The release of phosphorus from sediment into water in subtropical wetlands: a warming microcosm experiment

Global warming poses a great threat to wetland ecological stability and water quality improvement. In this paper, we sampled six types of wetlands representing different kinds of land utilisation around the TaiHu Lake Basin in southeast China. An outdoor computerized microcosm was set up in May 2008 to simulate climate scenarios of ambient temperature (control) and a warmed ambient temperature (+5 °C) using a novel minute‐scale daily and seasonal temperature manipulation technology. The 18‐month incubation indicated that warming impaired the ecological sink of sediment (fixing P from porewater) while strengthening the role of the ecological source, moreover, the rate of P release from sediment into porewater (19–113% for total phosphorus) was much stronger than from top sediment into overlying water. Warming enhanced the activity of neutral and alkaline phosphatases for P‐deficient wetland sediments and neutral phosphatases for P‐rich sediments, at the 14th month of incubation. A significant increase in total phospholipid fatty acids (PLFAs) occurred under warming in sediments with relatively low levels of PLFAs, but bacterial abundance in the sediment biomass tended to decrease (18%) along with an increase (4·5%) of the fungi‐to‐bacteria ratio. The variations of carbon consumption and availability indicated by measured dissolved organic carbon in sediment may have contributed to P release from sediments to water. Copyright © 2011 John Wiley & Sons, Ltd.     

Comparison of benthic invertebrate assemblages at Spartina alterniflora marshes reestablished after an oil spill and existing marshes in the Arthur Kill (NY/NJ)

In January 1990, an oil spill damaged salt marshes along the banks of the Arthur Kill (New York and New Jersey, USA). In the years following the spill, Spartina alterniflora seedlings were planted at a number of the oil damaged sites and successfully reestablished at these sites. In 1996, the National Marine Fisheries Service began a study to compare the benthic invertebrate assemblages at the reestablished S. alterniflora marshes to those at nearby existing marshes in the Arthur Kill. Oligochaetes, nematodes, and the small tube-building polychaete, Manayunkia aestuarina were the dominant taxa in the study. Significant differences were found in the abundances of all invertebrate individuals, oligochaetes, and nematodes between the September and May sampling times but not between reestablished and existing marshes. Although benthic invertebrate community structure was similar at reestablished and existing marshes three to four years after planting, the functional similarity of these marshes was not assessed in this study.     

Temperature–time paths from phosphate accessory phase paragenesis in the Honey Brook Upland and associated cover sequence, SE Pennsylvania, USA

Analysis of monazite-bearing lithologies from the Precambrian Honey Brook Upland (HBU) and overlying metasedimentary Paleozoic Chester Valley Sequence (CVS) (SE PA, USA) reveals overprinting of primary major and accessory phase parageneses by texturally and compositionally disparate secondary accessory phase parageneses. Two-pyroxene temperatures of 915–945 °C for reconstituted pyroxene reflect emplacement temperatures of felsic plutonic rocks (opdalite, charnockite) prior to Mesoproterozoic metamorphism. Monazite in metavolcanic felsic gneiss yields three age domains at 1009 ± 4 Ma (2 s.e.), 965 ± 6, and 876 ± 10 Ma. The first two domains record metamorphism of the HBU after anorthosite intrusion; peak monazite–xenotime temperatures for the monazite core domain are 700 °C, and high Th/U values in the second (overgrowth) age domain likely reflect a second high-T monazite growth episode. Formation of cummingtonite coronas on orthopyroxene in opdalite constrains maximum 1010 Ma metamorphic temperatures in the “granulite-facies” terrane to 730–740 °C. Evidence of increased Cl fluid activity in the 965 Ma metamorphism includes higher Cl content of matrix apatite relative to garnet-included apatite (metavolcanics), and Cl-bearing K-hornblende succeeding cummingtonite in coronal overgrowths (opdalite). Extreme monazite Th/U values (75–250) in the rim domain suggest growth during low-T hydrothermal alteration. In the opdalite, secondary singe-grain monazite and monazite + xenotime metasomites in apatite yield ages of 714 ± 24 and 586 ± 88 Ma, temperatures of 325–425 °C, and are interpreted to reflect thermal disturbances associated with late Proterozoic plutonic and volcanic activity in the Upland. This thermal disturbance may be recorded by Rb–Sr age of 567 Ma for biotite from a HBU gneiss. Monazite age domains in metaquartzite (378 ± 28, 272 ± 44 Ma) suggest that low-grade metamorphism (260–320 °C, Mnz–Xno thermometry) of the CVS is not a result of Taconian orogenesis.     

