Estimates of non-tidal exchange transport between the Sea of Okhotsk and the North Pacific

The outflow from the Sea of Okhotsk to the North Pacific is important in characterising the surface-to-intermediate-depth water masses in the Pacific Ocean. The two basins are separated by the Kuril Islands with numerous straits, among which the Bussol and the Kruzenshterna Straits are deeper than 1000 m. The physics governing the transport between the two basins is complicated, but when the semidiurnal and diurnal tides are subtracted, the observed density and velocity structures across the Bussol Strait suggest a significant contribution from geostrophic balance. Using a two-layer model with the interface at 27.5σ _θ , part of the upper layer transport that is not driven by tides is estimated using two previously unexplored data sets: outputs from the Ocean General Circulation Model for Earth Simulator (OFES), and historical hydrographic data. The Pacific water flows into the Sea of Okhotsk through the northeastern straits. The greatest inflow is through the Kruzenshtern Strait, but the OFES results show that the contributions from other shallower straits are almost half of the Kruzenshtern inflow. Similarly, the outflow from the Sea of Okhotsk is through the southwestern straits of the Kuril Islands with the largest Bussol Strait contributing 60% of the total outflow. The OFES and hydrographic estimates agree that the exchange is strongest in February to March, with an inflow of about −6 to −12 Sv (negative indicates the flow from the North Pacific, 1 Sv = 10⁶ m³s⁻¹), and an outflow from the Sea of Okhotsk of about +8 to +9 Sv (positive indicates the flow from the Sea of Okhotsk), which is weakest in summer (−3 to +1 Sv through the northeastern straits and +0 to +3 Sv through the southwestern straits). The estimated seasonal variation is consistent with a simple analytic model driven by the difference in sea surface height between the two basins.     

Tracing origins of sewage and organic matter using dissolved sterols in Masan and Haengam Bay,Korea

Masan and Haengam Bays in Korea are highly polluted and semi-enclosed. Domestic and industrial effluents are directly or indirectly discharged into the bays through sewage treatment plants (STP) and creeks. In this study, 15 dissolved sterol compounds were determined in order to understand their sources and relative contribution. Freshwater samples were taken from 13 creeks and at two STP sites on a monthly basis. Total dissolved sterol concentrations ranged from 993 to 4158 ng/L. The concentrations of sterols in winter were higher than in summer. Among the sterols analyzed, cholesterol, β-sitosterol, coprostanol and cholestanone were major compounds in creek water. Seawater samples were concurrently collected at 21 stations in Masan Bay. Total sterol concentrations ranged 118–6,956 ng/L. Inner bay showed high concentrations of sterols in summer, while outer bay showed high sterol concentrations in winter. Among the sterols, cholesterol, β-sitosterol and brassicasterol were major compounds in seawater. In order to examine the contribution of urban sewage, the concentration of coprostanol and fecal sterol ratios were calculated. Most of the creek water, inner bay and near STP outlet samples were affected by sewage. Terrestrial organic matters accounted for a high proportion of dissolved organic matter origin. Fecal origins were relatively high in the inner bay areas and in the STP outlet, while sterols of marine origin were high in the outer bay areas.     

Analysis of types and changes of village-level economy in rural Gongyi city,Henan Province since 1990

Based on the research on the rural living standard in China in terms of annual net income per capita, we define six types of village-level economy, i.e. ＂to be extremely poor＂, ＂to make a basic living＂, ＂to dress warmly and eat one＇s fill＂, ＂to try to enrich （to disengage poverty）＂, ＂to be well-off＂ and ＂to be affluent＂. The data of average annual net income of all the 292 villages between 1990 and 2004 in rural Gongyi City, Henan Province were collected, verified and classified. By using standard deviation, coefficient of variation and regression analysis, it is found that the Gongyi＇s rural economy has boosted up remarkably from the relative-poverty and absolute-poverty stages in 1990 to the well-off in 2004. However, the absolute differences between villages present a trend of enlargement, while the relative differences fluctuating. On the other hand, spatial analysis of village-level economy shows that most villages with relatively high economic development level were located along national expressway and most villages with absolute-poverty lay in remote mountainous areas in 1990. Since the 1990s, the rapid urbanization and industrialization have had strongly positive effects on rural economic growth. Initial economic foundation, natural resources and traditional techniques also contribute to village economy. From the perspective of geography, villages with location advantages, such as near urban center or industrial parks, have more chances for their economic development and the ＂core-periphery＂ economic structure has been presented in the process of rural development.     

