Outdoor small-scale automatic water quality monitoring stations (hereinafter referred to as water stations) primarily monitor surface water. Surface water exists on the Earth's crust and is exposed to the atmosphere. It is a general term for four types of water bodies: rivers, glaciers, lakes, and swamps, also known as "terrestrial water." It is one of the important sources of water for human life and a major component of water resources in various countries. According to the "China Environmental Status Bulletin" published by the Ministry of Ecology and Environment, in 2014, China's surface water was generally moderately polluted, with the eutrophication of lakes (reservoirs) being particularly prominent. The main factors causing surface water eutrophication are chemical elements such as N, P, organic matter, and NH4- in the water. Therefore, monitoring chemical indicators such as total phosphorus, total nitrogen, ammonia nitrogen, and permanganate index in surface water has become a necessary task. Combined with the simultaneous monitoring of conventional five parameters (dissolved oxygen, turbidity, conductivity, temperature, pH), it comprehensively reflects water environment indicators. In response to the national strategy of strengthening environmental protection, maintaining natural ecological balance, and promoting sustainable economic development, and based on market needs, our company has independently developed and produced outdoor small-scale automatic water quality monitoring stations. These stations integrate national standard methods with advanced computer technology, achieving full automation of the measurement process. They can be widely used for monitoring surface water quality in rivers, lakes, and other water bodies. 2.2 Monitoring Principle of Outdoor Water Stations This outdoor water station adopts an integrated design principle, including a water sampling and distribution system, detection units (five measurement modules for total phosphorus, total nitrogen, permanganate index, ammonia nitrogen, and conventional five parameters), a quality control unit, and auxiliary units (waste liquid collection, lightning protection, air conditioning, etc.). The core unit is the detection unit, where total phosphorus, total nitrogen, permanganate index, and ammonia nitrogen strictly follow the chemical analysis methods specified by national standards. The conventional five parameters (dissolved oxygen, conductivity, turbidity, temperature, pH) are measured using a multi-electrode integrated approach.