Stable isotopes and C/N ratios in marine sediments as a tool for discriminating anthropogenic impact

Abstract

Sources of anthropogenic pollution were categorised by combining elemental and isotopic techniques (C/N ratios and δ(13)C, δ(15)N) on samples of surficial sediments in the harbour of Naples (Southern Tyrrhenian Sea, Italy). The study area, due to the intense and diversified industrial and commercial activities, is an appropriate natural laboratory to verify reliability and relevance of geochemical methodologies applied to exploration of sources, pathways and fate of contaminants in highly polluted coastal marine systems. Application of cluster analysis to the whole dataset and resolution of a δ(13)C and δ(15)N Moore-Penrose system equation provided information to reliably discriminate and identify anthropogenic point sources in the studied sediments. In particular, effects of oil spilling and wastewater discharge within the area of the harbour of Naples were clearly discriminated thus suggesting high-potential of the two numerical techniques, applied to the C and N elemental and isotopic values, to explore effects of anthropogenic impact in marginal and confined coastal basins. The δ(15)N values showed high sensitivity to discriminate sewage discharges (treated or untreated organic matter), clearly indicating the point of emissions. The δ(13)C shows indirect capability of discriminating crude oil and petroleum products.

Spatial distribution and sources of organic carbon in the surface sediment of Bosten Lake, China

“…Apart from the lake's own characteristics (such as lake current and depth), other factors may have influences on the dynamics of TOC. For example, land use changes such as agricultural development and fertilization would enhance the riverine input of nutrients, leading to changes in lake productivity and subsequently altering TOC burial in the sediment (Rumolo et al, 2011;Lami et al, 2010;Lamb et al, 2006). There has been evidence of climate change and human activities over the past decades in the surrounding region, which has caused remarkable lake level changes in Bosten Lake (Guo et al, 2014).…”

“…It is well known that there are large differences in C : N ratio and 13 C org value between exogenous and endogenous organic materials (Brodie et al, 2011;Kaushal and Binford, 1999). For example, aqueous organic matter has low C : N ratios (4-10) (Meyers, 2003) whereas vascular land plants have much higher C : N ratios (> 20) (Rumolo et al, 2011;Lamb et al, 2004;Sifeddine et al, 2011). On the other hand, due to the difference in isotopic fractionation during photosynthesis, δ 13 C org value is more negative (ranging from −33 to −22 ‰) in terrestrial C 3 plants (Pancost and Boot, 2004;Wang et al, 2013) and lake plankton (Bertrand et al, 2010;Vuorio et al, 2006) than in C 4 plants (ranging from −16 to −9 ‰) (Pancost and Boot, 2004;Wang et al, 2013).…”

“…One of the common approaches is to use twoor three-end-member mixing models with combined use of TOC to total nitrogen (TN) ratio (C : N) and stable carbon isotope in organic material (δ 13 C org ) (Rumolo et al, 2011;Yu et al, 2010;Liu and Kao, 2007). It is well known that there are large differences in C : N ratio and 13 C org value between exogenous and endogenous organic materials (Brodie et al, 2011;Kaushal and Binford, 1999).…”

Seasonal variations in the source of sea bottom organic matter off Catalonia coasts (western Mediterranean): links with hydrography and biological response

“…We calculated a mean F T and F M per station/ season by combinations of terrestrial and marine food sources (C end-members) of areas comparable to ours in the Catalan Sea [for δ 13 C T : −26.3 ± 0.6 ‰, reviewed by Rumolo et al (2011) …”

Distribution and sources of aliphatic hydrocarbons and fatty acids in surface sediments of a tropical estuary south west coast of India (Cochin estuary)

“…Stable isotopic ratios provide complementary information to OC/TN ratios and are used to identify the organic matter sources in estuarine systems (Andrews et al 1998;Goni and Thomas 2000;Goni et al 2003;Wu et al 2003;Liu et al 2006;Rumolo et al 2011;Gao et al 2012;Gireeshkumar et al 2013). The interpretation of bulk elemental proxies is complicated by the fact that bulk materials represent mixtures of carbon from several sources, and thus they reflect the integration of different sources.…”