National Council of Examiners for Engineering and Surveying (NCEES) Fundamentals of Engineering (FE) Civil Practice Exam 2025 - Free FE Civil Practice Questions and Study Guide

Bioavailable phosphorus is a form of phosphorus readily available for uptake by aquatic organisms, particularly plants and algae. A common characteristic of bioavailable phosphorus is that it generally does not exceed 60% of the total phosphorus present in aquatic environments. This is significant because it indicates that while a portion of phosphorus is bioavailable, a substantial amount exists in forms that are not readily accessible to aquatic life.

Understanding the limits on bioavailable phosphorus helps in assessing water quality and nutrient management, particularly in the context of preventing algal blooms and ensuring healthy aquatic ecosystems. If bioavailable phosphorus were to consistently exceed certain thresholds, it could lead to excessive growth of aquatic plants, often referred to as eutrophication.

From the context of the other options, some do not align with the nature of bioavailable phosphorus. For instance, filtration does not typically remove soluble phosphorus readily since bioavailable phosphorus is often in dissolved forms. Additionally, high concentrations of bioavailable phosphorus would likely promote aquatic plant growth rather than decrease it, which is contrary to what is presented in the question. Thus, the correct answer pertains to the expected levels of bioavailable phosphorus within a specific range, which is indicative of its ecological interactions and management implications.