Central Delta Research Articles

Primary central nervous system gamma delta cytotoxic T-cell lymphoma

Primary T-cell lymphomas of the central nervous system (CNS) are uncommon, but aggressive and increasing in incidence. We describe a rare case of T-cell lymphoma in a cerebellar location, to our knowledge the first reported case demonstrating gamma/delta receptor expression. Additionally, we elaborate on key diagnostic features and review all nine patients with primary CNS lymphoma of cytotoxic T-cell phenotype reported in the literature. A 26-year-old female medical student presented with a 6week history of nausea, vomiting and dizziness. MRI revealed a 2cm cerebellar mass. The tumor was subtotally resected, and pathologic examination of a subtotal resection specimen demonstrated peripheral T-cell lymphoma, not otherwise specified, with a gamma/delta cytotoxic T-cell phenotype. She subsequently started high dose methotrexate and cytarabine. We report a unique case of primary CNS gamma delta CD8+ T-cell lymphoma lineage in a young female patient. While these are rare entities, it is an important differential diagnosis to consider. Therapy should be tailored to the patient, and involves resection with adjuvant chemotherapy, radiotherapy or autologous stem-cell based treatments.

Calibration and Validation of DSSAT V.4.6.1, CERES and CROPGROModels for Simulating No-Tillage in Central Delta, Egypt

Crop simulation programs allow analyzing and exploring various tillage-rotation combinations and management. This study was conducted to apply and evaluate the DSSAT program under Egyptian conditions. The study was carried out to investigate the effect of tillage system, fertilizer rates and cereal/legume rotation on the crop yield and soil quality. The CERES-maize and CROPGRO-broad bean models were used to simulate the studied crop yield. Field observations showed that, the effect of tillage systems during the summer season of 2013 did not differ significantly due to studied maize traits. Regarding, winter season of 2013/2014), the results showed that, CA tillage system increased significantly all studied broad bean traits as compared with the other tillage systems. Referring to, the summer season of 2014, CA system scored the significant high values for the studied maize traits. As for the effect of studied NPK fertilizer levels, results indicated that, 100% of the recommended doses of NPK favored the values of the studied maize and broad bean traits significantly during summer 2013 and winter 2013/2014, as compared by 50% of the recommended dose of NPK fertilizers, while, there are no-significant difference between the two fertilizer levels for maize traits in the third season (summer, 2014). With regard to, the first order interaction effect between the tested factors, results of the three trial seasons revealed that, growing maize or broad bean under the condition of conservation agriculture (CA) and fed by 100% or 50% of the recommended dose of NPK fertilizers scored the greatest values for most of maize studied traits and broad bean, and the differences between them did not reach the significant level. On contrast, the lowest value were resulted under the condition of Conventional agriculture (CT) and fed by the 50% of the recommended dose of NPK fertilizers. The models that were used in this study also reflected this trend. The CERES-maize and CROPGRO-broad bean models greatly discovered stimulation for grain yield/fed., harvest index as affected by interaction effect between tillage systems and fertilizer rats, which their RMSE ranged between excellent and good, RMSE = (8.44, 12.19) and (11.70,16.79) and (0.15, 12.02) for summer 2013, winter 2013/2014 and summer 2014 seasons respectively, through (maize→ broad bean→ maize) crop sequence.

Life Cycle Assessment of Diesel Fuel and Solar Pumps in Operation Stage for Rice Cultivation in Tanta, Nile Delta, Egypt

This paper aims at using life cycle assessment (LCA) to assess the environmental impacts of groundwater pumping systems diesel fuel and solar power for lifting irrigation water for one feddan (1.037 acre) of rice. The study area lies in Tanta semi-arid central Nile Delta, Egypt. LCA via SimaProv8.04.30 is used to study the environmental impacts of pumping water using two types of pumping systems. Environmental impacts of diesel pump and solar pump systems are compared for different hydraulic head and area of rice cultivation scenarios. Results indicated that the diesel-powered pumping systems are more harmful to the environment than solar power pumps. The contribution to midpoint environmental impacts of the diesel fuel pump impacts reach 70% for natural resources, 18% for human health, 10% for climate change and 2% for ecosystem quality. On the other hand, solar pumping system contributes to 3% to climate change, 2% to human health and natural resources impacts, and 0.5% to ecosystem quality. The results confirm that for groundwater pumping, diesel fuel energy has the highest environmental impacts on human health, the ecosystem quality, climate change and resources depletion. It is highlighted that the type of power source must be considered when ranking pumping systems based on environmental performance.

