Spatial and temporal dynamics of stream chemistry in a forested watershed

Abstract

Abstract. Spatial dynamics of solute chemistry and natural abundance isotopes of nitrate ( 15 N and 18 O) were examined in seven locations and at the watershed outlet in 2001 and 2002 in a forest watershed in the Adirondack Mountains of New York State, USA. Temporal dynamics were examined during five discharge periods: winter, snowmelt, spring, summer, and fall, based on discharge levels at the watershed outlet. Solute concentrations were variable across space and time with significant (p≤0.05) interaction effects. Year*period was significant for pH, NH + 4 , NO − 3 , total N, DOC, and total Al suggesting that inter-annual variability in discharge levels was more important for these solutes than intra-annual variability. Period*sampling point was significant for pH, Mg 2+ , Ca 2+ , sum of base cations, Si, and total Al suggesting that the differences in concentration of these solutes among sampling points were moderated by discharge levels. In general, groundwater sources located in upper watershed controlled stream chemistry at higher elevations with highest pH, Ca 2+ , sum of base cations, Si, and SO 2− 4 concentrations, with higher values in summer, and dilution effects during snowmelt. Two low elevation wetlands had a substantial influence over stream chemistry at those locations contributing lowest NO − 3 and highest DOC. Snowmelt exhibited among the lowest pH, sum of base cations, and SO 2− 4 , and highest NO

Effects of land-use patterns on in-stream nitrogen in a highly-polluted river basin in Northeast China

“…In this study, correlation and regression analyses show significant relationships between land-use types and nitrogen variables during different seasons. The results indicate trends also seen in other studies that built-up land, dry farmland, and paddy land uses all have positive contributions to river nitrogen pollution (Woli et al, 2004;Lee et al, 2009), whereas forestland use has negative contribution to river nitrogen pollution (Nakagawa and Iwatsubo, 2000;Piatek et al, 2009). Built-up land use correlates with most of nitrogen variables or predicts them seasonally, indicating nitrogen pollution of the river is directly caused by the discharges of industrial and domestic wastewater in urban areas (Schoonover and Lockaby, 2006;Bu et al, 2011;Wilson, 2015).…”

“…Some nitrogen pollutants are fixed or adsorbed by forestland effects before running into the river (Nakagawa and Iwatsubo, 2000;Piatek et al, 2009). Nevertheless, forestland combined with built-up land or paddy land in June positively contributes to river nitrogen.…”

“…Expansion of built-up land including industrial and urban land uses also results in increased nitrogen in river water due to the nitrogenous wastewater discharges (Schoonover and Lockaby, 2006;Wilson, 2015). Forest lands can provide mitigating and removing effects on riverine nitrogen due to their fixation and absorption effects for nutrients (Nakagawa and Iwatsubo, 2000;Piatek et al, 2009;Bu et al, 2014). Consequently, land-use patterns to some degree determine in-stream nitrogen concentrations.…”

Impacts of Land Use on Surface Water Quality in a Subtropical River Basin: A Case Study of the Dongjiang River Basin, Southeastern China

“…RDA and Spearman analyses corroborated that nutrient parameters (e.g., TP, TN, NH3-N) were strongly negatively correlated with the Pforest and positively correlated with Purban in both seasons. The opposite effects might be the result of low anthropogenic inputs and a high retention of nutrients in forest, which is in contrast to the high loadings and low retention of nutrients in urban lands [41,53,54]. Forested land use generally acts as a nutrient detention zone as nutrients move down stream, which suggests strong biological nutrient retention (e.g., microbial and plant assimilation and microbial denitrification) [23].…”

Importance of within-lake processes in affecting the dynamics of dissolved organic carbon and dissolved organic and inorganic nitrogen in an Adirondack forested lake/watershed

“…Arbutus Lake watershed has been the site of various hydrologic and biogeochemical studies of DOC and DON. Piatek et al (2009) showed that wetlands in the inlet (Archer Creek) catchment played an important role in controlling DOC concentrations within the Arbutus Lake watershed. Mitchell et al (2006) reported on relationships between precipitation patterns and the export of DOC after late summer storms due to increases in water derived from upper soil layers and concomitant decrease in the proportion of ground water contributions.…”