Removal of heavy metals from contaminated water using ethylenediamine-modified green seaweed (Caulerpa serrulata)

The demand for clean water is on the increase as the population increases. One of the ways to address the water shortage is to treat the polluted water through removal of the contaminants. The use of adsorbents for pollutant removal is one of the promising methods. Seaweed is an aquatic plant and its sorption ability for selected metals in water was investigated in this study. We report the performance of the seaweed (Caulerpa serrulata) before and after modification with ethylenediamine (EDA), on adsorption of copper, lead and cadmium in aqueous solution. The adsorption capacities for Cu, Cd and Pb were 5.27 mg g⁻¹, 2.12 mg g⁻¹ and 2.16 mg g⁻¹, respectively, with the EDA-modified seaweed, and 3.29 mg g⁻¹, 4.57 mg g⁻¹ and 1.06 mg g⁻¹, with the unmodified weed, respectively. The pH for maximum adsorption was found to be within the range of pH 4–pH 6. In a separate investigation, it was found that 0.1 g of dried seaweed leached 20 mg of dissolved organic carbon (DOC) using 100 ml of distilled-deionised water. The resulting solution was green. The leaching phenomenon contributes to secondary pollution. Modification of the seaweed with EDA reduced the DOC content by half (50%) and also removed the green colouration. Kinetic studies showed that the adsorbent was able to take up to 95% of the metals (in synthetic standard solutions) in less than 10 min. The adsorbed metals were then stripped using a solution of 0.5 M HNO₃ indicating that the adsorbent can be regenerated. In addition, the study revealed that modification improved the thermal stability of the adsorbent such that even when the temperature was raised to 1000 °C, more than 80% (compared to <50% for unmodified weed) of the modified adsorbent was not degraded, indicating that modification had a significant influence on the thermal stability of seaweed. The modified seaweed has been shown to have great potential for the removal of metals and DOC in polluted water. The modified adsorbent can therefore be applied for the removal of metals in polluted waters hence suitable for treatment of water for domestic consumption at a point of use.     

Content and distribution of trace metals in surface sediments from the northern Bering Sea,Chukchi Sea and adjacent Arctic areas

Concentrations of trace metals (Zn, Cr, Cu, V, Cd and Pb), total organic carbon (TOC), black carbon (BC) and their granulometry were examined in 25 surface sediment samples from the northern Bering Sea, Chukchi Sea and adjacent areas. Trace metal concentrations in the sediments varied from 21.06–168.21 mg kg⁻¹ for Zn, 8.91–46.94 mg kg⁻¹ for Cr, 2.69–49.39 mg kg⁻¹ for Cu, 32.46–185.54 mg kg⁻¹ for V, 0.09–0.92 mg kg⁻¹ for Cd, and 0.95–15.25 mg kg⁻¹ for Pb. The geoaccumulation index (I_geo) indicated that trace metal contamination (Zn and Cd) existed in some stations of the study area. The distribution of grain size plays an important role in influencing the distribution of trace metals (Zn, Cr, Cu, V, and Pb) in sediments from the Chukchi Sea and adjacent areas.     

Magnetic susceptibility and Cs-137 inventory variability as influenced by land use change and slope positions in a hilly,semiarid region of west-central Iran

