RESUMO
Dissolved organic matter (DOM) is a heterogeneous mixture of dissolved material found ubiquitously in aquatic systems and dissolved organic nitrogen is one of its most important components. We hypothesised nitrogen species and salinity intrusions affect the DOM changes. Here, using the nitrogen rich Minjiang River as an easily accessible natural laboratory 3 field surveys with 9 sampling sites (S1-S9) were conducted in November 2018, April and August 2019. The excitation emission matrices (EEMs) of DOM were explored with parallel factor (PARAFAC) and cosine-histogram similarity analysis. Four indices including fluorescence index (FI), biological index (BIX), humification index (HIX) and the fluorescent DOM (FDOM) were calculated and the impact of physicochemical properties was assessed. The results suggested that the highest salinities of 6.15, 2.98 and 10.10, during each campaign corresponded to DTN concentrations of 119.29-240.71, 149.12-262.42 and 88.27-155.29 µmol·L-1, respectively. PARAFAC analysis revealed the presence of tyrosine-like proteins (C1), tryptophan-like proteins or a combination of the peak N and tryptophan-like fluorophore (C2) and the humic-like material (C3). The EEMs in the upstream reach (i.e. S1-S3) were complex with larger spectra ranges, higher intensities and similar similarity. Subsequently, the fluorescence intensity of three components decreased significantly with low similarity of EEMs (i.e. S4-S7). At the downstream, the fluorescence levels dispersed significantly and no obvious peaks were seen except in August. In addition, FI and HIX increased, while BIX and FDOM decreased from upstream to downstream. The salinity positively correlated with FI and HIX, and negatively related to BIX and FDOM. Besides, the elevated DTN had a significant effect on the DOM fluorescence indices. Altogether, salinity intrusion and elevated nitrogen are relevant for the distribution of the DOM, which is helpful for the water management tracing the DOM source according to the on-line monitoring of salinity and nitrogen in estuaries.
RESUMO
A range of power generating approaches, such as integration with clothing, fashion accessories, or textiles, allow electronic devices to be charged in environmentally friendly ways. Stretchable, efficient, stable, and even washable solar cells are considered the next necessary component to supply continuous wearable energy. However, ultra-thin photo-active materials are often fragile, which inevitably raises challenges for electron conduction during stretching and washing processes, thus resulting in unsatisfactory output performance. Herein, we have removed the stumbling block by designing a kirigami-inspired unique island-chain structure with serpentine interconnects, which prevented the photo-active layer of subcells from being subjected to excessive strain. Notably, this is the first time perovskite solar cell arrays met the above wearable requirements simultaneously. The obtained devices exhibited a high yet stable power output (efficiency of 17.68%) accompanied by a robust cycling performance (87% of the initial PCE) even after 300 times of continuous stretching with a large ratio of 80%. The efficiency of the optimized PSCs maintains promising stability after being exposed in a harsh environment (80% humidity) for 10 days. As textile-compatible power sources, the successfully designed stretchable and moisture-resistant photovoltaics add power-generation functionality to clothing, opening a new avenue for applications as long-term power sources for wearable electronics.