Abstract This study belongs to one part of FATES research program, which studies the fate of terrestrial substances in Kaoping river-sea system. The task is to study the components and properties of sediments and spatial distribution of sedimentation rates off the southwest Taiwan by analyzing water content, TOC, CaCO3, grain size, P-wave velocity and radionuclides 210Pb and 137Cs in sediments. Thirty cores collected for this study were divided into three groups based on topography and they are Kaoping continental shelf, slope and canyon. The highest TOC content is 1.53 % in ORI732-ST31 and TOC content ranges from 0.20~0.93 % for the rest of sediments from other stations. The highest CaCO3 content is found in ORI732-ST18, 30, ORI779-ST1, and ST12. Most of the CaCO3 content is greater than 4% at these four stations. Probably because of the lower sedimentation rates that result in less terrestrial substances for diluting the CaCO3. In the shelf and slope regions, the distribution of grain size progressively decreases as the water depth increases. Grain size in the stations farther down the canyon, however, is coarser than those at upper canyon. It suggests that there is other sediment source for stations in the canyon in addition to the Kaoping river. The sedimentation rates derived from 210Pbex profiles range from 0.073~0.168 cm/yr in shelf, 0.033~0.670 and 0.094~0.411 cm/yr in continental slope and canyon, respectively. Sedimentation rates are all less than 0.2 cm/yr in the shelf area, but there are five stations with sedimentation rates higher than 0.2 cm/yr in the slope and canyon areas. Among the five stations, the sedimentation rate is up to 0.670 cm/yr (ORI779-ST9), suggesting that 302~822 m deep in the slope and 975~1156 m deep in the canyon are the deposition centers. In some stations, anomalously low 210Pbex activities exist in surface or sub-surface sediments, indicating that the low 210Pbex activity sediments may be typhoon-induced turbidite sediments. According to Central Weather Bureau¡¦s typhoon catalog, in the year of coring there were seven typhoons striking Taiwan. Among these typhoons, Hai-tang was the strongest one, suggesting that the turbidite sediments mentioned above were likely caused by typhoon Hai-tang. Besides, turbidite sediments appear at water depth of over 700 m, indicating episodic turbidite events are an important way to transport particles offshore.

This study has analyzed Pb-210 activity in cores taken from northern coastal South China Sea (SCS) and the area west of the Luzon Strait (LS) in order to estimate the sedimentation rates and the mass accumulate rates which allow a direct comparison with measured settling particulate fluxes. Also, the particulate and dissolved Po-210 and Pb-210 distributions in a water column located to the west of the LS were measured and compared with earlier data. Core samples were collected at Stations G and H (box cores) during the ORI-688 cruise (July, 2003) and at M1, F and 1 (box cores) during the ORI-722 cruise (June and July, 2004). The water column samples were collected at S7 during the ORI-763 curise (August, 2005). Stations H, G and 1 are located in the continental shelf of the northern SCS; Stations, M1, F and S7 are located in the deep water area west of the LS. The water content of the cores at F and M1 west of the LS is mostly around 40%~55%, while that of the cores at H, G and 1 in the coastal area of the northern SCS ranges about 25%~37%. The total organic matter as estimated from the total loss on ignition at F and M1 is, respectively, about 6% and 12% on the average. The coastal cores contain about 3%~8% total organic matter. The Pb-210 activity generally decreases with the core depth but reaches a constant at a certain depth, below which the excess Pb-210 vanishes in the core. Based on the excess Pb-210 distributions in the cores, the estimated sedimentation rates vary between 16 and 52cm/100yr. At M1 station, the mean Pb-210 flux and the mean mass flux are, respectively, 129 dpm/m2/d and 0.55 g/m2/d as determined from the deepest sediment trap(2848m) (Chung et al., 2004). These values are much smaller than what were estimated from the cores: the Pb-210 flux at 201 dpm/m2/d and the mass flux at 5.3 g/m2/d. The Pb-210 flux obtained from the trap is 65% of that measured from the core, and the mass flux from the trap is only 10% of that from the core. These large differences may arise from an over estimation of the sedimentation rate in the core (due to bioturbation) and near-bottom lateral transport of sediments from elsewhere. Compared to the basin west of the LS, the mass flux at the coastal area is much higher but the Pb-210 flux is much lower, probably due to the fact that shallow water has little amount of Pb-210 to be scavenged and no boundary scavenging effect has been observed. The Pb-210 specific activity at S7 station ranges from 155 to 900 dpm/g; the Po-210 activity at this station ranges from 78 to 507dpm/g. The particulate Po/Pb ratio is about unity at 1800m depth, but the ratio at all other depths is less than unity, indicating that the Po-210 is deficient relative to Pb-210 in particles at this station. The total (dissolved + particulate) Po/Pb ratio in the water column is generally less than unity, showing Po-210 deficiency relative to Pb-210 probably due to absorption and/or adsorption of Po-210 by plankton and other organisms. The Po/Pb ratio for the water column averages about 0.6, corresponding to a mean residence time of 0.83yr for Po-210 removal.

