In August of 2003 a severe wildfire burnt the majority of Fishtrap Creek, a 170 km² catchment in central British Columbia, Canada. The objective of this study was to determine the short-term (15-month) influence of the wildfire on the amount and composition of fine sediment delivery and retention in the system and to compare it to a similar unburnt catchment. In the spring of 2004 automatic water samplers were installed at a gauging site on Fishtrap Creek to collect suspended sediments from the snowmelt runoff and gravel traps were deployed on the channel bed surface to collect composite samples of suspended fine sediment. Jamieson, the reference creek, exhibits similar geology and pre-burn vegetation and was sampled in the same manner for comparison. Composite suspended sediment collected in the traps was removed from the streams in mid-summer and early September. Quantitative estimates of the amount and particle size structure of the naturally stored fine sediment in, and on, the gravel creekbed were obtained in pre-melt, mid and late-summer conditions. Estimates of suspended sediment yields indicated that while the burnt system delivered 66% more material per unit area, the total seasonal suspended sediment yield was low (855 kg km-²) compared to other fire-disturbed systems. While the burnt catchment was primed to deliver sediment, the hydrologic drivers were not of sufficient magnitude to generate a substantial response, suggesting that in this first post-fire year the system was transport-limited, not supply-limited. Differences were noted in the spatial and seasonal composition of the <500 more OM% composite suspended sedimentswith the burnt catchment having significantly (P<=0.05) more OM%. Seasonally a significant increase of OM% in late summer samples was associated with instream biofilms and possible delivery of black carbon. The system's post-fire response was not geomorphically substantial but significant biological differences were noted in the short-term.

In order to improve and optimize phytoremediation of PAH we propose to focus on the rhizospheric processes controlling PAH degradation. In this paper the effect of root exudates on PAH availability is studied. Model organic compounds (malic acid, malonic acid and EDTA) representing root exudates have been tested for their effect on phenanthrene sorption on a reference non polluted agricultural soil material. Phenanthrene adsorption isotherms were first obtained with batch experiments. Results showed linear isotherms and phenanthrene sorption was enhanced as the concentration of organic compounds in the solution increased. Column leaching experiments were then used to simulate the effect of root exudation following the soil pollution. Inlet solutions containing the different organic acids used were flowed through the column containing the artificially polluted soil material. Elution curves showed that the phenanthrene was less easily eluted when the solution injected contained the organic acids. However, magnitude of the phenomena did not fit with adsorption constants obtained in batch experiments. Phenanthrene desorption appeared limited by sequestration but organic acids seemed able to partially disturb the soil material structure to limit the sequestration effect.

To reconstruct a history of polycyclic aromatic hydrocarbon (PAH) pollution in the Gulf of Trieste, one of the largest urbanized areas in the Adriatic Sea, we analyzed three long sediment cores collected between 1996 and 1997. Concentrations of total PAHs, the sum of 16 PAH compounds and six of their methylated analogues, in all three cores show a decrease from 600-800 ng g-¹, at the surface, to levels below 250 ng g-¹ in deepest layers (down to 3 m). The same trend was shown with separate representative pyrogenic PAHs (pyrene, benzofluoranthene and phenanthrene). Using Hg as a recent geochronological tracer, we observe an increasing input of PAHs since the beginning of the 20th Century and, especially, after the Second World War coinciding with increasing industrialization and urbanization of the region. This correlation is supported by PAH ratios that are indication of combustion processes and represent a marker for anthropogenic inputs. No correlation exists between PAHs and black carbon within the core profiles, indicating two different fractions of the 'black carbon continuum'.

