international web sites and databases to offer a wider range of information on technologies concerning agricultural and conservation practices.     

Numerical Analyses of Soft Bottom Macroinvertebrates to Diagnose the Pollution in Tropical Coastal Waters

Soft bottom benthic organisms especially polychaetes are known to adapt as r or k selected strategies to different gradients of pollution. This will result in changes of benthic community structure from that of normal structure. There are a number of techniques to assess the impact of pollution on benthic community structure. Hence, to test this hypotheses some of the univariate and multivariate techniques were applied to soft bottom macro-invertebrates data of coastal waters of Mangalore, central west coast of India, a hot-spot area. Univariate techniques such as Pearson Rosenberg Model (PRM), abundance biomass comparison curve (ABC), geometrical class distribution, dominance-diversity curve, benthic community structure indices and multivariate techniques such as cluster classification, multidimensional scaling (MDS) and principal component analysis (PCA) were used to discriminate and diagnose the disturbance among the sites. Effectiveness and applicability of some of the above techniques are highlighted and discussed with the present set of data for environmental impact assessment studies.     

Pool of Dust Particles over the Asian Continent: Balloon-borne Optical Particle Counter and Ground-based Lidar Measurements at Dunhuang, China

Measurements of aerosols were made in 2001 and 2002 at Dunhuang (40 degrees 00'N, 94 degrees 30'E), China to understand the nature of atmospheric particles over the desert areas in the Asian continent. Balloon-borne measurements with an optical particle counter suggested that particle size and concentration had noticeable peaks in super micron size range not only in the boundary mixing layer but also in the free troposphere. Super-micron particle concentration largely decreased in the mid tropopause (from 5 to 10 km; above sea level, a.s.l.). Lidar measurements made during August 2002 at Dunhuang suggested the possibility that mixing of dust particles occurred from near the ground to about 6 km even under calm weather conditions, and a large depolarization ratio of particulate matter was found in the aerosol layer. The top of the aerosol layer was found at heights of nearly 6 km (a.s.l.). It is strongly suggested that nonspherical dust particles (Kosa particles) frequently diffused in the free atmosphere over the Taklamakan desert through small-scale turbulences and are possible sources of dust particles of weak Kosa events that have been identified in the free troposphere not only in spring but also in summer over Japanese archipelago. Electron microscopic experiments of the particles collected in the free troposphere confirmed that coarse and nonspherical particles observed by the mineral particle were major components of coarse mode (diameter larger than 1 microm) below about 5 km over Dunhuang, China.     

Total versus inhalable sampler comparison study for the determination of asphalt fume exposures within the road paving industry

Exposure to asphalt fumes has a threshold limit value (TLV of 0.5 mg m(-3) (benzene extractable inhalable particulate) as recommended by the American Conference of Governmental Industrial Hygienists (ACGIH). This reflects a recent change (2000) whereby two variables are different from the previous recommendation. First is a 10-fold reduction in quantity from 5 mg m(-3) to 0.5 mg m(-3). Secondly, the new TLV specifies the "inhalable" fraction as compared to what is presumed to be total particulate. To assess the impact of these changes, this study compares the differences between measurements of paving asphalt fume exposure in the field using an "inhalable" instrument versus the historically used 'total' sampler. Particle size is also examined to assist in the understanding of the aerodynamic collection differences as related to asphalt fumes and confounders. Results show that when exposures are limited to asphalt fumes, a 1:1 relationship exists between samplers, showing no statistically significant differences in benzene soluble matter (BSM). This means that for the asphalt fume ACGIH TLV, the 'total' 37-mm sampler is an equivalent method to the "inhalable" method, referred to as IOM (Institute of Occupational Medicine), and should be acceptable for use against the TLV. However, the study found that when confounders (dust or old asphalt millings) are present in the workplace, there can be significant differences between the two samplers' reported exposure. The ratio of IOM/Total was 1.37 for milling asphalt sites, 1.41 for asphalt paving over granular base, and 1.02 for asphalt over asphalt pavements.     

Utility of dynamics as indicators of stress in population models

The relationships between the dynamics of environmentally and chemically stressed populations and indicators of the effects of the stressor are explored in a model framework. The physiologically structured population, represented by a system of McKendrick–von Foerster hyperbolic partial differential equations, includes the dynamics of numerous individuals distinguished by ecotype. Chemical uptake of nonpolar narcotics is modeled by first order kinetics. Classical methodologies, frequency analysis and phase space reconstruction, are explored in a search for indicators of magnitude of stress. When these techniques proved generally unsuccessful for the objective of indicator selection in our model setting, summary statistics, as related to bifurcation diagrams, were constructed and appear more useful as indicators. It is concluded that physiological structures generally lead to more feasible measurable indicators of magnitude of stress than do specifics of population dynamics.     

Risk assessment of water pollutants

The sources of toxic xenobiotics and different factors such as ecological diversity, differences in comparative anatomy, physiology and biochemistry, food chain variation, interrelationship within species and life span, etc., are considered during risk assessment of pollutants, and their impact on aquatic ecotoxicology is identified. A fugacity and multimedia compartment model is suggested, based on toxicodynamic (toxicity of the chemical) and toxicokinetic (metabolism of the chemical) considerations to predict and screen the behaviour of pollutants quantitatively in the aquatic environment. The significance of the risk analysis approach in anticipatory actions and regulation of pollution levels is discussed.     

Application of remote sensing to exposure monitoring

Although exposure assessments cannot be completed remotely, remote sensing techniques provide an invaluable adjunct in exposure monitoring programs. Exposure can be defined as the summation over time, in all media, of the amount of a pollutant available at the exchange boundaries of the receptor during a specified period. This paper describes a few remote monitoring techniques that provide direct measurement input into an exposure assessment and several that furnish quantitative or qualitative information leading to decisions regarding how to monitor, such that the source-exposure-dose relationships can be fully defined. Two general classes of remote sensing systems are included in this discussion-passive and active. Passive systems depend on a measurement of the energy reflected or emitted by a target and active systems use an energy source, e.g., a laser to perform the environmental interrogation. Airborne as well as ground-based remote monitoring measurements or systems are also considered in this paper.