We conducted an inverse modeling analysis, using a variety of data streams (tower-based eddy covariance measurements of net ecosystem exchange, NEE, of CO2, chamber-based measurements of soil respiration, and ancillary ecological measurements of leaf area index, litterfall, and woody biomass increment) to estimate parameters and initial carbon (C) stocks of a simple forest C-cycle model, DALEC, using Monte Carlo procedures. Our study site is the spruce-dominated Howland Forest AmeriFlux site, in central Maine, USA. Our analysis focuses on: (1) full characterization of data uncertainties, and treatment of these uncertainties in the parameter estimation; (2) evaluation of how combinations of different data streams influence posterior parameter distributions and model uncertainties; and (3) comparison of model performance (in terms of both predicted fluxes and pool dynamics) during a 4-year calibration period (1997–2000) and a 4-year validation period (“forward run”, 2001–2004). We find that woody biomass increment, and, to a lesser degree, soil respiration, measurements contribute to marked reductions in uncertainties in parameter estimates and model predictions as these provide orthogonal constraints to the tower NEE measurements. However, none of the data are effective at constraining fine root or soil C pool dynamics, suggesting that these should be targets for future measurement efforts. A key finding is that adding additional constraints not only reduces uncertainties (i.e., narrower confidence intervals) on model predictions, but at the same time also results in improved model predictions by greatly reducing bias associated with predictions during the forward run.

Selection of an appropriate model for respiration (R) is important for accurate gap-filling of CO2 flux data, and for partitioning measurements of net ecosystem exchange (NEE) to respiration and gross ecosystem exchange (GEE). Using cross-validation methods and a version of Akaike's Information Criterion (AIC), we evaluate a wide range of simple respiration models with the objective of quantifying the implications of selecting a particular model. We fit the models to eddy covariance measurements of whole-ecosystem respiration (Reco) from three different ecosystem types (a coniferous forest, a deciduous forest, and a grassland), as well as soil respiration data from one of these sites. The well-known Q10 model, whether driven by air or soil temperature, performed poorly compared to other models, as did the Lloyd and Taylor model when used with two of the parameters constrained to previously published values and only the scale parameter being fit. The continued use of these models is discouraged. However, a variant of the Q10 model, in which the temperature sensitivity of respiration varied seasonally, performed reasonably well, as did the unconstrained three-parameter Lloyd and Taylor model. Highly parameterized neural network models, using additional covariates, generally provided the best fits to the data, but appeared not to perform well when making predictions outside the domain used for parameterization, and should thus be avoided when large gaps must be filled. For each data set, the annual sum of modeled respiration (annual ΣR) was positively correlated with model goodness-of-fit, implying that poor model selection may inject a systematic bias into gap-filled estimates of annual ΣR.

Thirty five years of water quality data from a pumped, mostly flooded, mine-pool were examined for trends in mine drainage parameters.At the start of pumping in 1970, the Lancashire 15 mine-pool discharged acidic water with average iron (Fe) concentration exceeding 900 mg/L.Average sulfate (SO 4 ) concentration was about 3700 mg/L.After 14 years of pumping about 21 minepool volumes, Fe and SO 4 were about 20% of their initial concentrations.Alkalinity had increased from less than 50 to about 120 mg/L, and pH was about 6.0.In 1986, an overlying mine complex closed and flooded.Its' waters have low concentrations of Fe and SO 4 , and are hydraulically connected to the Lancashire 15 mine-pool.The combined mine-pool waters reduced Fe by about 50% in Lancashire 15.Since 1986, Fe and SO 4 concentrations have continued a slow, irregular decline at the rate of 1 to 2 mg/L/yr for Fe and about 10 to 15 mg/L/yr for SO 4 .Short term fluctuations due to seasonal and pump rate variations occur, but long term concentration trends can be described with curvilinear models.The Lancashire 15 discharge is sodium-sulfate (Na-SO 4 ) type water.Geochemical calculations show that cation exchange of calcium (Ca) for Na is a feasible explanation for the observed water composition.Mixing calculations show that mine-pool composition can be explained by cation exchange; continuing dissolution of iron and sulfur bearing minerals, iron oxyhydroxide formation and about 80% of recharge as leakage from adjacent and overlying mines, and 20% recharge from unmined strata.The Lancashire 15 mine-pool quality has improved significantly since closure and flooding.After leaching an estimated 55 pool volumes, Fe concentrations are about 5% of original values, and the waters are net alkaline.Continued mineral dissolution, and inefficient leaching due to dispersion and short circuiting, are likely responsible for current water quality conditions.