The objective of this study was to explore the slope position and land use change effects on the variability in magnetic susceptibility and ¹³⁷Cs inventory as the soil redistribution indicators in a hilly semiarid calcareous area in Iran. The selected study area is located in a hilly region with pasture and cultivation land use of Fereydunshahr, Isfahan Province in west-central Iran. In the two mentioned dominant ecosystems, four slope positions including summit, shoulder, backslope and footslope were identified and in each land use and slope position, three cores were selected to collect 72 soil samples from three depths (0–10, 10–20, 20–30 cm) in an area of 15 × 15 cm. Additional 28 soil samples were collected from the reference site for soil loss and deposition calculations by using the Cs-137 measurement. The results of the study with the use of the Cs-137 technique showed that the average soil loss in the pasture land (46.4 t ha^− 1 yr^− 1) was significantly (p < 0.05) lower than the average soil loss in the cultivated land (80.4 t ha^− 1 yr^− 1). The highest soil loss in both land uses was obtained in the shoulder position, 60.1 and 84.4 t ha^− 1 yr^− 1, respectively, for the pasture and cultivated lands. Moreover, the highest rates of soil deposition was observed in a footslope position in both land uses and they were 34 and 32.4 t ha^− 1 yr^− 1 for the pasture and cultivated lands, respectively. Magnetic susceptibility was significantly (p < 0.05) greater in pasture (χ_lf = 41.51 × 10^− 8 m³/kg) than in the cultivated land (χ_lf = 34.90 × 10^− 8 m³/kg). The pasture land with a lower soil loss rate, indicated significantly higher magnetic susceptibility in all landform positions as compared to that in the cultivated land. The results of the correlation analysis showed that among the studied soil physico-chemical properties, χ_lf (r = 0.83, p < 0.01) in the pasture land had the highest correlation with the Cs-137 inventory. Throughout the non-linear regression analysis, χ_lf was introduced for relating soil parameters and the cesium inventory explained 68% and 79% of the total variability of ¹³⁷Cs in the pasture and cultivated lands, respectively. The results implied that the variability in the magnetic susceptibility within the hillslope is consistent with the variation of the Cs-inventory; and the results thus demonstrate the slope and land use effects on soil redistribution.     

A reassessment of current volcanic emissions from the Central American arc with specific examples from Nicaragua

The Central American volcanic arc supplies a significant proportion of the persistent annual global sulphur dioxide emissions from volcanoes. In November/December 2003, we completed a survey of the arc section from Mombacho to San Cristóbal in Nicaragua recording individual mean fluxes of 800, 530 and 220 Mg day^− 1 in the plumes from San Cristóbal, Telica and Masaya, respectively. An assessment of fluxes published since 1997 along the entire Central America arc yields a mean total arc flux of SO₂ of 4360 Mg day^− 1 or 8–16% of the annual estimated global volcanic SO₂ flux to the troposphere. New field data shows that Masaya volcano continues to show stable HCl/SO₂ and HF/SO₂ ratios, suggesting a sustained flux of these components of ∼ 220 and 30 Mg day^− 1, respectively (1997 to 2004). Masaya's plume composition also appears to have been stable, between 2001 and 2003, with respect to all the particulate species measured, with significant fluxes of SO₄²⁻ (4 Mg day^− 1), Na⁺ (0.9–1.3 Mg day^− 1) and K⁺ (0.7 Mg day^− 1). Extrapolating the Masaya plume species ratios to the entire Central American arc gives mean HCl and HF fluxes of 1300 and 170 Mg day^− 1 and a particulate sulphate flux of 40 Mg day^− 1 for 1997 to 2004, although without further understanding of the degassing processes and sources at depth of these different volatiles, these arc-scale estimates should be treated with caution. Combining our arc scale mean SO₂ flux with published measurements of volcanic gas compositions with respect to CO₂ and H₂O allows us to estimate mean CO₂ fluxes of 4400–9600 Mg day^− 1 and H₂O fluxes of 70,000–78,000 Mg day^− 1 for the arc. Preliminary comparisons of these estimates of outgassing rates with published volatile input fluxes into the Central American subduction zone, suggest that Cl is more efficiently recycled through the subduction zone than CO₂. The results for H₂O are inconclusive.     

Variability of the dissolved nutrient (N,P, Si) concentrations in the Bay of Annaba in relation to the inputs of the Seybouse and Mafragh estuaries

Dissolved inorganic nitrogen (DIN), phosphate (PO₄) and silicic acid (Si(OH)₄) loads from the Seybouse and the Mafragh estuaries into the Bay of Annaba, Algeria, were assessed at three stations of the Bay over three years. The Seybouse inputs had high levels of DIN and PO₄, in contrast to the Mafragh estuary’s near-pristine inputs; Si(OH)₄ levels were low in both estuaries. The DIN:PO₄ molar ratios were over 30 in most samples and the Si(OH)₄:DIN ratio was less than 0.5 in the Seybouse waters, but nearly balanced in the Mafragh. The specific fluxes of Si–Si(OH)₄ (400–540 kg Si km⁻² yr⁻¹) were comparable in the two catchments, but those of DIN were several-fold higher in the Seybouse (373 kg N km⁻² yr⁻¹). The inner Bay affected by the Seybouse inputs had high levels of all nutrients, while the Mafragh plume and the outer marine station were less enriched.     

