Environment & Ecology · Environmental Pollution & Chemical Fire Retardants

With reference to chemical fire-retardant systems employed in large-scale wildfire suppression, consider the following statements: I. Certain phosphate-based retardants reduce fire intensity by interfering with pyrolysis and promoting formation of a protective carbon-rich layer over vegetation. II. The persistence of such retardants on vegetation after water evaporation is one of the reasons they are preferred over exclusive water-dumping operations in some wildfire zones. III. Excessive deposition of nitrogen- and phosphorus-rich retardants in ecologically sensitive regions may contribute to nutrient imbalance in nearby freshwater ecosystems. IV. All modern aerial fire retardants used globally are legally classified as non-toxic to aquatic organisms under environmental regulations. Which of the statements given above are correct?