Relationship between element concentrations and body size in the Lake Maggiore population of Unio pictorum mancus (Mollusca, Bivalvia)

The study focused on using a fresh-water mussel (Unio pictorum mancus) as a bioindicator of various pollutants, and particularly metals. The elements considered were: Al, As, Ca, Cd, Co, Cr, Cu, Fe, Mn, Mo, Ni, Pb, V and Zn. This research was carried out at a site where various other studies have been conducted on important characteristics of the same population of Unio. This site is a small bay called "Sabbie d\u27Oro" located on the south-east coast of Lake Maggiore. Our study involved quantifying the capacity of this mollusc to concentrate large amounts of metal in its body without evident consequences by using detoxification mechanisms. We analysed not only element concentrations, but also their variability (expressed as CV%) in the soft tissues and in the shell, for two main reasons: i) the sampling design should include a preliminary analysis to determine how many specimens is necessary collect to ensure a specified level of precision; ii) the sample variability value may be combined with the value of analytical precision (BCR) to obtain an estimate of the "experimental" precision. In soft tissue, Ca accumulation tended to increase with size, and Al accumulation decreased with size. In shell, Ca and Ni were stored more than in soft tissue, but not proportionally to size. V, Cr and Mo tended to accumulate in the shell progressively over the years, whereas Co and Al are "diluted" during growth, or are absorbed mainly during the juvenile stage. Partition between shell and soft tissue resulted roughly the same in the juvenile and adult stages for the following elements: Fe, Al, Co, As, Pb. The relationships among the various elements were schematized in a hierarchical tree plot

Effect of cultivation practices on cadmium concentration in rice grain

Cadmium (Cd) is one of the most toxic heavy metals, polluting the general environment. The application of sewage sludge, wastewaters and Cd-containing fertilizers causes an increase in Cd content in agricultural soils. Cd is easily taken up by plants and then enters the food chain, resulting in a serious health issue for humans. There is increasing concern regarding the occurrence of cadmium in rice, not only in the rice-growing areas of the Far East, but also in Europe. In this work we highlighted that, even when the agricultural soil is unpolluted and the concentration of Cd is low, e.g. 0.96 mg kg$^{-1}$, the Cd content of rice may still exceed the regulatory limit of 0.2 mg kg$^{-1}$. To reduce the uptake of Cd by rice, paddy-field flooding and soil amendment with lime and compost were tested in a field trial during 2003 and 2004 in Rosate, near Milan, Italy. We found that submersion was the main factor decreasing the Cd concentration in rice grain, producing maximum concentrations of 0.14 mg kg$^{-1}$ in 2003 and 0.06 mg kg$^{-1}$ in 2004. By comparison, Cd concentrations was at least two times higher for rice cultivated by irrigation only. Moreover, the addition of lime decreased the Cd concentration of rice by about 25% versus control under dry conditions. Lime addition thus appears to be a promising technique to reduce the bioavailability of soil Cd and minimize Cd concentrations in the produced rice. In contrast, the application of compost alone does not produced a significant effect. Differences in uptake over the years, with concentrations up to 40% lower in 2004, can be explained by differences in transpiration. These results shows that the influence of climatic conditions on Cd uptake in plants should not be underestimated. Such agronomic information represents a very helpful tool for rice growers, in particular in the case of cultivation of Cd-polluted soils and production of Cd-contaminated rice grain

A multielement analysis of Cu induced changes in the mineral profilesof Cu sensitive and tolerant populations of Silene paradoxa L.

tThis work investigates the Cu induced changes in element profiles in contrasting ecotypes of Silene para-doxa L. A metallicolous copper tolerant population and a non-metallicolous sensitive population weregrown in hydroponics and exposed to different CuSO4treatments. Shoot and root concentrations of Ca,Cu, Fe, K, Mg, Mn, Mo, Na, P, S and Zn were evaluated through ICP-OES.Results indicated that increasing the environmental Cu concentration had a population dependenteffect on element profiles, shoot-to-root ratios and correlations among the elements. Generally, in thetolerant population Cu treatment induced a higher element accumulation in roots and had minimaleffects on the shoot element profile, thus resulting in a progressively decreasing shoot-to-root ratio foreach element. In the sensitive population element concentrations in root and shoot were much moreaffected and without a consistent trend. Copper treatment also affected the correlations between theelements, both in roots and shoots of the two populations, but more so in the sensitive population thanin the tolerant one. Thus, Cu exposure strongly disturbed element homeostasis in the sensitive population,but barely or not in the tolerant one, probably mainly due to a higher capacity to maintain proper rootfunctioning under Cu exposure in the latter. Differences in element profiles were also observed in theabsence of toxic Cu exposure. These differences may reflect divergent population-specific adaptations todifferential nutrient availability levels prevailing in the populations’ natural environments. There is noevidence of inherent side-effects of the Cu tolerance mechanism operating in the tolerant population

Soil enzyme activity can decodify controversial trace elements toxicity data.

