I believe the answer is incomplete dominance. Incomplete dominance creates a mix of the two phenotype(white and dark purple flowers) to create a third phenotype (lavender). Lavender is a mix.
Whereas, co-dominance would not be a mix but both traits would exist within the organism. In your question, it would be codominance if the dark purple flower and the white flower created a flower with white and dark flower pedals. This would not be a mix of the phenotype, but a co-existance of both phenotype.
Nutrient pollution is the process where too many nutrients, mainly nitrogen and phosphorus, are added to bodies of water and can act like fertilizer, causing excessive growth of algae. Nutrients can run off of land in urban areas where lawn and garden fertilizers are used
