@prefix iop: <https://w3id.org/iadopt/ont/> .
@prefix rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#> .
@prefix rdfs: <http://www.w3.org/2000/01/rdf-schema#> .
@prefix skos: <http://www.w3.org/2004/02/skos/core#> .
@prefix ex: <http://example.org/iadopt/challenge/> .
@prefix sosa: <http://www.w3.org/ns/sosa/> .
@prefix uom: <http://www.ontology-of-units-of-measure.org/resource/om-2/> .
@prefix iopp: <https://w3id.org/iadopt/pattern/> .
@prefix patt: <http://example.org/iadopt/pattern> .

ex:C20
    a 
        iop:Variable ;
    rdfs:label 
        "Concentration of DDT impacted by industry" ;
    rdfs:comment 
        """Concentration of DDT in a given year at a site impacted by industry, measured in ng/g.""" ;
    ex:issue "https://github.com/mabablue/I-ADOPT-examples-playground/issues/26" ;
    iop:hasObjectOfInterest 
        _:b0 ;
    iop:hasProperty 
        <https://qudt.org/vocab/quantitykind/MassFraction> ;
    iop:hasConstraint 
        [ a iop:Constraint ;
             rdfs:label "source: industry" ;
             iop:constrains <https://www.wikidata.org/entity/Q163648> ;
        ] .

_:b0
    a 
        iop:Entity ,
        iop:AsymmetricSystem ;
    iop:hasNumerator 
        <https://www.wikidata.org/entity/Q163648> ;
    iop:hasDenominator 
        <https://www.wikidata.org/entity/Q36133> .

<https://qudt.org/vocab/quantitykind/MassFraction>
    a 
        iop:Property ;
    rdfs:label 
        "mass fraction" .

<https://www.wikidata.org/entity/Q163648>
    a 
        iop:Entity ;
    rdfs:label 
        "DDT" .

<https://www.wikidata.org/entity/Q36133>
    a 
        iop:Entity ;
    rdfs:label 
        "soil" .