Degradation of carbohydrates and lignins in buried woods

Spruce, alder, and oak woods deposited in coastal sediments were characterized versus their modern counterparts by quantification of individual neutral sugars and lignin-derived phenols as well as by scanning electron microscopy, ¹³C NMR, and elemental analysis. The buried spruce wood from a 2500 yr old deposit was unaltered whereas an alder wood from the same horizon and an oak wood from an open ocean sediment were profoundly degraded. Individual sugar and lignin phenol analyses indicate that at least 90 and 98 wt% of the initial total polysaccharides in the buried alder and oak woods, respectively, have been degraded along with 15–25 wt% of the lignin. At least 75% of the degraded biopolymer has been physically lost from these samples. This evidence is supported by the SEM, ¹³C NMR and elemental analyses, all of which indicate selective loss of the carbohydrate moiety. The following order of stability was observed for the major biochemical constituents of both buried hardwoods: vanillyl and $\text{p-}\text{hydroxyl}$ lignin structural units > syringyl lignin structural units > pectin > α-cellulose > hemicellulose. This sequence can be explained by selective preservation of the compound middle lamella regions of the wood cell walls. The magnitude and selectivity of the indicated diagenetic reactions are sufficient to cause major changes in the chemical compositions of wood-rich sedimentary organic mixtures and to provide a potentially large in situ nutrient source.     

Carbon isotope fractionation in wood during carbonization

A significant uncertainty exists as to whether δ¹³C values in charcoal meaningfully represent the stable isotopic content of the original material, with studies suggesting variable responses to both natural and laboratory heating. An extensive study was undertaken using fully homogenised samples of wood taken from Eucalyptus spp., Quercus robur and Pinus radiata. The results demonstrate that the duration of heating had no tangible effect on the final composition of the charred material, with the δ¹³C and carbon content of wood fixed after 30 min of heating. Furthermore, all three wood types become progressively depleted in ¹³C with increasing temperature. The results demonstrate that even at temperatures commonly reached in natural fires (<450 °C) isotopic fractionation of up to 1.3‰ can take place indicating that the absolute values obtained from charcoal extracted for paleoenvironmental reconstruction must be interpreted with caution.     

Wood chips as soil conservation in field conditions

The soil conditioner in processes of soil conservation is important especially in heavily eroded areas. Because in this study done in Educational and Research Forest Watershed of Tarbiat Modares University, north of Iran, the experiments created four treatments of control and different wood chips with rates of 0.5, 1, and 1.5 kg m^?2, by rainfall simulation in rainfall intensity of 60 mm h^?1, and plot scale of 1 m² on changing ponding time, runoff coefficient, sediment concentration, and soil loss. The results showed that the average change ponding time in control treatment and wood chip treatments with rates of 0.5, 1, and 1.5 kg m^?2 were 4.25, 7.48, 11.63, and 12.45 min. Also, the average change runoff coefficient in control treatment and wood chip treatments with rates of 0.5, 1, and 1.5 kg m^?2 were 50.03, 26.27, 15.28, and 13.17 %. The results also indicated that the wood chips could decrease average soil loss with the rates of ?52.15, ?82.18, and ?89.35 % compared with control treatment for 0.5, 1, and 1.5 kg m^?2 of wood chips, respectively. The one-way ANOVA results showed that the runoff coefficient, sediment concentration, and soil loss decreased with increasing wood chip amount, and the effect of conservation treatment was significant on study variables (R ² = 0.99). But, the ponding time increased with increasing wood chip amount, and this effect was significant on study variables (R ² = 0.99).     