The extreme well-loss component of drawdown in two deep artesian wells in Israel

Hydrogeology Journal - The water-level drawdown in pumping wells is the sum of two components: aquifer loss and well loss. The latter results from mostly turbulent and nonlaminar flow in and around...     

Experimental partitioning of Be,Cs, and other trace elements between cordierite and felsic melt,and the chemical signature of S-type granite

The trace-element signature that cordierite (Crd) imparts to silicic magmas was evaluated by experiment using metapelite mineral mixtures to produce cordierite-bearing peraluminous granitic melts at 200 MPa (P_H2O), from 700 to 850 °C. Most elemental partition coefficients vary with T. Beryllium is strongly compatible, with D_Be^Crd/melt values decreasing linearly from 202.0 to 6.7 as T rises from 700 to 850 °C. Manganese is compatible (D_Mn^Crd/melt=7.67 to 1.92 over the same range of T), and shows similar values to those reported for biotite in silicic melts. Incompatible components include Li, Rb, B, F and P, although Cs is nearly compatible in cordierite, especially at higher T (D_Cs^Crd/melt=~0.19 to 0.60) where the large alkalis are better accommodated structurally. Cordierite appears to be the most effective crystalline reservoir of Be and Cs in metapelites and their anatectic melts. Natural data support the hypothesis that Crd, when present in granitic melts, sequesters Be, Cs and, in the absence of garnet, Mn. S-type granitic rocks containing Crd show consistently low Be contents (mean=0.8 ppm Be with an average range of <1 to 1.20) whereas Crd-free granites (e.g., containing accessory garnet) exhibit distinctly higher Be contents (mean=6 ppm Be with an average range of 3 to 12). These values increase further in evolved facies (mean=69 ppm Be with a an average range of 11 to 145) which commonly give rise to beryl-bearing pegmatites. Whole-rock signatures of Be discriminate source environments of silicic magmas at a resolution equal to the boundaries of the cordierite stability field - e.g., at the P-T-X conditions where cordierite gives rise to garnet+aluminum silicate. Cordierite-bearing granitic rocks contain low Cs contents (mean=1.8 ppm Cs) compared to the Crd-free equivalents (mean=18 ppm Cs). Mn contents also correlate with the presence (mean=0.01 wt% MnO) or absence of Crd (mean=0.09 wt% MnO). Depending on its contribution to anatexis, cordierite may either give or take S-type chemical character from granitic liquids, resulting in a distinctive Crd-associated group of S-type elements. This signature is different from that of micas (high Li, F and, to a lesser degree, Be and Mn). Whole-rock compositions of granites, coupled with notable absences of beryl in their associated pegmatites, indicate that a sizable population of S-type granites originated from Crd-bearing sources. The normative Crd component of silicic peraluminous melts is Д wt% to 850 °C. Higher modal contents of cordierite reflect either restite entrainment or peritectic reactions which produce Crd after magma ascent to shallow depths. The distinctive trace-element signature of cordierite now provides improved resolution of the source mineralogy for S-type magmas.     

Temporal Geochemical Evolution of Neogene Magmatism in the Baguio Gold–Copper Mining District (Northern Luzon, Philippines)

Baguio, in the Central Cordillera of Northern Luzon, is a district that displays porphyry copper and epithermal gold mineralization, associated with Early Miocene–Pliocene–Quaternary calc‐alkaline and adakitic intrusions. Systematic sampling, K‐Ar dating, major and trace elements, and Sr, Nd, Pb isotopic analyses of fresh magmatic rocks indicate three magmatic pulses: an Early Miocene phase (21.2–18.7 Ma), a Middle–Late Miocene phase (15.3–8 Ma) and finally a Pliocene–Quaternary event (3–1 Ma). The first phase emplaced evolved calc‐alkaline magmas, essentially within the Agno Batholith complex, and is thought to be related to the westward‐dipping subduction of the West Philippine Basin. After a quiescence period during which the Kennon limestone was deposited, magmatic activity resumed at 15.3 Ma, in connection with the start of the subduction of the South China Sea along the Manila Trench. It emplaced first petrogenetically related and relatively unradiogenic low‐K calc‐alkaline lavas and intermediate adakites. Temporal geochemical patterns observed from 15.3 to 1 Ma include progressive enrichment in K and other large ion lithophile elements, increase in radiogenic Sr and Pb and corresponding decrease in radiogenic Nd. These features are thought to reflect the progressive addition to the Luzon arc mantle wedge of incompatible elements largely inherited from South China Sea sediments. The origin of the long quiescence period, from 8 to 3 Ma, remains problematic. It might represent a local consequence of the docking of the Zambales ophiolitic terrane to Northern Luzon. Then, magmatic activity resumed at 3 Ma, emplacing chemically diversified rocks ranging from low K to high K and including a large proportion of adakites, especially during the Quaternary (dacitic plugs). The authors tentatively relate this diversity to the development of a slab tear linked with the subduction of the fossil South China Sea ridge beneath the Baguio area.     

