Water bodies of river-lake systems can act as barriers in the movement of nutrients and toxic heavy metals outside their water catchment area. These components can be suspended in the water column, deposited in bottom sediments or bioaccumulated by the vegetation in the water body. A constant exchange of substances takes place between bottom sediments and macrophytes. The composition of bottom sediments and their distribution affects the intensity of nutrients and metals assimilation by macrophytes in the river-lake systems. The aim of research was to analyse the effect of bottom sediments on the nutrients and metal content in macrophytes. It was demonstrated that tissues of plants anchored in sediments that were more abundant in nutrients had higher contents of biogenic components and heavy metals. The properties of bottom sediments, mainly their granulometric composition, but also organic matter content and pH, determine the content of biogenes and heavy metals in macrophytes to a significant extent. On the other hand, it was demonstrated that aquatic plants could affect the grain size in the sediments. Macrophytes and sediments of river-lake systems play a very important role in reducing the transport of nutrients outside the area of the system, through capturing and incorporating them into the tissues of aquatic plants.

The aim of the study was to evaluate the effects of increased rates of meat and bone meal (MBM) to the soil on biomass yield, nitrogen (N) and phosphorus (P) content, and their accumulation in above ground biomass Salix viminalis, as well as the content of mineral N and available P forms in the soil. A two-year pot experiment was conducted at Warmia and Mazury University in Olsztyn (north-eastern Poland). Average biomass yield from two seasons of the studies was three higher from MBM treatments comparing to unfertilized control. Higher rates of MBM particularly in the second year showed higher yielding potential compared with mineral fertilizers. Willow biomass harvested from MBM treatments generally showed lower content of studied nutrients than willow from control treatment. It was found that in relation to the control accumulation of N in willow above ground biomass was significantly lower for 0.5% MBM treatment and significantly higher for the treatment with the highest rate (2.0%). The higher accumulation of P was found in the second year after MBM application, except treatment with the lowest MBM rate. Correlation coefficients values indicated that there is a relation between MBM rate and content of mineral N and available P in soil.