Polluted soils are systems of great complexity where toxicity due to to trace elements at high concentrations can be counteracted by a high amount of organic matter added symultaneously. Arylsulfatase (arys) beta-glucosidase (b-gluc), esterase (est), leucine aminopeptidase (leu) and alkaline phosphatase (alkP) activity were measured by microplates and fluorogenic substrates in soil extracts from 27 soil samples coming from a site illegally dumped. Soil samples were characterized for organic matter, total P and N and for both aqua regia and pore-water (rhizon soil moisture samplers) content of As, Cd, Cu, Cr, Pb and Zn, soil organic matter, total P; all these parameters were increased by the pollution event except As, which remained at the natural content, i.e. about 25 mg kg-1. The higher the pollution, the higher the content of Cu and Cd in soil solution, which were significantly correlated with soil organic matter. At the same time, however, there was an increase of enzymatic activity, clearly indicating that the beneficial effect of added soil organic matter overcame the toxic effect of trace metals on soil micro-organisms. Pore-water As was significantly correlated with total P, indicating that pollution event increased toxicity of this highly toxic trace element. According to PCA and CANCORR analysis, enzyme activities were positively correlated to As in solution, organic matter and total phosphorus. Thus, paradoxically, an increase of soluble As was paralleled by an increase of in soil enzyme activity. We hypothesize that the large amount of P added with illegal dumping competed for adsorbing sites on soil surfaces thus increasing As in solutions

Detremination of arsenic species using the Diffusive Gradients in Thin films (DGT) device.

The Diffusive Gradient in Thin films (DGT) technique, utilizing a ferrihydrite adsorbent, has been investigated for the accumulation of different arsenic species. The results, obtained by application of HPLC-ICP-MS, has confirmed that DGT is a reliable method for pre-concentration of total dissolved Arsenic (As) and is able to maintain the arsenic species without risk of speciation changes

Coupling of DGT and HPLC-ICP-MS as a tool in assessing the risk from contaminated soils: a new approach?

Bioavailability, toxicity, persistence and accumulation of arsenic and mercury in living organisms are strongly influenced by chemical speciation. This study was realized to test two innovative techniques, HPLC-ICP-MS, which allows the chemical speciation, and DGT, which measures lability in soil solution and soil resupply, in the evaluation of risk from contaminated soil. The presence of arsenic and mercury in the examined soil is considerable, but speciation and DGT analysis suggest that availability of these trace elements is low. Modification of mobility and availability to living organisms induced by plant cultivation, fertilization and mycorrhiza inoculation both in soil and solution were also investigated. HPLC-ICP-MS and DGT techniques were confirmed as complementary in the assessment of the risk from contaminated soil

Relationship between element concentrations and body size in the\u2028Lake Maggiore population of Unio pictorum mancus (Mollusca, Bivalvia).

The study focused on using a fresh-water mussel (Unio pictorum mancus) as a bioindicator of various pollutants, and particularly metals. The elements considered were: Al, As, Ca, Cd, Co, Cr, Cu, Fe, Mn, Mo, Ni, Pb, V and Zn. This research was carried out at a site where various other studies have been conducted on important characteristics of the same population of Unio. This site is a small bay called "Sabbie d\u2019Oro" located on the south-east coast of Lake Maggiore. Our study involved quantifying the capacity of this mollusc to concentrate large amounts of metal in its body without evident consequences by using detoxification mechanisms. We analysed not only element concentrations, but also their variability (expressed as CV%) in the soft tissues and in the shell, for two main reasons: i) the sampling design should include a preliminary analysis to determine how many specimens is necessary collect to ensure a specified level of precision; ii) the sample variability value may be combined with the value of analytical precision (BCR) to obtain an estimate of the "experimental" precision. In soft tissue, Ca accumulation tended to increase with size, and Al accumulation decreased with size. In shell, Ca and Ni were stored more than in soft tissue, but not proportionally to size. V, Cr and Mo tended to accumulate in the shell progressively over the years, whereas Co and Al are "diluted" during growth, or are absorbed mainly during the juvenile stage. Partition between shell and soft tissue resulted roughly the same in the juvenile and adult stages for the following elements: Fe, Al, Co, As, Pb. The relationships among the various elements were schematized in a hierarchical tree plot

A multielement analysis of Cu induced changes in the mineral profiles of Cu sensitive and tolerant populations of Silene paradoxa L.

This work investigates the Cu induced changes in element profiles in contrasting ecotypes of Silene para- doxa L. A metallicolous copper tolerant population and a non-metallicolous sensitive population were grown in hydroponics and exposed to different CuSO4 treatments. Shoot and root concentrations of Ca, Cu, Fe, K, Mg, Mn, Mo, Na, P, S and Zn were evaluated through ICP-OES. Results indicated that increasing the environmental Cu concentration had a population dependent effect on element profiles, shoot-to-root ratios and correlations among the elements. Generally, in the tolerant population Cu treatment induced a higher element accumulation in roots and had minimal effects on the shoot element profile, thus resulting in a progressively decreasing shoot-to-root ratio for each element. In the sensitive population element concentrations in root and shoot were much more affected and without a consistent trend. Copper treatment also affected the correlations between the elements, both in roots and shoots of the two populations, but more so in the sensitive population than in the tolerant one. Thus, Cu exposure strongly disturbed element homeostasis in the sensitive population, but barely or not in the tolerant one, probably mainly due to a higher capacity to maintain proper root functioning under Cu exposure in the latter. Differences in element profiles were also observed in the absence of toxic Cu exposure. These differences may reflect divergent population-specific adaptations to differential nutrient availability levels prevailing in the populations’ natural environments. There is no evidence of inherent side-effects of the Cu tolerance mechanism operating in the tolerant population