Distribution and Habitat Associations of California Black Rail (Laterallus jamaicensis coturniculus) in the Sacramento–San Joaquin Delta

Author(s): Tsao, Danika C.; Melcer, Jr., Ronald E.; Bradbury, Michael | Abstract: Past studies documenting the distribution and status of state “Threatened California black rail (Laterallus jamaicensis coturniculus; hereafter black rail) have largely omitted the Sacramento—San Joaquin Delta (hereafter Delta). During March to May of 2009–2011, we conducted call–playback surveys to assess the status of the species within a wide range of wetland habitats of the central Delta region. We detected black rails at 21 of 107 discrete wetland sites, primarily on in-channel islands with dense cover. To better understand the habitat and land cover characteristics, we developed a model of habitat suitability from these occurrence data and a fine-scale vegetation and land use dataset using MaxEnt. We also evaluated differences in the size of wetlands at sites where black rails were detected versus where they were not. Through surveys and quantitative modeling, we found black rail presence differed from other regions within California and Arizona, in that it was positively associated with tall (1 to 5 m) emergent vegetation interspersed with riparian shrubs. Specific plants correlated with black rail presence included emergent wetland (Bolboschoenus acutus, B. californicus, B. acutus, Typha angustifolia, T. latifolia, Phragmites australis) and riparian (Salix exigua, S. lasiolepis, Rosa californica, Rubus discolor, Cornus sericea) species. Median patch size was significantly larger and perimeter-to-area ratios were significantly lower at wetland sites where black rails were found. These results provide a preliminary characterization of black rail habitat in the Delta region and highlight the need for better understanding of this listed species’ population size and habitat use in the region, in light of anticipated climate change effects and proposed large-scale restoration in the Delta.

Assessing the Population Status of the Critically Endangered Niger Delta Red Colobus (Piliocolobus epieni)

Abstract: A survey to assess the conservation status of the Niger Delta red colobus (Piliocolobus epieni) was carried out across the species' range in central Niger Delta in 2013. The survey results suggest that the population has declined significantly since it was first assessed in 1996; c. 90% lower than the previous estimate of <10,000 individuals about 20 years ago. Using cumulative observation data, I suggest that the current estimate of the total population surviving in the wild can only number in the hundreds rather than the thousands. The major threats are habitat loss and degradation, but hunting is still a significant threat to the species’ survival. Based on spatial analysis of forest cover within the species range over a 22-year period, it is estimated that deforestation occurs at an average of 1.2% annually, thus, suggesting that if the species' decline is primarily driven by habitat loss, it may become extinct in 5 years or less. Only two areas were found where viable populations of the spe...

Depositional facies and sequence of the latest Pleistocene to Holocene incised valley fill in Kushiro Plain, Hokkaido, northern Japan

The development of the latest Pleistocene to Holocene incised valley fill in the Kushiro area, Hokkaido, Japan is investigated in this study. Nine boring core samples drilled in the Kushiro marsh were examined using depositional facies analysis, total sulfur content (TSC) measurement, and radiocarbon dating methods. Based on these methods, 12 depositional facies were recognized including marsh, subaqueous talus, bay-head delta, sand dune, beach, shoreface, barrier sand body, drowned valley-central basin, salt marsh, fluvial, pond, and pyroclastic deposits. The incised valley fill forms a depositional sequence primarily controlled by glacio-eustatic sea-level changes. The lowstand systems tract is composed of river deposits. The transgressive systems tract includes salt marsh, drowned-valley fill central basin, bay-head delta, barrier sand body, central basin, and subaqueous talus deposits. The highstand systems tract is composed of barrier sand body, shoreface, beach, sand dune, central basin bay-head delta, marsh, salt marsh, subaqueous talus, fluvial, and pond facies. Radiocarbon dating analysis indicates that the period of maximum marine flooding was around 7 ka cal. BP.

