Experimental observations of vertical and horizontal distribution of total suspended sediment using high frequency acoustic backscattering technique

2002 ◽  
Author(s):  
I. Jaya
Keyword(s):  
Suspended Sediment ◽  
High Frequency ◽  
Horizontal Distribution ◽  
Total Suspended Sediment ◽  
Acoustic Backscattering ◽  
Vertical And Horizontal Distribution

Mesoscale Aggregations of Euphausiid Sound Scattering Layers on the Continental Shelf of Vancouver Island

1989 ◽  
Vol 46 (7) ◽  
pp. 1238-1249 ◽  
Author(s):  
Yvan Simard ◽  
David L. Mackas
Keyword(s):  
Continental Shelf ◽  
High Frequency ◽  
Dry Weight ◽  
Distribution Patterns ◽  
Vancouver Island ◽  
Horizontal Distribution ◽  
Swimming Behavior ◽  
Shelf Break ◽  
Shelf Area ◽  
Vertical And Horizontal Distribution

High frequency acoustics (104 kHz) and stratified (BIONESS) net tows were used to map the vertical and horizontal distribution of macrozooplankton scattering layers on and seaward of the continental shelf off Vancouver Island, in June and August of 1986. The macrozooplankton scattering layers were dominated by euphausiids, primarily Euphausia pacifica and Thysanoessa spinifera. During both surveys, dense aggregations were found in the same two general regions. The first was along the shelf break, where highest biomass was observed (averages over a few kilometres of transect reaching to about 200 mg dry weight∙m−3 = about 40 individuals∙m−3 and > 4 g dry weight∙m−2). A second, broader and more diffuse aggregation occupied the deeper southeast end of the shelf (area about 200 km2, biomass 1–2 g∙m−2). The scattering layers showed a consistent diel vertical migration. Daytime depth was deeper at the shelf break (~ 150–200 m) than on the shelf (~ 100–150 m) and occasionally extended to the bottom. These day-depths corresponded to the California Undercurrent waters of 6–7 °C, a salinity of 33.75–34‰ and sigma-T > 26.5. Distribution patterns were coincident with those of upwelled regions, high phytoplankton biomass, and high hake and herring biomass. They were also associated with the shelf break jet and the recurrent Tully eddy. There is a strong possibility of aggregation in restricted areas through the coupling of advection and vertical swimming behavior of the animals.

scholarly journals Response of Total Suspended Sediment and Chlorophyll-a Concentration to Late Autumn Typhoon Events in the Northwestern South China Sea

2021 ◽  
Vol 13 (15) ◽  
pp. 2863
Author(s):  
Junyi Li ◽  
Huiyuan Zheng ◽  
Lingling Xie ◽  
Quanan Zheng ◽  
Zheng Ling ◽  
...  
Keyword(s):  
South China Sea ◽  
Continental Shelf ◽  
Suspended Sediment ◽  
Chlorophyll A ◽  
South China ◽  
Total Suspended Sediment ◽  
Offshore Area ◽  
Chl A ◽  
Late Autumn ◽  
China Sea

Strong typhoon winds enhance turbulent mixing, which induces sediment to resuspend and to promote chlorophyll-a (Chl-a) blooms in the continental shelf areas. In this study, we find limited Chl-a responses to three late autumn typhoons (typhoon Nesat, Mujigae and Khanun) in the northwestern South China Sea (NWSCS) using satellite observations. In climatology, the Chl-a and total suspended sediment (TSS) concentrations are high all year round with higher value in autumn in the offshore area of the NWSCS. After the typhoon passage, the Chl-a concentration increases slightly (23%), while even TSS enhances by 280% on the wide continental shelf of the NWSCS. However, in the southern area, located approximately 100 km from the typhoon tracks, both TSS and Chl-a concentrations increase 160% and 150% after typhoon passage, respectively. In the deeper area, the increased TSS concentration is responsible for the considerable increase of the Chl-a. An empirical analysis is applied to the data, which reveals the TSS and Chl-a processes during typhoon events. The results of this study suggest a different mechanism for Chl-a concentration increase and thus contribute toward further evaluation of typhoon-induced biological responses.

