Licia Guzzella

Advanced oxidation and adsorption technologies for organic micropollutant removal from lake water used as drinking-water supply.

The goal of this research is to evaluate the effectiveness of innovative drinking-water treatments designed to remove toxic and mutagenic organic micropollutants from lake waters used for human consumption. The widely used adsorption on granular activated carbon (GAC) filter technique was compared with the more innovative resin column techniques (XAD4 and Ambersorb-563) and with the advanced oxidation processes (AOPs) with UV/O3 and UV/O3/ H2O2. The water samples, collected from lake Como, treated with these techniques were analysed for mutagenic activity using Ames assay, toxicity using bioluminescent bacteria and organic compound were characterized using the GC-MS technique. The results found a decrease of the mutagenic and toxic activities of the lake water after adsorption on GAC and resins, while the AOP process generally increased these parameters. The absence of mutagenic activity was found only when a GAC adsorption step was performed in addition to the AOP process. Similar results were obtained by the toxicological and chemical analyses. In addition, the GC-MS analysis identified some possible mutagenic agents.

Comparative assessment of genotoxicity of mineral water packed in polyethylene terephthalate (PET) and glass bottles.

The potential migration of genotoxic compounds into mineral water stored in polyethylene terephthalate (PET) bottles was evaluated by an integrated chemical/biological approach using short-term toxicity/genotoxicity tests and chemical analysis. Six commercial brands of still and carbonated mineral water bottled in PET and in glass were stored at 40 degrees C for 10 days in a stove according to the standard EEC total migration test (82/711/EEC), or at room temperature in the dark. After treatment, the samples were analysed using gas-chromatography/mass spectrometry (GC/MS) to detect volatile and non-volatile compounds, the Microtox test to evaluate potential toxicity of the samples, and three mutagenicity tests -Tradescantia and Allium cepa micronucleus tests and the Comet assay on human leukocytes - to detect their genotoxic activity. GC/MS analysis did not detect phthalates or acetaldehyde in the water samples. The Microtox test found no toxic effects. Mutagenicity tests detected genotoxic properties of some samples in both PET and glass bottles. Statistical analyses showed a positive association between mineral content and mutagenicity (micronuclei in A. cepa and DNA damage in human leukocytes). No clear effect of treatment and PET bottle was found. These results suggest the absence of toxic compounds migrating from PET regardless of time and conditions of storage. In conclusion, bottle material and stove treatment were not associated with the genotoxic properties of the water; the genotoxic effects detected in bottled water may be related to the characteristics of the water (minerals and CO(2) content).

Decabromodiphenyl ether (BDE-209) enters the food web of the River Po and is metabolically debrominated in resident cyprinid fishes.

Decabromodiphenyl ether (BDE-209), the primary constituent of a widely used flame retardant formulation, is present at relatively high levels in sediments and macroinvertebrates of the River Po. Since it was demonstrated that BDE-209 can be biotransformed to smaller and more toxic polybrominated dipheyl ethers (PBDEs), the main objective of this study was to assess whether the large quantities of BDE-209 present in the River Po are bioavailable to the higher levels of the food web and are biotransformed in feral fishes. To this aim, 23 cyprinids, mainly common carp, were analysed for the hepatic contents of PBDEs. Contrary to sediments and invertebrates of the same area, no fish sample contained detectable levels of BDE-209. All fishes contained typical PBDE representatives, e.g. BDE-47, BDE-99, BDE-100, BDE-153 and BDE-154, but more importantly they contained three congeners, i.e. BDE-179, BDE-188 and BDE-202, which are not present in any technical formulations and are known products of BDE-209 debromination in fish. The age of carps had no effects on the bioaccumulation of PBDEs. Conversely, the contents of PCBs, which also were determined in the same fish samples, showed a positive correlation with age. Both groups of chemicals displayed a tendency to a higher contamination in male fish. This study shows that BDE-209 enters the food web of the River Po contributing to the load of lower brominated PBDEs and thus to the load of chemical stressors threatening the aquatic life of the major Italian watercourse.

