Phosphorous dynamics within Lake Sirio (NW Italy) were investigated, considering both water and sediments. The total phosphorus (TP) concentration in the water is about 79 μg l-¹ after the winter mixing, that is in homogeneous conditions; then TP content increases up to an average of 360 μg l-¹ in late autumn in the deep hypolimnium (30-45 m). This deep lake portion accounts for only 1/12 of the water volume. Close to the water-sediment interface, TP concentrations up to 530 μg l-¹ are observed. Sediment sampled at depths of 20 and 33 m contains less than 2,000 mg kg-¹ of TP, whereas cores from the deepest sediments (46 m) display TP values of 2,000-4,000 mg kg-¹ at the water-sediment interface, increasing with depth to 16,000 mg kg-¹ at about 60-100 cm. In these deep sediments the main chemical form is the Al-Fe-Mn bound P (about 90% in the high TP cores) and Fe and Mn are also highly enriched (3 and 9 times more than in the shallow sediments respectively). The P-Fe association is confirmed by SEM-EDS and XRD analyses. The vertical distribution of the P content in the water column is consistent with its release from sediments, but in this hypothesis an unrealistic P release rate from 8.1 to 3.0 g m-²y-¹ was estimated. A more complex model is therefore proposed, involving a process of P concentration in the sediments of the central (deepest) part of the lake, and a short term sediment-water exchange. The TP vertical variability and speciation in the cores suggests a change in the sediment retention capacity, connected to the lake shift to more eutrophic conditions.

To assess the effect of changes in traffic density and fuels used for heating at the beginning of the 1990s, 1992-2005 monthly averages of PM₁₀, SO₂, NO₂, NO, CO and O₃ from Prague, the Czech capital, were analyzed together with long term trends in emissions of major pollutants, fuel consumption and number of vehicles registered in Prague. The data from all monitoring stations were retrieved from the database of the state automated monitoring system. Correlation coefficients between ambient monthly averaged temperature and all pollutants of concern showed distinct seasonal trends. The results showed that while SO₂ and to some extent also CO concentrations dropped namely in the first half of the analyzed period (1992-1997) as a result decreased fossil fuel consumption for local heating, the behaviour of other pollutant concentrations followed a different pattern. PM₁₀ concentrations decreased during the beginning of the 1990s but showed a sign of increase after 2000. Concentrations of ozone and NO₂ did not reveal any significant change throughout the whole studied period. It can be concluded that during the studied period traditional urban sources of pollution, such as coal and oil combustion, lost their importance but were simultaneously substituted by pollutants from automotive transport (namely PM and NO₂) making the problem of air quality even worse.

This paper presents a study on the batch adsorption of a basic dye, methylene blue (MB), from aqueous solution onto ground hazelnut shell in order to explore its potential use as a low-cost adsorbent for wastewater dye removal. A contact time of 24 h was required to reach equilibrium. Batch adsorption studies were carried out by varying initial dye concentration, initial pH value (3-9), ionic strength (0.0-0.1 mol L⁻¹), particle size (0-200 μm) and temperature (25-55°C). The extent of the MB removal increased with increasing in the solution pH, ionic strength and temperature but decreased with increase in the particle size. The equilibrium data were analysed using the Langmuir and Freundlich isotherms. The characteristic parameters for each isotherm were determined. By considering the experimental results and adsorption models applied in this study, it can be concluded that equilibrium data were represented well by Langmuir isotherm equation. The maximum adsorption capacities for MB were 2.14 x 10⁻⁴, 2.17 x 10⁻⁴, 2.20 x 10⁻⁴ and 2.31 x 10⁻⁴ mol g⁻¹ at temperature of 25, 35, 45 and 55°C, respectively. Adsorption heat revealed that the adsorption of MB is endothermic in nature. The results indicated that the MB strongly interacts with the hazelnut shell powder.

