Table 9.3       Summary Statistics of Marine Water Quality in the Southern WCZ at Station SM2

Parameter

 

EPD Monitoring Station (SM2)

Water Quality Objectives

(in marine waters)

Temperature (oC)

 

23.4

(16.8-27.9)

Natural daily level ± 2 oC

Salinity (ppt)

 

32.8

(31.4-34.0)

natural ambient level ± 10 %

Dissolved Oxygen (DO)

(mg L-1)

 

5.8

(4.1-7.6)

³ 4 mg L-1

 

Bottom

5.6

(3.6-7.6)

³ 2 mg L-1

DO (% saturation)

 

81

(62-95)

-

 

Bottom

79

(53-95)

-

pH value

 

8.2

(8.0-8.4)

6.5 - 8.5 (± 0.2 from natural range)

Secchi disc depth (m)

 

2.4

(1.8-4.5)

-

Turbidity (NTU)

 

9.0

(5.2-15.7)

-

SS (mg L-1)

 

5.5

(1.7-13.5)

£ natural ambient level + 30%

Silica (as SiO2)

(mg L-1)

 

0.6

(0.2-1.3)

-

BOD5 (mg L-1)

 

0.8

(0.4-1.4)

-

Nitrite Nitrogen (mg L-1)

 

0.01

(<0.01-0.07)

-

Nitrate Nitrogen (mg L-1)

 

0.04

(<0.01-0.13)

-

Ammonia Nitrogen

(mg L-1)

 

0.02

(0.01-0.04)

-

Unionised Ammonia

(mg L-1)

 

0.002

(<0.001-0.005)

£ 0.021 mg L-1

Total Inorganic Nitrogen (mg L-1)

 

0.08

(0.01-0.21)

£  0.1 mg L-1

Total Nitrogen

(mg L-1)

 

0.19

(0.10-0.32)

-

Orthophosphate Phosphorus(mg L-1)

 

<0.01

(<0.01-0.01)

-

Total Phosphorus

(mg L-1)

 

0.02

(0.02-0.02)

-

Chlorophyll-a

(µg L-1)

 

2.1

(0.9-9.4)

-

E. coli (cfu per 100 mL)

 

35

(2-350)

< 610 cfu per 100 mL

Faecal Coliform

(cfu per 100 mL)

 

72

(6-590)

-

Notes:

1.             Data source: EPD (2004). Marine Water Quality In Hong Kong in 2003.

2.             Except as specified, data presented are depth-averaged data.

3.             Data presented are arithmetic means except for E. coli and faecal coliforms that are geometric means.

4.             Data enclosed in brackets indicate ranges.