Single particle characterisation of inorganic and organic North Sea suspension

Automated electron probe X-ray micro-analysis and scanning transmission electron microscopy were used to characterise the chemical and mineral composition of individual suspended particles, collected in the Southern Bight of the North Sea. The suspended matter contains 13 particle types, which can be classified in seven genetic groups: (i) terrigenous (aluminosilicate and calcium carbonate particle types); (ii) terrigenous-biogenic (silica type); (iii) terrigenous-hydrogenous (Fe-rich type); (iv) biogenic-authogenic (S-containing type); (v) terrigenous-anthropogenic (Ti- and Al-rich types); (vi) biogenic-anthropogenic (organic type); and (vii) terrigenous-anthropogenic-authogenous (heavy metal rich type). Staining the suspended matter with RuO4, revealed extra information about their organic matter content. Organic matter coatings were detected on all of the suspended particles. A high concentration of organic material was detected in all Mn-rich, Cr-rich, Zn-rich and Ni-rich particles. A strong correlation between organic- and heavy metal-rich particles which was revealed by factor analysis, may indicate that organic matter is complexing heavy metals. Organic material in the southern part of the North Sea is least abundant in fall and winter, and most common, but also very variable, during primary bioproduction boom in spring. The amount of suspended matter was relatively constant throughout the year close to the Westerschelde estuary

Individual particle analysis of Western Mediterranean sediment cores, Rhône suspended matter and Sahara aerosols: investigation of inputs to the sediments

Individual particle analysis using electron probe X-ray microanalysis was performed on sediment cores from the Gulf of Lions (Western Mediterranean Sea), on atmospheric aerosols sampled in Corsica and originating from Northern Africa, and on Rhône suspended matter. Cluster analysis was done to yield major particle types and kriging spatial analysis was applied to obtain the distributions of the particle types in the sediment surface layers. For three sediment cores, the depth profiles of particle groups were examined. The predominant particle types composing the sediment material in the Gulf of Lions were found to be Si-rich particles (quartz and biogenic silicate), aluminosilicate minerals (illite, kaolinite, chlorite) and Ca-rich particles (aragonite, calcite, high-Mg calcite). During the diagenesis, dissolution and crystallization processes occurred, yielding the substitution of quartz and Si-rich particles by calcium carbonates in deeper sediment layers. Only a small amount of Fe-S-rich (pyrite) particles was found in the analyzed sediments. An evident impact of Rhône derived and offshore eroded material was noticed in the sedimentation area investigated. Yet, the input of Northern Africa aerosols to the sediment vicinity was not so evidently noticeable from these results