The use of vermicompost was expanded as natural adsorbent for cationic dyes retention. The adsorption profiles in batch and flow modes for crystal violet and methylene blue on vermicompost material were evaluated. In batch mode, a retention index higher than 97% was obtained for both compounds, while in flow condition, 40 g of dried adsorbent material were enough to remove 100 mg of crystal violet or methylene blue at column flow rates of 5 and 20 mL min⁻¹. Adsorption isotherms showed adsorptive maximum capacities for vermicompost of 0.78 and 5.47 mg g⁻¹, respectively, which were compatible with the literature. Due to this good efficiency capacity, incineration steps can be considered as acceptable disposal procedures for enriched vermicompost. From these characteristics, economical and environmental advantages of the proposed material for the evaluated cationic dyes retention were evidenced.

Episodic acidification of surface waters has been observed in the Great Smoky Mountains National Park, similar to other forested watersheds with base-poor bedrock in the eastern US receiving acids from atmospheric deposition. Three remote, forested, high-elevation streams were selected in the Little Pigeon River watershed for study; two of which brook trout have extirpated, and believed to have resulted from severe acidity during stormflows. This research characterized stream chemistry during episodes in order to better understand potential factors that contribute to rapid drops in pH and acid neutralizing capacity (ANC) during stormflows. Autosamplers initialized by sondes, collected samples during storm events for analysis of pH, ANC, cations, and anions over a 15-month period. ANC and pH depressions, and increased concentrations in sulfate, nitrate, and organic acids were observed for all storms at each study site. ANC contribution analysis indicated sulfate was the strongest contributor to ANC depressions, but nitrate, cation dilution, and organic acids were also significant in some cases. Acidic deposition appears to be the primary source of episodic acidification, supported also by the finding that larger stormflows preceded by long, dry periods resulted in significantly larger pH depressions. It appears stream acidification episodes may be driven by acid deposition. However, this study documents the variability of several ion contributors to observed stormflow ANC depressions illustrating the spatial and temporal complexity of watershed processes that influence this phenomenon.

The relation among the mean slope angle of a watershed, the stream water quality, and the chemical composition of the plagioclase component of granite was examined for 17 watersheds located in the southern part of the Northern Japan Alps in central Japan. The 17 watersheds were mainly composed of the granite. The ionic composition of the stream water can be classified into two patterns: the Ca-HCO₃-type and the Ca·Na-HCO₃-type. In all the watersheds, Na⁺ and Ca²⁺ occur in the groundwater that flows into the stream mainly due to the kaolinization of plagioclase. As compared to the watersheds with Ca-HCO₃-type stream water, the Na⁺/Ca²⁺ ratio for stream water in watersheds with Ca·Na-HCO₃-type stream water was closer to that for plagioclase in granite. This implies that the groundwater flowing in the Ca·Na-HCO₃-type watersheds is deeper than that in the Ca-HCO₃-type watersheds. The mean slope angle of Ca·Na-HCO₃-type watersheds was less acute as compared to that of Ca-HCO₃-type watersheds. The mean slope angle of the watersheds is negatively correlated with the Na⁺/Ca²⁺ ratio for stream water (r = -0.78, P <= 0.001). It is suggested that the groundwater quality at greater depths, which is comparable with the Na/Ca ratio of plagioclase, contributes more to the stream water quality in the gently sloping watersheds than in the steep watersheds. This study clarified that there is a close relation between the mean slope angle of watersheds and the depth of groundwater discharged to the stream. Moreover, it is believed that the relationship between the mean slope angle of watersheds and the Na⁺/Ca²⁺ ratio for stream water is an effective and simple index for understanding the relative depth of groundwater.

Surface runoff transporting sediment with high phosphorus (P) concentrations has been identified as a major hydrological pathway for sediment-associated P delivery to surface waters and is considered a major threat to water quality, due to the ability of P to cause eutrophication in fresh water. Not all P-rich sediment that is mobilised by erosion will however be delivered directly to the channel. Some may instead be deposited in intermediate storage away from its source area. The aim of this contribution was to determine the influence of land use and soil type on the P content of surface runoff sediment and sediment deposited in intermediate storage and was undertaken in the largely agricultural and rural catchments of the Rivers Frome and Piddle in Dorset, UK. The study formed part of a larger investigation of hydrological and hydrogeochemical processes and fluxes in lowland permeable catchments in the UK (LOCAR). Soil samples were collected from the main land use types; freshly deposited sediment was sampled from ditches, hedge boundaries and depressions in fields, and sediment-laden runoff was collected during heavy rainfall events. The concentrations of total phosphorus (TP) and the P fractions found in the surface runoff sediment were significantly different from those measured in the original source soils, with a greater degree of enrichment associated with surface runoff sediment from cultivated land than from pasture land. For cultivated land, concentrations of TP and the P fractions in deposited sediment were higher than those in the original source material, while for pasture soils, concentrations of TP and the P fractions tended to be lower than in the original source soils. The relative importance of the P fractions associated with surface runoff sediment and sediment deposits also differed from that for the original soil samples. Surface runoff sediment was finer than source pasture and cultivated soils, reflecting the particle size selectivity of sediment mobilisation and transport. Soil physical properties and land use can both influence the P content of surface runoff and deposited sediment.

A box-core 3576 (PO287-26-1B) collected from the Tagus Prodelta in 2002 was analysed for organic carbon, ²¹⁰Pb, ²²⁶Ra, major (Al, Fe, Ca, Ti, Mg and Mn) and trace elements (Ba, Hg, Cr, Cu, Li, Ni, Pb, Sb, Sn, Sr, and Zn). Maximum concentrations of contaminants in ²¹⁰Pb-dated samples were reached in the decades between 1960 and 1980, followed by a slightly decrease in up-core metal trends. Trace metal concentrations increased in the bottom of the core (²¹⁰Pb dated as 1925) to maximum values during the 1970s. Factor analysis of geochemical data was used to reduce the 18 variables into four factors that reveal distinct origins or accumulation mechanisms controlling the chemical composition in the study area. Changes in the dominance of these factors through the time indicate not only changes in industrial activity, but also the increase of biological productivity towards the present.