Elucidating the chemical structure of pyrogenic organic matter by combining magnetic resonance,mid-infrared spectroscopy and mass spectrometry

Fire-derived organic matter (pyrogenic organic matter, or PyOM), despite its apparent long term stability in the environment, has recently been reported to degrade faster than previously thought. Current studies have suggested that the composition and structure of PyOM can provide new insights on the mechanisms by which C and N from pyrolyzed biomaterials are stabilized in soils. To better understand the chemical structure of PyOM produced under typical fire conditions in temperate forests, samples of dual-enriched (¹³C/¹⁵N) Pinus ponderosa wood and the charred material produced at 450 °C were analyzed by solid state nuclear magnetic resonance (ssNMR), electron paramagnetic resonance (EPR), diffuse reflectance Fourier transform infrared (DRIFT) spectroscopy, and both isotopic and elemental composition (C, H, O, and N). Notably, the use of high magnetic field strengths in combination with isotopic enrichment augmented the NMR detection sensitivity, and thus improved the quality of molecular information as compared with previously reported studies of pyrogenic materials. The key molecular groups of pine wood and the corresponding PyOM materials were determined using magic-angle spinning (MAS) ¹³C, ¹⁵N, and ¹H NMR. Together with DRIFT and EPR measurements, ssNMR revealed the formation of a free radical-containing disordered blend of nitrogenous aromatics and heat resistant aliphatics in the PyOM due to incomplete combustion of the precursor wood. ¹³C ssNMR and DRIFT analyses showed the removal of oxygenated aliphatics due to pyrolysis of the precursor wood and the dominant contribution of multiply-bonded and oxygenated aromatic structures in the resulting PyOM. However, the ¹⁸O isotopic analyses indicated selective retention of ligneous moieties during charring at 450 °C. ¹⁵N ssNMR studies implied that the nitrogenous species in PyOM corresponded to thermally altered rather than heat resistant domains of the pine wood precursor. Our molecular characterization suggests that biomaterials pyrolyzed near 450 °C may degrade in soils faster than those pyrolyzed at higher temperatures and may not represent a stable C sink in terrigenous ecosystems.     

The effect of low-rate sand filtration and modified feed management on effluent quality,pond water quality and production of intensive shrimp ponds

Pond water in intensive shrimp ponds is typically high in nutrients, solids, and BOD and may have an adverse environmental impact when discharged to natural waters. As part of ongoing research to develop intensive production technologies that minimize the potential for environmental impact, a study investigated the effect of lowrate, coarse-grain sand filtration on the quality of effluent being discharged from an intensive shrimp pond receiving 5% d^?1 water exchange. The effect of sand filtration on a recirculating no-exchange pond was also examined. For comparison, a third pond received no water exchange and no filtration. Sand filtration removed some particulate matter, but levels of dissolved and particulate organic and inorganic nutrients were changed little and were sometimes higher as the result of in situ decomposition. Low-rate sand filtration is not seen as a cost-effective method of increasing the carrying capacity of no-exchange shrimp ponds or drastically improving the effluent quality of ponds with water exchange. Compared to previous studies with decreased or no water exchange, the application of feed in these ponds was more stable with small portions fed at frequent intervals with a constant rate of 80 kg ha^?1 d^?1. These ponds, stocked with 40 m^?2 juvenilePenaeus vannamei, had excellent survival and normal growth, resulting in productions levels approaching 7,000 kg ha^?1 crop^?1 without water exchange. This indicates that intensive shrimp farming may be possible in static no-exchange systems, thereby minimizing the potential impact of effluent as long as feed inputs do not overwhelm the assimilative capacity of the pond ecosystem. *** DIRECT SUPPORT *** A01BY069 00011     

Distribution of thallium and accompanying metals in tree rings of Scots pine (Pinus sylvestris L.) from a smelter-affected area

Distribution of Tl, Zn, Cd, Pb, K, Ca, Mg and Mn and Pb isotopic composition in tree rings of Scots pine (Pinus sylvestris L.) from an area affected by primary Zn smelting (Olkusz, southern Poland) were investigated. Elevated concentrations of Tl (up to 0.8 mg kg⁻¹) in pine trees imply that conifers tend to accumulate this metal to some extent. A generally positive relationship between soil and tree-ring Tl levels was identified. The Tl patterns in stem wood did not correspond to changes in Tl deposition; the lateral translocation of Tl in the sapwood and its accumulation at the sapwood-heartwood boundary (i.e., in the inner sapwood) is suggested. It is probable that the specific behavior of Tl in trees results from its biogeochemical analogy with K. In contrast, tree-ring patterns of Zn and Cd significantly correlated with their deposition; nevertheless, a partial shift of these metals towards the stem center cannot be excluded. The isotopic composition of Pb (²⁰⁶Pb/²⁰⁷Pb ~ 1.172–1.184) in trees and underlying soils revealed the predominant influence of smelter emissions (²⁰⁶Pb/²⁰⁷Pb ~ 1.17) on Pb contamination. Analysis of main nutrients (Ca, Mg and Mn) in wood reflected environmental changes related to acid deposition.     