Use of a borehole camera in a hydrologic investigation, can yield information that may not be otherwise obtainable. The camera permits confirmation of stratigraphy, fracture and bedding plane separation locations, ground water inflow zones, fracture accentuation due to mine subsidence, and other features. A borehole camera also permits viewing of well bore features that otherwise may be unknown to exist, such as the conditions of the well bore, casing, and pumping system, historic water levels indicated by staining or corrosion, presence or absence of bacterial growths, existence of other organisms, the presence of foreign objects, and influx of gases. Combined with other instruments, the borehole camera can greatly enhance the information derived from either individually. A camera has been used in conjunction with a pump or an electrical specific conductance meter to determine the location of water-bearing and non-water bearing fractures. The flow direction of water within the hole has been determined using the camera with a neutral-buoyancy tape attached. Subsidence features (e.g., fractures, sheared casing, and borehole offsets) have been documented using a borehole camera.

FLUXNET is a global network of micrometeorological flux measurement site's that measure the exchanges of carbon dioxide, water vapor, and energy between the biosphere and atmosphere. At present over 140 sites are operating on a long-term and continuous basis. Vegetation under study includes temperate conifer and broadleaved (deciduous and evergreen) forests, tropical and boreal forests, crops, grasslands, chaparral, wetlands, and tundra. Sites exist on five continents and their latitudinal distribution ranges from 70 degreesN to 30 degreesS.FLUXNET has several primary functions. First, it provides infrastructure for compiling, archiving, and distributing carbon, water, and energy flux measurement, and meteorological, plant, and soil data to the science community. (Data and site information are available online at the FLUXNET Web site, http://www-eosdis.oml.gov/FLUXNTET/.) Second, the project supports calibration and flux intercomparison activities. This activity ensures that data from the regional networks are intercomparable. And third, FLUXNET supports the synthesis, discussion, and communication of ideas and data by supporting project scientists, workshops, and visiting scientists. The overarching goal is to provide information for validating computations of net primary productivity, evaporation, and energy absorption that are being generated by sensors mounted on the NASA Terra satellite.Data being compiled by FLUXNET are being used to quantify and compare magnitudes and dynamics of annual ecosystem carbon and water balances, to quantify the response of stand-scale carbon dioxide and water vapor flux densities to controlling biotic and abiotic factors, and to validate a hierarchy of soil-plant-atmosphere trace gas exchange models. Findings so far include 1) net CO2 exchange of temperate broadleaved forests increases by about 5.7 a C m(-2) day(-1) for each additional day that the growing season is extended; 2) the sensitivity of net ecosystem CO2 exchange to sunlight doubles if the sky is cloudy rather than clear; 3) the spectrum of CO2 flux density exhibits peaks at timescales of days, weeks, and years, and a spectral gap exists at the month timescale. 4) the optimal temperature of net CO2 exchange varies with mean summer temperature; and 5) stand age affects carbon dioxide and water vapor flux densities.

