A phytochelatin-based bioassay in marine diatoms useful for the assessment of bioavailability of heavy metals released by polluted sediments

The aim of the present work was to develop a new bioassay involving the presence of phytochelatins (PCs), detoxifying intracellular metal-binding peptides, in microalgae as response to metal bioavailability in re-suspensions of metal-polluted marine sediments. For this purpose, the synthesis of PCs has been studied in laboratory cultures of three marine diatoms, namely Phaeodactylum tricornutum, Thalassiosira weissflogii and Skeletonema costatum, exposed to elutriates of sediments collected in a polluted coastal area in the province of Pisa (Tuscany, Italy). Short- and long-term incubations in the elutriates of two marine sediments (named A and B) exhibited an increase of PCs synthesis in all the phytoplanktonic species examined, when the elutriate concentration increased from 0% to 100%. Elutriate B, which was mainly contaminated by Cd, was shown to be more effective to induce PCs than elutriate A, which was richer in Cu and TOC. The results show that the PCs response, in the microalgae examined, was species-specific. Our data also show that the PCs synthesis occurred before the growth rate was affected, thereby indicating that PCs can be considered as an early warning response of metal exposure. The PCs response in exponentially growing cultures of T. weissflogii, which was found to be the most sensitive alga, increased when the initial cellular density decreased. Finally, the positive relationship obtained between the cellular PCs concentration in T. weissflogii and the degree of metal contamination of the elutriates from twelve sediments collected in a metal-polluted coastal area, confirmed that the PCs-induction test can be applied in field studies. In conclusion, the response of these marine microalgae suggests that these cellular peptides could represent an excellent biomarker of metal exposure, which is useful for the assessment of sediment toxicity, by carrying out PCs-induction tests on sediment elutriates.     

Abundance,distribution, and characteristics of microplastics in coastal surface waters of the Colombian Caribbean and Pacific

Environmental Science and Pollution Research - Microplastic pollution has become a global concern due to its distribution, high abundance, and negative impacts on aquatic ecosystems. These...     

Dodonaea viscosa (Sapindaceae) as a phytoremediator for soils contaminated by heavy metals in abandoned mines

Environmental Science and Pollution Research - Dodonaea viscosa (L.) Jacq. is a plant with a wide distribution that expands throughout almost all Mexican territory and is used in traditional...     

Transplacental amniocentesis: Is it really a higher-risk procedure?

The aim of this study was to compare transplacental with non-transplacental amniocentesis in terms of related complications. Between January 1991 and December 1992, 4564 genetic amniocenteses were performed in 4527 patients (4491 singleton, 35 twin, and one triplet pregnancy) at 15–16 weeks of gestation. All the procedures were ultrasound-guided and performed by the same operator. In 1487 cases, an anterior placenta was traversed with the needle, whereas in 3077 cases, the needle was inserted directly into the amniotic cavity without traversing the placenta. After the exclusion of patients in whom amniotic cell culture failed or in whom an abnormal karyotype was obtained, and of patients lost to follow-up, a total of 4454 patients (98 per cent) were followed for 30 days after amniocentesis. Two spontaneous abortions occurred after a transplacental procedure, and five after a non-transplacental procedure (P = not significant). There were no episodes of amniotic fluid leakage in the first group, whereas 16 ruptures of the membranes that resolved spontaneously occurred in the second group (P<0·01). Our data suggest that transplacental amniocentesis carries a similar abortive risk to and a lower risk of transient rupture of the membranes than non-transplacental amniocentesis and may therefore be preferred at the gestational period examined (15–16 weeks). However, the risk of feto-maternal haemorrhage, which is reported to be higher for a transplacental procedure, must be considered in the case of an anterior placenta.     

Determining sediment quality for regulatory proposes using fish chronic bioassays

Sediment quality assessments for regulatory purposes (i.e. dredged material disposal) are characterized by linking chemical and acute ecotoxicological data. The design of chronic bioassays that incorporate more sensible endpoints than acute tests is discussed to address sediment quality for environmental quality assessment and regulatory proposes. The chronic tests use juveniles of commercial species of fish Sparus aurata and Solea senegalensis, to assess sediment toxicity in samples collected along different littoral areas in the North and the South of Spain. The organisms were exposed during 60 days and sublethal endpoints were selected including biomarkers of exposure to metals (metallothioneins - MTs) and to organic contaminants (ethoxyresorufin-O-deethylase activity - EROD activity) and biomarkers of effect (histopathology in different tissues, gill and liver). A Multivariate Analysis Approach was conducted in order to associate these biological responses with sediment metal concentration from the ports and with chemical residues in biological tissues exposed to sediments under laboratory conditions.     

Alkali activation processes for incinerator residues management

Incinerator bottom ash (BA) is produced in large amount worldwide and in Italy, where 5.1 millions tons of municipal solid residues have been incinerated in 2010, corresponding to 1.2–1.5 millions tons of produced bottom ash. This residue has been used in the present study for producing dense geopolymers containing high percentage (50–70 wt%) of ash. The amount of potentially reactive aluminosilicate fraction in the ash has been determined by means of test in NaOH. The final properties of geopolymers prepared with or without taking into account this reactive fraction have been compared. The results showed that due to the presence of both amorphous and crystalline fractions with a different degree of reactivity, the incinerator BA geopolymers exhibit significant differences in terms of Si/Al ratio and microstructure when reactive fraction is considered.     

Enhancement of source traceability of atmospheric PM by elemental chemical fractionation

During a 1-year study (“Fine dust” Project) funded by the Lazio regional government (Italy), about 1000 daily PM₁₀ and PM_2.5 samples collected from six sites in the region were subjected to chemical fractionation based on differences in elemental solubility. In this way, it was possible to achieve meaningful characterization of the elemental composition of individual samples. For most of the investigated elements, we found significant differences between the extracted and the mineralized residual fraction. In general, fine particulate was best characterized by the composition of the extracted fraction, while coarse particles from traffic-related sources were best characterized using residues. For several metals (Cd, Pb, Sn, Sb and V) having a critical environmental impact, this result was particularly clear.The application of Principal Component Analysis (PCA) and receptor modelling (PCR) to the data set allowed us to evidence the enhancement of selectivity towards different emission sources that is obtained when chemical fractionated data are considered instead of total element content. Chemical fractionation seems to generate very selective markers for specific emission sources and in particular for re-suspended road dusts, one of the main factors responsible for the increase of elemental concentrations in urban areas.