Photoproduction of hydrogen peroxide in aqueous solution from model compounds for chromophoric dissolved organic matter (CDOM)

To explore whether quinone moieties are important in chromophoric dissolved organic matter (CDOM) photochemistry in natural waters, hydrogen peroxide (H₂O₂) production and associated optical property changes were measured in aqueous solutions irradiated with a Xenon lamp for CDOM model compounds (dihydroquinone, benzoquinone, anthraquinone, napthoquinone, ubiquinone, humic acid HA, fulvic acid FA). All compounds produced H₂O₂ with concentrations ranging from 15 to 500 μM. Production rates were higher for HA vs. FA (1.32 vs. 0.176 mM h⁻¹); values ranged from 6.99 to 0.137 mM h⁻¹ for quinones. Apparent quantum yields (Θ_app; measure of photochemical production efficiency) were higher for HA vs. FA (0.113 vs. 0.016) and ranged from 0.0018 to 0.083 for quinones. Dihydroquinone, the reduced form of benzoquinone, had a higher production rate and efficiency than its oxidized form. Post-irradiation, quinone compounds had absorption spectra similar to HA and FA and 3D-excitation–emission matrix fluorescence spectra (EEMs) with fluorescent peaks in regions associated with CDOM.     

Mantle-derived carbon in Hercynian granites. Stable isotopes signatures and C/He associations in the thermomineral waters,N-Portugal

Na–HCO₃–CO₂-rich thermomineral waters issue in the N of Portugal, within the Galicia-Trás-os-Montes region, linked to a major NNE-trending fault, the so-called Penacova-Régua-Verin megalineament. Along this tectonic structure different occurrences of CO₂-rich thermomineral waters are found: Chaves hot waters (67 °C) and also several cold (16.1 °C) CO₂-rich waters. The δ²H and δ¹⁸O values of the thermomineral waters are similar to those of the local meteoric waters. The chemical composition of both hot and cold mineral waters suggests that water–rock reactions are mainly controlled by the amount of dissolved CO₂ (g) rather than by the water temperature. Stable carbon isotope data indicate an external CO₂ inorganic origin for the gas. δ¹³C_CO2 values ranging between ? 7.2‰ and ? 5.1‰ are consistent with a two-component mixture between crustal and mantle-derived CO₂. Such an assumption is supported by the ³He/⁴He ratios measured in the gas phase, are between 0.89 and 2.68 times the atmospheric ratio (Ra). These ratios which are higher than that those expected for a pure crustal origin (≈ 0.02 Ra), indicating that 10 to 30% of the He has originated from the upper mantle. Release of deep-seated fluids having a mantle-derived component in a region without recent volcanic activity indicates that extensive neo-tectonic structures originating during the Alpine Orogeny are still active (i.e., the Chaves Depression).     

Paleomagnetic dating of Phanerozoic kimberlites in Siberia

Diamond bearing kimberlite pipes are exposed across the north-central part of the Siberian platform. Three main time intervals are considered to be the age of emplacement: the Devonian–Early Carboniferous, Triassic, and Cretaceous. However, isotopic age data from of the pipes are scattered and provide a very broad age interval for the magmatic activity. New paleomagnetic poles from four kimberlite pipes (Eastern Udachnaya, Western Udachnaya, International and Obnazhennaya) are obtained to estimate their paleomagnetic age. The mean primary magnetization directions for the pipes are as follows: D = 4.3°, I = − 44.5° (k = 29.4, α₉₅ = 7.4°, N = 14); D = 340.5°, I = − 65.6° (k = 12.9, α₉₅ = 19.4°, N = 6); D = 291.1°, I = − 78.1° (k = 27.5, α₉₅ = 14.9°, N = 5); and D = 306.7°, I = − 82.6° (k = 38.4, α₉₅ = 5.8°, N = 17), respectively. On the basis of a comparison with the Siberian apparent polar wander path (APWP) we estimate the age of kimberlite magmatism, assuming primary magnetizations in these rocks. The paleomagnetic ages are as follows: 428 ± 13 Ma for Eastern Udachnaya; 251 ± 30 Ma for International pipe; and 168 ± 11 Ma for Obnazhennaya pipe. The Western Udachnaya pipe was remagnetized and no clear paleomagnetic age could be determined. The ages of magmatic activity span the Early Silurian to Middle Late Jurassic. Early Silurian magmatism could be associated with the formation of the Viluy rift. Middle to Late Jurassic magmatic activity is most likely related to subduction related to the accretion of surrounding terranes to Siberia.     