Terrestrial Model Ecosystems (TMEs) are frequently used to assess the potentially harmful effects of contaminants on terrestrial organisms. Therefore we have used this tool to simulate the leaching phenomena from agricultural soils, within the drainage basin of Lake Vela (Figueira da Foz, Central Portugal), and to perform a subsequent evaluation of the toxicity of the leachates obtained, after the treatment of soil-cores with the herbicide Lasso® on non-target freshwater species. Hence, standard (algae: Pseudokirchneriella subcapitata; cladoceran: Daphnia magna) and autochthonous (algae: Aphanizomenon flos-aquae; cladoceran: Daphnia longispina) species were exposed to several dilutions of leachates obtained from the application of different treatments to soil-cores collected in an agricultural field in the Lake Vela surrounds: RW-soil-core irrigated with artificial rain water; RW+L-soil-core irrigated with artificial rain water after the application of Lasso®; GW+L-soil-core irrigated with groundwater collected in local wells, after the application of Lasso®. Chemical analysis confirmed the presence of alachlor (active ingredient of Lasso®) in the leachates RW+L and GW+L at concentrations of 88 and 16.9 μg L⁻¹ respectively. As expected, the results demonstrated that the leachate RW was not toxic for the tested species. However, leachates where the herbicide was applied, particularly the RW+L, was highly toxic to P. subcapitata (96 h-IC₅₀ = 9.7%), contrasting with the absence of toxic effects in A. flos-aquae. Notwithstanding the effects on algae, the reproduction and growth of both daphnids were not affected by the potential toxicity of leachates. Nevertheless, our results were consistent with the chemical analysis and alachlor ecotoxicity data reported in the literature. Our study confirmed that the current use of pesticides in the lands near Lake Vela, especially Lasso®, combined with the specific properties of local soils, can contribute to the contamination of surface and groundwater resources, through leaching, and could compromise the weak balance of the freshwater ecosystem by affecting one of the main trophic levels: the primary producers.

Adenoviruses are emerging pathogens which may represent new indicators of microbial water quality. In the present study, environmental samples of seawater, estuarine water, and influents of sewage treatment plants underwent both standard bacteriological and viral analyses (adenovirus identification, typing and quantification) in order to evaluate the role of surface water contamination as a possible vehicle for the transmission of adenovirus, and the relevance of adenoviruses as an additional tool in water quality assessment. Qualitative PCR methods were used for the detection and typing of adenoviruses. This was done through the sequencing and phylogenetic analysis of segments of the hexon- and fiber-coding regions of the viral genome. Subsequently, quantitative PCR assays based on TaqMan probe hydrolysis technology were used to assess virus concentrations in environmental samples. Results showed a widespread presence of adenovirus in the environment, even in the absence of bacterial indicators, confirming the relevance of evaluating these viruses as possible indicators of viral contamination of water.

In the daily and final landfill cover barrier system, the hydraulic properties of compacted soil liners and the strength of soil can be adversely affected by desiccation cracking, resulting in the loss of effectiveness and integrity of the containment system as a barrier. Recently, there is an interest of using fiber additive to overcome the desiccation cracking problem. In this study, the desiccation crack test was conducted to investigate the effect of fiber additive on suppressing desiccation cracks in compacted Akaboku soils. Polypropylene (C₃H₆) fiber was used as an additive material for soil sample. The percentages of fiber used were varied as 0.0%, 0.2%, 0.4%, 0.6%, 0.8%, 1.0% and 1.2% (by dry weight of samples). The soil specimens were compacted under the conditions of maximum dry density and optimum water content. The surficial cracking area was measured to determine the crack intensity factor (CIF) of the soil samples. The desiccation crack test results indicated that the percentage of volume change of the compacted soil specimen decreased with addition of fiber. The change in the soil surface area decreased with increasing in the fiber content (FC), and consequently, the volumetric shrinkage strain decreased. The CIF for the soil without fiber (FC = 0.0%) were significantly higher than the soil with fiber additive. The CIF of soil at FC = 0.0% decreased from 2.75% to 0.6% for the soil at FC = 0.2%. It was also found that the maximum crack depth reaches almost 50% of the thickness of the soil without fiber additive. This study suggests the potential application of the fiber additives to soils as an available method to suppress desiccation cracks encountered in landfill cover barriers.

During the seasons 2003/04, 2004/05 and 2005/06, a study was made of the evolution of runoff as well as soil and available P and K losses in the sediment carried away in a conventional till system--that most used at the present time--and in a no till system with added pruning remains in an olive grove of the picual variety located in Torredonjimeno (Jaén, Spain). A group of microplots for sediment collection in a randomized complete block design was established. The samples were collected in the field after each storm. In the study period, a total of 21 storms were recorded, with a precipitation of 450 mm in 2003/04, 179 mm in 2004/05 and 388 mm in 2005/06. The erosivity of the rainfall was characterized and the cover percentage in the plots throughout the time was determined. The establishment of pruning remains reduced soil loss with respect to conventional tillage (CT) in the 3 years (72%). Likewise, the available P loss greatly declined in the study (46.4%) under conservation agriculture. The reduction in available K loss (72.4%) was much greater than that of available P. The close relationship between both variables and sediment production also stands out. Runoff was the parameter on which the pruning remains had the least influence with only an 11% average reduction.