Quantifying pyrogenic carbon from thermosequences of wood and grass using hydrogen pyrolysis

Previously studied thermosequences of wood (chestnut) and grass (rice straw) biochar were subjected to hydrogen pyrolysis (hypy) to evaluate the efficacy of the technique for determining pyrogenic carbon (C_P) abundance. As expected, biochar from both wood and grass produced at higher temperature had higher C_P amount. However, the trend was not linear, but more sigmoidal. C_P/C_T ratio values (C_T = total organic carbon) for the wood thermosequence were ⩽0.03 at biochar production temperature (T_CHAR) ⩽ 300 °C. They increased dramatically until 600 °C and remained relatively constant and near unity at higher biochar production temperature. Grass biochar was similar in profile, but C_P/C_T values rose dramatically after 400 °C. The findings are consistent with the hypothesis that hypy residues contain polycyclic aromatic hydrocarbons (PAHs) with a degree of condensation above at least 7–14 fused rings, with labile organic matter and pyrogenic PAHs below this degree of condensation removed by hypy.Both wood and grass thermosequences displayed δ¹³C_P values that decreased with increased T_CHAR, indicating that recalcitrant carbon compounds (pyrogenic aromatic PAHs with a relatively high degree of condensation) were first formed from structural components with relatively high δ¹³C values (e.g. cellulose). Relatively constant δ¹³C values at T_CHAR ⩾ 500 °C suggested the dominant pyrolysis reaction was condensation of PAHs with no additional fractionation. Comparison of hypy with benzene polycarboxylic acid (BPCA), ‘ring current’ NMR and pyrolysis gas chromatography–mass spectrometry (GC–MS) results from the same suite of samples indicated a consistent overview of the structure of C_P, but provided unique and complimentary information.     

Conifer fossil woods from the Santa Marta Formation (Upper Cretaceous), Brandy Bay,James Ross Island,Antarctica

Conifer fossil woods from the Santonian to lower Campanian Santa Marta Formation are anatomically studied in detail. The wood flora is dominated by conifers, mainly Araucariaceae. Conifer fossil woods represent 84% of the samples (26 of 31) of the assemblage. The remaining samples are dicotyledon woods which are not included in this study. Woods are mostly calcified and preservation is often excellent. Fossil woods include three species of Agathoxylon, Phyllocladoxylon antarcticum, Cupressinoxylon hallei and a new species of Cupressinoxylon, C. rotundum Pujana sp. nov. The conifer-dominated forests are consistent with the pollen and macrofloras previously described from sediments of the same stratigraphic unit. This fossil wood assemblage contributes to understand the floristic changes that took place in the Cretaceous forests.     

δ13C food web analysis of a Texas sand dune community

Stable carbon isotope ratios (δ¹³C) were determined for 31 plant and 16 animal species from a sand dune community on the south Texas coast. Plants and insects had similar δ¹³C values, forming two distinct groups, while herbivorous rodents formed a third intermediate group. This suggests that insects at the study site are specialists which feed on C₃ or C₄ plants, while the rodents are generalists, feeding on plants of both groups.     

