We prove an integral version of the Schur--Weyl duality between the
specialized Birman--Murakami--Wenzl algebra $B_n(-q^{2m+1},q)$ and the quantum
algebra associated to the symplectic Lie algebra sp_{2m}. In particular, we
deduce that this Schur--Weyl duality holds over arbitrary (commutative) ground
rings, which answers a question of Lehrer and Zhang [Strongly multiplicity free
modules for Lie algebras and quantum groups, J. Algebra (1) 306 (2006),
138--174] in the symplectic case.
We study the Brauer-Schur-Weyl duality between the quotient
$\bb_n(-2m)/\bb_n^{(f)}$ of the Brauer algebra $\bb_n(-2m)$ and the symplectic
group $Sp(V)$ on the space $\mathcal{HT}_n^{\otimes f}$ of partially harmonic
tensors of valence $f$ in $V^{\otimes n}$, where $\bb_n^{(f)}$ is the two-sided
ideal generated by $e_1e_3... e_{2f-1}$ and $1\leq f\leq [n/2]$.