Palaeotopography related plant succession stages in a coal forming deltaic succession in early Jurassic in Hungary

An integrated palaeoecological study was performed regarding the Early Jurassic coal bearing succession (Mecsek Coal Formation) of the Mecsek Basin (S Hungary) focusing on boreholes from Máza-South and Rücker areas representing the periphery and the central part of the coastal plain of a delta respectively. Comparative investigations were based on a previous palaeobotanical ecogroup model and on the integrated interpretation of sedimentological and palaeobotanical data from Máza-South.Sedimentary isopach and coal seam ash content data were applied to reconstruct palaeotopography and coal seam thickness data to detect plant growing intensity at Máza-South (10km2). Plant fossils identified from the corresponding strata were used as sources for the identification of four topography-related plant succession stages determined by sequential facies changes. Channel banks and small islands are characterised by underdeveloped associations composed of colonist elements. Exposed slopes or levees, or local elevations in overbank conditions are covered with assemblages of small herbaceous plants. Crevasse splay complexes are characterised by more developed plant cover and swamps in floodplain depressions are characterised by typical swampy successions. Based on these succession stages, plant remains from Rücker were also interpreted, however, mainly swampy and elevated overbank habitats alternated at Rücker reflecting continuous floods.According to the results, Máza-South was a small area located very close to the bayline between the alluvial plain and the coastal plain of a delta, less favourable for intensive plant growing where dry land was restricted to levees and crevasse splays. This resulted in more dynamic plant changes, typical for deltaic peripheral territories. In contrast, Rücker represents the central part of the delta plain environment dominated by woody forms of large growth. In the uppermost sequence plant composition at Máza-South became similar to that of Rücker indicating that, with transgression, the central delta plain environment, permanent at Rücker, advanced towards the peripheral zone represented by Máza-South.

Role of hydrogeochemical process in increasing groundwater salinity in the central Godavari delta

Groundwater salinization is an ever increasing problem in coastal aquifers due to seawater intrusion resulting from excessive groundwater withdrawals, lithological conditions of the aquifer and industrial and agriculture pollutant loads. Identification of salinity sources is challenging and a prerequisite for the protection of coastal fresh water aquifers. The present aim of the study is to identify the salinity sources and to understand its dynamics in the central Godavari delta, Andhra Pradesh where groundwater is highly saline with total dissolved solids (TDS) of ∼5000 mg/L at shallow depths of <3 m bgl. Groundwater samples were collected from 42 representative observation wells in the area and analyzed for major ions and stable isotopes (δ18O). Different hydro-chemical mixing models and multivariate statistical techniques, including factor and cluster analysis, are applied to these data sets. The results revealed that very high salinity (∼25,000 mg/L) in pumping wells is due to up-coning of salt water and the salinity is palaeo in origin. The salinity in the wells along the drains and near the coast (∼10,000 mg/L) is due to the infiltration of marine waters resulting from backwaters and intrusion of seawater along the drains. The salinity (∼5000 mg/L) in the wells away from the coast is attributed to dissolution of evaporites in the groundwater and ion exchange process.

Myoclonic status in non-progressive encephalopathies or Dalla Bernardina syndrome

We present an update of a series of patients with myoclonic status in non-progressive encephalopaties (MSNPE) describing the electroclinical features and outcome. Between February 1, 1990 and June 30, 2011, 41 patients who met diagnostic criteria of MSNPE were seen at our department and followed up to the present time. Three main subgroups were identified. The first subgroup of 27 patients presented with myoclonic absences and rhythmic myoclonias followed by a brief silent period associated with subcontinuous delta-theta activity involving the central areas and rhythmic delta waves with superimposed spikes mainly involving the parietooccipital regions and often activated by eye closure. This pattern was found in all children with a genetic etiology. The second subgroup included seven patients showing a pattern characterized by inhibitory phenomena associated with a dystonic component and sudden irregular rapid lightning-like jerks. The electroencephalography showed subcontinuous multifocal slow spike-waves, predominating in frontocentral regions. These patients had a cortical malformation or the etiology was unknown. The third subgroup included seven children who initially suffered from myoclonic absences. The status was initially characterized by subcontinuous generalized spike-wave-type paroxysms related to rhythmic myoclonia of face and limbs. After 1 to 3 wk, the electroencephalography showed sharp theta waves with very slow pseudorhythmic continuous spikes in the central regions and vertex. The etiology was found to be perinatal anoxic injury. MSNPE is a well-defined epileptic syndrome in the group of epileptic encephalopathy secondary to different, but mostly genetic, etiologies.