The liquid argon target of the DEAP-3600 dark matter detector is contained by an extremely radiopure acrylic vessel. Alpha decays from the inner surface of the acrylic vessel are a source of background. If a fraction of the alpha energy is observed, or if the recoiling nucleus from the alpha decay is observed, the event will not be separated from a dark matter candidate event. In addition to the low level of inherent contamination from uranium and thorium, the Pb-210 from Rn-222 diffusion during manufacturing must be measured. The limit for the DEAP-3600 acrylic vessel is 1.1 × 10^−20 g/g Pb-210. By vaporizing a large quantity of acrylic and counting the concentrated residue with an ultralow background HPGe well detector and a low background alpha spectrometer, the bulk acrylic was found to have an upper limit of 10^−19 g/g Pb-210. The design, installation, commissioning, operation, and analysis for various aspects of the acrylic assay are described. / Thesis (Master, Physics, Engineering Physics and Astronomy) -- Queen's University, 2014-01-14 19:27:47.533

The purposes of this study are to understand and compare: the distributions of the particulate and dissolved 210Po and 210Pb in the northern South China Sea and in the east and west sides of the Luzon Strait; the associated biogeochemical processes, including their mechanisms and rates involved in the area; and the disequilibrium between 226Ra and the 210Pb as observed in profiles. Seawater samples were collected from three stations in the northern South China Sea (station I, J, and F) and one station to the east of the Luzon Strait (station S5) using a Rosette sampling system during three Ocean Researcher I cruises (ORI-688 in July, 2003, ORI-707 in February, 2004, and ORI-734 in October, 2004). The dissolved 210Pb in surface water generally displays higher activities (around 14-28 dpm/100kg) relative to deep water, reflecting atmospheric input. The dissolved 210Pb profile as seen at station F displays a maximum of 26 dpm/100kg at 200 m and lower values at about 10 dpm/100kg below 1500 m. Highest value at 28 dpm/100kg was observed at S5 surface water. It is probably due to being on the path of the Kuroshio which has accumulated atmospheric 210Pb continually from the northern Equatorial Current on its way. The mean residence time with respect to particle scavenging is about 0.62 years for total 210Po within a 50 m mixed layer, and ranges between 0.34 to 1.13 years for total 210Pb in the mixed layer. 210Po is deficient relative to 210Pb in most profiles, suggesting that 210Po is more readily scavenged. The mean scavenging residence time is about 87 years for total 210Pb in the deep water at station F, and 60 years at station J. This residence time is longer than that in both the Pacific and East China Sea deep waters, i.e. a lower scavenging rate in the South China Sea. As the upwelling rate is much higher in the South China Sea than in the Pacific, it may effectively reduce the sinking rate of the sinking particulates, resulting in higher 210Pb residence time in the water columns of the South China Sea.

