Identifying fossil contamination from surface waters in native algae grown over floating artificial substrates

Abstract

Environmental pollution with chemical inputs from chronic and punctuated spills can occur in aquatic environments and reflect a risk in maritime activities, induce detrimental ecological consequencesand affect human health. In this study, native green algae grown on artificial substrates and exposed to a pollution gradient in a eutrophic coastal estuary are investigated to assess fossil-derived contamination. A substantial proportion of the pollution in such environments originates from fossil fuel sources, which are devoid of radiocarbon (

C). Therefore, radiocarbon analysis, together with n-alkane characterization, provides an excellent tracer for identifying fossil pollutants and assessing their magnitude and geographic distribution. Our findings highlight the ability of algae to accumulate n-alkane hydrocarbons under differing sites and growth stages, with radiocarbon analysis showing up to 49% of fossil carbon in algae, and the Total n-alkanes concentrations between 1.45 and 125.38

mu μ $\mu$

g.g

Superscript negative 1 − 1 ${{\rm{\;}}^{ - 1}}$

DW, with a median of 6.9

mu μ $\mu$

g.g

Superscript negative 1 − 1 ${{\rm{\;}}^{ - 1}}$

DW (N = 10). The sample with the lowest biogenic fraction was near a ferryboat station at Feb/2022, with a prominence of

normal n minus normal upper C 27 n − C 27 ${\rm{n}} - {{\rm{C}}_{27}}$

(18.9

mu μ $\mu$

g.g

Superscript negative 1 − 1 ${{\rm{\;}}^{ - 1}}$

DW) accounting for 15% of Total n-alkanes (algae with 23 days of growth). In contrast, two from four samples from the mussel farm presented no traces of contamination (biogenic fraction 100%), and recorded with

normal n minus normal upper C 15 n − C 15 ${\rm{n}} - {{\rm{C}}_{15}}$

contributing to 50.5% of the 10.02

mu μ $\mu$

g.g

Superscript negative 1 − 1 ${{\rm{\;}}^{ - 1}}$

DW Total n-alkanes concentration. Among the samples analyzed 30% depicted a compound other than

normal n minus normal upper C 17 n − C 17 ${\rm{n}} - {{\rm{C}}_{17}}$

as the maximum value, substituted by

normal n minus normal upper C 27 n − C 27 ${\rm{n}} - {{\rm{C}}_{27}}$

(20%) and

normal n minus normal upper C 15 n − C 15 ${\rm{n}} - {{\rm{C}}_{15}}$

. Results present the potential of green algae to support the monitoring and removal of contaminants from aquatic systems.