Analysis of spatial variation of phosphates in Batang Arau River, Indonesia

This study aims to study the spatial variation of phosphates (orthophosphate, total phosphate, and organic phosphate) in the Batang Arau River, West Sumatera, Indonesia. Sampling was conducted at eight stations along the river from March to May 2014. The results indicate that the three types of phosphates have similar spatial distribution patterns, with an increasing trend in concentration from upstream to downstream. The results also showed that the average orthophosphate and total phosphates concentrations at most of sampling sites had exceeded the quality standard for river water in West Sumatera (class II < 0.2 mg/L) except in the upstream. The mean concentrations of orthophosphate, total phosphates and organic phosphate were 0.054-0.423 mg/L, 0.067-0.446 mg/L, and 0.013-0.072 mg/L, respectively. Analysis of spatial variation with ANOVA at 95% confidence level indicated that differences in land use and human activities along the Batang Arau River resulted in significant differences in phosphates concentration (p < 0.05), except for organic phosphate