Po-210 and Pb-210 are particle-reactive natural radionuclides which can be removed from seawater by their incorporation with various particulate materials, resulting in radioactive disequilibria with respect to their parent nuclides. Previous studies showed that Po-210/Pb-210 activity ratio in surface seawater ranges from about 0.2 to 1 due to atmospheric input of Pb-210 and effects of biological productivity and upwelling. In order to evaluate the effects of plankton on Po-210 and Pb-210 distributions, plankton samples were collected by surface-trawling of plankton net in Taiwanese water. These plankton samples were analyzed for Po-210 and Pb-210 in order to obtain their concentrations and activity ratio, which may indicate the enrichment or discrimination of these nuclides in the marine planktonic phase around Taiwan. The results show that the Po-210/Pb-210 activity ratio of planktonic samples ranges from 23.06 to 51.40 in northeastern Taiwan, whereas the activity ratio in southwest Taiwan varies within and outside of the sampleing locations: stations 1, 2, 3 and 4 yield range of 10.72-43.90, 16.40-47.87, 13.86-23.37 and 9.35-13.82, respectively. Two marine algae (Sargassum polycystum C.Agardh and Hypnea charoides Lamouroux) yield values of 2.24-8.57, and 3.72-5.96, respectively. These Po-210/Pb-210 activity ratios are much greater than unity, and their activities comparison to those of inorganic particulates support the contention that the plankton preferentially incorporates Po-210 but discriminates against Pb-210. However, the mechanism or process of Po-210 to be incorporated in the plankton remains unclear. In comparison of the activities between Po-210 and Pb-210 in organic particulates, one finds that Po-210 is effectively enriched while Pb-210 is clearly discriminatied by the organic particulates. These results are consistent with those reported in literatures.

O Pantanal da Nhecolândia, localizado no estado do Mato Grosso do Sul, é parte do Pantanal Brasileiro e possui características específicas, dentre elas a existência de lagos salinos, comumente conhecidos como Salinas. Para se estimar uma possível influência humana no Pantanal da Nhecolândia quatro perfis de sedimento foram coletados, em 2010, nas Salinas A, 6, M e V com o objetivo de se fazer a caracterização química inorgânica dos sedimentos determinando os elementos As, Ba, Ca, Ce, Co, Cr, Cs, Eu, Fe, Hf, K, La, Lu, Na, Nd, Rb, Sb, Sc, Sm, Ta, Tb, Th, U, Yb e Zn pela técnica de análise por ativação com nêutrons instrumental nas frações fina (silte + argila) e grossa (areia média + areia fina) do sedimento e também determinar as taxas de sedimentação e idade do sedimento pelo método do 210Pb. Para auxiliar na interpretação dos resultados determinou-se a composição granulométrica e o conteúdo de água das amostras de sedimento. A análise granulométrica indicou que as Salinas possuem um percentual da fração fina oscilando entre 3,5 % na Salina M a 70 % na Salina A, o que é característico dessa região. Os quatro perfis de sedimento apresentaram diferentes taxas de sedimentação, o que está provavelmente relacionado aos períodos de seca e enchentes. Os resultados obtidos de concentração dos elementos químicos foram comparados com os valores da Upper Continental Crust UCC e da North American Shale Composite NASC, e alguns elementos, como As, Hf, Rb e Sb, apresentaram valores acima destes nas duas frações granulométricas do sedimento, sugereindo à existência de depósitos naturais destes elementos nas quatro Salinas estudadas. Os resultados de concentração dos elementos estudados indicam a não existência de influência antrópica na região. Calculou-se também o fator de enriquecimento - FE dos elementos químicos usando como valores de referência os valores da UCC, NASC, e os valores da base do perfil-FEB, concluindo-se que o FEB foi a melhor metodologia para se avaliar o enriquecimento dos elementos. / Nhecolândia Pantanal, geographically located in the state of Mato Grosso do Sul, is part of the Brazilian Pantanal, and has it specific characteristics, one being the existence of saline lakes, commonly known as Salinas. Therefore, to estimate a possible human influence, a study was initiated in the Nhecolândia Pantanal in 2010, where four sediment cores were collected in Salinas A, 6, M e V. The elements As, Ba, Ca, Ce, Co, Cr, Cs, Eu, Fe, Hf, K, La, Lu, Na, Nd, Rb, Sb, Sc, Sm, Ta, Tb, Th, U, Yb and Zn were determined using instumental neutron activation analysis (INAA), in the fine (silt + clay) and coarse (medium sand + fine sand) fraction of the sediment. The sedimentation rates and age of the sediments were determined using the 210Pb method. The grain size analysis and the water content of the sediment samples were also determined to assist in the interpretation of the results. The four sediment cores showed different sedimentation rates, which is probably related to drought and flood periods. The grain size analysis showed that the Salinas have a percentage of the fine fraction oscilating from 3,5 % in Salina M to 70 % in Salina A, which is characteristic of this region. The results were compared with the values of the Upper Continental Crust - UCC and the North American Shale Composite - NASC, and some elements showed values above these, including the elements As, Hf, Rb and Sb, in the two frations of the sediment, these results of concentration of the elements in the four Salinas suggest the existence of natural deposits of these elements. The results of concentration of the studied elements in the present work suggest that there is no anthropogenic influence in the region. To evaluate these concentration values the enrichment factor - EF was calculated using reference values from the UCC, NASC and values of the core basis - BEF. It was possible to conclude that the best methodology to evaluate the elements enrichment in the Pantanal, for the present study, was the BEF.

