Interdisciplinary science affords new opportunities but also presents new challenges for biogeosciences collaboration. Since 2007, we have conducted site-based interdisciplinary research in central PA, USA, at the Susquehanna Shale Hills critical zone observatory. Early in our collaboration, we realized the need for some best practices that could guide our project team. While we found some guidelines for determining authorship on papers, we found fewer guidelines describing how to collaboratively establish field sites, share instrumentation, share model code, and share data. Thus, we worked as a team to develop a best practices document that is presented here. While this work is based on one large team project, we think many of the themes are universal, and we present our example to provide a building block for improving the function of interdisciplinary biogeoscience science teams.

New techniques are needed to distinguish between leakage of methane (CH4) into surface waters from gas wells and natural sources. Here, scientists worked with >50 citizen scientists in a hydrocarbon-rich basin (Pennsylvania, U.S.A.) to measure methane concentrations ([CH4]) in streams. These measurements were combined with published observations to form a reconnaissance dataset. The dataset was then used to categorize sites as background or as impacted by other sources of gas. For 479 samples at 131 sites, 470 were supersaturated with respect to the atmosphere (>0.08 mu g/L). Sites with the lowest concentrations generally were located in low-productivity, sandstone-underlain upland streams, while other streams contained CH4 from sources in addition to atmospheric. The median of 63 sites not located near wetland habitats and not affected by known thermogenic influxes yielded an estimate of background [CH4] in the streams, 0.5 mu g/L. The highest individual measurements (approximate to 70 mu g/L) in the stream dataset were observed in one site near a wetland and one site near a putatively leaking gas well. Inspection of the dataset revealed that values of [CH4] above a threshold for non-wetland sites, 4 g/L, signals gas is likely deriving from sources such as leaking gas wells, shallow organic-rich shales, coal, or landfills. Using historical and local volunteer knowledge, we discovered 12 non-wetland sites above the threshold that are potentially contaminated by such sources. Although sources of CH4 cannot be proven from such surveys of [CH4], stream sampling with nonscientists nonetheless allows discovery of sites of potential contamination that can be further investigated.

Core Ideas Two new subcatchments are used to test the importance of lithology and land use. Differences in lithology and land use result in differences in soils and waters. Despite differences, all catchments have a shallow and a deep water table. The relative importance of flow paths controls distinct chemistry response to discharge. Cross‐site comparison will ultimately enable upscaling from the catchment to large scale. The footprint of the Susquehanna Shale Hills Critical Zone Observatory was expanded in 2013 from the forested Shale Hills subcatchment (0.08 km2) to most of Shavers Creek watershed (163 km2) in an effort to understand the interactions among water, energy, gas, solute, and sediment. The main stem of Shavers Creek is now monitored, and instrumentation has been installed in two new subcatchments: Garner Run and Cole Farm. Garner Run is a pristine forested site underlain by sandstone, whereas Cole Farm is a cultivated site on calcareous shale. We describe preliminary data and insights about how the critical zone has evolved on sites of different lithology, vegetation, and land use. A notable conceptual model that has emerged is the “two water table” concept. Despite differences in critical zone architecture, we found evidence in each catchment of a shallow and a deep water table, with the former defined by shallow interflow and the latter defined by deeper groundwater flow through weathered and fractured bedrock. We show that the shallow and deep waters have distinct chemical signatures. The proportion of contribution from each water type to stream discharge plays a key role in determining how concentrations, including nutrients, vary as a function of stream discharge. This illustrates the benefits of the critical zone observatory approach: having common sites to grapple with cross‐disciplinary research questions, to integrate diverse datasets, and to support model development that ultimately enables the development of powerful conceptual and numerical frameworks for large‐scale hindcasting and forecasting capabilities.