We investigated the coupling of abundance of bacteria, phytoplankton and ciliates with hydrocarbons in the surface water and sediments of five interconnected ponds in the arid Sfax solar salterns. This study aimed at determining the potential sources of hydrocarbons and the effects of salinity gradients on microorganism metabolism. Hydrocarbon analysis was performed by gas chromatography (GC-FID) and gas chromatography coupled with mass spectrometry (GC-MS). The GC-FID allowed the detection of aliphatic hydrocarbons and n-alkanes ranging from n-C₁₃ to n-C₃₀. Total aliphatic hydrocarbon concentrations varied from 92.5 mg. l-¹ in the first pond (having marine characteristics) to 661.1 mg. l-¹ in the last pond (crystallizer) (316.8 ± 120.1 mg. l-¹) for water samples and from 26.7 to 127.8 μg. g-¹ dry weight for sediment samples. The GC-MS enabled us to detect halogenated hydrocarbons (bromoalkanes and chloroalkanes) and n-alkenes. The distribution of n-alkanes indices coupled to several environmental factors suggests that a major fraction of hydrocarbons resulted from both prokaryotic (bacteria) and eukaryotic (protists) developments. A low hydrocarbon fraction might be petrogenic.

Communities of aquatic macroinvertebrates, fish density and biomass, and environmental variables were investigated in three Patagonian mountain rivers affected by urbanization. The rivers Las Minas, Esquel and Carbón that flow through the towns of Cholila, Esquel and Corcovado, respectively (northwest Chubut, Argentina) were selected to assess the degree of impairment. A reference site and an urban site were established on each river. Water quality variables including conductivity, major nutrients, total suspended solids (TSS) and dissolved oxygen, habitat conditions and quality of riparian ecosystems were investigated in autumn, winter, spring and summer 2005–2006. Macroinvertebrates were sampled concurrently in three riffles and three pools at each site. Invertebrate species richness, EPT richness, the Shannon–Weaver diversity index, % EPT density, and the BMPS index were lower at urban sites, whereas % collectors increased. The most impaired site was below Esquel, the largest town. Senzilloides panguipulli (Plecoptera), Polypedilum and Rheotanytarsus species (Diptera: Chironomidae), Nais communis (Oligochaeta) and Meridialaris chiloeensis (Ephemeroptera) dominated assemblages at reference and moderately impaired sites in summer, whereas the strongly polluted reach below Esquel had low flow in summer and a community dominated by Limnodrilus spp. (Oligochaeta), Helobdella spp. (Hirudinea), and two Hyallela species (Amphipoda). Canonical correspondence analysis indicated that ammonia, conductivity and TSS were important variables structuring invertebrate assemblages. In contrast, fish density and biomass varied in a non-systematic manner among sites. Overall, urbanization resulted in varying degrees of habitat degradation, sedimentation and nutrient enrichment that were reflected by the macroinvertebrate assemblages, which can be used effectively to monitor the effects of urban communities on Patagonian mountain streams.

The present study aims to understand the hydrochemistry vis-à-vis As-exposure from drinking groundwater in rural Bengal. The characteristic feature of the groundwaters are low Eh (range, -151 to -37 mV; mean, -68 mV) and nitrate (range, 0.01-1.7 mg/l; mean, 0.14 mg/l) followed by high alkalinity (range, 100-630 mg/l; mean, 301 mg/l), Fe (range, 0.99-38 mg/l; mean, 8.1 mg/l), phosphate (range, 0.01-15 mg/l; mean, 0.54 mg/l), hardness (range, 46-600 mg/l; mean, 245 mg/l) and sulphate (range, 0.19-88 mg/l; mean, 7.2 mg/l), indicating reducing nature of the aquifer. The land use pattern (sanitation, surface water bodies, sanitation coupled with surface water bodies and agricultural lands) demonstrates local enrichment factor for As/Fe in groundwater. Among these, sanitation is the most prevailing where groundwater is generally enriched with As (mean, 269 μg/l) and Fe (mean, 9.8 mg/l). Questionnaire survey highlights that ~70% of the villagers in the study area do not have proper sanitation. This demonstrating the local unsewered sanitation (organic waste, anthropogenic in origin) could also cause As toxicity in rural Bengal. In the agricultural lands, higher mean values of alkalinity, phosphate, sulphate, hardness and electrical conductivity was observed, and could be linked with the excessive use of fertilizers for agricultural production. Bio-markers study indicates that the accumulation of As in hair and nail is related with the construction of exposure scenario with time dimension. The strength and weakness of the on-going West Bengal and Bangladesh drinking water supply scenario and achievability towards alternative options are also evaluated.