O Pantanal da Nhecolândia, localizado no estado do Mato Grosso do Sul, é parte do Pantanal Brasileiro e possui características específicas, dentre elas a existência de lagos salinos, comumente conhecidos como Salinas. Para se estimar uma possível influência humana no Pantanal da Nhecolândia quatro perfis de sedimento foram coletados, em 2010, nas Salinas A, 6, M e V com o objetivo de se fazer a caracterização química inorgânica dos sedimentos determinando os elementos As, Ba, Ca, Ce, Co, Cr, Cs, Eu, Fe, Hf, K, La, Lu, Na, Nd, Rb, Sb, Sc, Sm, Ta, Tb, Th, U, Yb e Zn pela técnica de análise por ativação com nêutrons instrumental nas frações fina (silte + argila) e grossa (areia média + areia fina) do sedimento e também determinar as taxas de sedimentação e idade do sedimento pelo método do 210Pb. Para auxiliar na interpretação dos resultados determinou-se a composição granulométrica e o conteúdo de água das amostras de sedimento. A análise granulométrica indicou que as Salinas possuem um percentual da fração fina oscilando entre 3,5 % na Salina M a 70 % na Salina A, o que é característico dessa região. Os quatro perfis de sedimento apresentaram diferentes taxas de sedimentação, o que está provavelmente relacionado aos períodos de seca e enchentes. Os resultados obtidos de concentração dos elementos químicos foram comparados com os valores da Upper Continental Crust UCC e da North American Shale Composite NASC, e alguns elementos, como As, Hf, Rb e Sb, apresentaram valores acima destes nas duas frações granulométricas do sedimento, sugereindo à existência de depósitos naturais destes elementos nas quatro Salinas estudadas. Os resultados de concentração dos elementos estudados indicam a não existência de influência antrópica na região. Calculou-se também o fator de enriquecimento - FE dos elementos químicos usando como valores de referência os valores da UCC, NASC, e os valores da base do perfil-FEB, concluindo-se que o FEB foi a melhor metodologia para se avaliar o enriquecimento dos elementos. / Nhecolândia Pantanal, geographically located in the state of Mato Grosso do Sul, is part of the Brazilian Pantanal, and has it specific characteristics, one being the existence of saline lakes, commonly known as Salinas. Therefore, to estimate a possible human influence, a study was initiated in the Nhecolândia Pantanal in 2010, where four sediment cores were collected in Salinas A, 6, M e V. The elements As, Ba, Ca, Ce, Co, Cr, Cs, Eu, Fe, Hf, K, La, Lu, Na, Nd, Rb, Sb, Sc, Sm, Ta, Tb, Th, U, Yb and Zn were determined using instumental neutron activation analysis (INAA), in the fine (silt + clay) and coarse (medium sand + fine sand) fraction of the sediment. The sedimentation rates and age of the sediments were determined using the 210Pb method. The grain size analysis and the water content of the sediment samples were also determined to assist in the interpretation of the results. The four sediment cores showed different sedimentation rates, which is probably related to drought and flood periods. The grain size analysis showed that the Salinas have a percentage of the fine fraction oscilating from 3,5 % in Salina M to 70 % in Salina A, which is characteristic of this region. The results were compared with the values of the Upper Continental Crust - UCC and the North American Shale Composite - NASC, and some elements showed values above these, including the elements As, Hf, Rb and Sb, in the two frations of the sediment, these results of concentration of the elements in the four Salinas suggest the existence of natural deposits of these elements. The results of concentration of the studied elements in the present work suggest that there is no anthropogenic influence in the region. To evaluate these concentration values the enrichment factor - EF was calculated using reference values from the UCC, NASC and values of the core basis - BEF. It was possible to conclude that the best methodology to evaluate the elements enrichment in the Pantanal, for the present study, was the BEF.

