Environmental magnetism data of Brantas River bulk surface sediments, Jawa Timur, Indonesia

Magnetic susceptibility in the assessment of toxic heavy metal elements in the surface sediments of Inner Ambon Bay, Maluku province, Indonesia

The Inner Ambon Bay (IAB) is an important area for the economic development of the city of Ambon, one of only a few urban areas in eastern Indonesia. This study is intended to monitor the anthropogenic impact on IAB by employing combined rock magnetic and geochemical analyses on 20 samples collected from IAB and the surrounding rivers. Magnetic susceptibility values of samples in the IAB averaged 26.37× 10-8 m3/kg, which is relatively high and comparable to that of contaminated coastal environments. Magnetic susceptibility correlated positively with certain metals such as Cr, Co, Ni, and Mn but negatively with Hg. Geochemical analyses showed that Hg and Ag contents were relatively high but pose only moderate risk to the environment based on the geo-accumulation index. Furthermore, the potential ecological risk index (PERI) showed that there were two points that showed moderate ecological risk. Multivariate statistical analysis (principal component analysis (PCA), Pearson's correlation coefficient (PCC), and hierarchical cluster analysis (HCA)) outlined that the metallic accumulation in the sediments of IAB was related to lithological, geological, and anthropogenic impacts. Therefore, oil spills and household waste are likely major reasons for anthropogenic pollution in the sediments of the IAB.

Comparison of heavy metal bioaccessibility between street dust and beach sediment: Particle size effect and environmental magnetism response

Direct ingestion of urban sediment particles represents an important pathway of human exposure to heavy metals. The effect of particle sizes on metal bioaccessibilities in human digestive system has not been fully understood. In this study, an in-vitro simulation experiment (PBET), along with environmental magnetic measurements, is conducted on two urban sediments (street dusts and beach sediments) with different particle sizes (Φ31.1 ± 7.36 μm for street dusts and Φ134 ± 21.1 μm for beach sediments) for the purposes of assessing the particle size effect on metal bioaccessibilities in simulated gastric and intestinal tracts, and exploring the environmental magnetism response to different digestion processes. For street dusts, the bioaccessibilities of heavy metals decrease significantly from gastric (12.1 (Cu) ~ 39.9% (Pb)) to intestinal phase (0.41 (Pb) ~ 2.08% (Cd)) due to an increase in digestive juice pH. However, for beach sediments, the metal bioaccessibilities in the intestinal phase is similar to, or even higher than, those in the gastric phase. These demonstrate that clay minerals and Fe/Mn oxides concentrated in fine particles play an important role in adsorbing and fixating heavy metals in neutral intestinal tract. Compared with those of the original samples, the χ_fd% values of the PBET treated street dusts decrease significantly, and the decreasing extents (Δχ_fd%) are positively correlated with the concentrations of the PBET extracted Fe (p < 0.05). However, a reverse trend is observed for the beach sediment samples. These findings suggest that the magnetic minerals formed during the digestion process might affect the metal bioaccessibilities in gastrointestinal tract.