Measurement of diffractive dissociation cross sections inppcollisions ats=7 TeV

Measurements of diffractive dissociation cross sections in pp collisions at sqrt(s) = 7 TeV are presented in kinematic regions defined by the masses M[X] and M[Y] of the two final-state hadronic systems separated by the largest rapidity gap in the event. Differential cross sections are measured as a function of xi[X]= M[X]^2/s in the region -5.5 < log[10]xi[X] < -2.5, for log[10]M[Y] < 0.5, dominated by single dissociation (SD), and 0.5 < log[10]M[Y] < 1.1, dominated by double dissociation (DD), where M[X] and M[Y] are given in GeV. The inclusive pp cross section is also measured as a function of the width of the central pseudorapidity gap Delta eta for Delta eta > 3, log[10]M[X] > 1.1, and log[10]M[Y] > 1.1, a region dominated by DD. The cross sections integrated over these regions are found to be, respectively, 2.99 +/- 0.02 (stat) +0.32 -0.29 (syst) mb, 1.18 +/- 0.02 (stat) +/- 0.13 (syst) mb, and 0.58 +/- 0.01 (stat) +0.13 -0.11 (syst) mb, and are used to extract total SD and DD cross sections. In addition, the inclusive differential cross section, d sigma /d Delta eta[F], for events with a pseudorapidity gap adjacent to the edge of the detector, is measured over Delta eta[F] = 8.4 units of pseudorapidity. The results are compared to those of other experiments and to theoretical predictions, and found compatible with slowly-rising diffractive cross sections as a function of center-of-mass energy.

Seasonal Abundance and Phenology of Oebalus pugnax (Hemiptera: Pentatomidae) on Graminaceous Hosts in the Delta Region of Mississippi.

The rice stink bug, Oebalus pugnax (F.), is a graminaceous feeder, and the most injurious insect pest of heading rice, Oryza sativa L., in the United States. Rice growers are aware of the economic importance of host grasses in O. pugnax abundance. However, the need for increased knowledge of host sequence relative to O. pugnax abundance is vital. Densities of O. pugnax on 15 graminaceous hosts were evaluated in the central Mississippi Delta from April through August in 2011 and 2012. Two cultivated and 13 wild host grasses were sampled using a sweep net. Overall, populations of O. pugnax were lower in 2012 than in 2011. Italian ryegrass, Lolium perenne L. ssp. multiflorum (Lambert), was the main host that supported O. pugnax survival and reproduction from overwintering to early summer. Echinochloa spp., Digitaria spp., and Eriochloa spp. maintained greater populations of O. pugnax in the summer. Browntop millet, Urochloa ramosa (L.) Nguyen, and broadleaf signalgrass, U. platyphylla (Munro ex C. Wright) R. D. Webster, were important for populations of O. pugnax populations immediately prior to overwintering. Host switching was also an important factor that contributed to O. pugnax abundance. The evolution of Italian ryegrass resistance to the broad spectrum herbicide glyphosate in the central Mississippi delta has become an important component of O. pugnax population dynamics because of its increased abundance in and around agricultural areas. Cultural control measures on host grasses before flowering could result in less use of insecticides, thereby reducing cost of rice production.

English

We used available data to estimate changes in land use and wet, non-farmable, and marginally farmable (WNMF) areas in the Delta from 1984 to 2012, and developed a conceptual model for processes that affect the changes observed. We analyzed aerial photography, groundwater levels, land–surface elevation data, well and boring logs, and surface water elevations. We used estimates for sea level rise and future subsidence to assess future vulnerability for the development of WNMF areas. The cumulative WNMF area increased linearly about 10-fold, from about 274 hectares (ha) in 1984 to about 2,800 ha in 2012. Moreover, several islands have experienced land use changes associated with reduced ability to drain the land. These have occurred primarily in the western and central Delta where organic soils have thinned; there are thin underlying mud deposits, and drainage ditches have not been maintained. Subsidence is the key process that will contribute to future increased likelihood of WNMF areas by reducing the thickness of organic soils and increasing hydraulic gradients onto the islands. To a lesser extent, sea level rise will also contribute to increased seepage onto islands by increasing groundwater levels in the aquifer under the organic soil and tidal mud, and increasing the hydraulic gradient onto islands from adjacent channels. WNMF develop from increased seepage under levees, which is caused by changing flow paths as organic soil thickness has decreased. This process is exacerbated by thin tidal mud deposits. Based primarily on projected reduced organic soil thickness and land–surface elevations, we delineated an additional area of about 3,450 ha that will be vulnerable to reduced arability and increased wetness by 2050.