Core Ideas Studying the critical zone requires targeted research on water, energy, gas, solutes, and sediments. The SSHCZO targets a 165‐km2 watershed on sedimentary rocks in the northeastern United States. One SSHCZO subcatchment, Shale Hills, provides extraordinary data describing a shale CZ. The Susquehanna Shale Hills Critical Zone Observatory (SSHCZO) was established to investigate the form, function, and dynamics of the critical zone developed on sedimentary rocks in the Appalachian Mountains in central Pennsylvania. When first established, the SSHCZO encompassed only the Shale Hills catchment, a 0.08‐km2 subcatchment within Shaver's Creek watershed. The SSHCZO has now grown to include 120 km2 of the Shaver's Creek watershed. With that growth, the science team designed a strategy to measure a parsimonious set of data to characterize the critical zone in such a large watershed. This parsimonious design includes three targeted subcatchments (including the original Shale Hills), observations along the main stem of Shaver's Creek, and broad topographic and geophysical observations. Here we describe the goals, the implementation of measurements, and the major findings of the SSHCZO by emphasizing measurements of the main stem of Shaver's Creek as well as the original Shale Hills subcatchment.

Shale formations account for 25% of the land surface globally and contribute a large proportion of the natural gas used in the United States. One of the most productive shale-gas formations is the Marcellus, a black shale that is rich in organic matter and pyrite. As a first step toward understanding how Marcellus shale interacts with water in the surface or deep subsurface, we developed a reactive transport model to simulate shale weathering under ambient temperature and pressure conditions, constrained by soil and water chemistry data. The simulation was carried out for 10,000 years since deglaciation, assuming bedrock weathering and soil genesis began after the last glacial maximum. Results indicate weathering was initiated by pyrite dissolution for the first 1000 years, leading to low pH and enhanced dissolution of chlorite and precipitation of iron hydroxides. After pyrite depletion, chlorite dissolved slowly, primarily facilitated by the presence of CO2 and organic acids, forming vermiculite as a secondary mineral. A sensitivity analysis indicated that the most important controls on weathering include the presence of reactive gases (CO2 and O-2), specific surface area, and flow velocity of infiltrating meteoric water. The soil chemistry and mineralogy data could not be reproduced without including the reactive gases. For example, pyrite remained in the soil even after 10,000 years if O2 was not continuously present in the soil column; likewise, chlorite remained abundant and porosity remained small if CO2 was not present in the soil gas. The field observations were only simulated successfully when the modeled specific surface areas of the reactive minerals were 1-3 orders of magnitude smaller than surface area values measured for powdered minerals. Small surface areas could be consistent with the lack of accessibility of some fluids to mineral surfaces due to surface coatings. In addition, some mineral surface is likely interacting only with equilibrated pore fluids. An increase in the water infiltration rate enhanced weathering by removing dissolution products and maintaining far-from-equilibrium conditions. We conclude from these observations that availability of reactive surface area and transport of H2O and gases are the most important factors affecting rates of Marcellus shale weathering of the in the shallow subsurface. This weathering study documents the utility of reactive transport modeling for complex subsurface processes. Such modelling could be extended to understand interactions between injected fluids and Marcellus shale gas reservoirs at higher temperature, pressure, and salinity conditions. (C) 2017 Elsevier Ltd. All rights reserved.

Background To date, the majority of protein-based radiopharmaceuticals have been radiolabelled using non-site-specific conjugation methods, with little or no control to ensure retained protein function post-labelling. The incorporation of a hexahistidine sequence (His-tag) in a recombinant protein can be used to site-specifically radiolabel with 99m Tc-tricarbonyl ([ 99m Tc(CO) 3 ] + ). This chemistry has been made accessible via a technetium tricarbonyl kit; however, reports of radiolabelling efficiencies and specific activities have varied greatly from one protein to another. Here, we aim to optimise the technetium tricarbonyl radiolabelling method to produce consistently >95% radiolabelling efficiencies with high specific activities suitable for in vivo imaging. Methods Four different recombinant His-tagged proteins (recombinant complement receptor 2 (rCR2) and three single chain antibodies, α-CD33 scFv, α-VCAM-1 scFv and α-PSMA scFv), were used to study the effect of kit volume, ionic strength, pH and temperature on radiolabelling of four proteins. Results We used 260 and 350 μL [ 99m Tc(CO) 3 ] + kits enabling us to radiolabel at higher [ 99m Tc(CO) 3 ] + and protein concentrations in a smaller volume and thus increase the rate at which maximum labelling efficiency and specific activity were reached. We also demonstrated that increasing the ionic strength of the reaction medium by increasing [Na+] from 0.25 to 0.63 M significantly increases the rate at which all four proteins reach a >95% labelling efficiency by at least fourfold, as compared to the conventional IsoLink® kit (Covidien, Petten, The Netherlands) and 0.25 M [Na+]. Conclusion We have found optimised kit and protein radiolabelling conditions suitable for the reproducible, fast, efficient radiolabelling of proteins without the need for post-labelling purification.

