Box coring

Box cores were collected at two stations at the Farallon Islands site and at seven stations at the Hudson Canyon site. Cores were also collected by manned submersibles the PYCES IV in the Pacific and the DMV ALVIN in the Atlantic. After each box core was taken, the water overlying the sediment was carefully removed by a siphon and several sub-cores of 66.7 mm diameter were collected for the various participants in the project. The submersible cores were collected by the mechanical arm of the submersible which pushed a 66.7 mm core liner into the sediments. On deck the cores were sectioned into 2 cm fractions for gamma radionuclide measurements and into 1 cm fractions for 210Pb measurements. 

Figure 8. The 230Th excess profile in a box core from the DOMES area (data from Ref. 14). The mixed-layer thickness in the core is about 8 cm.

In the Strait of Georgia, Canada, a study was performed on the fate of AgPEO in marine sediments [28]. Box core sediment samples were taken in a region heavily impacted by two municipal wastewater effluents. The sewage only receives primary treatment, which is clearly reflected in the results of this study. 

Sediment Core. Three replicate subcores were taken from a 10- X 10- X 4-inch box core retrieved from the 160-m station. Each subcore was sectioned at 0.5-cm intervals from 0.0 to 3.0 cm and at 1.0-cm intervals from 3 to 15 cm. Sectioned sediment samples for chemical analyses were immediately frozen and later freeze-dried before acid digestion. 

The reproducibility of the U 7 values in surface sediments from the same region can be quite extraordinary. Figure 8 displays two regions where our laboratory was able to obtain recent sediments from a number of box cores off the coast of California. The temperature estimates derived from U37 analysis not only agree closely with MAST using the Prahl/Muller equation, but they agree with each other to very nearly the analytical error. 

Mackensen A. and Douglas R. G. (1989) Down-core distribution of live and dead deep-water benthic foraminifera in box cores from the Weddell Sea and the California continental borderland. Deep-Sea Res. 36, 879-900. 

Lyons T. W. (1991) Upper Holocene sediments of the Black Sea summary of leg 4 box cores (1988 Black Sea Oceanographic Expedition). In Black Sea Oceanography. NATO ASI Series (eds. E. Izdar and J. W. Murray). Kluwer, pp. 401-441. 

Figure 14.3. Particle size distribution, (a) Discrete and continuous cumulative particle size distribution, (b) Discrete and continuous particle size distribution, (c) Volume distribution plotted in accordance with equation 3. (d) Particle size distributions at four depths in a calcareous sediment from west equatorial Pacific Ocean, 1°6.0 S, 161 36.6 E, box core No. 136, water depth 3848 m. (From Lerman, 1979.)...

Sediment sampling of the seven stations using the CS equipment was carried out by running transects with the survey vessel parallel to, and as close as possible to, the marker buoys. The CS underwater seafloor sediment sampler was pulled at a speed of three knots and, when abreast of each buoy, the sediment collected was recorded as being from that station. The sediment wafers prepared aboard ship from the collected slurries were immediately analyzed by XRF for three elements (Mn, Fe, and Ti) and were stored for further land-based analyses of other elements. A comparison of the elemental content of the sediments collected from the seven stations by box coring and with the use of the CS equipment constituted the basis for ground-truth evaluation of the CS system. 

The 30-mm sediment slices of the segmented cylindrical cores obtained from box coring at the seven stations were dried, pulverized, and thoroughly mixed to yield a uniform sample for analysis. Sediment from each of these slices was analyzed by two independent methods. The first method used a Perkin-Elmer model 5000 atomic absorption spectrophotometer (AA) for the elements Fe, Mn, Ti, Pb, Zn, Cu, Cr, Ni, Co, Hg, and Cd (9). The second method utilized a Philips PW 1410 X-ray fluorescence spectrometer for the analysis of elements Fe, Mn, Ti, Ca, K, P, Si, Al, Mg, Na, Pb, Zn, Cu, Cr, V, and Ba (10). The AA analysis was chosen because of the known accuracy and sensitivity to a wide spectrum of elements. The XRF analysis was chosen for its accuracy and similar nondestructive mode of analysis equivalent to the shipboard XRF analysis. Good agreement between the AA and the XRF values was felt to be imperative because the Philips XRF equipment was to be used in the land-based multielement analysis of the CS -collected sediment samples. 

This study entailed the comparison of the sediment obtained by both box coring and CS sampling by the three different analytical systems described. 

Table V shows the comparative elemental analyses of the surficial sediments obtained from the seven stations by box coring and the CS system. Three elements (Fe, Mn, and Ti) were selected for comparison because of their presence in high levels in the marine sediments and the good sensitivity for detection by the Perkin-Elmer AA, the Philips XRF, and the ship-...

Samples IJB(0-3) and NB(29-31) were derived from the 0-3 cm and 29-31 cm horizons of a large volume box core taken at Station 67 of Summerhayes et al. (30) In Buzzards Bay, near New Bedford, Mass. 

Hessler, R.R. and Jumars, P.A. (1974) Abyssal community analysis from replicate box cores in the central North Pacific. Deep-Sea Research, 21, 185—209. 

At sea, flocculent surface sediments were siphoned off the tops of Soutar box cores and gently sieved, taking care to keep the sediment material at in-situ temperatures. The >75 p,m fraction was kept in bottom water at in-situ temperatures for the duration of each cruise, and returned to the laboratory in Columbia, SC, where stock foraminiferal cultures were maintained in a 7 °C environmental chamber. Separate sediment samples from the top 0.5 cm of cores collected at each site were incubated on board the ship at in-situ temperature with the vital probe CeUTracker Green (Molecular Probes, Invitrogen Detection Technologies) to label foraminifera that were alive at the time of core collection (Bernhard 2000), and these sediments were then preserved for later foraminiferal identification and shell chemistry analyses on shore. 

Appendix B. Box-Core and Gravity-Core Data from Long Island Sound.322... 

Based on direct observation of the bottom on numerous occasions and sieve analysis ( l-mm mesh) of box cores taken at FOAM, NWC, and DEEP (Rhoads et al., 1977 Yingst and Rhoads, 1978 Appendix 1), a composite description of the fauna at each station can be made. These fauna are shown schematically in Figs. 3, 6, and 9. 

All stations are subject to a sinusoidal variation in temperature during the year with a low temperature of about 2°C in February-March and a high of about 22° in August-September (Riley, 1956a). A summary of bottom temperatures at NWC, taken by inserting a thermometer into the top 1 cm of diver-taken box cores, for the 2-yr sampling period is given in Fig. 12. 

The sampling dates and types of cores taken at each station, for which data are presented, are given in Table III. Often more than one core of each type was taken and only the best (e.g., longest, straightest insertion) was used for analysis. In general, box cores were taken in summer, fall, and winter-spring periods at each station and represent times of warmest, intermediate, and coldest water temperature. Sampling was carried out over 2-yr periods at FOAM and NWC and for 1 yr at DEEP. 

Fig. 16. Seasonal pore-water S05 profiles from box cores at FOAM FOAM-1 and FOAM-2 after Goldhaber e/ al. (1977) overlying water range 21.5-23 mM.

Fig. 18. Seasonal pore-water SO4 profiles from box cores at DEEP overlying water...

---