Respiration and Calcification of <Emphasis Type="Italic">Crassostrea gigas</Emphasis>: Contribution of an Intertidal Invasive Species to Coastal Ecosystem CO<Subscript>2</Subscript> Fluxes

Respiration and calcification rates of the Pacific oyster Crassostrea gigas were measured in a laboratory experiment in the air and underwater, accounting for seasonal variations and individual size, to estimate the effects of this exotic species on annual carbon budgets in the Bay of Brest, France. Respiration and calcification rates changed significantly with season and size. Mean underwater respiration rates, deducted from changes in dissolved inorganic carbon (DIC), were 11.4 μmol DIC g⁻¹ ash-free dry weight (AFDW) h⁻¹ (standard deviation (SD), 4.6) and 32.3 μmol DIC g⁻¹ AFDW h⁻¹ (SD 4.1) for adults (80–110 mm shell length) and juveniles (30–60 mm), respectively. The mean daily contribution of C. gigas underwater respiration (with 14 h per day of immersion on average) to DIC averaged over the Bay of Brest population was 7.0 mmol DIC m⁻² day⁻¹ (SD 8.1). Mean aerial CO₂ respiration rate, estimated using an infrared gas analyzer, was 0.7 μmol CO₂ g⁻¹ AFDW h⁻¹ (SD 0.1) for adults and 1.1 μmol CO₂ g⁻¹ AFDW h⁻¹ (SD 0.2) for juveniles, corresponding to a mean daily contribution of 0.4 mmol CO₂ m⁻² day⁻¹ (SD 0.50) averaged over the Bay of Brest population (with 10 h per day of emersion on average). Mean CaCO₃ uptake rates for adults and juveniles were 4.5 μmol CaCO₃ g⁻¹ AFDW h⁻¹ (SD 1.7) and 46.9 μmol CaCO₃ g⁻¹ AFDW h⁻¹ (SD 29.2), respectively. The mean daily contribution of net calcification in the Bay of Brest C. gigas population to CO₂ fluxes during immersion was estimated to be 2.5 mmol CO₂ m⁻² day⁻¹ (SD 2.9). Total carbon release by this C. gigas population was 39 g C m⁻² year⁻¹ and reached 334 g C m⁻² year⁻¹ for densely colonized areas with relative contributions by underwater respiration, net calcification, and aerial respiration of 71%, 25%, and 4%, respectively. These observations emphasize the substantial influence of this invasive species on the carbon cycle, including biogenic carbonate production, in coastal ecosystems.     

Biocalcification in the Eastern Oyster (<Emphasis Type="Italic">Crassostrea virginica)</Emphasis> in Relation to Long-term Trends in Chesapeake Bay pH

Anthropogenic carbon dioxide (CO₂) emissions reduce pH of marine waters due to the absorption of atmospheric CO₂ and formation of carbonic acid. Estuarine waters are more susceptible to acidification because they are subject to multiple acid sources and are less buffered than marine waters. Consequently, estuarine shell forming species may experience acidification sooner than marine species although the tolerance of estuarine calcifiers to pH changes is poorly understood. We analyzed 23 years of Chesapeake Bay water quality monitoring data and found that daytime average pH significantly decreased across polyhaline waters although pH has not significantly changed across mesohaline waters. In some tributaries that once supported large oyster populations, pH is increasing. Current average conditions within some tributaries however correspond to values that we found in laboratory studies to reduce oyster biocalcification rates or resulted in net shell dissolution. Calcification rates of juvenile eastern oysters, Crassostrea virginica, were measured in laboratory studies in a three-way factorial design with 3 pH levels, two salinities, and two temperatures. Biocalcification declined significantly with a reduction of ∼0.5 pH units and higher temperature and salinity mitigated the decrease in biocalcification.     

The response of fishes to submerged aquatic vegetation complexity in two ecoregions of the mid-Atlantic bight: Buzzards Bay and Chesapeake Bay

Estuarine seagrass ecosystems provide important habitat for fish and invertebrates and changes in these systems may alter their ability to support fish. The response of fish assemblages to alteration of eelgrass (Zostera marina) ecosystems in two ecoregions of the Mid-Atlantic Bight (Buzzards Bay and Chesapeake Bay) was evaluated by sampling historical eelgrass sites that currently span a broad range of stress and habitat quality. In two widely separated ecoregions with very different fish faunas, degradation and loss of submerged aquatic vegetation (SAV) habitat has lead to declines in fish standing stock and species richness. The abundance, biomass, and species richness of the fish assemblage were significantly higher at sites that have high levels of eelgrass habitat complexity (biomass >100 wet g m^?2; density <100 shotts m^?2) compared to sites that have reduced eelgrass (biomass <100 wet g m^?2; density <100 shoots m^?2) or that have completely lost eelgrass. Abundance, biomass, and species richness at reduced eelgrass complexity sites also were more variable than at high eelgrass complexity habitats. Low SAV complexity sites had higher proportions of pelagic species that are not dependent on benthic habitat structure for feeding or refuge. Most species had greater abundance and were found more frequently at sites that have eelgrass. The replacement of SAV habitats by benthic macroalgae, which occurred in Buzzards Bay but not Chesapeake Bay, did not provide an equivalent habitat to seagrass. Nutrient enrichment-related degradation of eelgrass habitat has diminished the overall capacity of estuaries to support fish populations.     