In this study, the sediment cores taken in the northern South China Sea (SCS) as well as the settling particulates collected from time-series sediment traps deployed in the same area have been analyzed for Pb-210 activities in order to estimate the sedimentation rate and mass flux from core data and to obtain temporal variations in mass flux and Pb-210 from the time-series sediment traps. The main purposes are to compare and to discuss the mass balance problem between the sediment trap and core results in terms of mass flux, Pb-210 activity and its fluxes. The time-averaged particulate fluxes measured from different depths at M3S and M1T sites in the northern SCS generally increase with depth, reflecting an increasing effect of the lateral transport. The upper and middle traps display a synchronous trend in mass flux variations. The mean particulate flux at S5 site near Luzon Strait is clearly higher than the two sites mentioned above probably because of the effect of topography and bottom current. Distributions of Pb-210 are influenced by particulate scavenging: the longer the settling particles stay in the water column the more the surrounding Pb-210 will be scavenged. The temporal variations of Pb-210 at M3S show a similar trend and an increase with depth. At M1T site, the temporal variations of Pb-210 show no clear trend due to insufficient samples. It has been commonly observed in the marginal sea that Pb-210 activity is inversely correlated with the associated mass flux, i.e. higher Pb-210 is associated with lower mass flux in terms of their temporal variations. This study is also in line with such observations. The mean water content of the core at I located near the shelf break in the northern SCS is about 28%, and its mean loss on ignition (L.O.I.) is 3.2%. These are similar to those observed previously in the northern SCS (water content: 25-37%; L.O.I.: 3%-8%). The sedimentation rate as determined from the excess Pb-210 profile at core I is 18cm/100yr which is at the lower end of the previous study (16-52 cm/100yr) (Wu, 2006). The sediment flux and sedimentation rate estimated from both the Pb-210 inventory (I) and the upper limit of sedimentation rate are identical, respectively, at 0.32 g/cm2/yr and 18cm/100yr. Thus the mixing effect could be neglected. The Pb-210 flux estimated from the deep sediment trap at 2163m (M3S, 77.4 dpm/m2/d) is much lower than that observed from the core sediment (F, 761.1 dpm/m2/d). Although the specific Pb-210 activity of the particles is much greater than that in the surface sediment, the particle flux is too small relative to the mass flux of the sediment, suggesting that additional sediment with Pb-210 has been transported laterally from elsewhere and deposited here. This results in a large imbalance between the sinking particulates and the underlying sediment in mass flux and Pb-210 flux.

