Podejście do jakości wody w zlewni osadzonej w krajobrazie rolno-leśnym nieznacznie zdegradowanym przez działalność rolniczo-hodowlaną

Abstract

The headwater streams constitute landscapes with their own entity and are strongly influenced by their environment. They have a large impact on health and integrity, both for water quality and wildlife downstream. Studies on water quality from atlantics agroforestry catchments are scarce. Knowledge about water quality in agroforestry headwater catchments is important for assessing downstream effects and as a baseline for net impacts of land-use change. We analyzed physicochemical water variables of a headwater stream framed in a rural-agroforestry catchment with very little agricultural area, low livestock density and very little human population in NW Spain. Stream water samples were collected at the catchment outlet at approximately biweekly intervals over three years. All water samples were analyzed for the following quality parameters: pH, water temperature (T), electrical conductivity (EC), dissolved oxygen (DO), chemical oxygen demand (COD), major cations (Ca, Mg, Na, K), anions (Cl, SO4), nutrients [total dissolved carbon (TDC), dissolved organic carbon (DOC), nitrites nitrogen (NO2-N), nitrate nitrogen (NO3-N), ammonium nitrogen, Kjeldahl nitrogen (KN), total nitrogen (TN), dissolved, particulate and total phosphorus (DP, PP, TP)], and suspended solids (SS). Discharge was also measured. The mean concentrations of major anions, cations and different forms of carbon, nitrogen and phosphorus were rather low compared to global “average” values. Overall, the mean values of the main physicochemical water quality indicators offers similar values to those found in other rural catchment in humid temperate climates with low agricultural activity and demography, although such concentrations could have been underestimated as they mostly correspond to regular sampling and therefore ignore the influence of rainfall-runoff events.