Late Pleistocene–Holocene evolution of the Doce River delta, southeastern Brazil: Implications for the understanding of wave-influenced deltas

Abstract Brazil's coast displays many wave-influenced deltas that are still incompletely understood, despite their significance for reconstructing the history of Late Pleistocene–Holocene sea-level changes in this region and the potential to advance in the knowledge of wave-influenced deltas. Among them, the Doce River delta is the most expressive, given its larger geographic extension. The present work shows that this is a wave-influenced delta that evolved within the context of Late Pleistocene–Holocene sea-level fluctuations, rather than a mid-Holocene lagoonal delta as proposed elsewhere. The delta had an initial progradation at an OSL age of 132.7 (± 9.1) ka after the Marine Isotope Stage (MIS) 5e, which was followed by major progradation between 45,775–49,391 and 29,678–29,226 cal yr BP. Beach ridges/spits formed during these phases were in part destroyed during an ensuing transgression between 8161–7933 and 4974–4850 cal yr BP. The central delta remained dominated by fluvial processes, which kept pace with the rising sea level due to relatively high rainfall in the Doce River drainage basin. The Doce River delta started to grow again after the late-Holocene transgression, a process still on-going at the present time. During this evolution, the Doce River was deflected northward and then southward, a process that did not result in any significant facies change when the updrift and downdrift sides of the river's mouth are compared. Such a pattern is in disagreement with previously proposed asymmetry index models for wave-influenced deltas, which predict an uneven distribution of sandy- or muddy-rich deposits in the updrift and downdrift sides of the river's mouth, respectively. Several other deltas along the Brazilian coast also display facies configuration similar to the Doce River delta or have patterns opposed to those proposed by the asymmetry index models. Based on these analogs, it can be stated that the geometries and facies patterns of wave-dominated deltas are not determined simply by the interplay of fluvial and marine processes. Instead, they can be strongly influenced by the fluvial influx, sea-level changes and/or tectonic reactivations, as it appears to be the case of Brazilian wave-influenced deltas, including the Doce River delta. Such a conclusion calls for a word of caution when applying processes-based facies models to reconstruct wave-influenced deltas in the sedimentary record.

Cholera, Colonialism, and Pilgrimage: Exploring Global/Local Exchange in the Central Egyptian Delta, 1848–1907

From the 1850s to the 1890s, Tanta, the largest city in the Egyptian delta appeared in print media throughout the world as an epicenter of cholera. Medical journals, periodicals, and missionary tracts reproduced the death tolls from the 1848 cholera epidemic that killed three thousand people in Tanta. Collectively, colonial administrators, missionaries, and physicians pigeon-holed Tanta as an epicenter of cholera that threatened to spread westward. This article uses Tanta’s emergence into the global discourse of public medicine as a vehicle to understand the dynamic relationship between global and local engagements. It argues that the 1848 outbreak took on new meaning over the second half of the nineteenth century as it played into larger debates about germ theory, colonialism, and global trade. It shows that Tanta’s engagement with the global discourse reflects the inherently symbiotic relationship between world and local histories.

Mica and Heavy Minerals as Markers to Map Nile Delta Coastline Displacements during the Holocene

ABSTRACT Stanley, J.-D. and Clemente, P.L., 2014. Mica and heavy minerals as markers to map Nile Delta coastline displacements during the Holocene. Mica and heavy minerals in sediments of Egypt's Nile Delta are examined to test if measured proportions of these two mineral groups and their distributions can be used to define former coastline positions and their shifts in time and space during the Holocene. The premise of the study is based on the sufficiently different attributes of these two components, especially their shape, density, and size, which could induce their segregation and dissimilar dispersal patterns during sediment transport. To test this hypothesis, mineralogical data from more than 1400 samples from 87 sediment cores recovered across the northern third of the delta margin were analyzed. The marked contrast in both temporal and spatial distributions of high proportions of mica and of heavy minerals indicates distinct separation occurred primarily north of the central delta, in an area fro...