Recycling of harbor sediment as lightweight aggregate

Sediment sampled from Taichung Harbor was mixed with local reservoir sediment at different weight ratios to prepare lightweight aggregate at 1050, 1100, and 1150 °C. A pressure of 3000 or 5000 psi was used to shape the powder mixtures into pellets before the heating processes. The results indicate that the leaching levels of trace metals from the lightweight aggregate samples are considerably reduced to levels less than Taiwan Environmental Protection Administration regulatory limits. Increasing final process temperature tends to reduce the bulk density and crushing intensity of lightweight aggregate with a concomitant increase in water sorption capability. Lightweight aggregate with the lowest bulk density, 0.49 g cm⁻³ for the 5000 psi sample, was obtained with the heating process to 1150 °C. Based on the X-ray absorption near edge structure results, FeSO₄ decomposition with a concomitant release of SO_x (x = 2, 3) is suggested to play an important role for the bloating process in present study.     

Effects of tributyltin at concentrations below ambient levels in seawater on Caprella danilevskii (Crustacea: Amphipoda: Caprellidae)

Hatched juveniles of Caprella danilevskii (Crustacea: Amphipoda) were exposed to one of two concentrations of tributyltin (TBT) (1.1 and 10.7 ng TBT L⁻¹) for 49 d at 20 °C. These concentrations are near or below ambient levels in seawater. In both treatments and control, the survival rate was 100% at maturation, and >85% at the end of the experiments. Females reached maturation at 20 (median) to 21.5 d at instar VII, and repeated spawning 4–5 times during the experiment. The total number of juveniles per female decreased significantly from 39.5 in the control to 24.5 and 17.5 in 1.1 ng L⁻¹ and 10.7 ng L⁻¹ treatments, respectively. An earlier study reported that as the TBT concentration in seawater increased from a 0–10 ng L⁻¹ regime to a 10–20 ng L⁻¹ regime, the number of stations where Caprella spp. could be collected decreased along the coast of the Seto Inland Sea, of Japan. Thus, the present study indicates the possibility that the extremely low concentration of TBT measured in Japanese waters after 2000 lead to a reduction in reproductive success of Caprella spp.     

The replacement of native plants by exotic species may affect the colonization and reproduction of aquatic hyphomycetes

The tropical riparian zone has a high diversity of plant species that produce a wide variety of chemical compounds, which may be released into streams. However, in recent decades there has been an extensive replacement of tropical native vegetation by Eucalyptus monocultures. Our objective was to compare fungal colonization of Eucalyptus camaldulensis leaves with fungal colonization of native plant species from riparian zones in Brazilian Cerrado (savannah) streams. The fungal colonization and enzymatic activity significantly influenced leaf litter decomposition. Fungal sporulation rates from leaf litter varied significantly with leaf species, with E. camaldulensis showing the highest sporulation rate (1226 conidia mg⁻¹AFDM day⁻¹) and leaf mass loss (23.2 ± 0.9%). This species has the lowest lignin content and highest N concentration among the studied species. Among the studied native species, we observed the highest sporulation rate for Protium spruceanum (271 conidia mg⁻¹AFDM day⁻¹), Maprounea guianensis (268 conidia mg⁻¹AFDM day⁻¹) and Copaifera langsdorffii (196 conidia mg⁻¹AFDM day⁻¹). Overall, native plant species of the Brazilian Cerrado exhibited recalcitrant characteristics and a higher lignin:N ratio. Therefore, variations in the physical and chemical characteristics of the leaf litter could explain the higher decay rate and reproductive activity observed for E. camaldulensis. However, the detritus of this species were colonized almost exclusively by Anguillospora filiformis (99.6 ± 0.4%) and exhibited a reduction in aquatic hyphomycetes species diversity. Our results suggest that the disturbance in the composition of riparian vegetation and consequently, in the diversity of leaf litter input into streams, could change the patterns and rates of leaf litter utilization by microbial decomposers. These changes may have important consequences in the processing of organic matter and, consequently, in the functioning of freshwater ecosystems.     

