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Microplastic transport in the marginal seas is a key process influencing their ultimate fate in the open oceans. In the present study, we collected seawater samples from the western Pacific Ocean (WP) and the South China Sea (SCS) to investigate the distribution, transport, and possible sources for microplastics. Generally, the range of microplastic levels were 187-1816, 146-1563, and 34.2-622 particles/m

We present the concentrations and distribution patterns of nine acid leachable trace metals (ALTMs) Fe, Mn, Cr, Cu, Ni, Co, Pb, Zn, and Cd in the soil samples from the five century old Pachuca-Mineral de Monte mining district of the Central Mexico. The ALTMs do not show any significant correlation with pH, EC, CaCO3, and organic carbon. The metal concentration indicates three distinct distribution patterns. Fe, Mn, Cr, Pb, and Zn show enrichment in the high altitude region of the northern and central part of the study area. Likewise, Cu and Cd are enriched in the northern mountainous terrains. Both these groups show strong positive correlation with Mn indicating that they are associated with Mn-bearing minerals. However, we relate the first group of metals to excessive vehicular transportation and second group to mining waste dumps. The third group of ALTMs Co and Ni indicates its direct relationship to ore processing activities. Comparison of ALTMs concentrations from this study and various other studies throughout the world suggests the need to take precautionary measures of surface soil in high altitude areas to avoid metal enrichments and its subsequent environmental problems.

This study deals with the geochemical nature of distribution, enrichment of total trace metals (Fe, Mn, Cr, Cu, Ni, Co, Pb, Zn, Cd) in bulk sediments and its association with sediment texture, carbonates and organic carbon. Sixty surface sediment samples were collected during two different seasons in 2002 and 2003 along the coastal regions in three transects from Nagapattinam town, north of Point Calimere in southeast coast of India. The sediments are mostly sandy silt and are dominated by the carbonate content. Organic carbon distribution indicates that they are brought in by the minor river input. Enrichment of trace metals is clearly identified by the domination of Pb, Zn, Cd with high values than the average crustal values and comparison of trace metals from other coastal regions in the southeast coast of India. Statistical analysis clearly indicates that Fe and Mn control the distribution of trace metals and are concentrated in the finer particles and organic carbon fraction. The increase in concentration signifies the need for regular monitoring of the offshore coastal region in southeast coast of India which was recently destroyed by the 2004 December tsunami event, and which is also located near the Sethu Samuthram Ship Canal Project.