  The statistical properties of species undergoing chemical reactions in a
turbulent environment are studied. We focus on the case of reversible
multi-component reactions of second and higher orders, in a condition close to
chemical equilibrium sustained by random large-scale reactant sources, while
the turbulent flow is highly developed. In such a state a competition exists
between the chemical reaction that tends to dump reactant concentration
fluctuations and enhance their correlation intensity and the turbulent mixing
that on the contrary increases fluctuations and remove relative correlations.
We show that a unique control parameter, the Damkh\"{o}ler number ($Da_\theta$)
that can be constructed from the scalar Taylor micro-scale, the reactant
diffusivity and the reaction rate characterises the functional dependence of
fluctuations and correlations in a variety of conditions, i.e., at changing the
reaction order, the Reynolds and the Schmidt numbers. The larger is such a
Damkh\"{o}ler number the more depleted are the scalar fluctuations as compared
to the fluctuations of a passive scalar field in the same conditions, and
vice-versa the more intense are the correlations. A saturation in this
behaviour is observed beyond $Da_\theta \simeq \mathcal{O}(10)$. We provide an
analytical prediction for this phenomenon which is in excellent agreement with
direct numerical simulation results.