Latitudinal patterns of export production recorded in surface sediments of the Chilean Patagonian fjords (41–55°S) as a response to water column productivity

The Chilean Patagonian fjords region (41–56°S) is characterized by highly complex geomorphology and hydrographic conditions, and strong seasonal and latitudinal patterns in precipitation, freshwater discharge, glacier coverage, and light regime; all of these directly affect biological production in the water column. In this study, we compiled published and new information on water column properties (primary production, nutrients) and surface sediment characteristics (biogenic opal, organic carbon, molar C/N, bulk sedimentary δ¹³C_org) from the Chilean Patagonian fjords between 41°S and 55°S, describing herein the latitudinal pattern of water column productivity and its imprint in the underlying sediments. Based on information collected at 188 water column and 118 sediment sampling sites, we grouped the Chilean fjords into four main zones: Inner Sea of Chiloé (41° to ～44°S), Northern Patagonia (44° to ～47°S), Central Patagonia (48–51°S), and Southern Patagonia (Magellan Strait region between 52° and 55°S). Primary production in the Chilean Patagonian fjords was the highest in spring–summer, reflecting the seasonal pattern of water column productivity. A clear north–south latitudinal pattern in primary production was observed, with the highest average spring and summer estimates in the Inner Sea of Chiloé (2427 and 5860 mg C m^?2 d^?1) and Northern Patagonia (1667 and 2616 mg C m^?2 d^?1). This pattern was closely related to the higher availability of nutrients, greater solar radiation, and extended photoperiod during the productive season in these two zones. The lowest spring value was found in Caleta Tortel, Central Patagonia (91 mg C m^?2 d^?1), a site heavily influenced by glacier meltwater and river discharge loaded with glacial sediments. Biogenic opal, an important constituent of the Chilean fjord surface sediments (Si_OPAL ～1–13%), reproduced the general north–south pattern of primary production and was directly related to water column silicic acid concentrations. Surface sediments were also rich in organic carbon content and the highest values corresponded to locations far away from glacier influence, sites within fjords, and/or semi-enclosed and protected basins, reflecting both autochthonous (water column productivity) and allochthonous sources (contribution of terrestrial organic matter from fluvial input to the fjords). A gradient was observed from the more oceanic sites to the fjord heads (west–east) in terms of bulk sedimentary δ¹³C_org and C/N ratios; the more depleted (δ¹³C_org ?26‰) and higher C/N (23) values corresponded to areas close to rivers and glaciers. A comparison of the Chilean Patagonian fjords with other fjord systems in the world revealed high variability in primary production for all fjord systems as well as similar surface sediment geochemistry due to the mixing of marine and terrestrial organic carbon.     

Low-degree melting of a metasomatized lithospheric mantle for the origin of Cenozoic Yulong monzogranite-porphyry,east Tibet: Geochemical and Sr–Nd–Pb–Hf isotopic constraints

