The labile chlorophyll a (Chl a 1 ) degradation product, 13 2 , 17 3 -cyclopheophorbide a enol (CPP516), was only recently found in marine sediments, where it can contribute a significant fraction to solvent-extractable sedimentary chlorins. We developed a new chromatographic method for the analysis of CPP516 to study its distribution and sources in the marine environment. We found high concentrations of CPP516 in surficial sediments and particulate matter collected in sediment traps. It contributed 40 to 70% to the sum of all Chl a 1 degradation products in fecal material from herbivorous microzooplankton and macrozooplankton. We did not find CPP516 in exponentially growing or stationary phase algal cultures. These data suggest that a major source of CPP516 is herbivores feeding on phytoplankton. We also found a series of compounds similar to CPP516 in sediments and sediment-trap samples. Mass-spectrometric and ultraviolet(UV)/visible-spectrometric analyses suggest that these are CPP516 analogs of divinyl-Chl a and Chl bs and Chl cs, conclusions that have to be confirmed by synthesis. CPP516, dissolved in organic solvents, easily degrades to 13 2 -oxopyropheophorbide a and chlorophyllone a under oxic conditions. When associated with particles, CPP516 is stable in oxic aquatic environments on a timescale of days, possibly stabilized by the chelation of metal cations. The chromophore of CPP516 differs substantially from that of other Chl a 1 degradation products; it has absorption maxima at 360, 426, and 688 nm. CPP516 does not fluoresce as other Chl a 1 degradation products. As a consequence, it is invisible to fluorescence-based analyses of ''pheopigments.'' Thus, rates of grazing and growth derived from such measurements, as used in conjunction with the gut fluorescence and the Chl-budget method, will be underestimates of true rates when CPP516 contributes significantly to total chlorins.

Utilities with uncovered finished water reservoirs face many water quality, security, and regulatory challenges. These utilities will need to provide covered storage or treatment to comply with the Long Term 2 Enhanced Surface Water Treatment Rule (LT2ESWTR) requirements. This article provides an overview of the history of uncovered reservoirs, identifies drivers for improving protection of uncovered reservoirs, discusses options for compliance with the LT2ESWTR, presents an approach to decision‐making regarding compliance, and presents case studies that demonstrate how utilities have implemented various compliance alternatives. A variety of cover and treatment options are potentially appropriate for LT2ESWTR compliance, and many evaluation criteria must be considered when selecting a compliance alternative. It is recommended that each utility determine, prioritize, and rank its alternatives based on criteria that are specific to its regulatory compliance and project goals. Typical evaluation criteria include regulatory compliance, water quality effects, site aesthetics, operations and maintenance requirements, vulnerability/ public safety, cost, permitting requirements, and design life.