The remediation of metal-impacted soils requires either the enhanced mobility (and capture) of the target analytes or their effective complexation/immobilisation. In this study, a range of ameliorants (activated carbon, bonemeal, bentonite and CaSx (calcium polysulphide)) were compared to assess their effectiveness in immobilising metals in soils. In addition to chemical analysis (pH and trace element analysis), microbial biosensors were used to assess changes in the water-soluble biotoxicity of metals as a consequence of ameliorant dosing. Management of soil ameliorants requires an enhancement of K d (solid/solution partition coefficient) if soil leachate is to meet predefined environmental quality standards. Of the ameliorants tested, CaSx was the most effective per unit added for both laboratory-amended and historically contaminated soils, regardless of the metal tested. At the ameliorant concentrations used to effectively immobilise the metals, the biosensor performance was not impaired. Microbial biosensors offered a rapid and relevant screening tool to validate the reduced toxicity associated with the ameliorant dosing and could be calibrated to complement chemical analysis. While laboratory-amended soils were a logical way to evaluate the performance of the ameliorants, they were generally associated with K d values an order of magnitude lower than those of historically contaminated soils.

The influence of long-term exposure to background pollution on the response and recovery of the invasive species Corbicula fluminea to ammonia stress was investigated using a multi-marker approach. Wild clams of the tidal freshwater areas of two estuaries of the NW Iberian coast with different levels of pollution, the estuaries of Minho river (reference) and of Lima river (contaminated), were collected and exposed individually to different treatments: 8 and 14 days in dechlorinated tap water (DTW), 8 and 14 days in 1 mg L⁻¹of ammonia (AM), and 8 days in AM followed by 6 days in DTW. After each defined time (0, 8, and 14 days), the clams were sacrificed and the activity of the enzymes glutathione S-transferase (GST), catalase (CAT), glutathione reductase (GR), glutathione peroxidase (GPx), cholinesterase (ChE), octopine dehydrogenase (ODH), and the lipid peroxidation (LPO) levels were used as effect criteria. At the beginning of the bioassay, the clams from the polluted estuary presented significantly higher background levels of GST, CAT, GR, GPx, and LPO than those from the reference one indicating long-term exposure to oxidative stressors. In general, C. fluminea from both estuaries presented little sensibility to ammonia with no significant differences found between exposed and control clams for most of the biomarkers. That low sensibility of C. fluminea could be seen as advantageous for its invasion ability.

Chelating reagents impregnated or incorporated into solid sorbents have been widely used in the preconcentration of metal species. In this work, polystyrene-divinylbenzene functionalized with 2-hydroxyacetophenone was used for the preconcentration and determination of cadmium, cobalt, and nickel in sediment samples by flame atomic absorption spectrometry. The sorbent was characterized by infrared spectroscopy and scanning electron microscopy. The influence of variables on the extraction of the metal ions was studied. Under optimized conditions, the method showed enrichment factors of 20 (Cd), 37 (Co), and 32 (Ni) and detection limits of 0.1 (Cd), 0.8 (Co), and 0.6 μg L⁻¹(Ni). The accuracy of the method was tested by analysis of a certified reference material composed of inorganics in marine sediment (NIST 2702). The method was applied to the determination of cadmium, cobalt, and nickel in real sediment samples. Cadmium and cobalt were not found in the sediment samples. Nickel was found in two samples (5.2 and 8.2 μg g⁻¹).

