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M. Fabiano et al.
between 100 and 875 m for fractionated POM analysis. Bottom depths ranged
from 100 to 3500 m (Table 1). The volumes of water filtered for each parameter
ranged between 500 ml (in the photic layer) and 2000 ml (in the aphotic layer).
Water samples (prefiltered through 200-pm mesh net) were filtered through
Nudepore polycarbonate filters (0.2- and 2.0-pm pore size) for total suspended
matter (TSM), carbohydrates (CHO), proteins (PRT) and lipids (LIP). Since
Nudepore filters tend to clog rapidly, it is possible that the larger size class is contaminated with smaller particles. This would also lead to an underestimate of the
finer particles. In order to minimize this problem, the filtrations were terminated
when the filtration rate dropped significantly. Samples were then stored at -20°C.
TSM was assessed gravimetrically after desiccation (60 °C, 24 h) using a Mettler
M3 balance (accuracy ±1.0 pg [17]). Carbohydrates were analyzed using the phenol-sulforic acid method [18]. d(+)-glucose was used as a standard. Protein analyses were carried but according to Hartree [19], based on a modification of the
Lowry method using the protein reaction with rameic tartrate and Folin-Ciocalteau
reagent. Bovine albumin was used as a standard. Lipid extraction was carried out
according to Bligh and Dyer [20]. The analyses were performed by carbonization
using the method of Marsh and Weinstein [21]. Tripalmitin was used as standard.
Method accuracy was tested against prepared standards. Standard solutions
were prepared from dilutions of a 100-pg l’1 stock solution. Final concentrations
were 0, 2, 5, 10, 20 50 and 100 pg T1 for ail standards utilized. For ail analyses,
blanks were analyzed for 0.2- and 2.0-pm pore size Nudepore filters. For carbohydrate analysis, which presented the higher blank values, the détection limit was
estimated through the analysis of the blank filters with internai standards (final
concentrations 0.5,1.0,1.5,2.5,5.0 pg ml’1). The method was sensitive to addition
of 1.5 pg glucose ml1.
Single samples were normally collected. However, a sériés of replicate samples
was collected in Terra Nova Bay from surface waters, in order to define the coefficient of variation for the different parameters. The inter-sample variability
(unpubl. data, based on samples collected using 0.4-pm pore size Nudepore filters), expressed as the coefficient of variation (CV), was: 13% for TSM, 11% for
CHO, 3% for PRT and 11% for LIP. The déviations (CV) from real standard values
were 7.8 % for LIP, 6.0% for CHO and 6.6% for PRT.
Samples for the détermination of ATP were filtered immediately using 0.2- and
2.0-pm Nudepore polycarbonate filters. ATP déterminations were carried out
according to Holm-Hansen and Booth [22] and Bulleid [23]. Standard solutions
were prepared with crystalline ATP (Sigma). Analyses were performed on two
replicates using an ATP 3000 photometer (Biospherical Instruments).
2.4 Définition of Size Classes
Total particulate matter was defined as the fraction between 0.2 and 200 pm
( retained by 0.2-pm pore size Nudepore), microparticulate matter was defined as
the fraction of particles ranging from 2.0 to 200 pm (retained by 2.0-pm pore size
Nudepore) and picoparticulate (0.2 to 2.0 pm) matter was calculated as the différence between total and microparticulate matter.
M. Fabiano et al.
between 100 and 875 m for fractionated POM analysis. Bottom depths ranged
from 100 to 3500 m (Table 1). The volumes of water filtered for each parameter
ranged between 500 ml (in the photic layer) and 2000 ml (in the aphotic layer).
Water samples (prefiltered through 200-pm mesh net) were filtered through
Nudepore polycarbonate filters (0.2- and 2.0-pm pore size) for total suspended
matter (TSM), carbohydrates (CHO), proteins (PRT) and lipids (LIP). Since
Nudepore filters tend to clog rapidly, it is possible that the larger size class is contaminated with smaller particles. This would also lead to an underestimate of the
finer particles. In order to minimize this problem, the filtrations were terminated
when the filtration rate dropped significantly. Samples were then stored at -20°C.
TSM was assessed gravimetrically after desiccation (60 °C, 24 h) using a Mettler
M3 balance (accuracy ±1.0 pg [17]). Carbohydrates were analyzed using the phenol-sulforic acid method [18]. d(+)-glucose was used as a standard. Protein analyses were carried but according to Hartree [19], based on a modification of the
Lowry method using the protein reaction with rameic tartrate and Folin-Ciocalteau
reagent. Bovine albumin was used as a standard. Lipid extraction was carried out
according to Bligh and Dyer [20]. The analyses were performed by carbonization
using the method of Marsh and Weinstein [21]. Tripalmitin was used as standard.
Method accuracy was tested against prepared standards. Standard solutions
were prepared from dilutions of a 100-pg l’1 stock solution. Final concentrations
were 0, 2, 5, 10, 20 50 and 100 pg T1 for ail standards utilized. For ail analyses,
blanks were analyzed for 0.2- and 2.0-pm pore size Nudepore filters. For carbohydrate analysis, which presented the higher blank values, the détection limit was
estimated through the analysis of the blank filters with internai standards (final
concentrations 0.5,1.0,1.5,2.5,5.0 pg ml’1). The method was sensitive to addition
of 1.5 pg glucose ml1.
Single samples were normally collected. However, a sériés of replicate samples
was collected in Terra Nova Bay from surface waters, in order to define the coefficient of variation for the different parameters. The inter-sample variability
(unpubl. data, based on samples collected using 0.4-pm pore size Nudepore filters), expressed as the coefficient of variation (CV), was: 13% for TSM, 11% for
CHO, 3% for PRT and 11% for LIP. The déviations (CV) from real standard values
were 7.8 % for LIP, 6.0% for CHO and 6.6% for PRT.
Samples for the détermination of ATP were filtered immediately using 0.2- and
2.0-pm Nudepore polycarbonate filters. ATP déterminations were carried out
according to Holm-Hansen and Booth [22] and Bulleid [23]. Standard solutions
were prepared with crystalline ATP (Sigma). Analyses were performed on two
replicates using an ATP 3000 photometer (Biospherical Instruments).
2.4 Définition of Size Classes
Total particulate matter was defined as the fraction between 0.2 and 200 pm
( retained by 0.2-pm pore size Nudepore), microparticulate matter was defined as
the fraction of particles ranging from 2.0 to 200 pm (retained by 2.0-pm pore size
Nudepore) and picoparticulate (0.2 to 2.0 pm) matter was calculated as the différence between total and microparticulate matter.