title: New indexes for compound prioritization and complexity quantification on environmental monitoring inventories.
abstract: BACKGROUND
  Lists of compounds resulting from environmental monitoring may be conveniently represented in a very general way using Pareto distributions, after ranking them on descending order according to their concentration or hazard quotient expressed as percentages, depending on whether the objective of the monitoring is focussed on mass load occurrence or risk assessment respectively.
  
  
  METHODS
  Ranked distributions are characterized using appropriate indexes, such as h (Hirsch), well known in other disciplines like bibliometry. Furthermore, to such ordered distributions, simple numerical power type equations relating rank order and occurrence probability can be fitted, following the so-called power or Zipf law. Both h indices and the characteristic power law exponents are interpreted as measures of complexity of the overall mixture. On the other hand, compounds included within the h index may be seen as the most relevant in the mixture, thus providing a reasonable indication of what is worth analyzing. These concepts have been applied, as case study, to the characterization of the pharmaceutical compounds found in the input and output streams of wastewater treatment plants.
  
  
  CONCLUSIONS
  Whereas both the concentration load and ecotoxicity of pharmaceuticals in WWTPs obviously decrease in the output of the treatment (influent > effluent, sludge), complexity quantified using the proposed indexes does not follow the same trend, being this behaviour common to the three plants examined.
  
  
  CONCLUSIONS
  The joint combination of h compounds of the three plants studied allowed optimizing the list of compounds to be analyzed, which must be considered the key ones for the scenario under study.
authors: Department of Environmental Chemistry, Institute of Environmental Assessment and Water Research (IDAEA), Spanish Council for Scientific Research (CSIC), Jordi Girona 18-26, 08034 Barcelona, Spain. agmqam@cid.csic.es
authors: Antoni
authors: A
authors: Ginebreda
authors: Aleksandra
authors: A
authors: Jelić
authors: Mira
authors: M
authors: Petrović
authors: Miren
authors: M
authors: López de Alda
authors: Damià
authors: D
authors: Barceló
mesh_terms: D002851:Chromatography, High Pressure Liquid; D004784:Environmental Monitoring / Q000379:methods*; D013058:Mass Spectrometry; D004364:Pharmaceutical Preparations / Q000032:analysis*; D011336:Probability; D012722:Sewage / Q000032:analysis* / Q000737:chemistry; D013030:Spain; D014874:Water Pollutants, Chemical / Q000032:analysis*
chemical_list: D004364:Pharmaceutical Preparations; D012722:Sewage; D014874:Water Pollutants, Chemical