Response of mineral particles in inland lakes to water optical properties and its influence on chlorophyll-a estimation.

Many chlorophyll-a (Chl-a) remote sensing estimation algorithms have been developed for inland water, and they are proposed always based on some ideal assumptions, which are difficult to meet in complex inland waters. Based on MIE scattering theory, this study calculated the optical properties of mineral particles under different size distribution and refractive index conditions, and the Hydrolight software was employed to simulate remote sensing reflectance in the presence of different mineral particles. The findings indicated that the reflectance is significantly influenced by the slope (j) of particle size distribution function and the imaginary part (n') of the refractive index, with the real part (n) having a comparatively minor impact.

Sources and seasonal variations of nitrate in the coastal multiple-aquifer groundwater of Beihai, southern China.

Elevated nitrate (NO) loadings in groundwater may cause health effects in drinking water and nutrient enrichment of aquatic ecosystems. To reveal the sources and seasonal variations of NO in the coastal groundwater of Beihai, southern China, we carried out hydrochemical and isotopic (δN-δO in NO) investigations in the summer and winter, respectively, concerning multiple-aquifer groundwater, rainwater, seawater, and surface water. The sources of the main elements present in the waters were interpreted by ionic ratios.

[Hydrochemical Characteristics and Formation Mechanism of Groundwater in the Western Region of Hepu Basin, Beihai City].

Beihai City is a typical coastal city where groundwater provides a strong support for social and economic development. Studies on the hydrochemical characteristics and formation mechanism in Beihai City play an important role in the scientific management of water resources and coastal ecological environment protection. In this study, we revealed the main hydrogeochemical processes controlling groundwater quality by means of groundwater survey and water sample collection in the western region of Hepu Basin, Beihai City, combined with hydrochemistry and isotope theories and methods.

An operational approach for large-scale mapping of water clarity levels in inland lakes using landsat images based on optical classification.

Water clarity is a critical parameter of water, it is typically measured using the setter disc depth (SDD). The accurate estimation of SDD for optically varying waters using remote sensing remains challenging. In this study, a water classification algorithm based on the Landsat 5 TM/Landsat 8 OLI satellite was used to distinguish different water types, in which the waters were divided into two types by using the a(443)/a(443) ratio.

A classification-based approach to mapping particulate organic matter (POM) in inland water using OLCI images.

Particulate organic matter (POM) plays a major role in freshwater ecosystems by serving as a bridge for the conversion of various nutrients. The composition and sources of POM in inland lakes are complex, making it difficult to estimate its concentration accurately via remote sensing. Therefore, a classification-based method based on the sources and composition of POM is proposed for estimating POM concentrations in inland lakes.

Long-term monitoring particulate composition change in the Great Lakes using MODIS data.

Particulate composition provides important information for understanding the changes in underwater light fields and primary productivity. In this study, a semianalytical algorithm, based on Rayleigh-corrected reflectance at 678 nm and 748 nm on Moderate Resolution Imaging Spectroradiometer (MODIS) images was used to estimate the ratio of chlorophyll a to total suspended solids (Chla/TSS), which characterizes the particulate composition of the Great Lakes. The long-term spatial and temporal characteristics of Chla/TSS in the Great Lakes from 2000 to 2020 were obtained.

Is there any difference on cyanobacterial blooms patterns between Lake Chaohu and Lake Taihu over the last 20 years?

Serious cyanobacterial blooms (CBs) caused by lake eutrophication have become a global ecological and environmental problem and have adversely affected the production, life, and health of human beings. Lake Chaohu and Lake Taihu are two large closed shallow eutrophication lakes in the Yangtze River Delta in China with frequent CBs. In this study, the floating algae index (FAI) algorithm was applied to detect a long-time CBs sequence using Moderate Resolution Imaging Spectroradiometer (MODIS) images from 2000 to 2019.

[Hydrogeochemical Investigations of Groundwater in the Lingbei Area, Leizhou Peninsula].

Groundwater is an important source of water supply in the Leizhou Peninsula. In August 2018, five surface water samples, 18 shallow pore water samples, 14 middle-deep pore water samples, and 27 pore fissure water samples were collected in the Lingbei area, the northern part of the Leizhou Peninsula. Major ion concentrations, as well as H, O isotope composition (of O and H) were analyzed.

Characteristics of the chromophoric dissolved organic matter of urban black-odor rivers using fluorescence and UV-visible spectroscopy.

Urban black-odor water (BOW) is a typical phenomenon seen in the urban water environment; it is caused by excessive pollution by organic matter and other pollutants, such as nitrogen and phosphorous. Chromophoric dissolved organic matter (CDOM) is a major optical fraction of dissolved organic matter. In this study, optical properties and components of CDOM were obtained from 178 river samples collected from five cities in China, the sample were investigated using absorption and fluorescence spectroscopy.

Analytical model for plasmon modes in graphene-coated nanowire.

An analytical model for plasmon modes in graphene-coated dielectric nanowire is presented. Plasmon modes could be classified by the azimuthal field distribution characterized by a phase factor exp(imφ) in the electromagnetic field expression and eigen equation of dispersion relation for plasmon modes is derived. The characteristic of plasmon modes could be tuned by changing nanowire radius, dielectric permittivity of nanowire and chemical potential of graphene.

Sediment geochemistry and arsenic mobilization in shallow aquifers of the Datong basin, northern China.

Understanding the mechanism of arsenic (As) mobilization from sediments to groundwater is important for water quality management in areas of endemic arsenic poisoning, such as the Datong basin in northern China. The bulk geochemistry analysis of sediment samples from three 50-m boreholes drilled specifically for this study at As-contaminated aquifers, the groundwaters of which have an As concentration up to 1060 microg/l, revealed that the average bulk concentrations of major and trace elements of the samples are similar to those of the average upper continental crust. The average As content of the sediment samples (18.