In Situ Testing

Measurement of pH, DO, Conductivity, Salinity and Temperature were done by Polarographic method in situ. The probe we used at the site was a combined pH, DO, Conductivity, Salinity and Temperature probe.

The probe is immersed into a sample and the value of the respective parameters will be shown on the screen after the meter stabilises. The values are recorded down.

Conductivity vs TDS

There is a strong and significant relationship between the conductivity and total dissolved solids content of the different sites.

Both of theses parameters are co-related as Conductivity measurement is able to conduct a quick estimation on the amount of the Dissolved Solids (DS).The TDS content of the waters had consisted of ions that contributed to the electrical conductivity of the waters. They mainly came from the various kinds of dissolved substances such as detergent, soap, oils and bacteria from hands and face.

Hence, from the graph, we find that as the content of total dissolved solids increases, the conductivity of the water increases as well.

http://www.britannica.com/EBchecked/topic/424285/ocean/67070/Dissolved-organic-substances#tab=active~checked%2Citems~checked&title=ocean%20%3A%3A%20Dissolved%20organic%20substances%20--%20Britannica%20Online%20Encyclopedia

Conductivity

The conductivity in all the six sites is relatively high, between 100mho to 200mho, tap water being the lowest. This measurement suggests a high amount of ions dissolved in the water.

The presence of ions in the Grease Trap may have been caused by detergents and soaps which contained ions such as nitrates and phosphates. The decomposition of organic matter by bacteria to ions (e.g. food molecules) and chemicals that get washed down (e.g. pen ink) would have also contributed to the ionic content in the water.

As the water passes out of the Grease trap and into the phytoremediation system, Organic-Nitrogen is decomposed by bacteria into Ammonia-nitrogen and finally into Nitrate-Nitrogen which flows into the C1 Inlet causing the height in conductivity.

Taken up by the hydroponics, ion concentration decreases in C2 Outlet and Pond 1, resulting in the steady decrease of conductivity as well.

However, conductivity increases in Pond 2. We assume this is caused by the wastes generated by the organisms living in the or due to pollution by the air.