Hydrogeology,water quality,and microbial assessment of a coastal alluvial aquifer in western Saudi Arabia: potential use of coastal wadi aquifers for desalination water supplies

Wadi alluvial aquifers located along coastal areas of the Middle East have been assumed to be suitable sources of feed water for seawater reverse osmosis facilities based on high productivity, connectedness to the sea for recharge, and the occurrence of seawater with chemistry similar to that in the adjacent Red Sea. An investigation of the intersection of Wadi Wasimi with the Red Sea in western Saudi Arabia has revealed that the associated predominantly unconfined alluvial aquifer divides into two sand-and-gravel aquifers at the coast, each with high productivity (transmissivity?=?42,000 m²/day). This aquifer system becomes confined near the coast and contains hypersaline water. The hydrogeology of Wadi Wasimi shows that two of the assumptions are incorrect in that the aquifer is not well connected to the sea because of confinement by very low hydraulic conductivity terrigenous and marine muds and the aquifer contains hypersaline water as a result of a hydraulic connection to a coastal sabkha. A supplemental study shows that the aquifer system contains a diverse microbial community composed of predominantly of Proteobacteria with accompanying high percentages of Gammaproteobacteria, Alphaproteobacteria and Deltaproteobacteria.     

Evaluating the environmental risks associated with the use of chromated copper arsenate-treated wood products in aquatic environments

Chromated copper arsenate (CCA)-treated wood has been used worldwide since 1933. In properly fixed wood, the chromium, copper, and arsenic are tightly bound to the wood fibers. However, it has long been known that small amounts of these metals do leach from properly treated wood products. These metals, particularly the cupric ion (Cu²⁺), are known to be highly toxic to aquatic organisms at concentrations as low as 6 μg Cu l^?1. The United States Environmental Protection Agency has established a marine water quality standard of 2.9 μg Cu l^?1 total copper. Washington State has established a marine water quality standard of 2.5 μg Cu l^?1 and a marine sediment standard of 390 mg Cu g^?1 (dry sediment). Comparison of these standards with the results of bioassays suggests that these levels are sufficiently low to protect even the most sensitive organisms. Metal losses are an inverse function of time and decline to background levels within 60–90 d of treated wood immersion. Increasing use of CCA-treated wood to construct residential bulkheads in estuarine environments on the east coast of the United States has raised concerns regarding the near-term environmental risks associated with these uses. This paper reports the development of a spreadsheet-based computer model to predict water column and sediment concentrations of copper leached from bulkheads and piling. Model output is compared with data in Weis et al. (1991, 1993) and Weis and Weis (1992). The model predicts environmental levels of copper that are highly dependent on input parameters but below regulatory levels for most projects constructed in reasonably well-circulated bodies of water. The model does demonstrate the possibility of exceeding regulatory standards for up to 3 wk when bulkheads are installed in very poorly flushed aquatic environments or where the surface area of the CCA-treated wood structure is a significant proportion of the water body surface area.     

Large wood transport as significant influence on flood risk in a mountain village

An important issue that is not considered in most flood risk assessments in mountain villages in Spain is the transport of solids associated with the flood flow, in this case, large wood transport. The transport and deposition of this wood in urban areas may be a potentially worse hazard than the flood flow itself. Despite its importance, large wood is a key ecological element in rivers, so removing it could be an unsuccessful approach. Therefore, efforts are needed in the better understanding of wood transport and deposition in streams. To analyse this process, scenario-based 2D hydrodynamic flood modelling was carried out. Since flood risk assessment has considerable intrinsic uncertainty, probabilistic thinking was complemented by possibilistic thinking, considering worst-case scenarios. This procedure obtained a probabilistic flood map for a 500-year return period. Then, a series of scenarios was built based on wood budget to simulate wood transport and deposition. Results allowed us to identify the main infrastructures sensitive to the passing of large wood and simulate the consequences of their blockage due to wood. The potential damage was estimated as well as the preliminary social vulnerability for all scenarios (with and without wood transport). This work shows that wood transport and deposition during flooding may increase potential damage at critical stream configurations (bridges) by up to 50 % and the number of potentially exposed people nearby these areas by up to 35 %.     