SHRIMP zircon U–Pb dating, mineral chemical, element geochemical and Sr–Nd–Pb–Hf isotopic data have been determined for the Yulong monzogranite-porphyry in the eastern Tibet, China. The Yulong porphyry was emplaced into Triassic strata at about 39 Ma. The rocks are weakly peraluminous and show shoshonitic affinity, i.e., alkalis-rich, high K₂O contents with high K₂O / Na₂O ratios, enrichment in LREE and LILE. They also show some affinities with the adakite, e.g., high SiO₂ and Al₂O₃, and low MgO contents, depleted in Y and Yb, and enrichment in Sr with high Sr / Y and La / Yb ratios, and no Eu anomalies. The Yulong porphyry has radiogenic ⁸⁷Sr / ⁸⁶Sr (0.7063–0.7070) and unradiogenic ¹⁴³Nd / ¹⁴⁴Nd (ε_Nd = − 2.0 to − 3.0) ratios. The Pb isotopic compositions of feldspar phenocrysts separated from the Yulong porphyry show a narrow range of ²⁰⁶Pb / ²⁰⁴Pb ratios (18.71–18.82) and unusually radiogenic ²⁰⁷Pb / ²⁰⁴Pb (15.65–15.67) and ²⁰⁸Pb / ²⁰⁴Pb (38.87–39.00) ratios. In situ Hf isotopic composition of zircons that have been SHRIMP U–Pb dated is characterized by clearly positive initial ε_Hf values, ranging from + 3.1 to + 5.9, most between + 4 and + 5. Phenocryst clinopyroxene geothermometry of the Yulong porphyry indicates that the primary magmas had anomalously high temperature (> 1200 °C). The source depth for the Yulong porphyry is at least 100 km inferred by the metasomatic volatile phase (phlogopite–carbonate) relations. Detailed geochemical and Sr–Nd–Pb–Hf isotopic compositions not only rule out fractional crystallization or assimilation-fractional crystallization processes, but also deny the possibility of partial melting of subducted oceanic crust or basaltic lower crust. Instead, low degree (1–5%) partial melting of a metasomatized lithosphere (phlogopite–garnet clinopyroxenite) is compatible with the data. This example gives a case study that granite can be derived directly by partial melting of an enriched lithospheric mantle, which is important to understand the source and origin of diverse granites.     

Mercury levels in selected bycatch fish species from industrial shrimp-trawl fishery in the SE Gulf of California

Baseline Hg concentration in bycatch fish from the SE Gulf of California were determined in muscle and liver of 19 species. Levels of Hg in muscle were compared with legal limits of this element in national and international legislation. Considering all fish species, mean concentrations in liver (2.458 ± 1.997 μg g⁻¹) were significantly higher (p < 0.05) than in muscle (0.993 ± 0.670 μg g⁻¹). The sequence of averaged Hg concentrations in most ichthyofauna was liver > muscle. Highest level of Hg in muscle (2.556 μg g⁻¹) and liver (7.515 μg g⁻¹) corresponded to Diapterus peruvianus and Ophioscion strabo, respectively. Considering muscle samples, none of the species had levels of Hg above the limit (1.0 μg g⁻¹ wet weight) in the Mexican legislation; with respect to the Japanese (0.4 μg g⁻¹ wet weight) and British (0.3 μg g⁻¹ wet weight) legislations, 26.3% and 31.6% of the species respectively, were above the corresponding limits.     

Immune responses to combined effect of hypoxia and high temperature in the green-lipped mussel Perna viridis

Flow cytometry was used to examine immune responses in haemocytes of the green-lipped mussel Perna viridis under six combinations of oxygen level (1.5 mg O₂ l⁻¹, 6.0 mg O₂ l⁻¹) and temperature (20 °C, 25 °C and 30 °C) at 24 h, 48 h, 96 h and 168 h. The mussels were then transferred to normoxic condition (6.0 mg O₂ l⁻¹) at 20 °C for further 24 h to study their recovery from the combined hypoxic and temperature stress. Esterase (Est), reactive oxygen species (ROS), lysosome content (Lyso) and phagocytosis (Pha) were reduced at high temperatures, whereas hypoxia resulted in higher haemocyte mortality (HM) and reduced phagocytosis. For HM and Pha, changes were observed after being exposed to the stresses for 96 h, whereas only a 24 h period was required for ROS and Lyso, and a 48 h one for Est. Recovery from the stresses was observed for HM and Pha but not other immune responses.     