Multiple Critical Zone Observatories (CZO) have been established in recent years in the U.S.A. and elsewhere to conduct collaborative, multidisciplinary research on the earth's critical zone (CZ). As a result, a large amount of scientific data over space and time has been collected. However, heterogeneities in data documentation impede our ability for cross-site comparisons and for integrated analysis. To promote efficient data sharing, publishing, and integration, we developed a sample-based measurement ontology (SMO) to formalize data structures and unify variable terms in data documentations for the CZOs. "Sample" is the core of the SMO. Each sample is part of a "Medium" that represents an entity of the CZ such as soils. Characteristics of a sample are analyzed and the results are reported as values and errors. Based on the concepts of the SMO and geochemical data model of Lehnert et al. (2000), we created a relational database to accommodate CZ regolith geochemical data, namely CZchemDB, to bridge the gap between data collection, documentation and sharing among the CZOs. The CZchemDB has now been successfully implemented in the MS Access database management system for individual or small group uses. However, our ultimate goal is to integrate the CZchemDB with the online global geochemistry data portal, EarthChem, for broader data accessibility and reusability. Finally, we emphasize that the SMO is extensible to all media within the CZ and so CZchemDB can be used to store any sample-based chemical data measured on any medium such as minerals, water, gas, or biota in the CZ.

Soils developed on the Oatka Creek member of the Marcellus Formation in Huntingdon, Pennsylvania were analyzed to understand the evolution of black shale matrix porosity and the associated changes in elemental and mineralogical composition during infiltration of water into organic-rich shale. Making the reasonable assumption that soil erosion rates are the same as those measured in a nearby location on a less organic-rich shale, we suggest that soil production rates have on average been faster for this black shale compared to the gray shale in similar climate settings. This difference is attributed to differences in composition: both shales are dominantly quartz, illite, and chlorite, but the Oatka Creek member at this location has more organic matter (1.25wt.% organic carbon in rock fragments recovered from the bottom of the auger cores and nearby outcrops) and accessory pyrite. During weathering, the extremely low-porosity bedrock slowly disaggregates into shale chips with intergranular pores and fractures. Some of these pores are either filled with organic matter or air-filled but remain unconnected, and thus inaccessible to water. Based on weathering bedrock/soil profiles, disintegration is initiated with oxidation of pyrite and organic matter, which increases the overall porosity and most importantly allows water penetration. Water infiltration exposes fresh surface area and thus promotes dissolution of plagioclase and clays. As these dissolution reactions proceed, the porosity in the deepest shale chips recovered from the soil decrease from 9 to 7% while kaolinite and Fe oxyhydroxides precipitate. Eventually, near the land surface, mineral precipitation is outcompeted by dissolution or particle loss of illite and chlorite and porosity in shale chips increases to 20%. As imaged by computed tomographic analysis, weathering causes i) greater porosity, ii) greater average length of connected pores, and iii) a more branched pore network compared to the unweathered sample.This work highlights the impact of shale–water–O2 interactions in near-surface environments: (1) black shale weathering is important for global carbon cycles as previously buried organic matter is quickly oxidized; and (2) black shales weather more quickly than less organic- and sulfide-rich shales, leading to high porosity and mineral surface areas exposed for clay weathering. The fast rates of shale gas exploitation that are ongoing in Pennsylvania, Texas and other regions in the United States may furthermore lead to release of metals to the environment if reactions between water and black shale are accelerated by gas development activities in the subsurface just as they are by low-temperature processes in our field study.

