Cyanobacteria decay alters CH and CO produced hotspots along vertical sediment profiles in eutrophic lakes.

Cyanobacteria-derived organic carbon has been reported to intensify greenhouse gas emissions from lacustrine sediments. However, the specific processes of CH and CO production and release from sediments into the atmosphere remain unclear, especially in eutrophic lakes. To investigate the influence of severe cyanobacteria accumulation on the production and migration of sedimentary CH and CO, this study examined the different trophic level lakes along the middle and lower reaches of the Yangtze River.

Unexpected increase of sulfate concentrations and potential impact on CH budgets in freshwater lakes.

The continuous increase in sulfate (SO) concentrations discharged by anthropogenic activities lacks insights into their dynamics and potential impact on CH budgets in freshwater lakes. Here we conducted a field investigation in the lakes along the highly developed Yangtze River basin, China, additionally, we analyzed long-term data (1950-2020) from Lake Taihu, a typical eutrophic lake worldwide. We observed a gradual increase in SO concentrations up to 100 mg/L, which showed a positive correlation with the trophic state of the lakes.

Particulate organic carbon potentially increases methane emissions from oxic water of eutrophic lakes.

Lakes are hot spots for methane (CH) emissions and particulate organic carbon (POC) production, which describes the methane paradox phenomenon. However, the current understanding of the source of POC and its effect on CH emissions during eutrophication remains unclear. In this study, 18 shallow lakes in different trophic states were selected to investigate the POC source and its contribution to CH production, particularly to reveal the underlying mechanisms of the methane paradox.

Space-for-time substitution leads to carbon emission overestimation in eutrophic lakes.

Lacustrine eutrophication is generally considered as an important contributor of carbon emissions to the atmosphere; however, there is still a huge challenge in accuracy estimating carbon emissions from lakes. To test the effect of widely used space-for-time substitution on lake carbon emissions, this study monitored different processes of carbon emissions, including the carbon production potential, dissolved carbon concentrations, and carbon release fluxes in eight lakes along the trophic gradients on a spatial scale and the typical eutrophic Lake Taihu for one year on a temporal scale. Eutrophication promoted carbon production potential, dissolved carbon concentrations, and carbon release fluxes, especially for CH.

Second-order moments of Schell-model beams with various correlation functions in atmospheric turbulence.

The general formulae for second-order moments of Schell-model beams with various correlation functions in atmospheric turbulence are derived and validated by the Bessel-Gaussian Schell-model beams and cosine-Gaussian-correlated Schell-model beams. Our finding shows that the second-order moments of partially coherent Schell-model beams are related to the second-order partial derivatives of source spectral degree of coherence at the origin. The formulae we provide are much more convenient to analyze and research propagation problems in turbulence.

Condition for far-zone spectral isotropy of light transmitted from Young's pinholes scattering on a quasi-homogeneous medium.

The far-zone spectral isotropy of light transmitted from Young's pinholes on scattering from a quasi-homogeneous medium has been discussed. A sufficient condition for the far-zone spectral isotropy has been derived as a new scaling law. Our result not only is analogous with the scaling law for weak scattering in previous works but is also applicable for a more general situation where the incident light has an arbitrary spectral degree of coherence.

Simulation of generation and dynamics of polarization singularities with circular Airy beams.

The generation and dynamics of polarization singularities have been underresearched for years, while the focusing property of the topological configuration has not been explored much. In this paper, we simulated the generation of low-order polarization singularities with a circular Airy beam and explored the focusing property of the synthetic light field during propagation due to the autofocusing of the component. Our work researched the focusing properties of the polarization singularity configuration, which may help to develop its application prospect.

[Endpoint Temperature Prediction of the Basic Oxygen Furnace Based on the Flame Temperature Measurement at the Converter Mouth].

In the basic oxygen steelmaking process, the endpoint temperature of the molten steel is one of the key factors whether the molten steel is qualified for tapping. Currently, it mainly relies on the experienced operators to control the endpoint temperature of the molten steel, and the prediction precision may vary among different operators. In order to realize the effectively end-point steel temperature prediction of the basic oxygen furnace as well as to meet the requirement of different sizes of the converter mouth, a new method based on the flame temperature measurement at the converter mouth was proposed in this paper.

Effect of astigmatism on states of polarization of aberrant stochastic electromagnetic beams in turbulent atmosphere.

The effect of astigmatism on states of polarization of aberrant stochastic electromagnetic beams in turbulent atmosphere is investigated. Using the Gaussian-Schell model source with astigmatism, the analytical formula for the degree of polarization, the orientation angle, and the degree of polarization ellipse are derived. Analytical results show that different strengths of astigmatism have different effects on states of polarization on propagation.