Two lab-scale trickle-bed air biofilters were operated for investigating the difference in performance between a hydrophilic and a hydrophobic volatile organic compound (VOC). Methyl isobutyl ketone (MIBK) and styrene were selected as a model hydrophilic and hydrophobic VOCs, respectively. Effects of loading rates, biofilter re-acclimation, removal profile along biofilter depth, nitrogen consumption, and CO₂ production were compared under three operating conditions, namely, backwashing and two non-use periods (starvation and stagnant). Consistent over 99% removal efficiency up to loading rates of 3.26 kg COD/m³-day was obtained for the MIBK biofilter at 0.76 min empty bed retention time (EBRT) and 1.5 L/d nutrient flow. A similar performance for the styrene biofilter was obtained for loading rates up to 1.9kg COD/m³-day at 2.02 min EBRT and 2.4 L/d nutrient flow. The MIBK biofilter required only an initial acclimation period of 16 days while styrene biofilter required 46 days. Non-use periods can be used as another means of biomass control for both biofilters when the employed loading rate did not exceed 1.27 and 2.17 kg COD/m³-day for styrene and MIBK biofilters, respectively. The re-acclimation of both biofilter was delayed with increase of loading rate. MIBK biofilter re-acclimated in 90 min, while styrene biofilter re-acclimated in more than 600 min. Under similar loading rates, MIBK biofilter utilized less biofilter depth than styrene biofilter. Nitrogen consumption behaviors were apparently different between the two biofilters. Styrene biofilter had higher CO₂ production than MIBK biofilter and its CO₂ production was closely related to the theoretical complete chemical oxidation.

One of the methods to diminish the internal phosphorus (P) loading is inactivation of P by aluminum (Al). After addition of Al to lake water an Al(OH)₃ floc is formed, which settles to the bottom and initially form a lid on the sediment surface. The effects of Chironomus plumosus larvae on sediment nutrient fluxes and P binding-sites in the sediment after addition of Al were tested. C. plumosus larvae were added to sediment cores in which sediment-water fluxes of nutrients were measured four times. After one month, the sediment was sectioned with depth and P fractions were measured by sequential chemical extraction. The chironomids created burrows through the Al layer which caused a significantly increased efflux of P from the Al treated sediment, because the P had only limited contact to the added Al. The chironomids also affected the P fractions in the sediment by their bioturbating activity. Thus, they caused increased Al concentrations in the upper part of the Al treated sediment. This created an enhanced contact between Al and P in the upper 7 cm of the sediment and, as a result, an increased binding of P to Al and a lowered porewater P. The DIP efflux is therefore expected to be lowered after the initial phase. Al had no effects on the nitrogen fluxes, but the chironomids enhanced the [graphic removed] release, and decreased the [graphic removed] release or increased the [graphic removed] uptake by the sediments.

Sediment cores collected in eutrophic subalpine Lake Bled (NW Slovenia) were analyzed sedimentologically in terms of grain size, mineralogy and sedimentation rates, and geochemically in terms of metals and nutrients. Surficial sediment is composed of dark gyttya type clayey silt with 5%-10% of organic matter. The sediment below is fine laminated and composed of homogenous silt and clayey silt: Mineralogically, low-Mg calcite prevails, followed by dolomite, quartz, partially of diatomaceous origin, and feldspar. Clay minerals are composed of muscovite/illite and chlorite. Authigenic minerals are pyrite and 'lake chalk' (low-Mg calcite). Lake sediment is especially polluted by Pb, Zn and P. Higher contents were found in the northwestern and eastern parts due to the particle input by local inflows. Increasing eutrophication and pollution, indicated by Cd, Cu, V, Cr, Co and total N and P enrichment in the top layers of the cores, started almost 100 years B.P., and especially 50 years ago.

A benthic in situ flume and a 1D biogeochemical sediment model to evaluate solute fluxes across the sediment-water interface have been developed. The flume was successfully used to determine oxygen and nutrient fluxes at various locations of the Neckar River in Germany. The experimental results were linked with vertical pore water concentration profiles and independently verified with the model. By combining experimental and model results we assessed the influence of dissolved oxygen concentrations in the water column and the availability of degradable organic matter on sediment oxygen demand. The results and the derived relations can be used to parameterize the sediment module of large scale water quality models, allowing one to assess the influence of sediment-water interactions on various aspects of river water quality. Moreover, the biogeochemical sediment model can help to improve the general understanding of the processes governing solute concentrations and fluxes in sediments and across their interfaces.

