Fluoride and iodine enrichment in groundwater of North China Plain: Evidences from speciation analysis and geochemical modeling

Implications of depositional environment on the iodine enrichment in the sedimentary system: evidences from the N-alkane in sediments

“…Iodine is one of essential trace elements in human body, which is known as "intelligence element". The biogeochemical cycle of iodine is of great concern to many researchers [1,2] , especially the enrichment of iodine in groundwater system [2,3,4] , and watersediment interactions have a great impact on the occurrence of high iodine groundwater. It is critical to understand the sources and mobilization mechanisms of iodine in sedimentary system.…”

“…The North China Plain (NCP), bounded by the Bohai Sea to the east, takes groundwater as the main source of drinking water, however, millions of residents are threatened by waterborne rich iodine [3,4] . Although some studies have been conducted to understand the occurrence of high iodine groundwater at NCP [2,3,4] , the source of iodine in sediments is still not well understood. In this study, we analyze the N-alkane in the borehole sediments collected from a known iodine-contaminated site at NCP to understand the relationships between iodine in sediment and depositional environment.…”

“…The high iodine groundwater was distributed around the position of drill and the redox conditions could affect the migration of iodine [2,3] . The effect of redox condition on iodine enrichment during deposition is also provided by previous research conducted on recent marine sediment [14] , which suggests that high iodine concentration of oxidized sediment is mostly due to easier uptake of iodine relative to phytoplankton at the seafloor and iodine contained in planktonic matter originating in surface waters forms the bulk of iodine in reduced sediment.…”

“…Besides, it is assessed iodine mobilization in the aerobic environment is less than in the anaerobic environment based on laboratory experiment of microalgae [15] . Different geochemical behavior of iodine is related closely to its species, which is also controlled by the redox condition [1,2] . In comparison with iodide, iodate, generally existing in oxic environment, is considered to have greater adsorption ability onto the OM or metal oxides/hydroxides [16] .…”

Nitrogen behavior in the shallow groundwater–soil system within agricultural landscapes

“…This is particularly important for agricultural landscapes, since the content and balance of chemical species in shallow groundwater, as well as in soils, are affected by a serious anthropogenic load due to crop cultivation. Nowadays there is considerable scientific research devoted to the origin of the groundwater chemical composition, transformation and migration of chemical elements in water, in particular under an anthropogenic influence [1][2][3][4]. This research, however, is mainly devoted to the study of elements behavior in groundwater and does not include the soils, while it is obvious that the shallow groundwater-soil system should be considered as a whole [e.g., 5,6], because the formation of the chemical composition of shallow groundwater begins in a soil horizon.…”