Temperature and salinity effects on cadmium toxicity on lethal and sublethal responses of Amphibalanus amphitrite nauplii

The official protocol of an ecotoxicological assay employing larvae of the crustacean Amphibalanus amphitrite as a model organism has recently been published by the Italian regulatory authority UNICHIM. Such assay is now one of the applicable tests for water quality assessment under Italian law. While specific temperature and salinity values are recommended by ecotoxicology bioassay protocols for test set up, little information is available on response changes in case of parameter variations. In particular, information is totally lacking for this innovative model organism. Under the standard test protocol, 20°C and 37‰ temperature and salinity, respectively, are required to be set in A. amphitrite bioassay. In order to evaluate the environmental relevance of the test, laboratory experiments simulating the effect on larval responses due to variations of temperature and salinity expected in field collected samples were carried out. The effect of temperature and salinity changes on different end-points, involving increasing sensitivity levels, has been investigated, with and without the presence of cadmium nitrate, Cd(NO3)2, as a reference toxicant, to determine the possible interactions between pollutants and environmental parameters fluctuations. Three end-points - mortality, immobilization, and swimming speed alteration - were measured in order to evaluate the impact of a wide range of temperature (5, 10, 15, 20, 25, 30, 35, 40°C) and salinity values (10, 20, 30, 37, 40, 50, 60, 70‰) on response variation after 24 and 48h of exposure. For each parameter, a Non-Effect Range (NER) - namely the limit values within which no effect related to environmental parameter changes is observed - has been defined. For both parameters, NER resulted to be wider for the less sensitive end-points - such as mortality and immobilization - and for shorter exposure time (24h). Later, the same end-points have been evaluated by exposing the same organisms to a reference toxic compound, Cd(NO3)2 (0, 0.2, 0.4, 0.8, 1.6, 3.2mg/L), within the detected NER both for temperature and salinity. LC50 and EC50 values have been calculated for each end-point after 24 and 48h. Cadmium toxicity was shown to decrease at higher salinity values and increase at higher temperatures. Obtained results offer a better bioassay characterization, and the possibility of a more realistic estimation of ecotoxicological assessments performed on field collected samples. Further studies are needed, especially to investigate the effects of simultaneous salinity and temperature changes on end-points.

Synthesis, characterization and sorption properties of silica modified with some derivatives of β-cyclodextrin

Nanoporous β-cyclodextrin-containing silicas which differ by functional substituents of wide edge of attached cyclic oligosaccharide molecules (alcohol, bromoacetyl, thiosemicarbazidoacetyl groups) have been synthesized. The structure and chemical composition of the surface, porosity of obtained materials, their chemical and thermal stability have been characterized by scanning electron microscopy, IR spectroscopy, thermogravimetry, nitrogen ad-desorption, elemental and chemical analyses of solid surface. Sorption of trace amounts of cadmium (II) in the presence of ten- and hundred-fold excess of hardness salts by synthesized organosilicas has been studied. It has been demonstrated that the sorption equilibrium is reached after 30 min. The sorption of trace amounts of cadmium (II) from multi-component solutions does not decrease, but even increases in the presence of hardness salts, simulating soft and hard water. Coefficients of distribution and selectivity as well as the sorption parameters of Langmuir and Freundlich equations have been calculated. It was found that the driving force of cadmium (II) sorption on the surface of functional β-cyclodextrin-containing silicas is the formation of inclusion complexes "β-cyclodextrin-nitrate-anion". It has been proved the formation of supramolecular structures on the surface of synthesized organosilicas as a result of cadmium (II) sorption. Chemical composition of supermolecules depends on the structure of surface active centers.

Ephyra jellyfish as a new model for ecotoxicological bioassays

The aim of this study was a preliminary investigation on the possibility of using the ephyra of Scyphozoan jellyfish Aurelia aurita (Linnaeus, 1758), the common moon jellyfish, as an innovative model organism in marine ecotoxicology. A series of sequential experiments have been carried out in laboratory in order to investigate the influence of different culturing and methodological parameters (temperature, photoperiod, ephyrae density and age) on behavioural end-points (% of Frequency of Pulsations) and standardize a testing protocol. After that, the organisms have been exposed to two well known reference toxic compounds (Cadmium Nitrate and SDS) in order to analyse the acute and behavioural responses during static exposure. Results of this work indicate that the proposed behavioural end-point, frequency of pulsations (Fp), is an easily measurable one and can be used coupled with an acute one (immobilization) and that ephyrae of jellyfish are very promising model organisms for ecotoxicological investigation.