Having an accurate method to estimate and remove ionospheric effects is a major issue for low-frequency radio astronomy arrays, as the ionosphere is one of their largest error terms. One way to estimate the ionosphere is to measure total electron content (TEC) using dual frequency global positioning system (GPS) signals. This technique uses the dispersive nature of the ionosphere, as both group and phase velocities are (to first order) dependent on the inverse square of the frequency and on TEC. Using these properties, TEC can be measured to a high degree of accuracy by computing the delay difference between signals at GPS's two frequencies (L1=1575.42 and L2=1227.6MHz). Unfortunately, effects other than ionospheric dispersion also introduce differential delay differences. These additional differences, called biases, can be separated into those introduced by the satellite and those by the receiver. Receiver biases show the most significant variations, sometimes over intervals of hours. Changing temperature conditions at the receiver antenna, along the cable, or in the internal receiver hardware are thought to be responsible for some of these variations. We report here on an investigation of the temperature dependence of the GPS receiver bias. Our results show that for our particular receiver, antenna, and cable set-up, a temperature-dependent bias is clearly evident, and that this temperature dependence varies from receiver to receiver. When the receiver bias temperature dependence is removed, a noise level of 13 TEC units still remains in the bias estimation.

We recently described a novel amino acid sequence, KCKLAAALEHHHHHH, for site-specific radiolabelling of proteins with [99mTc(CO)3(OH2)3]+ or [Re(CO)3(OH2)3]+ with improved efficiency compared to conventional hexahistidine tags (His-tag). C2AH, a modification of the protein C2A (the phosphatidylserine (PS)-binding domain of rat synaptotagmin I) engineered to contain this novel C-terminal tag, was produced. Rhenium tricarbonyl conjugates of C2AH were analysed post tryptic digest by liquid chromatography-electrospray mass spectrometry (LC-MS), giving rise to a peak with the molecular weight corresponding to M+ = [Re(CO)3 + CK + LAAALEHHHHHH]+. This species arises as a result of trypsin cleavage on the C-terminus of both the lysine (Lys) residues on either side of the Cys while both fragments still remain bound to the rhenium. This confirmed that cysteine (Cys) was directly involved in the coordination of the rhenium tricarbonyl. To demonstrate the superiority of the cysteine containing His-tag sequences for binding [Re(CO)3]+, two peptides CKLAAALEHHHHHH and LAAALEHHHHHH were synthesised. In a competition experiment the mixed peptides were incubated with one molar equivalent of [Re(CO)3(H2O)3]+, and LC-ESMS demonstrated that 92% and 9% of CKLAAALEHHHHHH and LAAALEHHHHHH respectively were co-ordinated by one [Re(CO)3]+.

1552 Objectives Radiolabelling proteins site-specifically is important for the future development of molecular imaging. We previously demonstrated that a novel cysteine/hexahistidine sequence, KCKLAAALEHHHHHH, can be used for the improved (compared to the simple hexahistidine tag) site-specific labelling of proteins with [99mTc(CO)3(OH2)3]+ or [188Re(CO)3(OH2)3]+. Here, we report further studies to determine the role of the cysteine residue and investigate the combination of a Cys and His-tag for improved site-specific labelling of proteins. Methods A protein, C2AcH engineered to contain the novel tag was conjugated to [Re(CO)3]+ and subjected to tryptic digest. Peptide sequence analogues of the novel tag have been synthesised with and without the cysteine residue. Radiolabelling studies with [99mTc(CO)3]+ and LCMS/HPLC analysis with [Re(CO)3]+-bound peptides have been carried out. Results The [99mTc(CO)3]+ labelling efficiency of the cysteine/his-tag in comparison to the generic his-tag is substantially increased: a radiochemical yield of 97%, with fewer isomeric forms, can be achieved after 15 minutes at 37oC whereas without a cysteine the same yield is achieved after 1 hour. LCMS analysis post tryptic digest of the [C2AcH-Re(CO)3]+ revealed a fragment where M+ = [CK + LAAALEHHHHHH-Re(CO)3]+. Cleavage has occurred at the C-terminal of the lysine on either side of the cysteine. Both the hexahistidine sequence and the hydrolysed CK dipeptide remain bound to the [Re(CO)3]+. Further studies with MS/MS confirmed that once bound to [Re(CO)3]+ peptide fragmentation does not occur from the N-terminal cysteine. Conclusions The combination of a cysteine and his-tag has significantly improved the radiolabelling efficiency of proteins with [99mTc(CO)3]+ and [Re(CO)3]+. The cysteine is directly involved in the coordination to the rhenium core which suggests that improved labeling kinetics and stability is due to the binding of [Re(CO)3]+ to the imidazole groups of two histidines and the cysteine thiol

