Appendix 3. Biogeochemistry

• Streams and rivers in the region fall into three major biogeochemical categories that broadly define the ecosystems in those waters. These water types are: (i) Clearwater (low levels of dissolved ions, dissolved organic carbon (DOC) and fine suspended solids (FSS)); (ii) Blackwater (low levels of ions and FSS but high levels of DOC (iii) Whitewater (intermediate levels of DOC and high levels of ions and FSS) • Relative to temperate streams, most small streams in the region have naturally high levels of nitrogen as ammonia, but relatively low levels of other nutrients. • Human impact to a watershed can increase ion and nutrient concentrations. Although natural variability between sites obscures most human impacts from this one-time survey, some observations are noteworthy: • At the most impacted site, QLAJOYA, ion and nutrient concentrations are higher than any other site in this study. • The ratios of ammonium nitrogen to total dissolved inorganic nitrogen (DIN) are observably higher at sites suspected of receiving sewage or manure inputs. • Stable nitrogen isotopes (δ15N) of nitrate and of fine particulate organic matter (FPOM) at most agricultural sites show the characteristic enrichment due to manure and sewage inputs. • Stable carbon isotopes (δ13C) of FPOM suggest that although algae growth is generally not naturally important in the region due to shading by sediment or by forest canopy, removal of either by humans (ponding or cutting) will allow algae to bloom (i.e. QKM14)