Assessment of possibility of saltwater intrusion in the central Godavari delta region, Southern India

Oil exploration and development have taken place extensively in the near-shore waters of the Bay of Bengal for over two decades, with onshore coastal aquifers serving as a primary source of water injected into near-shore production wells for enhanced oil recovery. Field and modeling studies were initiated to assess the effects of potential seawater intrusion into the coastal aquifers and to improve strategies for groundwater development and management. Groundwater levels were measured at 42 locations in the central Godavari delta (295 km2) over a period of 2 years (2006–2007). These data indicated that the predominant groundwater flow direction consistently points toward the coast with no significant change in groundwater table elevations during the study period. Groundwater samples analyzed for major ions revealed the groundwater to be brackish in nature with an average salinity of ~5,000 mg L−1. A numerical model of variable density, groundwater flow, and solute transport (SEAWAT) was developed for the study region. After calibrating against observed hydraulic head data for the year 2006 at steady state, the model was used to predict the extent of seawater intrusion in the study area over the next 50 years. The estimated regional groundwater budget indicates a significant amount of groundwater outfall to the Bay of Bengal. The model predicts that the area will not be affected by seawater intrusion at the present rate of groundwater exploitation near the coast.

Trends of ambient fine particles and major chemical components in the Pearl River Delta region: Observation at a regional background site in fall and winter

In the fall and winter of 2007 to 2011, 167 24-h quartz filter-based fine particle (PM2.5) samples were collected at a regional background site in the central Pearl River Delta. The PM2.5 showed an annual reduction trend with a rate of 8.58μgm−3 (p<0.01). The OC component of the PM2.5 reduced by 1.10μgm−3yr−1 (p<0.01), while the reduction rates of sulfur dioxide (SO2) and sulfate (SO42−) were 10.2μgm−3yr−1 (p<0.01) and 1.72μgm−3yr−1 (p<0.01), respectively. In contrast, nitrogen oxides (NOx) and nitrate (NO3−) presented growth trends with rates of 6.73μgm−3yr−1 (p<0.05) and 0.79μgm−3yr−1 (p<0.05), respectively. The PM2.5 reduction was mainly related to the decrease of primary OC and SO42−, and the enhanced conversion efficiency of SO2 to SO42− was related to an increase in the atmospheric oxidizing capacity and a decrease in aerosol acidity. The discrepancy between the annual trends of NOx and NO3− was attributable to the small proportion of NO3− in the total nitrogen budget. Capsule abstractUnderstanding annual variations of PM2.5 and its chemical composition is crucial in enabling policymakers to formulate and implement control strategies on particulate pollution.

Organosulfates from pinene and isoprene over the Pearl River Delta, South China: seasonal variation and implication in formation mechanisms.

Biogenic organosulfates (OSs) are important markers of secondary organic aerosol (SOA) formation involving cross reactions of biogenic precursors (terpenoids) with anthropogenic pollutants. Until now, there has been rare information about biogenic OSs in the air of highly polluted areas. In this study, fine particle (PM2.5) samples were separately collected in daytime and nighttime from summer to fall 2010 at a site in the central Pearl River Delta (PRD), South China. Pinene-derived nitrooxy-organosulfates (pNOSs) and isoprene-derived OSs (iOSs) were quantified using a liquid chromatograph (LC) coupled with a tandem mass spectrometer (MS/MS) operated in negative electrospray ionization (ESI) mode. The pNOSs with MW 295 exhibited higher levels in fall (151 ± 86.9 ng m(-3)) than summer (52.4 ± 34.0 ng m(-3)), probably owing to the elevated levels of NOx and sulfate in fall when air masses mainly passed through city clusters in the PRD and biomass burning was enhanced. In contrast to observations elsewhere where higher levels occurred at nighttime, pNOS levels in the PRD were higher during the daytime in both seasons, indicating that pNOS formation was likely driven by photochemistry over the PRD. This conclusion is supported by several lines of evidence: the specific pNOS which could be formed through both daytime photochemistry and nighttime NO3 chemistry exhibited no day-night variation in abundance relative to other pNOS isomers; the production of the hydroxynitrate that is the key precursor for this specific pNOS was found to be significant through photochemistry but negligible through NO3 chemistry based on the mechanisms in the Master Chemical Mechanism (MCM). For iOSs, 2-methyltetrol sulfate ester which could be formed from isoprene-derived epoxydiols (IEPOX) under low-NOx conditions showed low concentrations (below the detection limit to 2.09 ng m(-3)), largely due to the depression of IEPOX formation by the high NOx levels over the PRD.