The complex weathering processes which govern the production of soil from bedrock have proven difficult to understand for many lithologies. Weathering of black shale is of particular interest because it releases organic carbon and heavy metals as solutes and therefore impacts the health of terrestrial and aquatic ecosystems. To understand black shale weathering, a geochemical survey was initiated for soils developed on shales of the Marcellus Formation at a zero-order catchment at a satellite site of the Susquehanna/Shale Hills Critical Zone Observatory located in Jackson Corner, Pennsylvania. This formation is an organic- and metal-rich, carbonaceous shale that underlies much of New York, Pennsylvania, Ohio and West Virginia. In this paper, we focus on the effects of weathering on variations of Cu isotopes in the shale. Cu concentration data for soil were normalized using Ti concentrations to document the mobility of Cu relative to bedrock. At both the ridgetop and valley floor, depletion profiles for Cu are documented in the soils. The Cu in the soils is depleted in 65Cu (average δ65Cu=−0.5‰±0.2) compared to the parent material (average δ65Cu=0.03‰±0.15). Consistent with loss of Cu from soils, the pore waters contain 10ppb Cu on average and are enriched in the heavy isotope (average value δ65Cu=1.14‰±0.44). Rayleigh fractionation models using the concentration and isotope data of the soils are consistent with pyrite weathering and loss of Cu from the ridgetop, but downslope transport and Cu re-precipitation at the valley floor.

Basaltic bedrock dissolves quickly, and its weathering rate is therefore important towards controlling the composition of natural waters, soil formation, and CO2 concentrations in the atmosphere. Despite its importance, however, few reports of basalt or diabase and gabbro weathering rates exist in the literature, and most have been measured in laboratory dissolution experiments or based on watershed studies. Here, using elemental profiles measured through regolith on a Jurassic diabase dike in south-central Pennsylvania, we calculate time-integrated log dissolution rates (molm−2s−1) of the primary minerals plagioclase (−14.9s−1) and augite (−14.8), and of smectite (−17.6), a secondary clay mineral formed in the soil. Characteristic patterns in elemental profiles are consistent with preserved signatures of corestone formation. Elemental and mineral signatures of the soils relative to the parent rock are compared to predictions from citrate-containing basalt column dissolution experiments. Depletion of apatite and of Al, Fe, Mn, Ti, P, Y, Ni, Cr, Sc, V, Ga, Cu, Zn, and La are observed in the upper meter of the profile relative to the parent rock.

Multiple Critical Zone Observatories (CZO) have been established in recent years in the USA and other international settings to conduct collaborative research on processes that occur at and near Earth’s surface, also known as the Critical Zone (CZ). Data documentation and data sharing are two persistent problems facing the CZOs that impede the ability for cross-site comparisons and integrated analysis. In this study, a relational database was developed for CZ rock and regolith geochemical data – CZChemDB. There are a total of 24 interrelated tables in the database, each representing different aspects of CZ features. The main data group includes tables of locations, sites, samples, subsamples, preparation/treatments, laboratory-analysis and data values. The meta-data group includes tables of methods, references, and data quality. Lookup tables (variables, units, etc.) contain lists of “controlled” vocabularies. The CZChemDB is currently implemented in the MS Access database management system. It is expected to be integrated into the EarthChem portal by summer of 2011 for broader online accessibility and usability. This integration also complements the EarthChem’s global geochemistry database with CZ regolith data. The structure of the CZChemDB is simple, straightforward, and flexible so that it has potential to accommodate other chemical data collected from CZOs, such as pore fluid data. Furthermore, the development of CZChemDB represents the first attempt toward the standardization of geochemical data documentation and data sharing among CZOs. This effort will establish a model to bridge the connections between data acquisition, data management, data sharing, and data searching/discovering that are all essential but weak in terms of linkages within most geoscience research projects.

