Behavior of metals (Cu, Zn and Cd) in the initial stage of water system contamination: Effect of pH and suspended particles

Behavior of metals (Cu, Zn and Cd) in the initial stage of water system contamination: Effect of pH and suspended particles
Publication Type
Journal Article
Year of Publication

Smolyakov BS, Ryzhikh AP, Bortnikova SB, Saeva OP, Chernova NY

Applied Geochemistry
ISBN Number

Freshwater bodies, Contamination, Heavy metals, phytoplankton, Biosorption, Mesomodelling, mesocosm, 2 m3, Novosibirskoye Reservoir, Russia


The fate of potentially harmful metals (PHM) after their entry into an unpolluted fresh water bodydepends on the physicochemical and biological parameters of the aquatic ecosystem. This paper considersthe effect of pH and suspended particles (SP) on the behavior of Cu, Zn and Cd when they enter a freshwater reservoir. In a field experiment, four mesocosms were constructed in the Novosibirskoye Reservoirto allow systematic variation of SP concentration (15 or 250 mg/L) and pH (8.5 or 6.5). The initial concentrationsof Cu, Zn and Cd in the mesocosms were 1000, 1000 and 200 lg/L, respectively. Natural bottomsediments were used to provide additional mineral SP, and water hyacinth was used as a floating plantspecies. Over 11 days, measurements were made of several indicators: residual metal concentration insolution ([PHM]w); metal concentration in SP ([PHM]s); primary productivity of the phytoplanktoncommunity; mass of settled SP; PHM concentration in settled SP; and PHM bioaccumulation by waterhyacinth. The ratio [PHM]w/[PHM]s in the water varied in the order Cu Zn > Cd) onto mineral SP andPHM biosorption by planktonic organisms. Phytoplankton acts as a renewable source of organic SP andplays an important role in metal removal from the water in the mesocosms. After 11 days the residualconcentrations of Cu, Zn and Cd in the mesocosm without SP addition (initial SP concentration was15 mg/L) were 272, 355 and 84 lg/L, respectively. The residual concentrations of Cu, Zn and Cd inmesocosms with SP addition were 57, 100 and 14 lg/L at pH 8.5 and 80, 172 and 20 lg/L at pH 6.5,respectively. Therefore, addition of SP resulted in faster and more complete removal of metals into thebottom sediments. Floating plants (water hyacinth) accumulated PHM (Cu > Zn > Cd) more effectivelyat pH 8.5 than at pH 6.5, and PHM concentrations in the roots were higher than in settling SP. The generaltrends of PHM removal from contaminated water via sedimentation and bioaccumulation are comparedwith changes of metal speciation in solution.

Date of Published
Accession Number
Type of Article
Alternate Journal