Spatiotemporal estimation of heavy metals pollution in the Mediterranean Sea from Volturno River, southern Italy: distribution, risk assessment and loads

Abstract

With the aim of assess the pollutant load from the Volturno River into the Mediterranean Sea, the amount of some heavy metals (As, Hg, Cd, Cr, Cu, Ni, Pb and Zn) was determined in water dissolved phase (DP), suspended particulate matter (SPM) and sediment samples. Total heavy metal concentrations were in the range 0.20-65.67 μg L −1 (mean value of 12.95 μg L −1 ) for DP, 1.37-601.77 μg L −1 (mean value of 105.39 μg L −1 ) for SPM and 14.62-157.33 mg kg −1 (mean value of 55.24 mg kg −1 ) for sediments. The total heavy metals input are evaluated in about 620.39 kg year −1 , suggesting that the river could be an important source of heavy metals in the Tyrrhenian Sea. The ecological risk characterisation was assessed based on the National Water Quality Criteria, by comparison with criterion concentration for chronic and acute toxicity (CCC and CMC), and sediment quality guidelines. Hg and Cd showed higher values than CMC and CCC for most water samples. The Index of Geoaccumulation (I geo ), Contamination Factor, Contamination degree, Pollution Load Index (PLI) and Potential Ecological Risk Index were evaluated. According to I geo and PLI, the Volturno River was uncontaminated or moderately polluted by heavy metals.

Assessing Heavy Metals in the Sele River Estuary: An Overview of Pollution Indices in Southern Italy

“…Water samples were collected in four different seasons to assess the spatio-temporal trends in HM concentrations near the Sele River estuary. The sampling was carried out during 2020–2021 in summer (July), autumn (November), winter (February), and spring (April) [ 33 , 35 , 36 ]. For sediment, samples were collected only in one season (April).…”

“…The methodology used for preparation and extraction was previously described [ 35 , 37 ]. Briefly, water samples were filtered using GF/F glass fiber filters (47 mm × 0.7 µm; Whatman, Maidstone, UK) in order to assess the levels of HMs in the dissolved phase (DP), while filters were used for suspended particulate matter (SPM).…”

“…Recognizing pollution origins and allocating their contribution play an essential role in heavy metal contamination analysis. Techniques like principal component analysis (PCA) are employed to pinpoint sources of heavy metal pollution [ 35 ]. PCA, a linear method aimed at reducing complexity, transforms various environmental factors into distinct sources utilizing only a handful of principal components.…”

“…Principal component analysis (PCA) was executed. The requirements were previously described [ 35 ]. Briefly, the first components with eigenvalues > 1 were considered for the amount of explained variance, and the components had to explain the 70–80% of the variance.…”

“…For lower LOQ levels, an LOQ half-value was used. The flow-averaged mean concentration (C aw ) and annual contaminant loads (F annual ) were obtained according to UNEP guidelines [ 43 ], based on Equations (1) and (2), respectively: where Q T represents the total river input for the study period, assessed using the sum of the monthly averaged water flow; C i is the instantaneous amount; and Q i is the load, expressed as the daily water flow average in kg/year [ 33 , 35 ]. In detail, the cumulative loads of heavy metals (HMs) introduced into the Mediterranean Sea from the Sele River were computed by taking into account the concentration values of individual contaminants at the river mouth during the four months of sampling.…”