Shen Zhen. New Territories. Stonecutters Island Kowloon. Victoria Harbor WM4 VM2 VM5 SM10. Hong Kong SM6. South China Sea.

Transcription

1 Shen Zhen Pearl River Estuary Latitude ( o N) New Territories Stonecutters Island Kowloon Victoria Harbor WM4 VM7 SM VM VM Hong Kong Lantau Islannd SM9 WM Island EM3 South China Sea Longitude ( o E) Fig.. The location of the sampling stations in Hong Kong waters. These stations are the same as the EPD stations. They represent a gradient from western eutrophic waters (NW) to eastern waters with much lower nutrients (). 8

2 Salinity Surface Bottom VM Temperature ( o C) Surface Bottom VM Fig.. Monthly average salinity and temperature at the and at stations from Vertical bars indicate ± SD. (Data from EPD, Hong Kong). 9

3 NO 3 (μm) VM SiO 4 (μm) 3 VM Fig. 3. Monthly average NO 3 and SiO 4 at the and at stations from Vertical bars indicate ± SD. Note the different concentration scale for different stations. (Data from EPD, Hong Kong). 3

4 NH 4 (μm) 3 VM PO 4 (μm) 3. VM Fig. 4. Monthly average NH 4 and PO 4 at the and at stations from Vertical bars indicate ± SD. Note the different concentration scale for different stations. (Data from EPD, Hong Kong). 3

5 TIN (μm) 4 3 VM Chl a (μg L - ) VM Fig.. Monthly average TIN (=NO 3 +NH 4 +NO ) e and at stations from Vertical bars indicate ± SD. Note the different concentration scale for different stations. (Data from EPD, Hong Kong).

6 N/P (molar ratio) VM Si/P (molar ratio) VM Fig. 6. Monthly averge N:P and Si:P ratios at the and at stations from Vertical bars indicate ± SD. The horizontal dashed line indicates the Redfield ratios of : for N:P and Si:P. (Data from EPD, Hong Kong ). 33

7 N/Si (molar ratio) VM SS (mg L - ) VM Fig. 7. Monthly average N:Si ratios and suspended solids (SS) at the and at stations from Vertical bars indicate ± SD. The horizontal dashed line indicates a Redfield N:Si ratio of :. (Data from EPD, Hong Kong). 34

8 P Limitation P Limitation VM P Limitation P Limitation P Limitation Si:P N Limitation Si:N=: Dec-Feb Mar-May Si Limitation Jun-Aug Si Limitation Si Limitation Sep-Nov N:P N Limitation Si:N=: N:P N Limitation Si:N=: N:P N Limitation Si:N=: Si Limitation N:P N Limitation Si:N=: Si Limitation N:P Fig. 8. Scatter diagrams of atomic nutrient ratios for the water during spring (Δ, Mar to May), summer (, Jun to Aug), autumn (, Sep to Nov) and winter (, Dec to Feb); N, P and Si represent dissolved inorganic N, P, and Si. Stoichiometric (= potential) limitation for N, P, and Si is indicated by the number of data points in the various quadrants (Data from EPD, Hong Kong).. 3

9 8 6 spring N Limitation P Limitation Si limitation 4 Potential Nutrient Limitation (%) summer autumn 8 winter 6 4 VM Fig. 9. Potential (%) N, P or Si limitation determined from plots in Fig. 8 for waters during spring (March to May), summer (June to August), autumn (September to November) and winter (December to February) at five stations in Hong Kong Waters from 986 to (Data from EPD, Hong Kong). 36

10 Concentrations of NO 3 and SiO 4 (mm) b=8 μm b=36 μm 9 r =.79 r = b=6 μm b=84 μm 6 r =. r = b= μm VM b= μm 6 r =.3 r =. 4 4 b=6 μm b=4 μm 3 r =.3 r = NO 3 SiO 4 b=6 μm b=8 μm r =.7 r = Salinity Fig.. Concentrations of NO 3 and SiO 4 versus salinity for the data for five stations from the time series from 986 to. The graphs with lines indicate a significant correlation between the two variables and the correlation coefficients are represented by r. The intercept of the regression line is represented by b (Data from EPD, Hong Kong). 37

11 Intercept concentrations of NO 3 and SiO 4 (μm) 4 NO 3 SiO Years Fig.. Intercept concentrations of NO 3 and SiO 4 at at from 986 to. p NO3 <. and p SiO4 >., indicates that the correlation is significant for NO 3, not SiO 4 at the. level (- tailed test) (Data from EPD, Hong Kong). 38

12 NH 4 (μm) y=.63x+. r = PO 4 (μm) Fig.. NH 4 versus PO 4 at VM for the concentrations from the time series from The regression equation of NH 4 to PO 4 and the correlation coefficients r are given. (Data from EPD, Hong Kong). 39

13 Chl a (μg L - ) 4 3 y=4e -.x y=e -.x r =.4 r =. Chl a (μg L - ) TIN (μm) y=3e -.68x 4 6 NH4 (μm) y=4e -.8x r =.6 r = PO4 (μm) 4 6 SiO 4 (μm) Fig.3. Chl a concentration versus nutrients (TIN, NH 4, PO 4 and SiO 4 ) at VM for the data from the time series from 986- (Data from EPD, Hong Kong). The regression equation of NH 4 to PO 4 and the correlation coefficients r are given. 4

14 Chl a (μg L - ) Chl a (mg L - ) VM p<. p<. r =.38 r = SS (mg L - ) SS (mg L - ) Fig. 4. Monthly average Chl a versus monthly average suspended solids (SS) for the data at and VM. The correlation coefficients, r, are given (Data from EPD, Hong Kong). 4