Variation of mercury (Hg) in sediments and biota from Coatzacoalcos estuary during the dry, rainy and windy seasons was estimated. In sediments, Hg concentrations ranged from 0.07 μg g⁻¹ in site 13 (Ixhuatepec) located upstream, to 1.06 μg g⁻¹ in site 3 (Coatzacoalcos river), located in the industrialized area. Highest enrichment factor (EF) and index of geoaccumulation (I geo) in surficial sediments were 53 and 5.1 respectively. From EF and I geo, it is considered that Coatzacoalcos estuary is from moderately contaminated to contaminated. In most fish species from Coatzacoalcos estuary, the sequence of Hg concentration was liver>muscle>gills. Average Hg concentrations in soft tissue of bivalves ranged from 0.09 μg g⁻¹ in Corbicula fluminea to 0.18 μg g⁻¹ in Polymesoda caroliniana. Biota-sediment accumulation factor (BSAF) ranged from 0.9 in P. caroliniana during the rainy season (site 4) to 3.8 in P. caroliniana from the same site during the windy season.

The emission of platinum group elements (PGEs) from automobile catalytic converters has led to rapid increases in Pt, Pd, and Rh concentrations in roadside media. This article represents the first systematic study in Greece to assess PGE levels in road dust and roadside soil and their temporal variation on a seasonal basis over a 12-month period. Road dust and roadside soil samples were analyzed by graphite furnace atomic absorption spectrometry following microwave digestion. Concentrations of PGE in all samples were above the average upper crust values and local background levels, with maximum values of 306.4 ng/g Pt, 18.2 ng/g Pd, and 64.6 ng/g Rh in road dust and 225 ng/g Pt, 14.0 ng/g Pd, and 49.5 ng/g Rh in roadside soil. PGE ratios were not consistent with known catalytic converter composition throughout the sampling period reflecting the high emission of Rh from new catalytic converters. Spatial variations were influenced by various factors like driving style, matrix composition, diurnal change in traffic volume, and climatic conditions. With regard to seasonal variations, systematic changes in the temporal distribution of PGE levels were observed and followed a similar pattern between the two matrices. Except PGEs, Pb levels were determined, since it has been a typical indicator of vehicle-derived environmental lead pollution. The data indicate that despite the use of unleaded gasoline, traffic-related sources of Pb that induce levels above the local background have not been eliminated.

Historic lead mining, milling and smelting on the floodplain soils of the upper reaches of the Vils River, Eastern Bavaria, Germany has led to heavy metal contamination within the younger floodplain sediments downstream. This study aims to date the lead pollution and possible primary sources, display and quantify its spatial distribution within the Vils River floodplain in accordance to soil horizons and characterise the binding forms of lead. One hundred fifty profiles were sampled to detect total contents of heavy metals. Sequential extractions were carried out to determine the binding forms; thus, the potential of lead mobility was characterised. The contamination of the floodplain soils act as an alluvial archive, providing a stratigraphical indicator of mining activities and related sedimentation. The age of the sediments displaying the initial lead peak in the alluvial loams corresponds with sediment accumulations at the onset of the mining period and its first phase of prosperity in the sixteenth century. Enrichments of lead in the oxidic gleysols revealed that dissolved fractions of lead precipitate in the groundwater table fluctuation zone. The sequential extraction proved that lead mobility increases in the psammic and hypersceletic fluvial horizons below the flood loams due to the modest salt contents of the extractants and low pH given in these layers. Thus, the risk of the particulate transport of lead has to be extended to include the danger of potential lead solubility in ground and surface waters. Further, the polluted alluvial sediments also act as a source of contamination, leading to the grave danger of the further pollution of so far uncontaminated areas downstream, especially if the reworking and dredging of the material is allowed to occur.

The goal of this work was to study quantitatively lead bioaccumulation from a lead-doped nutrient medium by using a living aquatic macrophytes Pistia stratiotes. Several sets of aquatic plants with approximately 30 g weight were grown in greenhouse conditions and in hydroponic solutions supplied with a non-toxic Pb²⁺ concentration. The synchrotron radiation total X-ray fluorescence spectrometry was used to determine the metal concentrations in dry plants and hydroponic media as a function of time. Four different non-structural bioaccumulation models were applied to describe the process dynamics and to estimate the accumulated lead maximum capacity and rate constants. According to the experimental data, both biosorption and bioaccumulation mechanisms can be considered. Due to the low desorption rate constant, the experimental data were well described by the irreversible kinetic model. The results concerning modeling of living macrophytes' metal bioaccumulation kinetics can be used to predict the heavy metal removal dynamics from wastewaters in artificial wetlands.

In this paper a novel methodology for estimating the parameters for an extended biokinetic model (Peev, Schönerklee, and De Wever, Water Science and Technology, 2004) of micropollutant removal in wastewater treatment is presented. In particular, the work concentrates on parameter estimation of the micropollutant degradation sub-model by specialised microorganisms in the case when only substrate measurement data are available. We have proven the structural identifiability of the model and have developed a new approach allowing practical identifiability on the basis of multiple substrate degradation curves with different initial concentrations. Experimental and related numerical methods for unambiguous parameter estimation have been developed. Finally, by means of simulated pseudo-experiments we have found convincing indications that the proposed algorithm is stable and yields appropriate parameter estimates even in unfavourable regimes.