cofactor influencing benthic community structure. The rest three
sediment samples were subjected to benthic community analysis.
Each sample was sieved through a 0.5 mm mesh with site water
and the retained organisms on screen mesh were preserved in
70% ethanol and stored at room temperature for further sorting.
Chemical analyses of the bulk sediment were carried out based
on the method described in the Specification for Marine Monitoring
Part 5: Sediment Analysis (CSBQTS, 2008), the detailed procedure
followed that described by Wu et al. (2014). Briefly, about
0.25 g sediment of each station was subjected to CiLAS-940L analyzer
for particle size analysis after removing the organic matters
(with 30% H2O2) and carbonates (with 10% acetic acid). TOC analysis
was carried out by using 0.1 g sample after removing inorganic
carbon (with 10% HCl) with Elementar Vario EL. Cu, Pb, Zn, Cd and
Cr were analyzed by atomic absorption spectroscopy (Shimadzu
AA-680) after being digested in a mixed acid solution of HNO3–
HClO4–HCl. Hg and As were analyzed by atomic fluorescence spectroscopy
(Jitian AFS-930) after treatment in mixed acid solution of
HCl–HNO3. The PHs were measured by fluorospectrophotometer
(Shimadzu RF-540) after extraction of 2 g dry sediment with petroleum
ether for 5 h. Quality assurance and quality control (QA/QC)
procedures, including analyses of method blanks, matrix blanks,
matrix spikes and reference standards for marine sediment
(GBW-07314), were performed during the determination processes.
All samples were determined in triplicate to obtain the analytical
precision (relative standard deviation) and the calculated
results were better than 6% for metals. The resulting recoveries
for metals ranged from 92% to 101%. And the recoveries for TOC
and PHs were 97% and 96%, respectively. Benthic samples were
counted and were usually identified to the species, which is typically
the lowest possible level under a microscope. Data from the
three replicates were then pooled to obtain the faunal composition
at each station.
cofactor influencing benthic community structure. The rest threesediment samples were subjected to benthic community analysis.Each sample was sieved through a 0.5 mm mesh with site waterand the retained organisms on screen mesh were preserved in70% ethanol and stored at room temperature for further sorting.Chemical analyses of the bulk sediment were carried out basedon the method described in the Specification for Marine MonitoringPart 5: Sediment Analysis (CSBQTS, 2008), the detailed procedurefollowed that described by Wu et al. (2014). Briefly, about0.25 g sediment of each station was subjected to CiLAS-940L analyzerfor particle size analysis after removing the organic matters(with 30% H2O2) and carbonates (with 10% acetic acid). TOC analysiswas carried out by using 0.1 g sample after removing inorganiccarbon (with 10% HCl) with Elementar Vario EL. Cu, Pb, Zn, Cd andCr were analyzed by atomic absorption spectroscopy (ShimadzuAA-680) after being digested in a mixed acid solution of HNO3–HClO4–HCl. Hg and As were analyzed by atomic fluorescence spectroscopy(Jitian AFS-930) after treatment in mixed acid solution ofHCl–HNO3. The PHs were measured by fluorospectrophotometer(Shimadzu RF-540) after extraction of 2 g dry sediment with petroleumether for 5 h. Quality assurance and quality control (QA/QC)procedures, including analyses of method blanks, matrix blanks,matrix spikes and reference standards for marine sediment(GBW-07314), were performed during the determination processes.All samples were determined in triplicate to obtain the analyticalprecision (relative standard deviation) and the calculatedresults were better than 6% for metals. The resulting recoveriesfor metals ranged from 92% to 101%. And the recoveries for TOCand PHs were 97% and 96%, respectively. Benthic samples werecounted and were usually identified to the species, which is typicallythe lowest possible level under a microscope. Data from thethree replicates were then pooled to obtain the faunal compositionat each station.
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