Application of different techniques to assess sediment quality and point source pollution in low-level contaminated estuarine recent sediments Lisboa coast, Portugal/

Several X-ray techniques have been used in order to consider the chemical and mineralogical characterisation of recent superficial clay}silty sediments collected from the coastal shelf of the Atlantic Ocean, near Lisboa. Multi-element analyses have been carried out by means of total reflection X-ray fluorescence TXRF. and radioisotope induced X-ray fluorescence RIXRF.. Mineralogical composition was determined using X-ray diffrac- tion XRD. methods. Particle size distribution was determined by means of a laser scattering technique. Statistical data treatment correlation matrix, regression and factorial analysis. was used to identify elemental affinities and relationships among chemistry, mineralogy, texture and geographical distribution. The elements Ni, Cu, As and Pb show a marked relationship with clay minerals whose content is also correlated with the decreasing grain-size. Ti, Mn, Zr and V are grouped and may be related to the iron oxide content. Carbonates, Ca, Sr and quartz are correlated with the coarser grain-size fraction.