( ( ( Any number ) ( of variables ) ) ( ( may ( be ( ( defined ( by ( the user ) ) ) ( to ( ( represent ( ( the concentrations ) ( of ( ( substances and ) particles ) ) ) ) ( ( ( ( in ( the ( water column ) ) ) , ) and ) ( of ( substances ( in ( the sediments ) ) ) ) ) ) ) ) ) ) . ) )
(ROOT (S (NP (NP (DT Any) (NN number)) (PP (IN of) (NP (NNS variables)))) (VP (MD may) (VP (VB be) (VP (VBN defined) (PP (IN by) (NP (DT the) (NN user))) (S (VP (TO to) (VP (VB represent) (NP (NP (DT the) (NNS concentrations)) (PP (IN of) (NP (NNS substances) (CC and) (NNS particles)))) (PP (PP (IN in) (NP (DT the) (NN water) (NN column))) (, ,) (CC and) (PP (IN of) (NP (NP (NNS substances)) (PP (IN in) (NP (DT the) (NNS sediments)))))))))))) (. .)))
Any number of variables may be defined by the user to represent the concentrations of substances and particles in the water column, and of substances in the sediments.
(ROOT (S (NP (NP (DT The) (NN number)) (PP (IN of) (NP (NP (NNS particles)) (PP (IN of) (NP (NP (DT a) (NN substance)) (PP (IN in) (NP (DT a) (VBN given) (NN volume)))))))) (VP (VBZ is) (VP (VBN known) (PP (IN as) (NP (DT the) (NN concentration))))) (. .)))