"What's up with the water?" and "The clot thickens" were the top projects in this year's Whanganui Regional Science Fair.
Whanganui Intermediate School students Sophia Bedwell and Josephine Perkins took first and second place respectively in the competition.
Organiser Keith Beautrais said Sophia tested water from the Waikato, Taranaki, Manawatu and Whanganui regions for levels of nitrates and phosphates. She discovered that Waikato water where dairy farming was most intensive had the highest levels of phosphate and then wrote about how this causes eutrophication (where the environment becomes enriched with excessive nutrients) and knock-on effects on aquatic life.
"She had to travel to and collect water from five sites in each region," Mr Beautrais said.
"The judges praised Sophia's determination and extraordinary efforts in pursuing a very topical issue that is a focus of debate in New Zealand today."
Runner-up Josephine Perkins researched blot clotting for her project, "The clot thickens".
"Because she is too young to work with human blood she chose a chemical analogue to test her hypothesis about clot size related to chemicals that inhibit and promote clotting," Mr Beautrais said.
"In her work she had to modify her measuring technique and repeat her exhaustive work until she got the results that she wanted. The judges praised her perseverance and accuracy."
This year's science fair attracted more than 150 entries from as far afield as Taoroa school near Taihape.
Chief Judge Dr Mike Dickison, of Whanganui Regional Museum, was impressed with the overall standard of entries and said that the winner addressed a serious issue in New Zealand today, the state of our waterways.
Sophia's entry won her a Go Pro Hero 5, valued at $500, from the chief sponsor TCL. There were other many prizewinners, thanks to sponsorship from the NZ Statistical Association, NZ Baking Industry Research Trust and Paige's Book Gallery.
Mr Beautrais said the local science fair committee was seeing some more teacher interest and would welcome more schools entering next year.