Pb-210 and Po-210, a parent-daughter pair, are particle-reactive radionuclides. Pb-210 tends to be associated with inorganic particles but Po-210 prefers organic particles. In the context of these characteristics the purpose of this study is to determine Po-210 and Pb-210 in the surface water plankton of the northern South China Sea (SCS) and the Luzon Strait (LS) areas in order to understand their temporal and spatial distributions and the extent of their radioactive disequilibrium. As the LS has provided a pathway for the exchange between the Kuroshio and the SCS waters, the study area has the characteristics of an open ocean and a marginal sea. The plankton Po-210 activities in the study area are about 10~400 dpm/g, but may reach 1200dpm/g in an El Nino year, the effect of which on Po-210 is not clear at present. The Po-210 in the plankton is mainly affected by the surface water Po-210 , biomass concentration, and the Po-210 in the surface water as well as plankton transported from other area(s). If the biomass concentration (as indicated by Chlorophyll-a) increases, the Po-210 in the plankton decreases, i.e. they are inversely correlated. Based on the planktonic Po-210 distribution, the Kuroshio water which has both high Po-210 and high Po-210-bearing plankton has evidently intruded into the northern SCS. The Pb-210 activities of in the plankton vary from 5 to 25dpm/g; the variation trend is similar to that of Po-210 but with much lower activity, resulting in a Po-210/Pb-210 ratio much greater than unity. Compared to the suspended particles, the plankton is highly enriched in Po-210 but it strongly repels Pb-210. Based on earlier studies and this one, the extent of Po-210 enrichment (as indicated by the Po-210/Pb-210 activity ratio) in various organisms increases sequentially from plankton to mussel, large swimmer and then to marine fish, i.e. the higher the level of organism in the food chain, the higher the ratio becomes. However, the Po-210 and Pb-210 activities per unit mass of these organisms are generally lower than those of plankton. Organisms of higher food-chain level may accumulate Po-210 in the digestive system, but part of it may be excreted. Po-210 accumulation does not occur in other parts of these organisms. In terms of adsorption, the plankton with greater surface area to volume ratio, can adsorb more Po-210 resulting in a higher specific activity, whereas large organisms with smaller surface area to volume ratio can adsorb less Po-210 yielding a lower specific activity. The enrichment of Po-210 in various organisms must have been achieved by absorption and adsorption with unknown proportion. Based on a simple box model calculation for the northern SCS water within the upper 100m layer, the excess Po-210 in the planktonic biomass can account for about 70% of the total deficit in this layer. But in the LS area, the excess and the deficit are balanced. This suggests that the Po-210 deficit in this surface water is due to absorption and adsorption by organisms as evidenced by their large Po-210 enrichment.

In order to understand the source, transport pathway and sink of settling particulates in the sea off northeast Taiwan, three moorings with six sediment traps (about 100 m and 300 m above bottom) were deployed on the northern slope of the Ilan ridge (T17S and T18S) and in the South Okinawa trough (T19S). The mooring deployed at T17S was lost due to a connecting ring which was rusted and broken. The duration of the mooring was 6 months (late November, 1999 to early May, 2000) with sampling intervals at 15 days each. When the moorings were recovered, seawater samples were collected for filtration near each station and a box core at T19S was also taken so that the settling particulates, suspended particulates and bottom sediments can be compared for their characteristics. The results show that higher apparent mass fluxes were observed in January, February and early April, 2000 at T18S. The apparent mass fluxes vary between 11 and 91 g/m2/d at T18S, and between 6 and 22 g/m2/d at T19S. The time-series variations of the Pb-210 activity are between 46 and 76 dpm/g at T18S, and between 79 and 122 dpm/g at T19S, the values of which are much higher than those of T18S. The temporal Po-210 variations range between 18 and 90 dpm/g at T18S, and from 65 to 193 dpm/g at T19S. The Po-210 activity and its variation are greater at T19S than at T18S. The 210Po/210Pb activity ratios are less than unity at about 0.8 at T18S, and greater than unity at about 1.3 at T19S. The total Po-210 activity in all water columns varies between 0.2 and 16 dpm/100kg while the total Pb-210 activity varies between 28 and 43 dpm/100kg. The mean total 210Po/210Pb activity ratio is about 0.3, indicating that Po-210 was easily scavenged and removed from water columns by particulate matter. The box core taken at T19S has Po-210 activity ranging from 54 to 121 dpm/g and Pb-210 activity from 51 to 90 dpm/g. The 210Po/210Pb activity ratio is greater than unity in the upper 6 cm, indicating an excess of Po-210 activity. Below 6 cm Po-210 and Pb-210 are nearly at equilibrium. The 210Po/210Pb activity ratios in the water columns observed after the first deployments were higher than those observed after the second deployments. However, the 210Po/210Pb activity ratios of the settling particulates collected from the first trap deployments were lower than those from the second trap deployments. These changes might be attributed to earthquakes which occurred mainly before the second mooring period. These earthquakes could have caused a large quantity of terrigenous particulates with higher 210Po/210Pb activity ratio to be transported out to the study area in addition to resuspended shelf and slope sediments. These settling particulates, being enriched in organic matter with higher activity ratio, could preferentially scavenge Po-210 from the water column, resulting in much higher 210Po/210Pb activity ratios.