The geochemical code PHREEQC was used in an investigation of potential recharge sources to a flooded pit affected by acid drainage. Pit water quality had been alkaline with low metals and moderate dissolved aluminum, manganese and sulfate. The recharge area for the flooded pit included a coal refuse pile, flooded underground mine works, flyash pile, surface mine spoil and a sediment pond. A set of water quality samples were analyzed for mine drainage parameters, major dissolved constituents and some trace metals. These data were inverse modeled using the flooded pit water as the end product. Mixing of several possible sources and single source recharge scenarios were run along the inferred ground water flow path. Mixing of coal refuse pile leachate with leakage from the sediment pond or mine spoil provided acceptable characterization as the principal sources controlling pit water chemistry. These results were consistent with the ground water flow path interpreted from water level measurements in wells, structure, air photos and mining history. The dominant rock-water interactions modeled were dissolution of carbonate minerals and stored sulfate salts. Simple binary mixing was not adequate to describe the reaction path and resultant water chemistry. Geochemical models were useful for assessing mine drainagemore » sources, and can be included as one of a collection of investigative tools.« less

Chemischer InformationsdienstVolume 5, Issue 2 Organoelement Compounds ChemInform Abstract: BOND MOMENTS, MOLECULAR MOMENTS, ELECTRONEGATIVITY, AND THE DIPOLE MOMENT OF METHYLSILANE JON M. BELLAMA, JON M. BELLAMASearch for more papers by this authorROBERT S. EVANS, ROBERT S. EVANSSearch for more papers by this authorJAMES E. HUHEEY, JAMES E. HUHEEYSearch for more papers by this author JON M. BELLAMA, JON M. BELLAMASearch for more papers by this authorROBERT S. EVANS, ROBERT S. EVANSSearch for more papers by this authorJAMES E. HUHEEY, JAMES E. HUHEEYSearch for more papers by this author First published: January 15, 1974 https://doi.org/10.1002/chin.197402273AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat No abstract is available for this article. Volume5, Issue2January 15, 1974 RelatedInformation

Atomic charges have been calculated by a simple model involving partition of total molecular bonding energy into “ionic” and “covalent” components. These charges agree well with those obtained by Politzer's electron-count method of assigning charge but not with charges obtained by populational analysis. It is argued that Politzer's definition of charge is closer to the intuitive use of the word “charge” by chemists than is that based on populational analysis. Further examples of the importance of consideration of valence state electronegativities and charge capacities are discussed.

A male, 47, developed chronic hemolytic anemia in association with high titers of cold agglutinins in 1966. His symptoms of the cold agglutinin syndrome began in 1951 with cyanosis of the extremities and face after exposure to cold. In 1956, hemoglobinuria was first noted after chilling. In 1962, the cold agglutinin titer was 1:16,000, and his red cells were coated with complement globulins. In 1966, he developed chronic hemolytic anemia and a macroglobulin M component appeared in the serum protein electrophoresis. The titer of cold agglutinins was 1:64,000. The hemolytic anemia responded to chlorambucil with a decrease in cold agglutinin titer and the level of macroglobulin. Serum complement (C) values returned toward normal. Cessation of chlorambucil was followed by relapse. There was a second response to chlorambucil, but reactivation of the hemolytic anemia occurred following a respiratory infection, despite the reduced titer of cold agglutinin. Chlorambucil was discontinued and has not been administered since. There have been remissions and exacerbations of the hemolytic anemia and a return of the macroglobulin and cold agglutinins toward pretreatment levels. During the past 2 yr there has been spontaneous improvement in his symptoms, and the level of macroglobulin has decreased. Despite the appearance of a monoclonal macroglobulin having kappa light chain and with cold agglutinin activity, there is reason to classify his abnormal immunoglobulin production as benign.

The crystal and molecular structures of the title compounds have been determined by three-dimensional single-crystal X-ray techniques. All crystallographic details are fully reported. The major chemical conclusion for the pair, [Rh(NH3)5Cl]Cl2 and [Rh(NH3)Br]Br2, is that neither Cl nor Br exert a static intramoleculartrans effect. Furthermore, the two halogens have the same static electronic structural effect on the [RhIII(NH3)5] fragment. The conclusions shed much light on spectroscopic, thermodynamic and kinetic data of other compounds.

Of eight patients with acquired immunohemolytic anemia, six had persistently negative and two reversibly negative direct antiglobulin tests (Coombs tests). In five of the six, the red cells were shown by a complement-fixing antibody consumption technic to have abnormal amounts of γG globulin on their surfaces, ranging from 70 to 434 molecules per red cell. The two whose red cells gave reversible direct antiglobulin tests were found to have 160 and 700 molecules of γG per red cell respectively. Concentrated eluates prepared from red cells of six of the eight patients sensitized normal red cells; three of the eluates failed to react only with Rh-null red cells. These findings indicate that immunohemolytic anemia can occur with concentrations of red-cell autoantibodies below that necessary to produce red-cell agglutination by antihuman globulin serum.

