Emma Dufbäck - Deltidsrapport

It was quite exhausting to harvest the biomass
in the wetland due to the heat, terrain and
logistics.

The objective of my project is to estimate the nitrogen uptake of the vegetation in the Wakkerstroom wetland.

The wetland receives partly untreated wastewater from the nearby sewage disposal system of the town in Wakkerstroom. The wetland is of regional importance as it detoxifies the wastewater and provides downstream users with clean water. There are several processes found in wetlands regarding removing or storing nitrogen, one is the nitrogen uptake of the wetland vegetation.

My approach for reaching the goal of my project is to harvest wetland vegetation, referred to as biomass, for estimating the Net Primary Production (NPP) of the wetland. I will then calculate annual NPP for the years 2000-2018 using remotely sensed data from an instrument called MISR. I will also perform a validation between the estimated NPP, based on harvested biomass, and the calculated NPP, obtained from remotely sensed data.

I have so far finished the harvest of the biomass. I spent two weeks in Wakkerstroom collecting the material. It was quite difficult because I had to walk in mud and water in waders to get to the biomass, with temperatures reaching up to about 30℃. The first obstacle was to dry the harvested material. My supervisor had built an “oven” for drying the samples, but it was not as efficient as we had hoped so

Wakkerstroom is a small town in the Mpumalanga
province in South Africa. 

I did not have enough time to dry all the samples. We changed the original plan and only dried a few samples, calculating a mean moisture content based on the dried samples.

The other obstacle was that we had harvested the wrong kind of plant. My supervisor pointed at the species I was supposed to sample, which I did. But a few days later I found out that it was the wrong species. I told my supervisor about this and asked what to do and he did not acknowledge it at first, which made me feel very stupid. I showed him the plant the day after and he still did not admit it kind of. I think that he is very uncomfortable being wrong and will not admit that he might have made a mistake. Fortunately, I only harvested 3 samples of that plant, and I do not think it represents the vegetation of the wetland, so my plan is to just neglect that species in my project.

Some samples of the harvested
biomass were dried in a drying oven.

My third obstacle appeared at the Wits University in Johannesburg, where I currently am. I needed a machine for grinding the samples to a fine powder, but after an entire day of searching, I realised it was nowhere to be found. I got quite annoyed knowing this because I thought that my supervisor had prepared for the preparation of the samples, or at least found out that the equipment was present at Wits. Luckily, a few days later, a suitable machine was founded. It does not grind as fine as needed, but it might do.

My latest problem appeared just a few days ago; I had prepared samples for being grinded in the machine, and my supervisor was going to show me how to grind them. It turned out that I had misunderstood him and mixed samples that were not supposed to be mixed. Fortunately, I have spare samples that I can use, but it is frustrating that I have to redo certain steps and spend valuable time on the “wrong things”.

Even though I have had a few problems, I am really enjoying my stay here. The climate is fantastic and most of the people I meet are very friendly and helpful. I think this is an experience I will learn a lot from and carry with me for the rest of my life.