Alligator Rivers region regional surface water quality monitoring : November 1978 - April 1981
Alligator Rivers Region - Regional Surface Water Quality Monitoring, Volumes 1,2,3 (Plus draft)
Northern Territory. Department of Transport and Works. Water Division, Environmental Section
E-Publications; E-Books; PublicationNT; Report ; 49/1983
At head of title: Water Division, Dept. of Transport & Works, Northern Territory. "April 1983".
Water quality -- Northern Territory -- Alligator Rivers Region; Hydrology -- Northern Territory -- Alligator Rivers Region
Northern Territory Government
Report ; 49/1983
3 volumes. ; 30 cm
Attribution International 4.0 (CC BY 4.0)
Northern Territory Government
https://hdl.handle.net/10070/672725 [Alligator Rivers region regional surface water quality monitoring : November 1978 - April 1981 - WRD83049_v_1.pdf]; https://hdl.handle.net/10070/672727 [Alligator Rivers region regional surface water quality monitoring : November 1978 - April 1981 - WRD83049_v_2.pdf]; https://hdl.handle.net/10070/672729 [Alligator Rivers region regional surface water quality monitoring : November 1978 - April 1981 - WRD83049_v_3.pdf]
Technical Report WRD83049 Viewed at 14:07:10 on 29/07/2010 Page 25 of 440. I I I I I I I I I I I I I I I I I I I I 24. TABLE 6 .l ANALYSIS RATIONALE AND COMHENTS PHYSICAL MEASUREMENTS These are carried out mainly in the field, and many are reproduced in ~~e laboratory. In general the laboratory measurement is poorer in quality as parameters change very quickly with time even with all possible efforts to preserve the sample. Sampling time Gauge height Conductivity Temperature pH This is important in that many parameters, particularly physical parameters, undergo diurnal cycles. These include pH, temperature, conductivity and dissolved oxygen. Stratification and gradients are set up overnight, and these are gradually dispersed during the day. This is related via cross sectional area and gradient to velocity and discharge of water in the stream. This is a very important parameter in estimating load of material, dilution, rainfall response, runoff etc. This depends upon the concentration of ions in solution. It is usually expressed back to 25C, specific conductivity. It may give an idea of concentrations of major ions in solution before analysis. It may change on storage due to oxidation, association and absorption of ions, and so is best measured in situ. This is a very basic measurement to be taken at time of sampling. It may affect various field measurements and reference may need to be made back to it in future analyses. The physical condition of biota may also be judged to some extent by the temperature, as may liminological stratification and mixing. It can of course only be taken in situ. This is a basic measurement of hydrogen ion concentration. Large changes, especially decreases may cause harm to biota, often antagonistically with other parameters. Also changes in pH may cause other substances to go into or out of solution, which maybe harmful to biota. It is a quick simple measurement, and convenient to measure in the field. Changes in pH may be caused by discharges, may occur naturally due to reducing conditions on the bottom of billabongs, or groundwater passing through carbonaceous rock.