The ability of untreated and acid-treated biomass from Pistia stratiotes (PL and APL, respectively) and Eichhornia crassipes (ELS and AELS, respectively) to remove color from anaerobically digested sugar cane stillage (ADS) was investigated. The effects of pH (3–8), particle size (< 0.75, 0.75–1, 1–4 mm), and biomass concentration (5–15 g/L) on decolorization of ADS were assessed using untreated biomass. After acid modification of biomass (acid-treated), the effects of pH (3–8), biomass concentration (6–10 g/L), time (20–480 min), and ADS dilution (non-diluted, 1:2, 1:10, 1:20) on color removal from ADS were evaluated. Scanning electron microscopy and Fourier transform infrared spectroscopy (FTIR) analyses were also performed. A clear effect of particle size on ADS decolorization was found (21.04 ± 0.75 and 27.87 ± 0.30 % for 0.75–1 and <0.75 mm, respectively, for ELS; 31.65 ± 0.23 and 37.82 ± 0.53 for 1–4 and 0.75–1 mm, respectively, for PL). Decolorization also increased when the untreated biomass concentration was higher (15.41 ± 0.3 and 27.89 ± 0.2 % for 5 and 10 g/L, respectively, for ELS; 15.61 ± 0.11 and 33.06 ± 1.09 % for 5 and 10 g/L, respectively, for PL). The use of acid-treated biomass enhanced the effect of pH on color removal (48.30 ± 1.27 and 12.96 ± 0.27 % for pH of 3 and 7, respectively, for AELS; 47.11 ± 1.72 and 6.62 ± 0.21 % for pH of 3 and 7, respectively, for APL). The highest rate of color removal obtained using acid-treated biomass was 55.58 ± 1.82 and 56 ± 0.77 % for AELS and APL, respectively. The FTIR spectra analysis suggested the electrostatic attraction between protonated carboxylic groups on biomass and anionic colored compounds as being one of the adsorption mechanisms for ADS decolorization. The use of dry biomass from invasive macrophytes is an effective alternative for color removal from ADS.

In the European registration procedure for pesticides, microcosm and mesocosm studies are the highest aquatic experimental tier to assess their environmental effects. Evaluations of microcosm/mesocosm studies rely heavily on no observed effect concentrations (NOECs) calculated for different population-level endpoints. Ideally, a power analysis should be reported for the concentration–response relationships underlying these NOECs, as well as for measurement endpoints for which significant effects cannot be demonstrated. An indication of this statistical power can be provided a posteriori by calculated minimum detectable differences (MDDs). The MDD defines the difference between the means of a treatment and the control that must exist to detect a statistically significant effect. The aim of this paper is to expand on the Aquatic Guidance Document recently published by the European Food Safety Authority (EFSA) and to propose a procedure to report and evaluate NOECs and related MDDs in a harmonised way. In addition, decision schemes are provided on how MDDs can be used to assess the reliability of microcosm/mesocosm studies and for the derivation of effect classes used to derive regulatory acceptable concentrations. Furthermore, examples are presented to show how MDDs can be reduced by optimising experimental design and sampling techniques.

Dairy soiled water (DSW) is water from concreted areas, hard stand areas and holding areas for livestock that has become contaminated by livestock faeces or urine, chemical fertilisers and parlour washings. Losses of DSW occur as point (e.g. storage, pivot irrigators) and diffuse losses (e.g. during or shortly after land application). The concept of a permeable reactive interceptor (PRI), comprising a denitrifying bioreactor woodchip cell to convert nitrate (NO₃⁻) to dinitrogen (N₂) gas and an adsorptive media cell for phosphorus (P) and ammonium (NH₄⁺) mitigation, attempts to simultaneously treat mixed pollutants. This study is the first attempt to test this concept at laboratory-scale. Washing of woodchip media prior to PRI operation produced low NO₃⁻but high NH₄⁺, dissolved reactive P (DRP) and dissolved organic carbon losses. Dairy soiled water was then treated in replicated PRIs containing woodchip in combination with zeolite or gravel compartments. In general, all PRIs were highly efficient at reducing NO₃⁻, NH₄⁺, DRP, dissolved unreactive phosphorus (DUP) and dissolved organic nitrogen (DON) from an influent water replicating DSW. Longitudinal and hydrochemical PRI profiles, as well as zeolite batch experiments, showed that woodchip can both enhance NO₃⁻reduction and adsorb nutrients. Since woodchip is likely to become saturated, it is important to place the reactive media cell further into the sequence of treatment. Even though the majority of the dissolved nutrients were mitigated, the PRIs also emitted greenhouse gases, which would need further remediation sequences.

This paper examined the gut digestive enzymes, trypsin and leucine aminopeptidase (LAP), in gypsy moth (Lymantria dispar, L.) larvae exposed to cadmium. We analyzed the 3-day acute effect, chronic effects from hatching until sacrifice, and recovery from long-term dietary treatment with cadmium concentrations of 10 and 30 μg Cd/g dry food. The activities of both examined enzymes declined at the higher level of cadmium after both acute and chronic treatments and did not recover within 3 days of feeding a diet with no added cadmium. Leucine aminopeptidase was more sensitive because its activity was inhibited after both short-term treatments. Three trypsin and one leucine aminopeptidase isoform were detected by electrophoresis. Egg hatches (full-sib families) differed in enzyme activities, index of phenotypic plasticity, and isozyme expression after different treatments. Statistically significant positive correlations between these enzymes pointed to common genetic regulation. Moreover, variances were higher for the control group than for cadmium treatment groups implying that these proteolytic enzymes did not participate directly in detoxification. These results suggest that, with additional research to discover the mechanisms of enzyme inhibition, trypsin and leucine aminopeptidase might be used as biomarkers to indicate the severity of gastrointestinal disease due to cadmium intake.