Variability of microcystin cell quota in metapopulations of Planktothrix rubescens: Causes and implications for water management

In this study, we investigated the relationships between microcystin (MCs) concentrations and the biovolumes of Planktothrix rubescens (BPr) in 2 natural lakes (Pusiano and Garda) and 2 artificially dammed reservoirs (Occhito and Ledro) in Italy. In all the considered water bodies, P. rubescens was the dominant cyanobacterium. All the lakes were characterized by significant relationships between MCs and BPr, with limited variability in the MC quota (the content of MCs per unit of biovolume) within each water body compared with the variability between sites. The results were consistent with the development of specific MC-genotypes, with moderate seasonal and spatial changes in the proportion between toxic and non-toxic strains. The MC cell quota obtained in our work (ECQ, Environmental Cell Quota) were in the same range of values computed on the basis of analyses made on environmental samples dominated by P. rubescens or Planktothrix agardhii, and on isolates of the same two species (<1 to over 10 μg mm(-3)). Besides the usual ordinary least square regressions, models have been evaluated by using quantile regression, a method that allows estimating the conditional median or other quantiles of the response variable. We showed that the use of quantile regressions has different advantages, which included the computation of MC quota based on the whole range of available data, the robustness against outliers, and the ability to estimate models also in cases where there is no or only weak relationships. The highest ECQ values estimated from 95% quantile regressions in specific water bodies might be used to estimate the worst-case MC concentrations from algal abundances. Nevertheless, it was stressed that a realistic assessment of toxicity and potential adverse health effects necessarily should take into account the toxicity potential of the more abundant MC-congeners produced by specific cyanobacteria populations.

POP and PAH contamination in the southern slopes of Mt. Everest (Himalaya, Nepal): long-range atmospheric transport, glacier shrinkage, or local impact of tourism?

Due to their physico-chemical properties, POPs and PAHs are subjected to long-range atmospheric transport (LRAT) and may be deposited in remote areas. In this study, the contamination with DDx, PCBs, PBDEs, and PAHs was investigated in sediments and soils collected on the southern slopes of Mt. Everest (Himalaya, Nepal) in two different sampling campaigns (2008 and 2012). The results showed a limited contamination with POPs and PAHs in both soil and sediment samples. Therefore, the southern slopes of Mt. Everest can be considered a remote area in almost pristine condition. The LRAT mechanism confirmed its primary role in the transfer of contaminants to remote regions, while the gradual melting of glaciers, due to global warming, and the subsequent release of contaminants was suggested to be a secondary source of pollution of the lake sediments. In addition, the increase of tourism in this area during the last decades might have influenced the present concentrations of PAHs in the sediments and soils.

Evaluation of genotoxicity of Italian lakewater for human consumption: A case study in Lombardy

A study was carried out on lake Como water, collected before and after potabilization treatment. The water samples were concentrated and the extracts were analyzed by gas‐chromatographic techniques and tested for potential mutagenic and toxic effects. Two different solid phase extraction methods (tC18 and Lichrolut EN) were compared for the evaluation of the more efficient recovery system of toxic compounds. The results showed the presence of toxic compounds and a mutagenic activity of the water samples lower than the one found in previous studies. The source of mutagenic compounds could be contamination of Cosia river influent.

Chemical and toxicological characterization of river water extracts with the Vibrio fzscheri photobacterium

Abstract The possible application of a bacterial assay (LUMIStox test) for the determination of the toxicity of river water extracts was evaluated. Ten river Po water samples were taken at the closing section of the basin (Pontelagoscuro, Ferrara), filtered with a Domnick Hunter system and passed through a column filled with XAD-2 resin, for the extraction of the organic micropollutants. The toxicity of the extracts was then evaluated by means of the bacterial assay LUMIStox, which uses Vibrio fischeri NRRL-B-11177 as the test organism. GC-NPD and GC-ECD were used for the chemical chracterization of the water extracts.

