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Studies of inorganic carbon cycle in natural waters provide important information on the biological productivity and buffer capacity. Determination of total inorganic carbon, alkalinity and dissolved carbon dioxide gives an indication of the balance between photosynthesis and respiration by biota, both within the water column and sediments, and carbon dioxide transfers from the water column to the atmosphere. There are few methods to measure and distinguish the different forms of inorganic carbon, but all require a measure or an indirect quantification of total inorganic carbon. A direct measurement of TIC in water is made possible by the introduction of electrolytic generated hydroxide eluent in ion chromatography which allows to detect a chromatographic peak for carbonate. The advantage of this method is that all the inorganic forms of carbon are converted in carbonate at eluent pH and can be detected as a single peak by conductivity detection. Repeatability of carbonate peak was evaluated at different levels from 0.02 to 6 mequiv.l(-1) both in high purity water and in real samples and ranged from 1 to 9%. The calibration curve was not linear and has to be fitted by a quadratic curve. Limit of detection was estimated to be 0.02 mequiv.l(-1). Accuracy has been estimated by comparing ion chromatography method with total inorganic carbon calculated from alkalinity and pH. The correlation between the two methods was good (R(2)=0.978, n=141). The IC method has been applied to different typologies of surface waters (alpine and subalpine lakes and rivers) characterised by different chemical characteristics (alkalinity from 0.05 to 2 mequiv.l(-1) and pH from 6.7 to 8.5) and low total organic carbon concentrations. This analytical method allowed to describe the distribution of TIC along the water column of two Italian deep lakes.

Bromate, a well known by-product of the ozonation of drinking water, has been included among the substances which have to be monitored in the drinking water according to the last EC Directive 251/98 on potable water with a regulated limit of 10 microg l(-1). The need of performing routine analysis at this limit is a driving force for the developing of new simple and sensitive methods of detection, which should be also able to overcome the effect of matrix composition. This work explored the use of mass spectrometry detection with electrospray ionisation hyphenated to a reagent free ion chromatograph with hydroxide gradient elution for the determination of bromate in drinking water. The use of a high capacity hydroxide selective column operated in gradient mode allowed to avoid the interference by carbonate peak, which moved to longer retention times. The effect of increasing chloride concentrations from 0 to 250 mg l(-1), which is the guideline limit for drinking water in Directive 251/98/EC, was to decrease absolute mass spectrometric response and chromatographic efficiency and, on the consequence, to increase the effective detection limits. The effect of the chloride concentration on the detection of bromate is discussed.

In the present work, the oligochaete Lumbriculus variegatus was exposed for 56 d to lake sediment spiked with 4-nonylphenol (4-NP), which is a breakdown product of alkylphenol polyethoxylates, an important class of nonionic surfactants. During the exposure period, the content of 4-NP was determined in the oligochaetes, sediment, overlying water, and pore water in order to monitor the distribution of the 4-NP in the compartments of the test system. Concentration of 4-NP in L. variegatus increased linearly over the course of the test, with an uptake rate coefficient of 1.9 x 10(-2) (+/- 0.2 x 10(-2); [g carbon/(g lipid x h)]). No steady state was reached at the end of the exposure period, suggesting that the elimination of 4-NP by the organism was negligible. Ingested sediments played an important role in the accumulation of 4-NP in L. variegatus, which may achieve very high 4-NP body concentrations. The 56-d biota sediment accumulation factor (BSAF) was 24 +/- 7 g carbon/g lipid. L. variegatus also was exposed to 4-NP-contaminated field sediment, and field oligochaetes and sediments were collected for 4-NP pollution assessment in aquatic ecosystem. The 4-NP uptake with natural sediment was in accordance with that measured with spiked sediments, suggesting that the bioavailability of sediment-associated 4-NP for L. variegatus was not affected by 4-NP sediment concentration and abiotic sediment characteristics. The BSAFs measured in field oligochaetes, ranging from 39 to 55 g carbon/g lipid, was relatively higher than the bioaccumulation factor measured in laboratory tests. The results suggest that 4-NP concentration can reach high levels in benthic oligochaetes; this can be an important way of exposure for their pelagic predators.

