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The migration, transformation, and accumulation of dissolved organic matter (DOM) in pore water of sediment cores play a pivotal role in lacustrine carbon cycling. In order to understand the dynamics of DOM in the sediments of large shallow eutrophic lakes, we examined the vertical profiles of DOM and the benthic fluxes of dissolved organic carbon (DOC) in sediment cores located in algae accumulated, dredged, and central areas of eutrophic Lake Taihu, China. Optical properties showed the significant influence of terrestrial inputs on the DOM components of pore water in the algae accumulated area but an abundant accumulation of autochthonous DOM in the central area. The benthic fluxes of DOC ranging from −458.2 to −139.4 mg·m−2·d−1 in the algae accumulated area displayed an opposite diffusion direction to the other two areas. The flux ranges of 9.5–31.2 mg·m−2·d−1 in the dredged area and 14.6–48.0 mg·m−2·d−1 in the central area were relatively smaller than those in the previously reported lake ecosystems with low trophic levels. Dredging engineering disturbed the pre-dredging distribution patterns of DOM in sediment cores. The deposition, accumulation, and transformation of massive algae scums in eutrophic lakes probably promoted the humification degree of sediments. HIGHLIGHTS Terrestrial input significantly affected the dissolved organic matter (DOM) components of the algae accumulated area.; DOC diffusion direction of the algae accumulated area was opposite to the other areas.; Dredging work disturbed the pre-dredging distribution patterns of DOM in sediment cores.; Biogeochemical processes of accumulated algae scums probably promoted humification.;

Due to the large amount of water supply, the water level difference between mid-layer water and shallow water increases. There is no authoritative answer whether there is a hydraulic connection between shallow and mid-layer water. Therefore, a clear understanding of hydrogeochemical characteristics and the water chemical connection of them is indispensable for groundwater protection and the safety of water supply. The results of the statistical analysis showed that shallow and mid-layer water were both neutral water. The content of SO42−, Cl− and Na+ in both exceeded the grade III standard limit in the Standard for Groundwater Quality of China. Piper diagram revealed shallow water was mainly of Na + Mg + HCO3− and Mg + Na + HCO3− type, and mid-layer water was mainly of Na + Mg + HCO3− + SO42− and Na + Mg + HCO3− type. Besides, using the coefficient variations method of comprehensive water quality index (pH, TDS, F−, and NO3−), it is found that except for a local area with thin thickness (less than 5 m) of the first aquiclude, the mid-layer water was not affected by shallow water in Sulin mining area. This study may be helpful for the safety of water supply in the study area and other mining areas in the Huaibei coalfield. HIGHLIGHTS First analysis on the hydraulic connection between shallow and mid-layer water by using comprehensive water quality indexes.; The relationship between the thickness of the first aquiclude and the vatiation of nitrate content in mid-layer water and shallow water.; Sources of fluorine in mid-layer water.;

Nitrate pollution in groundwater is a global environmental concern. As a result, accurate identification of potential sources for such pollution is of critical significance to the effective control of groundwater quality. In this study, forty-nine shallow groundwater samples were collected from the Huaibei mining area. Hydro-chemical characterization, geospatial analysis technique, dual nitrate isotopes (δ15N-NO3- and δ18O-NO3-), Bayesian model and health risk assessment model were adopted for exploring the conditions, sources, proportion, and potential health risks of nitrate pollution for the first time in the study area. The results showed that the nitrate concentration ranged from 0.00 to 293.21 mg/L, and that 18.37% groundwater samples exceeded the standard of drinking water in China (GB 5749–2006). Based on the dual isotopic values of nitrate, it could be concluded that nitrification was dominated migration and transformation process of nitrogen. The results of Bayesian model showed that the proportional contributions of the potential nitrate pollution sources in shallow groundwater were manure and sewage (M&S) (39.54 %), NH4+ in fertilizer and precipitation (NHF&P) (34.93 %), soil nitrogen (SN) (14.89 %), and NO3- in atmospheric deposition (NAD) (10.64 %). The health risk assessment indicated that non-carcinogenic risks posed by NO3--N was higher for children than adults. The primary exposure pathway was oral ingestion. Monte Carlo simulation were applied to evaluate model uncertainty. The probabilities of non-carcinogenic risks were up to 12.54 % for children and 5.22 % for adults. In order to protect water quality and drinking water safety, it was suggested that effective nitrate reduction strategies and better management practices can be implemented.

A crucial link of electroencephalograph (EEG) technology is the accurate estimation of EEG electrode positions on a specific human head, which is very useful for precise analysis of brain functions. Photogrammetry has become an effective method in this field. This study aims to propose a more reliable and efficient method which can acquire 3D information conveniently and locate the source signal accurately in real-time. The main objective is identification and 3D location of EEG electrode positions using a system consisting of CCD cameras and Time-of-Flight (TOF) cameras. To calibrate the camera group accurately, differently to the previous camera calibration approaches, a method is introduced in this report which uses the point cloud directly rather than the depth image. Experimental results indicate that the typical distance error of reconstruction in this study is 3.26 mm for real-time applications, which is much better than the widely used electromagnetic method in clinical medicine. The accuracy can be further improved to a great extent by using a high-resolution camera.