Pharmaceuticals in groundwater as indicators of land use practice and water management

Land use modification for agricultural use adds additional source for groundwater recharge, which is usually characterized by lower quality of recharging water. While the human health risk of Concentrated Animal Feeding Operations has been recognized, manure handling, irrigation with sewage water, disposal of sewage sludge and other disposal practices are currently undergoing critical revision. Additionally, the increasing water demand in agriculture is often met by using treated sewage water either directly or to stabilize the regional water budget.

Pharmaceutically active substances and metabolites are found at concentrations up to the microgram/L-level in groundwater samples from the Nuthegraben lowland area south of Berlin (Germany). Among the compounds detected in groundwater are clofibric acid (blood lipid regulator), diclofenac (anti-inflammatory), carbamazepine and primidone (both antiepileptic drugs). Pharmaceuticals are measured up to the mg/L range in surface and groundwater. However, concentrations detected in groundwater are generally much lower and there is significant variation in the distribution of pharmaceuticals in groundwater.

Groundwater and surface water was sampled for the main ions, for organic carbon and selected trace substances. Experiments in the laboratory were conducted using sediment material from the Berlin area to evaluate the transport and sorption behavior of selected drugs in the aquifer under conditions comparable to those in the Nuthegraben area. Results of the column experiments show that clofibric acid exhibits no degradation and almost no retardation (Rf = 1.1). Diclofenac shows quite high retardation at lower pH values indicating that most of diclofenac was sorbed in the unsaturated zone. Carbamazepine shows no degradation in the soil column experiments but significant retardation under the prevailing conditions. Based on carbamazepine and primidone concentrations we conclude that groundwater has been effected significantly by former land use practices whereas actual land use has only minor influence.