A multiplexed pumping system (MPS) for obtaining continuous water quality data at multiple locations was previously reported. The existing design was not practical for sampling water in volume-limited applications such as small mesocosms or porewater sampling. This paper discusses the design and performance of a small-volume MPS and illustrates two applications, showing spatial variability in replicate in situ mesocosms and short-circuiting in a woodchip bioreactor using porewater sampling.

Artificial water bodies are a major source of methane and an important contributor to flooded land greenhouse gas emissions. Past studies focussed on large water supply or hydropower reservoirs with small artificial water bodies (ponds) almost completely ignored. This regional study demonstrated ponds accounted for one-third of flooded land surface area and emitted over 1.6 million t CO₂ eq. yr⁻¹ (10 % of land use sector emissions). Ponds should be included in regional GHG inventories.

The dual nitrate isotope technique is one of the most commonly used approaches to study the origin and fate of N introduced in aquifers. In this study, we first demonstrate a large attenuation of groundwater N at a former industrial site, especially at the interface between surface and groundwater. We also provide evidence for a switch in the oxygen isotopic signature of groundwater due to this extensive N attenuation. This could be used to better quantify N attenuation processes in aquifers.

In the present study we combined measurements of dissolved inorganic carbon (DIC) isotopes with a set of different geochemical and microbiological methods in order to get a comprehensive view of biogeochemical cycling and groundwater flow in two limestone aquifer assemblages. This allowed us to understand interactions and feedbacks between microbial communities, their carbon sources, and water chemistry.

The influence of riparian evapotranspiration (ET) on stream hydrology and chemistry is poorly understood. We investigated temporal changes in riparian ET, stream discharge and nutrient chemistry along a Mediterranean catchment. Despite being a small component of annual water budgets (4.5 %), our results highlight that riparian ET drives stream and groundwater hydrology in Mediterranean catchments and, further, question the potential of the riparian zone as a natural filter of nitrogen loads.

The goal of this study was to compare how differences in urban stream restoration and sanitary infrastructure affect sources and fluxes of water and nutrients. Stream restoration reduced peak discharge and lowered nutrient export compared to unrestored streams, but was similar to a stream with upland stormwater management. The primary source of nitrate at all sites was leaky sanitary sewers, suggesting that combining stream restoration with sanitary pipe repairs may help reduce nutrient loads.

Development of unconventional energy resources if often associated with public concerns regarding potential contamination of shallow groundwater due to methane leakage. We combined chemical and isotopic analyses of gas and water samples obtained from shallow aquifers in Alberta (Canada) to assess baseline methane sources and found that > 67 % of the samples contained biogenic methane formed in situ in the aquifers. There was no evidence of deep thermogenic methane migration into shallow aquifers.