Hydrochemistry of an alluvial river was investigated employing the chemometric techniques such as cluster analysis (CA), principal component analysis (PCA), discriminant analysis (DA) and partial least square (PLS) with a view to extract information about the variables responsible for spatial and temporal variations in river hydrochemistry and water quality, the hidden factors explaining the structure of the hydro-chemical database of the river, factors/processes influencing the river hydro-chemistry. Analysis of spearman's correlation coefficient revealed non-significant correlation of the pollution indicator (BOD, COD, SO₄, F, NH₄-N, NO₃-N) variables with season and significant correlation with site, indicating contribution of the site-specific anthropogenic sources in the catchments. Spatial CA clustered the monitoring sites (10nos.) into three groups of relatively non-polluted sites, moderately polluted sites, and highly polluted sites. Temporal CA differentiated among the samples of monsoon and non-monsoon months. PCA rendered considerable data reduction, in terms of eight parameters explaining about 71% of the total variance and evolved six PCs. PCA grouped samples belonging to different seasons and sites distinctly correlating them with natural and anthropogenic variables. Temporal and spatial DA rendered 97 and 92% correct assignations of the samples, respectively, and revealed that temperature, pH, BOD, DO, alkalinity and Ca are the most significant variables to discriminate between the different seasons and account for most of the expected temporal variations in hydrochemistry of the river, whereas, hardness, DO, BOD, COD, Ca and Mg were the most significant discriminating variables in space. Spatial and temporal groupings of the samples were successfully achieved through PLS modeling. PLS showed that the summer season samples are dominated by PO₄, TDS, F, K, COD, BOD, Na, Cl, hardness and alkalinity, whereas, samples of winter season by DO, pH, NH₄-N and coliforms. Furthermore, PLS indicated site-specific dominance of anthropogenic contaminants suggesting for their pollution sources in the corresponding catchments of these sites.

Steady-state models for the prediction of P retention coefficient (R) in lakes were evaluated using data from 93 natural lakes and 119 reservoirs situated in the temperate zone. Most of the already existing models predicted R relatively successfully in lakes while it was seriously under-estimated in reservoirs. A statistical analysis indicated the main causes of differences in R between lakes and reservoirs: (a) distinct relationships between P sedimentation coefficient, depth, and water residence time; (b) existence of significant inflow-outflow P concentration gradients in reservoirs. Two new models of different complexity were developed for estimating R in reservoirs: [graphic removed] , where τ is water residence time (year), was derived from the Vollenweider/Larsen and Mercier model by adding a calibrated parameter accounting for spatial P non-homogeneity in the water body, and is applicable for reservoirs but not lakes, and [graphic removed] , where [Pin] is volume-weighted P concentration in all inputs to the water body (μg l-¹), was obtained by re-calibrating the OECD general equation, and is generally applicable for both lakes and reservoirs. These optimised models yield unbiased estimates over a large range of reservoir types.

In multiphase systems capillary pressures play a significant role on fluid movement and retention. The facility to predict the effect of different thermal remediation strategies requires the knowledge of the effect of temperature on capillary pressure-saturation relationships in the soils. The objective of recent study was (a) to develop a technique for routinely measuring the pressure-saturation curves of soil samples saturated with a nonpolar liquid at different regulated temperatures (b) to build a database using the measured pressure-saturation curves and the physical, chemical properties of the model soils (c) to establish the dependence of nonaqueous phase liquid retention on the soil properties and the temperature. The retention curves (extraction isotherms) with nonaqueous phase liquid were determined using a modified pressure plate extractor. The wetting phase was a non-aromatic hydrocarbon distillation product. Pressure plates were designed and constructed in the laboratory of our department. The temperature was held constant at 20, 40 and 60 [composite function (small circle)]C. Statistical analysis was performed involving selected soil parameters and the measured nonaqueous phase liquid retention data. The results show that knowing some easily measurable soil parameters (bulk density, particle size distribution, humus and lime content) we can estimate the nonaqueous phase liquid retention of the soils. The measured “extraction isotherms” provide essential information about the temperature-dependency of pressure-saturation curves.