Nutrient inputs from submarine groundwater discharge on the Santiago reef flat,Bolinao, Northwestern Philippines

Submarine groundwater discharge (SGD) on the reef flat of Bolinao, Pangasinan (Philippines) was mapped using electrical resistivity, ²²²Rn, and nutrient concentration measurements. Nitrate levels as high as 126 μM, or 1–2 orders of magnitude higher than ambient concentrations, were measured in some areas of the reef flat. Nutrient fluxes were higher during the wet season (May–October) than the dry season (November–April). Dissolved inorganic nitrogen (DIN = NO₃ + NO₂ + NH₄) and soluble reactive phosphorus (SRP) fluxes during the wet season were 4.4 and 0.2 mmoles m⁻² d⁻¹, respectively. With the increase population size and anthropogenic activities in Bolinao, an enhancement of SGD-derived nitrogen levels is likely. This could lead to eutrophic conditions in the otherwise oligotrophic waters surrounding the Santiago reef flat.     

Evapotranspiration in the Pampean Region using field measurements and satellite data

Evapotranspiration (LE) is an important factor for monitoring crops, water requirements, and water consumption at local and regional scale. In this paper, we applied the semi-empirical model to estimate the daily latent heat flux (LE_d = Rn_d + A − B(Ts − Ta)). LE_d has been estimated using satellite images (Thematic Mapper sensor) and a local dataset (incoming and outgoing short- and long-wave radiation) measured during three years. We first estimated the daily net Radiation (Rn_d) from a linear equation derived from the instantaneous net Radiation (Rn_d = CRn_i + D). Subsequently, coefficients A and B have been estimated for two different cover vegetations (pasture and soybean). For each vegetation cover, an error analysis combining Rn_d, A, B, and surface and air temperatures has been calculated. Results showed that Rn_d had good performance (nonbias and low RMSE). LE_d errors for pasture and soybean were ±28 W m⁻² and ±40 W m⁻² respectively.     

Sedimentary phosphorus species and sedimentation flux in the East China Sea

Core sediment samples were collected from the middle shelf of the East China Sea (ECS) to study the phosphorus forms, P accumulation rate (PAR), P burial efficiency and the burial flux in the ECS. The sediment samples were sequentially extracted and directly extracted to analyze different forms of sedimentary P: lossely sorbed P and iron-bound P (P_CDB); inorganic P associated with francolite (carbonate fluorapatite, CFA), biogenic hydroxyapatite, smecite, and CaCO₃ (P_CFA); detrital P (P_Detrital); organic P (P_Organic); and total P. In addition, the Fe contents in the citrate-dithionite-bicarbonate (CDB) extracted solution were also measured.The total concentrations of P in the surface sediments in the study area ranged from 13.5 to 22.3 μmol g⁻¹. Inorganic P was the major form and accounted for 72–93% of the total P pool. The average percentage of each fraction of P followed the sequence: P_Detrital (70%)>P_Organic (15.5%)>P_CDB (8.4%)>P_CFA (5.8%). The distribution pattern of total P in the surface sediment was similar to that of P_Detrital and P_Organic, but different from that of P_CDB and P_CFA. The profile variation of P_Organic was the most significant among the phosphorus forms at the study stations. The concentrations of P_CDB and P_CFA showed minor variation with depth. These results may suggest that transformations of P_Organic, P_CFA and P_CDB occurred at the study stations during sedimentary P burial.Based on the concentrations of total P, P_CDB and Fe_CDB obtained in the present study and the mass accumulation rate (MAR) reported in the literature, the values of the PAR, the P diffusion flux (J_PFe) supplied by reducible iron hydroxides and the P burial efficiency were calculated. The calculated results for PAR and J_PFe in the study area ranged from 1.02 to 24.23 μmol cm⁻² yr⁻¹ and from 0.1 to 2.11 μmol cm⁻² yr⁻¹, respectively. The phosphorus burial efficiency (PBE) was approximately 90%. The ECS is a phosphorus sink, and the average annual P burial flux has been reasonably estimated to be in the range of 20–25×10⁹ mol yr⁻¹.     