The processing, storage, and flux of inorganic carbon in rivers and streams play an influential role in the lateral transfer of atmospheric and terrestrial carbon to the marine environment. Quantifying and understanding this transfer requires a rapid and accurate means of measuring representative concentrations of dissolved inorganic carbon (DIC) and CO₂in field settings. This paper describes a field method for the determination of DIC based on the direct measurement of dissolved CO₂using a commercial carbonation meter. A 100-mL water sample is combined with 10 mL of a high ionic strength, low-pH, citrate buffer, mixed well, and the dissolved CO₂concentration is measured directly. The DIC is then calculated based on the dissolved CO₂concentration, buffer-controlled ionic strength, pH, and temperature of the mixture. The method was accurate, precise, and comparable to standard laboratory analytical methods when tested using prepared sodium bicarbonate solutions up to 40 mM DIC, North Atlantic seawater, commercial bottled waters, and carbonate spring waters. Coal mine drainage waters were also tested and often contained higher DIC concentrations in the field than in subsequent laboratory measurements; the greatest discrepancy was for the high-CO₂samples, suggesting that degassing occurred after sample collection. For chemically unstable waters and low-pH waters, such as those from high-CO₂mine waters, the proposed field DIC method may enable the collection of DIC data that are more representative of natural settings.

Extractions with mixtures of oxalic acid, ammonium oxalate, and ascorbic acid have been used to analyze trace metals that are occluded in Fe and Mn oxides in soil samples. In our experiments, the amount of Fe extracted from two Andisols decreased with increased extraction time using a mixture of 0.1 mol L⁻¹oxalic acid, 0.175 mol L⁻¹ammonium oxalate, and 0.19 mol L⁻¹ascorbic acid (OxAsc). Differential X-ray diffraction analysis showed the presence of Fe(II)C₂O₄ · 2H₂O in the residue after the extraction, and the amount of this precipitate increased with extraction time. These results indicate that the decrease in Fe extraction with time was caused by precipitation of Fe(II)C₂O₄ · 2H₂O. The amounts of some trace metals (Cd, Co, Mn, Ni, and Zn) extracted with OxAsc showed trends similar to that of Fe, whereas As, Cu, and Pb did not show this trend. A coprecipitation experiment showed that the concentrations of Cd, Co, Mn, Ni, and Zn markedly decreased after the precipitation of Fe(II)C₂O₄ · 2H₂O, whereas those of As, Cu, and Pb did not noticeably change. These results indicate that some trace metals coprecipitated with Fe(II)C₂O₄ · 2H₂O during extraction with OxAsc. This coprecipitation results in underestimation of oxide-occluded trace metals in soils; therefore, using mixtures of oxalic acid, ammonium oxalate, and ascorbic acid to extract some trace metals occluded in Fe and Mn oxides may yield erroneous data.

The feasibility of cyanobacteria removal from freshwater by a dielectric barrier discharge (DBD) process is investigated. Seven commercial and environmental cyanobacteria strains, as well as real algae-laden water, were tested. The removal of the cyanobacteria was evaluated by analyzing the changes in chlorophyll a content, total organic carbon (TOC) concentration, and cell morphology. Nearly total removal of chlorophyll a was achieved within 20 min, while the TOC analysis exhibited an increase-decrease-increase trend in 60 min of treatment, likely due to the oxidation of intracellular and intercellular materials. Observation under light microscopy revealed the disruption of intracellular and intercellular structures within 5 min of DBD treatment and thus supported the TOC analysis. Increasing the salinity of the medium from 0 to 5 parts per thousand (ppt) improved treatment efficiency, where similar level of chlorophyll a removal (around 93 %) was achieved in only half the treatment time. Application of DBD on real algae-laden water from a fish farm yielded higher treatment efficiency than in synthetic medium, indicating the promising application of DBD as a means to control cyanobacteria bloom in fresh and estuary water bodies.