Behavior and Distribution of Nonylphenol Ethoxylates and their Metabolites in Sediments of Nansi Lake, China

2011 ◽  
Vol 356-360 ◽  
pp. 1733-1738
Author(s):  
Fang He ◽  
Aya Obara ◽  
Shi Long Wang ◽  
Li Guo Wang
Keyword(s):  
Water Flow ◽  
Flow Direction ◽  
Sediment Cores ◽  
Sewage Treatment ◽  
Vertical Direction ◽  
Total Content ◽  
Horizontal Distribution ◽  
Nansi Lake ◽  
Increasing Trend ◽  
Vertical And Horizontal Distribution

The vertical and horizontal distribution of NPEOn and their metabolites of NP and NPEnC in the Upper Nansi Lake, North China were investigated using LC-MS and LC-MS/MS methods, sampling at three sites (St.1, St.2 and St.3) along the water flow direction. The total content of NPEOn (n=1–15) bound onto the sediment of this lake changed in the range of 60.7–631.5 μg/kg-dry with the horizontal flow direction and the vertical direction of the sediment cores with sediment thickness up to 35 cm. Compared to the presence levels of all detected NPEOn species, the content of NP was much higher, falling in 26.5–1,998.4 μg/kg-dry. A general increasing trend of the NP content along the water flow direction of this lake was revealed. NPEnC showed a roughly increasing trend from the upstream to the downstream, with the total concentrations being obviously lower than NPEOn and NP and falling in 2.13–23.1 μg/kg-dry. The short chain NPEOn dominant in NPEO mixtures in these sedimentary cores indicated that this lake received some effluents from STPs, and the sewage treatment ratio is relatively low in this area. Furthermore, the computed magnitudes of NPEO 1-2/NPEO1-15, NP/NPEO 1-15 and NPEC 1-10/NPEO 1-15 suggested that the non-oxidative hydrolytic transformation seemed to be a major process occurring within the sediment phase of Nansi Lake, while the oxidative hydrolytic transformation pathway was probably less involved.

scholarly journals Wątrobowce (Hepaticae) Beskidu Żywiecko-Orawskiego (Karpaty Zachodnie) [Liverworts (Hepaticae) of the Beskid Żywiecko-Orawski Range (Polish Western Carpathians)]

2014 ◽  
Vol 79 ◽  
pp. 1-144 ◽  
Author(s):  
Henryk Klama
Keyword(s):  
Endangered Species ◽  
Habitat Preferences ◽  
Horizontal Distribution ◽  
Western Carpathians ◽  
Vulnerable Species ◽  
Floristic Analysis ◽  
Vertical And Horizontal Distribution

The study area comprises two mountain groups – Wielka Racza and Pilsko – situated in western part of the Beskid Żywiecko-Orawski Range in Polish Western Carpathians. The flora of this area includes 111 species of liverworts and 2 species of hornworts. 81 species of liverworts and 2 species of hornworts were found in the area of the Wielka Racza group, 108 species of liverworts and 2 species of hornworts – in the area of the Pilsko group. The species new for the Polish part of the Beskid Żywiecki Range were found (27), as well as for the whole Range including the Slovakian part (22) and for the Western Beskids (2). Moreover, 20 species rare in the Western Beskids as well as 11 species rare in the whole area of the Western Carpathians were recorded. 6 species regarded as threatened in the Polish flora occur in the study area. Four of them belong to the category of endangered species (E):<em> Fossombronia wondraczekii, Frullania tamarisci, Porella baueri</em> and <em>P. platyphylla</em>, the remaining two belong to the category of vulnerable species (V): <em>Geocalyx graveolens</em> and <em>Metzgeria conjugata</em>. A particular attention should be payed to the species threatened on European scale: <em>Lophozia ascendens</em> (R category), <em>Porella baueri</em> (T) and <em>Scapania parvifolia</em> (T). The floristic analysis of habitats covered by liverworts as well as habitat groups of liverworts and habitat preferences of particular species arę presented in the paper. The phytogeographic characteristics of the flora is also given, including vertical and horizontal distribution of liverworts in the study area.

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