Swimming velocities and behavior of blue crab (Callinectes sapidus rathbun) megalopae in still and flowing water

Habitat selection capabilities of the recruiting larval stages of marine invertebrates are limited, in part, by their ability to maneuver in flowing water. Distributional and experimental evidence suggest that blue crab (Callinectes sapidus) megalopae may preferentially settle into vegetated habitats. However, the behavior and swimming capabilities of megalopae in flowing water have not previously been investigated. Laboratory experiments were conducted in a small, recirculating seawater flume to determine the swimming response of megalopae to varying flow velocities. Nighttime trials were conducted at six flow velocities: 0, 1.9, 3.6, 4.8, 6.3, and 9.3 cm s^?1. Behavior and swimming velocities of field-collected C. sapidus megalopae were video recorded. Megalopae exhibited negative phototaxis and were found in the water column at all flows in the dark. The maximum sustained swimming speed observed was 12.6 cm s^?1 and the mean swimming speed in still water was 5.0 cm s^?1, with short bursts in excess of 20 cm s^?1. Megalopae frequently oriented into the current and were capable of swimming upstream against the current at flow speeds <4.8 cm s^?1; at greater velocities they were not able to do so. The results suggest that at low to moderate current velocities C. sapidus megalopae have the ability to actively move in search of settlement sites and to maintain their positions in desirable sites rather than relying strictly on passive movements by currents.     

Influence of production variables and starting material on charcoal stable isotopic and molecular characteristics

We present a systematic study on the effect of starting species, gas composition, temperature, particle size and duration of heating upon the molecular and stable isotope composition of high density (mangrove) and low density (pine) wood. In both pine and mangrove, charcoal was depleted in δ¹³C relative to the starting wood by up to 1.6‰ and 0.8‰, respectively. This is attributed predominantly to the progressive loss of isotopically heavier polysaccharides, and kinetic effects of aromatization during heating. However, the pattern of δ¹³C change was dependant upon both starting species and atmosphere, with different structural changes associated with charcoal production from each wood type elucidated by Solid-State ¹³C Nuclear Magnetic Resonance Spectroscopy. These are particularly evident at lower temperatures, where variation in the oxygen content of the production atmosphere results in differences in the thermal degradation of cellulose and lignin. It is concluded that production of charcoal from separate species in identical conditions, or from a single sample exposed to different production variables, can result in significantly different δ¹³C of the resulting material, relative to the initial wood. These results have implications for the use of charcoal isotope composition to infer past environmental change.     

First Lower Cretaceous record of Podocarpaceae wood associated with dinosaur remains from Patagonia,Neuquén Province,Argentina

The first Podocarpaceae wood record is described from the Mulichinco Formation (Valanginian, Lower Cretaceous), Neuquén Basin, Argentina. The specimen was directly associated with a middle caudal vertebra of a diplodocid sauropod dinosaur. A new species – Podocarpoxylon prumnopityoides – is proposed based on features that include the presence of abietinean wood type (tracheid radial pitting), plus podocarpoid (cupressoid type) and some dacrydioid (taxodioid type) cross-field pits, diffuse axial parenchyma and low rays. This combination of anatomical characters is comparable to both Prumnopitys and Podocarpus, whereas the type of pits in the cross-fields resembles some members of the extant Prumnopitys. This is the first unequivocal record of the Family Podocarpaceae in the Valanginian of South America and confirms the hypothesis that the divergence between the “Podocarpoid-Dacrydioid” and “Prumnopityoid” clades occurred earlier than the Early Cretaceous.     

The variations of stable-carbon isotope ratios in Qilian juniper in northwestern China

This is the first study of δ¹³C values that considers elevational influences of the Qilian mountains of China. The δ¹³C values of different parts of the Qilian juniper (Sabina przewalskii Kom.) at different elevations of the Qilian mountains, China, were measured. Relatively constant differences in δ¹³C values existed between the tree leaves and the trunk wood. No strong dependency of δ¹³C values on elevation was found. The temporal changes of wood δ¹³C values with directions, elevations and height in the tree showed general similarity. These results suggest that the isotopic effects of environmental factors expressed initially at the site of photosynthesis, i.e., the leaves could be contained in the trunks of a tree. Regardless of elevation, direction or height in the tree, wood δ¹³C values have been decreasing during the past 60 years. A composite 600-year δ¹³C chronology developed from four trees showed that δ¹³C values remain relatively constant before 1800. After 1800 AD, however, δ¹³C values became significantly more negative. The trend in wood δ¹³C values was consistent with that obtained for δ¹³C values in atmospheric CO₂. The results showed that for Qilian juniper, tree-ring δ¹³C chronology could be established to ascertain fluctuations of the atmospheric δ¹³C.     