Anthropogenic and natural climate change affect processes in the atmosphere, biosphere, hydrosphere, and pedosphere. The impact of climate on soil evolution has not been well-explored, largely due to slow rates and the complexity of coupled processes that must be observed and simulated. The rates of mineral weathering in loess deposited 23kyr ago and experiencing soil formation for 13kyr are explored here using the WITCH model for weathering and the GENESIS model for climate simulation. The WITCH model, which uses rigorous kinetic parameters and laws with provision for the effect on rates of deviation from equilibrium, can successfully simulate the depletion profiles in the soil for dolomite and albite if soil CO2 is assumed to rise over the last 10kyr up to about 30–40× the present atmospheric pressure, and if the solubility product of the Ca-smectite is assumed equal to that of an Fe(III)-rich Ca-montmorillonite. Such simulations document that dissolution behavior for silicates and carbonates are strongly coupled through pH, and for Ca-smectite and feldspars through dissolved silica. Such coupling is not incorporated in simple geometric and analytical models describing mineral dissolution, and therefore probably contributes to the long-standing observation of discrepancies among laboratory and field mineral dissolution rates.

Soils developed over the last 10–13ky on Peoria loess along a transect parallel to the Mississippi River spanning ∼1600km from north to south were investigated to estimate the effects of climate on rates of chemical weathering. In the 22 soils, Na concentrations generally decreased from parent composition to the surface, defining depletion profiles that document the weathering of plagioclase. The integrated fraction of Na (f) dissolved from each profile varied from ∼0 in the north to 26% in the south. This variation is attributed to an increase in average precipitation and temperature from the north (today's average values: 0.5m/y, 7.5°C) to the south (1.2m/y, 20.3°C). We used the output from the GENESIS v2 Global Climate Model (GCM) to calculate the mean annual temperature, precipitation, and porefluid advection velocity, v, through the soils for three time points during the last 13,000y in order to quantify the effect of temperature on Na depletion. To interpret the soils quantitatively, the Na concentration-depth profiles were fit to a sigmoidal model equation that yielded three fit parameters: (i) a lumped kinetic parameter related to the reaction front thickness (K), (ii) the Na concentration in soil at the surface (Cz=0), and (iii) the Na concentration at depth in the parent (Co). The product Kv, the fraction f, and the concentration difference, Co−Cz=0, were all observed to vary with temperature along the transect. According to the derivation and assumptions of the sigmoidal model, these values are all functionally related to the dissolution rate constant of albite. The variation in temperature can be explained for Kv and (Co−Cz=0) based on laboratory values of the activation energy, Ea, for albite dissolution. In contrast, for the case of f, the temperature dependence is larger than Ea because it incorporates contributions from both Ea and the reaction enthalpy, ΔH, of albite dissolution. Furthermore, the temperature dependence determined from Co−Cz=0 yields the best estimate of activation energy for albite dissolution, Ea=75±14kJ/mol, because it is not dependent upon the assumptions of soil texture. Such quantitative interpretations of soil profiles will be useful in predicting the effects of climate on soil chemistry.

Sensitivity of the chemical weathering of the continents to environmental gradients Y. GODDERIS1*, A. VIOLETTE1, E. BEAULIEU1, J.Z. WILLIAMS2, C. ROELANDT3, N. VIGIER4, J. SCHOTT1, D. POLLARD2, M.-C. PIERRET5 AND S. BRANTLEY2 1LMTG, CNRS-Université de Toulouse, France (godderis@lmtg.obs-mip.fr) 2CEKA, PennState University, USA 3University of Bergen, Norway 4CRPG, Nancy, France 5CGS, Strasbourg, France