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We present the results of a mid-infrared imaging spectroscopy survey of YoungStellar Objects (YSOs) and their surrounding environment in four low-mass starformation regions: RCrA, Rho Ophiuchi, Serpens and Chamaeleon I. This surveywas performed using ISOCAM and its Circular Variable Filters (CVF) and observed42 YSO candidates. A number of spectral features were measured, most notablythe 9.7um silicate feature, the bending modes of both water and CO2 ices at 6.0and 15.2um respectively and the well-known unidentified feature at 6.8um. Thestrength of the unidentified feature was observed to correlate very well withthat of the water ice bending mode and far less strongly with the CO2 icebending mode. This suggests, in a manner consistent with previous observations,that the carrier of the unidentified feature is a strongly polar ice.Absorption profiles of the bending mode of CO2 ice are observed to show asignificant long wavelength wing, which suggests that a significant fraction ofthe CO2 ice observed exists in a polar (H2O-rich) phase. The sources observedin RCrA, Rho Oph and Serpens show similar spectral characteristics, whilst thesources observed in Cha I are somewhat anomalous. However this is consistentwith previous studies of this region of the Cha I cloud, which contains anunusual cluster of YSOs. We detect an apparent under-abundance of water icetowards the sources in Rho Oph. This may be indicative of differences inchemical composition between the different clouds, or may be due toevaporation. Finally the CO2:H2O ice ratios observed towards the sources in RhoOph show significantly greater scatter than in the other regions, possibly dueto varying local conditions around the YSOs in Rho Oph. (Abridged)

ISOCAM-CVF spectroscopy of the circumstellar environment of young stellar objects