Seasonal variation of nitrogen biogeochemical processes constrained by nitrate dual isotopes in cascade reservoirs, Southwestern China.

The increase of affected river reaches by reservoirs has drastically disturbed the original hydrological conditions, and subsequently influenced the nutrient biogeochemistry in the aquatic system, particularly in the cascade reservoir system. To understand the seasonal variation of nitrogen (N) behaviors in cascade reservoirs, hydrochemistry and nitrate dual isotopes (δN-NO and δO-NO) were conducted in a karst watershed (Wujiang River) in southwest China. The results showed that NO-N accounted for almost 90% of the total dissolved nitrogen (TDN) concentration with high average concentration 3.

Quadrupole detection FT-ICR mass spectrometry offers deep profiling of residue oil: A systematic comparison of 2ω 7 Tesla versus 15 Tesla instruments.

Mass resolving power is one of the key features of Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS), which enables the molecular characterization of complex mixtures. Quadrupole (2ω) detection provides a significant step forward in FT-ICR MS performance, as it doubles the resolving power for a given signal acquisition time. Whether this 2ω detection technique truly substitutes for a higher magnetic field remains unknown however.