). chemical speciationthe various states of oxidation, conformations, complexes or forms transitory represent chemical species distinct from an element and exploit an important role their biodisponibility and their toxicity or ecotoxicity. certain species of metal elements traces ( etm ) are more easily assimilable by the organizations than of others, which generates beneficial or harmful effects according to nature and the concentration of metal ( essential component or not ). one should not confuse the chemical speciation of an element with its fractionation or its partition. the scientific literature confuses these concepts sometimes what complexes research in these fields. chemical speciation : it is the distribution of an element according to various categories of chemical species in a system - fractionnement : it is the classification of an element or a group analyzed compared to its physical properties and / or chemical ( size of particles, solubility, strength bonding, etc ) - partition : distribution of a compound in the various phases of a system ( solid, liquid, atmosphere, organic matter, etc ) according to specific coefficients of partition this section thus describes the principal categories of chemical species relating to the etm and present of the chemical examples of species of varied toxic level. oxidation and reductionthe state of oxidation or reduction of metals in a system influences their effects on the organizations. for example, chromium oxidized cr ( iii ) is an essential component ( i. e. necessary for the good performance of the organization ) and penetrates with difficulty the lipidic membranes of the cells. on the other hand, cr ( vi ) proves to be toxic for certain genes, is carcinogenic and penetrates easily in the cells thanks to specific conveyers. moreover, the most reduced shapes of arsenic are generally most toxic : toxicity of ash3 > ace ( iii ) > ace ( v ). isotopic compositionthe isotopic composition of some elements influences their abundance or their toxicity in the environment. for example, lead comprises a score of isotopes on the whole and four of them are in a stable form : 204pb, 206pb, 207pb and 208pb. the 206pb and 207pb come from the degradation of uranium and the 208pb results from the degradation of thorium, two radioactive elements ; thus, the abundance of these isotopes increases in time, and the isotopic composition of lead thus evolves / moves according to the stimulated sources of emission. another interesting example of variation of toxicity is related to the isotopic composition


elements ; thus, the abundance of these isotopes increases in time, and the isotopic composition of lead thus evolves / moves according to the stimulated sources of emission. another interesting example of variation of toxicity is related to the isotopic composition of water ( h2o ) : to replace 60 % of the water of the body of rodents by h218o is without effect whereas a substitution of 30 - 40 % of this water by of d2o generates the death of these animals. composed and complex inorganicmetals are often combined with inorganic ligands to form compounds or inorganic complexes having of the different physicochemical properties. for example, the load, solubility, the coefficient of diffusion or the bonding strength of these compounds influence the transport and consequently the biodisponibility and toxicity of metals in the organizations. for example, certain nickel salts like the chlorides ( nicl2 ) and the sulfates ( niso4 ) are water soluble and of low oral toxicity, whereas the nickel sulfides ( ni3s2 ) are practically insoluble in water but are carcinogenic. composed organicthe organic compounds such sugars, organic acid, made up lipids or others low - weight organics molecular have more or less important affinities with metals. some of them, of the organic acids like the citric acid and the malic acid, contain a functional grouping ( hydroxylcarboxyle ) which binds easily to metals and which decrease their biodisponibility ; these compounds are very studied in terrestrial ecotoxicology because they are excreted by the roots of the plants and the micro - organisms of the ground, creating a synergy which decreases the toxicity of metals in the ground. some particular organic compounds as edta form very stable complexes with metals which one names chelating. the chelating ones are soluble ligands polydentes slightly acid which form thermodynamically strong complexes chelating - metal ; they are sometimes used for the restoration of water and the grounds contaminated with metals or in the chemical analytical methods to extract metals from a matrix. organometallic compoundthe compounds organometalliques contain a connection between carbon and metal. this connection can be of covalent or ionic nature ; for example, the connections carbon - sodium and carbon - potassium are strongly ionic, the connections carbon - tin, carbon - lead and carbon - mercury are strongly covalent and the bonds carbon - lithium and carbon magnesium are between the ionic connection and the covalent bond


