The distinctly different, εNd(0) values of the Atlantic, Indian, and Pacific Oceans requires that the residence time of Nd in the ocean (i.e., τNd) be on the order of, or less than, the ocean mixing time of ∼500–1500 yr. However, estimates of τNd, based on river influxes, range from 4000 to 15,000 yr, thus exceeding the ocean mixing time. In order to reconcile the oceanic Nd budget and lower th...

We analyze the combined effects of aquifer heterogeneity and pumping operations on seawater intrusion (SWI) in coastal aquifers, a phenomenon which is threatening Mediterranean and worldwide regions. We conceptualize the aquifer as a three-dimensional randomly heterogeneous porous medium, where the spatial distribution of permeability is uncertain. The geological setting of our study is pattern...

Water stored as ice and snow at high elevations is a resource that plays an important role in the hydrologic cycle, particularly in the timing and volume of downstream discharge. Here we use geochemical and isotopic values of water samples to evaluate relative contributions of melting glacier ice and groundwater to discharge in Bhutan. River water samples were collected between 3100 and 4500m i...

It is important to simulate a groundwater transport process, e.g., pollutant migration, through the vadose zone and subsequent mixing within the saturated zone to assess potential impacts of contaminants in the subsurface in preliminary stages. It is challenging to simulate heterogeneous soil characteristics and non-uniform initial contaminant concentration. This paper proposes a vertically het...

In the coastal multilayer aquifer system of a highly urbanized southern city (Recife, Brazil), where groundwaters are affected by salinization, a multi-isotope approach (Sr, B, O, H) was used to investigate the sources and processes of salinization. The high diversity of the geological bodies, built since the Atlantic opening during the Cretaceous, highly constrains the heterogeneity of the gro...

Keywords: Climate impacts Groundwater hydrology Infiltration Water supply Isotopes s u m m a r y High elevation groundwater basins in the western United States are facing changes in the amount and timing of snowmelt due to climate change. The objective of this study is to examine seasonal variability in a high elevation aquifer (Martis Valley Watershed near Truckee, CA) by analyzing (1) tritium...

We used the natural geochemical tracers radon-222 and radium isotopes (223Ra, 224Ra, 226Ra, 228Ra) to assess exchange rates between the Chao Phraya River and the Gulf of Thailand, and the magnitude of groundwater discharge in the estuary. We performed tracer surveys during two periods in 2004, in January (dry season, gauged river discharge 47 m3 s21) and in July (wet season, 430 m3 s21). The is...

Isotopic fingerprinting is an advanced technique allowing the classification of the nitrate source pollution of groundwater, but needs further development and validation. In this study, we performed measurements of natural stable isotopic composition of nitrate ((15)N and (18)O) in the groundwater body of the Brussels sands (Belgium) and studied the spatial and temporal dynamics of the isotope ...

Warm and cold subaquatic groundwater discharge into Lake Kivu forms the large-scale density gradients presently observed in the lake. This structure is pertinent to maintaining the stratification that locks the high volume of gases in the deepwater. Our research presents the first characterisation of these inflows. Temperature and conductivity profiling was conducted from January 2010 to March ...

The present study assessed the export of inorganic carbon, nitrogen, and phosphorus within a large agricultural basin in arid northwestern China. Groundwater of various depths and river water along a 160 km reach were sampled during contrasting flow conditions. Dissolved inorganic carbon (DIC) concentrations and δ13C-DIC values indicate that lithogenic carbonate weathering was the main source o...