Molluscan biostratigraphy and paleomagnetism of Campanian strata, Queen Charlotte Islands, British Columbia: implications for Pacific coast North America biochronology

A previously uncollected fauna of ammonites, bivalves, and other molluscs, associated with radiolarian microfossils, has been newly recognized near Lawn Hill on the east coast of central Queen Charlotte Islands, British Columbia. The regional biostratigraphic zonation indicates that the Lawn Hill fauna is correlative with the Nostoceras hornbyense zonule of the Pachydiscus suciaensis ammonite biozone, recognized in the Nanaimo Group of southeast Vancouver Island. The Nostoceras hornbyense Zone (new) is herein proposed for strata of Pacific coast Canada containing the zonal index. Several molluscan taxa present in the Lawn Hill section are new to British Columbia and the ammonite fauna suggests that the Nostoceras hornbyense Zone is late Campanian in age, supported by radiolarian taxa present in the section. Strata sampled in the Lawn Hill section preserve reversed-polarity magnetization, considered likely correlative with Chron 32r. The presence of the Nostoceras hornbyense Zone on Queen Charlotte Islands is the first recognition of this zone in Canada north of central Vancouver Island and represents the youngest Cretaceous known in this region. Campanian radiolarians identified from the Lawn Hill section are also the first recognized from the Pacific coast of Canada.     

The geomorphic development of wreck shoal,a subtidal oyster reef of the James River,Virginia

Wreck Shoal is a subtidal oyster reef located in the James River estuary, Virginia. This estuary has moved upstream and landward in response to rising sea level. The recent geomorphic history of Wreck Shoal is analyzed based on bathymetric records from the 1850’s to the 1980’s. The data indicate that the shallow oyster reef areas have lost elevation in the last 130 yr. This is attributed to intense harvesting activity during the last century. The late Holocene evolution of Wreck Shoal is developed based on the results of sub-bottom profiles and coring data. These suggest that the Wreck Shoal oyster reef has developed on the ridge and swale topography of a point-bar formed during the late Pleistocene epoch. Contemporary biodeposition processes on Wreck Shoal are evaluated. The results indicate that sediments of biogenic origin (fecal and shell material) potentially accumulate at rates in excess of 50 cm 100 years^?1. A model for subtidal oyster reef development is proposed that accounts for sea level rise, biodeposition, and the harvesting activity of man. The model is verified with field observations of reef elevation and radiocarbon dates of oyster shell material. The implications of these results are that oyster reefs should be considered a renewable natural resource, and therefore managed accordingly in concert with the oysters.     

Evaluation of heterogeneity and field-scale groundwater flow regime in a leaky till aquitard

Recent work in southern Ontario, Canada, demonstrates anomalously high vertical groundwater flow velocities (>1 m/year) through a thick (as much as 60 m), sandy silt till aquitard (Northern till), previously assumed to be of very low permeability (hydraulic conductivity <10^–10 m/s). Rapid recharge is attributed to the presence of fractures and sedimentary heterogeneities within the till, but the field-scale flow regime is poorly understood. This study identifies the nature of physical groundwater pathways through the till and provides estimates of the associated groundwater fluxes. The aquitard groundwater flow system is characterized by integrating details of the outcrop and subsurface sedimentary characteristics of the till with field-based hydrogeologic investigation and numerical modeling. Outcrop and subsurface data identify a composite internal aquitard stratigraphy consisting of tabular till beds (till elements) separated by laterally continuous sheet-like sands and gravels (interbeds) and boulder pavements. Individual till elements contain sedimentary heterogeneities, including discontinuous sand and gravel lenses, vertical sand dikes, and zones of horizontal and vertical fractures. Hydrogeologic field investigations indicate a three-layer aquitard flow system, consisting of upper and lower zones of more hydraulically active and heterogeneous till separated by a middle unit of relatively lower hydraulic conductivity. Groundwater pathways and fluxes in the till were evaluated using a two-dimensional aquitard/aquifer flow model which indicates a step-wise flow mechanism whereby groundwater moves alternately downward along vertical pathways (fractures, sedimentary dikes) and laterally along horizontal sand interbeds within the till. This model is consistent with observed hydraulic-head and isotope profiles, and the presence of tritiated pore waters at various depths throughout the till. Simulations suggest that a bulk aquitard vertical hydraulic conductivity on the order of 1×10^–9 m/s is required to reproduce observed hydraulic-head and tritium profiles. Electronic Publication