, the connections carbon - sodium and carbon - potassium are strongly ionic, the connections carbon - tin, carbon - lead and carbon - mercury are strongly covalent and the bonds carbon - lithium and carbon magnesium are between the ionic connection and the covalent bond. for example, the bioalkylation, i. e. the formation of an alkyl ( chx ) with a metal by specific micro - organisms, is a frequent process in the grounds and the sediments. however, although the methylation of metals ( ch3 - metal bond ) form of made up rather toxic, certain metal selenium and arsenic alkyls detoxify the metabolism of human and other living organisms. nevertheless, the majority of the organometallic products resulting from a bioalkylation are of origin anthropogenic, like certain fungicides or products of gasoline combustion, and are very toxic for the central nervous system of certain organizations ( like mercury or lead, the tin alkyl derivatives ). composed or complex macromolecularthe macromolecular compounds or complexes are in extreme cases of representation of the chemical species. they form despite everything a distinct category because they play a particularly important part in the biodisponibility of metals for the living organisms. indeed, the humic and fulvic acids resulting from the biological breakdown of the organic matter are anions mobilizing the etm contained in the grounds and water. the humic and fulvic acids have very variable and complex structures and a composition but would exploit a significant part the speciation of metals. other organic and inorganic particles the such biomass and the colloids adsorb metals and thus decrease their toxicity by reducing their biodisponibility. on the other hand, other anion macromolecules of the living organisms, like certain nucleic acids or the glycosaminoglycanes, bind involuntarily to the etm and cause detrimental mutageneses for the organization. parameters influencing the speciation of metalsthe speciation of metals in the aqueous and solid phases is influenced by several parameters ( see also environnement section of this page ) : ph : in general, an acid ph tends to solubilize metals whereas an alkaline ph supports their adsorption ; - organic matter : the organic matter adsorbs metals and is synonymous with stability ( not biodisponibility ) - the concentration of the ligands : more the concentrations of the inorganic and organic ligants is high


ph supports their adsorption ; - organic matter : the organic matter adsorbs metals and is synonymous with stability ( not biodisponibility ) - the concentration of the ligands : more the concentrations of the inorganic and organic ligants is high, more metal binds to this ligant and forms a populeuse chemical species - the force of the ionic or covalent bond : the stronger the bond metal - compound is, the more the chemical species associated with this compound will be stable ; - the stoichiometry : the stoechiometric principles must obviously be respected to generate the formation of the compounds. this speciation implies that chemical balance is reached. however, the complexation of metals with the inorganic ligands is very fast because they are numerous in the aqueous phase, but the complexation of metals with the organic ligands requires more time because the sites of adsorption or attachment are less accessible. consequently, it has been preferable to analyze the speciation of a metal contamination on a stable matrix contaminated for several years that a matrix coldly contaminated with an evolutionary chemical dynamics, without what the analyzes are likely to be skewed. moreover, the constant of balance relating to the concept of balance chemical can be illustrated by the reaction : metaln + + ligandn - - > metal - ligand the constante of balance keq associated with this equation varies according to the type of bond : - ionic bond : ~ 100 < keq < 104 - complex : ~ 104 < keq < 108 - chelating : ~ 108 < keq < 1020 thus, since keq is relatively weak for the ionic pairs and higher for the complexes, metals prefer to join in the long run the stable complexes that with the ionic pairs of weaker binding energy. environmentcontrary to the organic compounds, metals are not biodegradable by the micro - organisms. this characteristic generates certain problems of management of the metal contamination. indeed, the fate of metals in the environment poses analytical big challenges ; metals are found in several forms in the ground and water ( complex with the organic matter of the ground, minerals, precipitation, ions free, etc ) complexing the predictions of toxicity and ecotoxicity. toxicity and terrestrial ecotoxicitythe toxicity and the ecotoxicity of metals in the grounds are closely related on their chemical speciation and the concept of biodisponibility ; the more mobile the metal species is, the biodisponible it is and the more there is a risk of toxicity on the


a state space model is frequently used for a description of real systems. usually, some state variables are hidden and cannot be measured directly and some model parameters are unknown. then, the need for learning, i. e., the state filtering and parameter estimation, arises. probabilistic models provide a suitable description of the always uncertain reality and call for such approaches as bayesian learning. uncertainties are standardly modelled by the gaussian distribution. this leads to kalman - filter - based algorithms. however, the modelled quantities are often physically constrained. then, methods based on the gaussian distribution with unbounded support do not work properly and they have to be adapted. the alternative sophisticated algorithms based on “ unknown - but - bounded errors ” principle address the same problem but they are poorly harmonised with the subsequent dynamic decision making ( like control, prediction of hidden quantities or future measurements ) to which any learning serves. this research operates in probabilistic framework while coping with bounded uncer - tainties and physically constrained quantities. here, learning algorithms for models with constraints are constructed that ( i ) are based on the bayesian principle, ( ii ) are recursive and ( iii ) have relatively simple setting and maintenance, ( iv ) are at disposal to subsequent dynamic decision making.