[Primary study on enacting the lake nutrient control standard].

Area of Science:

• Environmental Science
• Limnology
• Water Quality Management

Background:

• Establishing effective lake nutrient control standards is crucial for water body management.
• China faces a deficit in nutrient control standards that account for regional variations and specific nutrient levels.

Purpose of the Study:

• To develop a practical five-step methodology for creating lake nutrient control standards.
• To establish specific nutrient control standards for Taihu Lake based on extensive monitoring data.

Main Methods:

• A five-step method was devised based on commonality, possibility, and practicability.
• Monitoring data from 1994-2005 was categorized into six trophic levels (oligotrophic to extro-eutrophic) using chlorophyll-a concentrations.
• Total nitrogen, total phosphate, and transparency data were analyzed using the frequency method, with 50% frequent values applied.

Main Results:

• Nutrient control standards were defined for Taihu Lake across six trophic states.
• Specific thresholds were determined for chlorophyll-a (<1.6 to >160 mg x m⁻³), transparency (0.7 to 0.25 m), total phosphate (0.03 to 0.18 mg x L⁻¹), and total nitrogen (0.6 to 6.2 mg x L⁻¹).

Conclusions:

• The developed methodology offers a transferable experience for establishing nutrient control standards in other Chinese lake regions.
• This research provides theoretical support for eutrophication control strategies within China.