Cyanobacteria blooms potentially enhance volatile organic compound (VOC) emissions from a eutrophic lake: Field and experimental evidence.

Eutrophication promotes massive cyanobacteria blooms (CBBs), leading to the release of volatile organic compounds (VOCs). To investigate the effects of cyanobacteria on VOC emissions, field campaigns were carried out in eutrophic Chaohu Lake at six sites with different microalgae densities during CBBs in summer 2019, and incubation experiments were performed in the laboratory. The results showed that the lake water was the primary source of VOCs at six sampling sites in Chaohu Lake during CBBs, with an average total VOC flux of 81.2 ± 20.6 µg m-2 h-1. Alkanes were the most abundantly emitted VOCs, with a share of 23.1-63.7% of total emitted VOCs, followed by aromatics (16.6-46.3%). The fluxes of total VOCs were significantly greater at sites B and/or C than at site A in July, and at site B' and/or C' than at site A' in August in Chaohu Lake. The fluxes of total VOCs from living and decayed cyanobacteria in the experimental treatments were two orders of magnitude higher than the corresponding values in the control treatments in the laboratory incubation. Taken together, these results suggested that CBBs potentially enhanced VOC emissions from the eutrophic lake, and that cyanobacteria acted as an important source of VOCs. Additionally, non-methane hydrocarbons (i.e., alkanes, alkenes, and aromatics) predominated among the released VOCs during the stabilization and senescence stages, while oxygenated volatile organic compounds (i.e. alcohols, aldehydes, ketones, esters, and furans) prevailed during the apoptosis stage and aromatics and volatile organic sulfur compounds predominated during the decomposition stage, suggesting that VOC emissions varied markedly at different life stages.

A programmable low power current source for bioimpedance measurement: Towards a wearable personalized health assistant.

Bioimpedance is a noninvasive measurement method that facilitates body composition analysis, besides being indicative of many other health parameters. In this work a novel programmable, low complexity, high output impedance, high voltage compliance and wideband current source for bioimpedance applications is presented. Previously, we designed, fabricated and tested in vivo a bio-patch for acquisition of multiple bio-signals. Upon integration with our previous work, this circuit is envisioned to constitute part of a personalized health assistant. Simulation at worst case corners and real operation conditions was carried out using UMC-180 nm 1 poly 6 metal CMOS process. Full duty cycle, shortened or stepped square waves can be generated. Amplitude control of 8 different current levels is supported. Frequency can be tuned up to 1 MHz and an output impedance of 2.8 MO @ 250 KHz is achieved at full current capacity. Total current consumption is comparable to the injected current, making the circuit highly efficient.