Endogenous origin of foams in lakes: a long-term analysis for Lake Maggiore (northern Italy)

The formation of foams on lakes is a complex phenomenon whose origin is often hardly identifiable. Recently (2007, 2008, and 2010) foam episodes started to occur in Lake Maggiore, northern Italy. The present work aimed to verify the hypothesis of an endogenous-natural origin of these foams, driven by trophic or climatic changes. To this purpose, a long-term (2000–2013) analysis of phytoplankton biovolumes, meteorological, and hydrological data has been performed together with the chemical characterization of foams. Foams resulted of endogenous origin and likely related to phytoplankton biomass degradation. Data analysis highlighted atypical warm temperature and residual lake stratification in winter in two of the three years of foam events, coupled with exceptional Bacyllariophyceae blooms in spring. Tabellaria flocculosa mostly contributed in terms of biomass in 2007 and 2008, but not in 2010; thus overall algal biomass seemed a better predictor of the risk of foam formation. Foam events occurred from July to December, driven by atypically windy conditions, and congruently with the time needed to degrade biomass into surface-active compounds. A co-occurrence of different factors resulted essential to generate foams, and climate changes likely contribute to enhance their occurrence in Lake Maggiore.

Performance of passive sampling with low-density polyethylene membranes for the estimation of freely dissolved DDx concentrations in lake environments

Laboratory and field studies were used to evaluate the performance of low-density polyethylene (PE) passive samplers for assessing the freely dissolved concentrations of DDT and its degradates (DDD and DDE, together referred to as DDx) in an Italian lake environment. We tested commercially available 25 μm thick PE sheets as well as specially synthesized, 10 μm thick PE films which equilibrated with their surroundings more quickly. We measured PE-water partitioning coefficients (Kpew) of the 10 μm thick PE films, finding good correspondence with previously reported values for thicker PE. Use of the 10 μm PE for ex situ sampling of a lake sediment containing DDx in laboratory tumbling experiments showed repeatability of ±15% (= standard deviation/mean). Next, we deployed replicate 10 μm and 25 μm PE samplers (N = 4 for 10 d and for 30 d) in the water and sediment of a lake located in northern Italy; the results showed dissolved DDx concentrations in the picogram/L range in porewater and the bottom water. Values deduced from 10 μm thick PE films compared well (95% of all comparison pairs matched within a factor of 5) with those obtained using PE films of 25 μm thickness when dissolved DDx concentrations were estimated using performance reference compound (PRC) corrections, whether left at the bed-water interface for 10 or 30 days. These results demonstrated the potential of this sampling method to provide estimation of the truly dissolved DDx concentrations, and thereby the mobile and bio-available fractions in both surface waters and sediment beds.

Persistent organic pollutants in sediments of high-altitude Alpine ponds within Stelvio National Park, Italian Alps

Abstract The concentrations of persistent organic pollutants (POPs), such as dichlorodiphenyltrichloroethane (DDT), polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs) and polycyclic aromatic hydrocarbons (PAHs), were investigated in sediments collected in 25 high-altitude Alpine ponds within Stelvio National Park, Italy. The total PAH concentrations in the lake sediments ranged from 27.8 to 5644 ng/g dry weight (dw), with the ratio between low and high molecular weight PAHs (LMW-PAHs/HMW-PAHs) indicating inputs from both pyrogenic and petrogenic sources (mostly fossil fuel combustion). Limited concentrations of PBDEs (less than the limit of detection [LOD] to 9.9 ng/g dw), PCBs (<LOD–40.9 ng/g dw), and DDx (sum of DDE+DDD+ DDT; <LOD–4.75 ng/g dw) were measured in the sediments, and the ratio (∑ o,p’+ p,p’− DDE +∑o,p’+ p,p’− DDD)/∑ o,p’+ p,p’− DDT indicated an overall-aged contamination of the analyzed samples. Potential sources of POP and PAH contamination in the sediments were further investigated by different statistical analysis, confirming the primary role played by the medium-range atmospheric transport (MRAT) mechanism in the transfer of POPs to remote Alpine regions. Our results showed that the analyzed sediment samples can be considered slightly contaminated by the target compounds, with concentrations comparable to those detected in other remote areas.