The role of colloids in regulating element transport, behavior, and bioavailability in aquatic systems is now well-established. It appears that further progress in this research field is being slowed by (i) a limited integration between the geochemical and the biological aspects of the research on colloids and (ii) a persistent gap between well-controlled laboratory studies and real field situations. This paper presents a simultaneous evaluation of the role of colloids in controlling element environmental fate and bioavailability at the confluence between a major river and a polluted tributary. Fractionation of trace elements among suspended particulate matter, colloids, and true solution suggests that colloids may play a role in the removal of trace elements from the water column to bed sediments during the mixing of the two rivers. Toxicity testing of water samples indicates that, in this specific system, contaminants associated with colloids can contribute to water toxicity for the rotifer Brachionus calyciflorus but not for the green alga Pseudokirchneriella subcapitata. To the best of our knowledge, the results for B. calyciflorus are the first ones pointing to the possible contribution of colloid-bound contaminants to water toxicity in environmental samples. Despite the uncertainties associated with field variability, the results of chemical analysis and toxicitytesting show several points of convergence. Following these observations, a few innovative research approaches are suggested to improve the understanding of trace element biogeochemistry in real field situations.

The efficiency of Microwave Assisted Solvent Extraction (MASE) for the simultaneous determination of nonylphenol (NP) and nonylphenol ethoxylates (NPE) in river sediments has been evaluated. An optimisation study was carried out in order to identify the variables having the greatest influence on the extraction efficiency. The comparison between the solvents (methanol and acetone-hexane 1:1) shows that the more polar solvent (i.e. methanol) allows a more effective extraction of NP and NPE from sediments. Analytical results show that there is not a considerable improvement by doubling extraction time, while the increase of solvent volume is significant. The comparative study with Soxhlet and pressurised liquid extraction (PLE) methods demonstrates that Microwave Assisted Solvent Extraction is a suitable alternative extraction method for the 4-NP and 4-NPE determination in river sediments, showing an accuracy and precision comparable to those obtained with PLE and better than those obtained with Soxhlet.

We monitored the mutagenicity of extracts of sediment fine particles collected, both in the cold season and in the hot season, from 10 reaches along the Po River, the main Italian watercourse. Each sample was representative of several kilometers of river stretch. At sub-toxic doses, the samples were not mutagenic to the Salmonella typhimurium his(-) strains TA98, TA100 and TA102, irrespective of the presence of S9 mix. However, they induced a mutagenic response in YG1024, which is typically reverted by frameshift mutagens that are metabolized in bacteria via acetyl-CoA:N-hydroxylamine O-acetyltransferase. Mutagenicity of sediments was higher during the cold season and had a spatial distribution consistent with the occurrence of pollution sources and confluence with polluted tributaries. Nevertheless, in the final stretch, near the Po delta into the Adriatic Sea, mutagenicity of sediments was low, comparable to that detected in the Po proximal reach, not far away from its springs. Genotoxicity biomarkers were evaluated in three cyprinid species, the "Italian nase" (Chondrostoma söetta), chub (Leuciscus cephalus), and barbel (Barbus plebejus), captured upstream and downstream of the confluence of a polluted tributary (Lambro River) with the Po River. There was no difference between the two areas concerning concentrations of fluorescent aromatic compounds in fish bile while, after metabolic activation, the bile of fish caught from the more polluted area became mutagenic to YG1024. Moreover, the levels of adducts to liver DNA were significantly higher in L. cephalus caught from the more polluted area, and the increase of micronucleated erythrocyte frequency was borderline to statistical significance, but only in C. söetta. Thus, certain biomarkers of exposure and effect in fish, as assessed under field conditions, correlate with the pollution of river sediments by mutagenic compounds.