Snowpack and precipitation samples were collected along two elevation gradients in the Tahoe Basin during winter and spring from 2011 to 2014 to evaluate spatial and temporal deposition patterns of nitrogen, phosphorus, and mercury. Study results reflect the highly dynamic nature of snowpack chemical storage, while basin-wide estimates identify snowpack chemical loading from atmospheric deposition as a substantial source of nutrient and pollutant input to the Lake Tahoe watershed each year.

Toxicity and effects on various soil microbial parameters of oily waste containing radionuclides in a leaching column experiment were estimated. Microbial metabolic quotient and cellulase activity were mainly influenced by oily components of the waste, but not by radionuclides, and the effect was more pronounced in the upper layer of the column. On the other hand, the structure of bacterial community analyzed using PCR-SSCP was shown to be affected by both hydrocarbons and radioactivity.

We developed a process-based model for evergreen Mediterranean forests. We used multiproxy data including eddy covariance CO2 flux and annual growth dendrochronological time series. The model explicitly takes into account the influence of climatic variability to calculate photosynthesis and carbon allocation. We analyzed long-time acclimation processes and climatic trade-offs between the C-source and the C-sink. There is much potentiality to apply the model at a larger scale.

Despite their global importance, redox reactions mediated by microorganisms are often crudely represented in biogeochemical models. We show that including the dynamics of microbial growth in such a model can cause sudden shifts between redox states in response to an environmental change. We identify the conditions required for these redox regime shifts, and predict that they are likely in the modern day sulfur and nitrogen cycles, and potentially the iron cycle in the ancient ocean.

As high latitudes warm, carbon and nitrogen stored in permafrost soil will be vulnerable to erosion and transport to Arctic streams and rivers. We sampled outflow from 83 permafrost collapse features in Alaska. Permafrost collapse caused substantial increases in dissolved organic carbon and inorganic nitrogen but decreased methane concentration by 90%. Upland thermokarst may be a dominant linkage transferring carbon and nutrients from terrestrial to aquatic ecosystems as the Arctic warms.

Siberian permafrost contains large amounts of organic carbon that may be released by climate warming. We collected and analysed samples from the East Siberian Sea, using GDGT biomarkers to trace the sourcing and deposition of organic carbon across the shelf. We show that branched GDGTs may be used to trace river erosion. Results from modelling show that organic carbon on the shelf is a complex process involving river-derived and coastal-derived material as well as marine carbon production.

Biogenic silica (BSi) is used as a proxy by soil scientists to identify biological effects on the Si cycle and by palaeoecologists to study environmental changes. We show the presence of tephra constituents can make measurements erroneous at low BSi concentrations, with repercussions for soil and palaeoecological studies. However, we also show that glass shards do not produce an identical dissolution signal to that of BSi, meaning they can be distinguished with appropriate experimental setups.

Riverine wetlands of the south Pacific coast of Mexico had large ecosystem C stocks (784.5 MgC ha-1 for mangroves, 722.2 MgC ha-1 for peat swamps, and 336.5 MgC ha-1 for marshes). Long-term soil C sequestration values in mangroves were 1.3 ± 0.2 MgC ha-1yr-1. C stocks, and soil nitrogen stocks were in general larger for mangroves in the upper than in the lower estuary.

We show that the stable (C, N, O) isotopic composition of the water flea Daphnia pulicaria is strongly related to that of its diet (C, N) and the water they live in (O). We also show that the stable isotopic composition of the sheaths of Daphnia resting eggs (ephippia) is indicative of the isotopic composition of Daphnia that produced them. This implies that stable isotope ratios of fossil Daphnia ephippia can provide information on past ecological and climatic developments in and around lakes.

Measurements of concentrations and fluxes of carbon dioxide (CO2) are fundamental to our understanding of carbon cycling and greenhouse gas balances. We are currently limited by the high cost of such measurements, making it difficult to properly investigate variability in space and time. This study presents measurement approaches that are very resource efficient in terms of equipment cost and measurement labor time, opening new opportunities to advance our knowledge of CO2 across landscapes.

Dissolved Fe (dFe) concentrations were measured in the vicinity of the Kerguelen Islands. Direct island runoff, glacial melting, and resuspended sediments were identified as important inputs of dFe that could potentially fertilise the northern part of the plateau. Overall, heterogeneous sources of Fe over and off the plateau, in addition to strong variability in Fe supply by vertical or horizontal transport, may explain the high variability in dFe concentrations observed during this study.

It is shown that inter-annual variations in the primary productivity of mountain grasslands are primarily governed by variations in the length of the snow-free period and to a much lesser extent by temperature and precipitation during the growing season. Meteorological variables controlling snow cover dynamics are thus of paramount importance to understand and model the amount and timing of biomass production in mountain pastures.

We examined the spatial variability in N2O emissions from a tea field in a wet season using 147 static chambers. The N2O fluxes for a 30min snapshot ranged from -1.73 to 1659.11 g N ha-1 d-1 (average flux of 102.24 g N ha-1 d-1). Cokriging with NH4Nt and NO3Nt as covariables (r=0.74 and RMSE=1.18) outperformed ordinary kriging (r=0.18 and RMSE=1.74), regression kriging with the sample position as a predictor (r=0.49 and RMSE=1.55) and cokriging with SOCt as a covariable (r=0.58 and RMSE=1.44).

Stable water isotopes (18O/16O and 2H/1H) are invaluable proxies for paleoclimate research. Here we use a coupled 18O/16O and 2H/1H biomarker approach based on plant-derived sugars and n-alkanes. Applying this innovative approach to a topsoil transect allows for (i) calculating the deuterium-excess of leaf water as a proxy for relative humidity and (ii) calculating the plant source water isotopic composition (~precipitation). The approach is validated by the presented climate transect results.