The advent of Large Language Models (LLMs) represents a fundamental shock to the economics of information production. By asymmetrically collapsing the marginal cost of generating low-quality, synthetic content while leaving high-quality production costly, AI systematically incentivizes information pollution. This paper develops a general equilibrium framework to analyze this challenge. We model the strategic interactions among a monopolistic platform, profit-maximizing producers, and utility-maximizing consumers in a three-stage game. The core of our model is a production technology with differential elasticities of substitution (σ_L > 1 > σ_H), which formalizes the insight that AI is a substitute for labor in low-quality production but a complement in high-quality creation. We prove the existence of a unique "Polluted Information Equilibrium" and demonstrate its inefficiency, which is driven by a threefold market failure: a production externality, a platform governance failure, and an information commons externality. Methodologically, we derive a theoretically-grounded Information Pollution Index (IPI) with endogenous welfare weights to measure ecosystem health. From a policy perspective, we show that a first-best outcome requires a portfolio of instruments targeting each failure. Finally, considering the challenges of deep uncertainty, we advocate for an adaptive governance framework where policy instruments are dynamically adjusted based on real-time IPI readings, offering a robust blueprint for regulating information markets in the age of AI.

翻译：大型语言模型（LLM）的出现对信息生产的经济学构成了根本性冲击。通过非对称地降低生成低质量合成内容的边际成本，同时保持高质量内容的生产成本高昂，人工智能系统性地激励了信息污染。本文构建了一个一般均衡框架来分析这一挑战。我们通过一个三阶段博弈模型，刻画了垄断平台、利润最大化的生产者与效用最大化的消费者之间的策略互动。模型的核心是一种具有差异化替代弹性（σ_L > 1 > σ_H）的生产技术，这形式化了以下洞见：人工智能在低质量生产中替代了劳动力，但在高质量创造中则与之互补。我们证明了存在唯一的“污染信息均衡”，并论证了其无效率性，这种无效率源于三重市场失灵：生产外部性、平台治理失灵以及信息公地外部性。在方法论上，我们推导出一个具有内生福利权重的、理论依据充分的“信息污染指数”（IPI），用以衡量生态系统健康度。从政策视角，我们表明实现最优结果需要一套针对每种失灵的政策工具组合。最后，考虑到深度不确定性的挑战，我们主张建立一个适应性治理框架，其中政策工具能够根据实时的IPI读数进行动态调整，从而为人工智能时代的信息市场监管提供了一个稳健的蓝图。