Evolution of Geochemical and Mineralogical Parameters during In Situ Remediation of a Marine Shore Tailings Deposit by the Implementation of a Wetland Cover

We present data of the time-evolution of a remediation approach on a marine shore tailings deposit by the implementation of an artificial wetland. Two remediation cells were constructed: one in the northern area at sea-level and one in the central delta area (above sea-level) of the tailings. At the beginning, the “sea-level” remediation cell had a low pH (3.1), with high concentrations of dissolved metals and sulfate and chloride ions and showed sandy grain size. After wetland implementation, the “sea-level” remediation cell was rapidly water-saturated, the acidity was consumed, and after four months the efficiency of metal removal from solution was up to 79.5%–99.4% for Fe, 94.6%–99.9% for Mn, and 96.1%–99.6% for Zn. Al and Cu concentrations decreased below detection limit. The “above sea-level” remediation cell was characterized by the same pH (3.1) and finer grain size (clayey–silty), and with some lower element concentrations than in the “sea-level” cell. Even after one year of flooding, the “above sea-level” cell was not completely flooded, showing on-going sulfide oxidation in between the wetland cover and the groundwater level; the pH increased only to 4.4 and metal concentrations decreased only by 96% for Fe, 88% for Al, 51% for Cu, 97% for Mn, and 95% for Zn. During a dry period, the water level dropped in the “sea-level” cell, resulting in a seawater ingression, which triggered the desorption of As into solution. These data show that the applied remediation approach for this tailings deposit is successful, if the system is maintained water-saturated. Metal removal from solution was possible in both systems: first, as a result of sorption on Fe(III) hydroxide/and/or clay minerals and/or co-precipitation processes after rise of pH; and then, with more reducing conditions, due to metal sulfides precipitation.

Impounded Marshes on Subsided Islands: Simulated Vertical Accretion, Processes, and Effects, Sacramento-San Joaquin Delta, CA USA

There is substantial interest in stopping and reversing the effects of subsidence in the Sacramento–San Joaquin Delta (Delta) where organic soils predominate. Also, the passage of California Assembly Bill 32 in 2006 created the potential to trade credits for carbon sequestered in wetlands on subsided Delta islands. The primary purpose of the work described here was to estimate future vertical accretion and understand processes that affect vertical accretion and carbon sequestration in impounded marshes on subsided Delta islands. Using a cohort-accounting model, we simulated vertical accretion from 4,700 calibrated years before present (BP) at a wetland area located within Franks Tract State Recreation Area (lat 38.059, long −121.611, hereafter, “Franks Wetland”)—a small, relatively undisturbed marsh island—and at the Twitchell Island subsidence-reversal demonstration project since 1997. We used physical and chemical data collected during the study as well as literature values for model inputs. Model results compared favorably with measured rates of vertical accretion, mass of carbon sequestered, bulk density and organic matter content. From 4,700 to model-estimated 350 years BP, the simulated rate of vertical accretion at Franks Wetland averaged about 0.12 cm yr-1, which is within the range of rates in tidal wetlands worldwide. Our model results indicate that large sediment inputs during the last 150 to 200 years resulted in a higher accretion rate of 0.3 cm yr -1. On Twitchell Island, greater organic inputs resulted in average vertical accretion rates as high as 9.2 cm yr -1. Future simulations indicate that the managed impounded marsh will accrete highly organic material at rates of about 3 cm yr -1. Model results coupled with GIS analysis indicate that large areas of the periphery of the Delta, if impounded and converted to freshwater marsh, could be restored to tidal elevations within 50 to 100 years. Most of the central Delta would require 50 to 250 years to be restored to projected mean sea level. A large portion of the western Delta could be restored to mean sea level within 50 to 150 years (large areas on Sherman, Jersey, and Bethel islands, and small areas on Bradford, Twitchell, and Brannan islands, and Webb Tract). We estimated that long-term carbon sequestration rates for impounded marshes such as the Twitchell Island demonstration ponds will range from 12 to 15 metric tons carbon ha-1 yr-1. Creation of impounded marshes on Delta islands can substantially benefit levee stability as demonstrated by cumulative force and hydraulic gradient calculations.