Paleoecology of late-glacial terrestrial deposits with in situ conifers from the submerged continental shelf of western canada

Extensive portions of the continental shelf off the coast of British Columbia were subaerially exposed during Late Wisconsinan deglaciation due to lowering of relative sea level by as much as 150 m. Paleoecological analyses were conducted at two sites on the emergent continental shelf where terrestrial surfaces with in situ conifers are preserved. The woody plant remains confirm that, during the latest period of subaerial exposure, terrestrial vegetation was established on the continental shelf. Microscopic identification of fossil wood, and analyses of pollen and plant macrofossils from the associated paleosols and overlying shallow pond sediments indicate that productive Pinus contorta-dominated communities with abundant Alnus crispa and ferns grew on the shelf adjacent to and on the Queen Charlotte Islands around 12,200 ¹⁴C yr B.P. Dwarf shrubs including Salix and Empetrum, and herbaceous plants such as Heracleum lanatum and Hippuris vulgaris, were also important components of the shelf vegetation. Near northern Vancouver Island, mixed coniferous forests dominated by Pinus contorta with Picea, Tsuga spp., Alnus spp., and ferns occupied the shelf at 10,500 ¹⁴C yr B.P.     

Sulfur and carbon isotope geochemistry of coal and derived coal-combustion by-products: An example from an Eastern Kentucky mine and power plant

The isotopic compositions of S (δ³⁴S) and C (δ¹³C) were determined for the coal utilized by a power plant and for the fly ash produced as a by-product of the coal combustion in a 220-MW utility boiler. The coal samples analyzed represent different lithologies within a single mine, the coal supplied to the power plant, the pulverized feed coal, and the coal rejected by the pulverizer. The ash was collected at various stages of the ash-collection system in the plant. There is a notable enrichment in ³⁴S from the base to the top of the coal seam in the mine, with much of the variation due to an upwards enrichment in the δ³⁴S values of the pyrite. Variations in δ³⁴S and in the amount of pyritic S in the coal delivered to the plant show that there was a change of source of coal supplied to the plant, between week one and week two of monitoring, supporting a previous study based on metal and sulfide geochemistry for the same plant. The fly ash has a more enriched δ³⁴S than the pulverized coal and, in general, the δ³⁴S is more enriched in fly ashes collected at cooler points in the ash-collection system. This pattern of δ³⁴S suggests an increased isotopic fractionation due to temperature, with the fly ash becoming progressively depleted in ³⁴S and the flue gas S-containing components becoming progressively enriched in ³⁴S with increasing temperatures. Substantially less variation is seen in the C isotopes compared to S isotopes. There is little vertical variation in δ¹³C in the coal bed, with δ¹³C becoming slightly heavier towards the top of the coal seam. An 83–93% loss of solid phase C occurs during coal combustion in the transition from coal to ash owing to loss of CO₂. Despite the significant difference in total C content only a small enrichment of 0.44–0.67‰ in ¹³C in the ash relative to the coal is observed, demonstrating that redistribution of C isotopes in the boiler and convective passes prior to the arrival of the fly ash in the ash-collections system is minor.     

Teredolites Leymerie in the Lower Greensand Group (Cretaceous) of the Isle of Wight and the problematic ichnology of reworked clasts

Nineteenth-century references to clavate borings in woody substrates in the Lower Greensand of the Isle of Wight used a variety of names, but Teredo (a wood-boring bivalve, not a boring), Teredolithes (a junior synonym of Teredolites) and Gastrochaena (a bivalve borer of rock and shelly substrates, not a boring in wood) are all nomenclatorially incorrect. Borings in a beach clast derived from the Lower Greensand Group and recently collected from Sandown Bay, Isle of Wight, are referred to Teredolites isp. cf. T. longissimus Kelly and Bromley. This specimen confirms the presence of Teredolites in the Lower Greensand Group and demonstrates a common ichnological problem of beach clasts; borings, either fossil or modern, are incompletely preserved, making confident classification below the level of ichnogenus problematic.