Environmental magnetic studies on surface sediments: a proxy for metal and hydrocarbon contamination

Abstract

Visakhapatnam is one of the major port cities, and it is developed into a hub of many large-and mediumscale industries. Due to growing industrialization and urbanization, coast is vulnerable to both organic and inorganic micro-pollutants. Twenty-five surface sediments were collected along the Visakhapatnam coast for the measurement of texture size, petroleum hydrocarbons, trace metals and environmental magnetic parameters. The percentage of coarser particles was more in the northern region, whereas the percentage of fine particles was increased toward south. Elevated levels of petroleum hydrocarbons and trace metals were attributed due to marine and land-based sources, in particular, those were due to shipping activities, treated and partially treated sewage and industrial wastes. The concentrations of trace metals, petroleum hydrocarbons and magnetic minerals were decreased from nearshore to seaward. Our results revealed that the magnetic mineralogy is dominated by magnetite with a small proportion of hematite, and the grain size of magnetic minerals was in the range of pseudo-single domain to multidomain nature with detrital origin. From the principal component analysis, the magnetic concentration and mineralogy-dependent parameters co-vary with the heavy metal and PHC concentrations, suggesting that the inputs of magnetic minerals, petroleum hydrocarbons and heavy metals in the Visakhapatnam shelf sediments were derived from the same anthropogenic sources. Thus, the large magnetic dataset can be used to reduce the number of chemical analysis; hence, environmental magnetic parameters were used as a proxy for both organic and inorganic micro-pollutants.

Lithogenic and Anthropogenic Components in Surface Sediments from Lake Limboto as Shown by Magnetic Mineral Characteristics, Trace Metals, and REE Geochemistry

“…The SIRM and % magnetite distributions (Figure 3b,c) were very similar. Higher SIRM values for polluted areas (resulting from vehicle emissions, residential and industrial wastes) have also been reported in previous studies [20,33,34]. The similarity in the mean χ FD % values for samples in the R and NR areas ( Table 1) implies that the samples contained both SP and non-SP grains [2,28,29].…”

Sources and Variability of Petroleum Hydrocarbon Residues in Sediments of Chilika Lagoon, East Coast of India

“…PHC concentrations obtained here are compared with previously reported values (Table 3). In the context of India, most previous studies have focused on coastal environments, such as the Visakhapatnam coast (Venkatachalapathy et al 2013), Tamilnadu coast , Chennai coast (Table 3). As classified by US National Academy of Sciences (NAS 1975), >70 ppm is considered as indication of pollution.…”

“…To date, there has been limited investigation on the extent of PHC in Indian lagoon ecosystems. Venkatachalapathy et al (2013), Lyla et al (2012) and have studied the distribution of PHC withinIndia. A total of 52 rivers and rivulets drain into the lagoon, out of which the northeast rivers contribute about 80% of the annual freshwater load.…”