Aluminum incorporation in α-PbO2 type TiO2 at pressures up to 20 GPa

Aluminum incorporation into the high pressure polymorph of TiO₂ with the structure of α-PbO₂ has been studied from 10 to 20 GPa and 1300 °C by XRD, high-resolution ²⁷Al MAS-NMR and TEM. Al-doped α-PbO₂ type TiO₂ can be recovered at atmospheric pressure. Al₂O₃ solubility in α-PbO₂ type TiO₂ increases with increasing the synthesis pressure. The α-PbO₂ type TiO₂ polymorph is able to incorporate up to 35 wt.% Al₂O₃ at 13.6 GPa and 1300 °C, being the substitution of Ti⁴⁺ by Al³⁺ on normal octahedral sites the mechanism of solubility. The transition to the higher pressure TiO₂ polymorph with the ZrO₂ baddeleyite structure, Akaogiite, has not been observed in the quenched samples at room pressure. The microstructure of the recovered sample synthesized at 16 GPa and 1300 °C points to the existence of a non-quenchable aluminum titanium oxide phase at these conditions.     

Os–Hf–Sr–Nd isotope and PGE systematics of spinel peridotite xenoliths from Tok,SE Siberian craton: Effects of pervasive metasomatism in shallow refractory mantle

Os–Hf–Sr–Nd isotopes and PGE were determined in peridotite xenoliths carried to the surface by Quaternary alkali basaltic magmas in the Tokinsky Stanovik Range on the Aldan shield. These data constrain the timing and nature of partial melting and metasomatism in the lithospheric mantle beneath SE Siberian craton. The xenoliths range from the rare fertile spinel lherzolites to the more abundant, strongly metasomatised olivine-rich (70–84%) rocks. Hf–Sr–Nd isotope compositions of the xenoliths are mainly within the fields of oceanic basalts. Most metasomatised xenoliths have lower ¹⁴³Nd / ¹⁴⁴Nd and ¹⁷⁶Hf / ¹⁷⁷Hf and higher ⁸⁷Sr / ⁸⁶Sr than the host basalts indicating that the metasomatism is older and has distinct sources. A few xenoliths have elevated ¹⁷⁶Hf / ¹⁷⁷Hf (up to 0.2838) and plot above the Hf–Nd mantle array defined by oceanic basalts.¹⁸⁷Os / ¹⁸⁸Os in the poorly metasomatised, fertile to moderately refractory (Al₂O₃ ≥ 1.6%) Tok peridotites range from 0.1156 to 0.1282, with oldest rhenium depletion ages being about 2 Ga. The ¹⁸⁷Os / ¹⁸⁸Os in these rocks show good correlations with partial melting indices (e.g. Al₂O₃, modal cpx); the intercept of the Al–¹⁸⁷Os / ¹⁸⁸Os correlation with lowest Al₂O₃ estimates for melting residues (∼0.3–0.5%) has a ¹⁸⁷Os / ¹⁸⁸Os of ∼0.109 suggesting that these peridotites may have experienced melt extraction as early as 2.8 Gy ago. ¹⁸⁷Os / ¹⁸⁸Os in the strongly metasomatised, olivine-rich xenoliths (0.6–1.3% Al₂O₃) ranges from 0.1164 to 0.1275 and shows no apparent links to modal or chemical compositions. Convex-upward REE patterns and high abundances of heavy to middle REE in these refractory rocks indicate equilibration with evolved silicate melts at high melt / rock ratios, which may have also variably elevated their ¹⁸⁷Os / ¹⁸⁸Os. This inference is supported by enrichments in Pd and Pt on chondrite-normalised PGE abundance patterns in some of the rocks. The melt extraction ages for the Tok suite of 2.0 to 2.8 Ga are younger than oldest Os ages reported for central Siberian craton, but they must be considered minimum estimates because of the extensive metasomatism of the most refractory Tok peridotites. This metasomatism could have occurred in the late Mesozoic to early Cenozoic when the Tok region was close to the subduction-related Pacific margin of Siberia and experienced large-scale tectonic and magmatic activity. This study indicates that metasomatic effects on the Re–Os system in the shallow lithospheric mantle can be dramatic.