Hard and soft acid-base interactions are investigated from the point of view of various factors contributing to the total bond energy. A method of estimating the total energy as the sum of three contributing energies is proposed. The three energies are the Madelung energy, derived from a coulombic model; the covalent energy, related to Pauling's geometric mean but allowing for loss of overlap with increasing ionicity; the electronegativity energy, the energy resulting from transfer of electron density from a less electronegative element to a more electronegative element. The latter is estimated from Mulliken-Jaffé electronegativies. The results correlate quite well (r = 0·98) with experimental enthalpies of atomization. It is concluded that hard-hard interactions contain considerable covalent bonding as well as Madelung energies. Fajans' rules and covalency, the “anomalous” bond energies of sodium and magnesium compounds, and the validity of the principle of electronegativity equalization are discussed.

The apparent conflict between the empirical HSAB rule and Pauling's Electronegativity Equation is examined and discussed in terms of more recent (Mulliken-Jaffé) electronegativity theory. It is concluded that no basic conflict exists but that Pauling's concept of “ionic resonance energy” neglects the variation in bond length from molecule to molecule, an error that is not serious in calculating electronegativities from bond energies but which is emphasized when applied to the prediction of enthalpies of HSAB reactions.

The effect of size upon the strength of hard and soft acid-base interactions is examined and it is concluded that hard-hard interactions are especially stabilized by small size that favors enhanced Madelung and covalent bonding energies. For the ionic species studied, the soft-soft interaction appears to be a negative one, i.e. it is imposed by the tendency of hard species to associate with each other. The homopolar bond energy may be related quite accurately (r = 0·975) to the bond length as EH = 132·5−37·1 r (EH = energy in kcal/mole; e = bond length in Ångstroms). Consideration of lone pair repulsions allows even better prediction of homopolar bond energy as a function of bond length.

The sera of four patients with chronic hemolytic anemia due to cold agglutinins deposited C' globulins on normal red cells at 37 degrees C. The circulating cells of the patients were heavily coated with C' complex and were relatively resistant to C' hemolysis by cold agglutinin. Such red cells were removed from the patients' circulation at an exponential rate with (51)Cr t((1/2)) that varied from 7 to 19 days. Normal red cells were removed rapidly by hepatic sequestration during the first hours in the patients' circulation. Thereafter, a slower rate of abnormal destruction occurred which was associated with the accumulation of C' complexes on the red cell and the development of resistance to C' hemolysis by cold agglutinin. Normal red cells coated with sufficient C' complex by action of cold agglutinins in vitro to produce resistance to C' hemolysis by cold agglutinins demonstrated varying degrees of improved survival during the first hours in the circulation of three of the patients. The levels of serum C' were reduced in all four patients with chronic hemolytic anemia due to cold agglutinins. Transfusion of large volumes of normal red cells into two patients further reduced serum C'. (51)Cr-labeled normal red cells survived longer after red cell transfusions than before, because of less rapid destruction during the first hours in the circulation. The reduction in serum C' levels appeared responsible for the improved survival. In subjects without cold agglutinins, the presence of the spleen decreased the survival of red cells from a patient who had previously undergone splenectomy. Splenic removal also predominated in the reduced survival of autologous red cells in one patient. Neither hepatic nor splenic mechanisms predominated in removing autologous C'-coated cells in the other two patients.

The incorporation of I131 into macromolecular cold agglutinins and purification by adsorption and elution from red cell stroma or whole red cells did not modify the serologic characteristics of the agglutinins. The radioiodination permits visualization of the relationship of antibody to red cells with varying concentration, temperature and pH. The equilibrium relationship between cold agglutinin and red cell is dependent on temperature but is also influenced by hydrogen ion concentration.