Total organic matter (TOM;%) = ((B-C)/B)*100
where B and C are the weights of dried sediment before and after combusting in the oven respectively.
Assessment of sediment contamination and ecological risk
To determine the degree of pollution by a given heavy metal in sediments
associated with anthropogenic inputs, numerous indices have been developed
to provide an overall view of the level of heavy metal contamination in the
sediments of Algerian mariculture.
In this study, five indices—including the enrichment ratio (ER), the geocumulative index (Igeo), enrichment factor (EF), the adverse effects index
(AEI), and the mean effects range medium quotient (MERM-Q)—were chosen
to provide a comprehensive assessment of heavy metal pollution in Azeffoun
fish farm (Table 2).
Descriptive and multivariate statistical analysis
In this research, descriptive statistics were used. Spatial variations of sediment
geochemical parameters were tested by Friedman rank sum test. The comparison
of the mean values between sites was made by Student’s t-test. The correlation
matrices were plotted using the R package {corrplot} to understand relationships
between total organic matter and heavy metal concentrations in upper sediments.
Principal component analysis (PCA) was used to identify the sources of heavy
metal contamination of the sediment, and hierarchical cluster analysis (CA) was
performed on the data set to identify homogenous groups. All statistical analyses
were performed using R Software (3.5.2). Microsoft Excel 2010 was used for
graphic display. Differences were considered as significant when P < 0.05.
Results and discussion
Elemental concentration and spatial distribution in the study area
Figure 2 shows the distribution of heavy metals (HM) and organic matter by
location throughout the study area compared to levels found in the reference
zone. Concentrations of measured metals and total organic matter in upper
sediment were as follows: Fe (21.30 to 24.00 mg/Kg), Cu (16.80–23.10 mg/Kg),
Table 1. Metal concentration in certified standards compared to that found in standards
reference IAEA-433.
Metal
Cd
Cu
Fe
Pb
Zn
Certified value
0.153
30.8
40.8
39.6
140.6
Found value
0.152
30.6
40.7
38.4
139.8
Recovery %
99.35
99.35
99.75
96.97
99.34
4
R. LOUNAS ET AL.
where B and C are the weights of dried sediment before and after combusting in the oven respectively.
Assessment of sediment contamination and ecological risk
To determine the degree of pollution by a given heavy metal in sediments
associated with anthropogenic inputs, numerous indices have been developed
to provide an overall view of the level of heavy metal contamination in the
sediments of Algerian mariculture.
In this study, five indices—including the enrichment ratio (ER), the geocumulative index (Igeo), enrichment factor (EF), the adverse effects index
(AEI), and the mean effects range medium quotient (MERM-Q)—were chosen
to provide a comprehensive assessment of heavy metal pollution in Azeffoun
fish farm (Table 2).
Descriptive and multivariate statistical analysis
In this research, descriptive statistics were used. Spatial variations of sediment
geochemical parameters were tested by Friedman rank sum test. The comparison
of the mean values between sites was made by Student’s t-test. The correlation
matrices were plotted using the R package {corrplot} to understand relationships
between total organic matter and heavy metal concentrations in upper sediments.
Principal component analysis (PCA) was used to identify the sources of heavy
metal contamination of the sediment, and hierarchical cluster analysis (CA) was
performed on the data set to identify homogenous groups. All statistical analyses
were performed using R Software (3.5.2). Microsoft Excel 2010 was used for
graphic display. Differences were considered as significant when P < 0.05.
Results and discussion
Elemental concentration and spatial distribution in the study area
Figure 2 shows the distribution of heavy metals (HM) and organic matter by
location throughout the study area compared to levels found in the reference
zone. Concentrations of measured metals and total organic matter in upper
sediment were as follows: Fe (21.30 to 24.00 mg/Kg), Cu (16.80–23.10 mg/Kg),
Table 1. Metal concentration in certified standards compared to that found in standards
reference IAEA-433.
Metal
Cd
Cu
Fe
Pb
Zn
Certified value
0.153
30.8
40.8
39.6
140.6
Found value
0.152
30.6
40.7
38.4
139.8
Recovery %
99.35
99.35
99.75
96.97
99.34
4
R. LOUNAS ET AL.