Dispersion function of Rayleigh waves in porous layered half-space system

Rayleigh wave exploration is based on an elastic layered half-space model. If practical formations contain porous layers, these layers need to be simplified as an elastic medium. We studied the effects of this simplification on the results of Rayleigh wave exploration. Using a half-space model with coexisting porous and elastic layers, we derived the dispersion functions of Rayleigh waves in a porous layered half-space system with porous layers at different depths, and the problem of transferring variables to matrices of different orders is solved. To solve the significant digit overflow in the multiplication of transfer matrices, we propose a simple, effective method. Results suggest that dispersion curves differ in a lowfrequency region when a porous layer is at the surface; otherwise, the difference is small.     

Targeted observation analysis of a Northwestern Tropical Pacific Ocean mooring array using an ensemble-based method

An important supplement for ocean observing systems, the Northwestern Tropical Pacific Ocean (NWTPO) mooring array including 15 moorings equipped with Acoustic Doppler Current Profilers (ADCP) devices was developed by the Chinese Academy of Sciences and deployed in 2013. This study assessed the performance of this mooring array in monitoring the intra-seasonal and low-frequency (above 91 days) variability of oceanic currents by conducting targeted observation analyses using an ensemble-based method. Key regions for monitoring intra-seasonal variability of the NWTPO circulation are the equator, Indonesian throughflow (ITF), headstream of the North Equatorial Countercurrent (NECC), and Subtropical Countercurrent (STCC). For monitoring intra-seasonal variability, the range of each mooring is confined to a local scale. Therefore, NWTPO moorings cannot adequately resolve intra-seasonal variability in areas of the ITF, the headstream of the NECC, and STCC due to location constraints of the moorings. For monitoring low-frequency variability of NWTPO circulation, the key regions are the Western Boundary Current (WBC), NECC, and the Equatorial Undercurrent (EUC). NWTPO moorings performed relatively well in monitoring the low-frequency variability, as indicated by the strong background correlations between each of the currents. The NWTPO mooring array plays an important role in monitoring the location and intensity of background currents. Because moorings are costly and require a high-density distribution for optimal performance, understanding the multi-timescale dynamical nature of the NWTPO current system is critical for the deploying future moorings in this region.     

Characterization of a chalcopyrite from Brazil by Mössbauer spectroscopy and other physicochemical techniques

We studied a chalcopyrite from a Cu ore deposit in Rio Grande do Sul, Brazil, by Mössbauer spectroscopy at room temperature and 110 K. Supporting methods to check for sample purity and to characterize further sample properties were slow-scanning X-ray powder diffraction and optical and microprobe analyses of polished sections of selected grains. Chemical analyses obtained using a scanning electron microscope equipped with an energy-dispersive X-ray spectrometer showed the sample to consist of homogeneous and essentially stoichiometric chalcopyrite (CuFeS₂). Mössbauer spectra taken at both the above temperatures consist of asymmetric magnetically ordered patterns with unequal intensities of the line pairs 1–6 and 2–5, pointing to the existence of non-equivalent or multiple Fe sites. Least-squares fittings evidenced that the resonance intensity ratio of subspectrum with lower quadrupole shift (indicative of a more symmetric environment) to that with higher shift is 69:31, at room temperature, and 68:32, at 110 K. Rietveld refinement of the XRD data indicates the existence of tetragonal [a = 0.52855(1) and c = 1.0412(1) nm] and cubic [a ₀ = 0.5273(2) nm] modifications in a proportion of 74:26, in good agreement with the Mössbauer data. The saturation magnetization of the sample was 32.7 J/(T kg), confirming the oxidation state of Fe as trivalent and pointing to little to no spin canting.     

Supporting farmer-managed irrigation systems in the Shigar valley,Karakorum: Role of the government and Aga Khan Rural Support Programme

Farmer-managed irrigation systems(FMIS) in the high altitude valleys of the Karakorum,Pakistan, continue to be managed effectively despite increased pressure on the social arrangements that sustain them. Colonial era records shows that over a century ago government agencies undertook irrigation support projects. In the past three decades,government agencies and the non-government agency Aga Khan Rural Support Programme(AKRSP), which channels foreign funds into the region, have actively engaged in the provision of irrigation support. This article seeks to explore whether such projects support or undermine farmer-managed irrigation systems and the complex institutional arrangements that underpin them. Field research using ethnographic and participatory methods was conducted in spring 2013 in the upper Shigar valley, Skardu district, GilgitBaltistan. The findings show that irrigation development is a political activity that involves village-based actors, religious leaders, local politicians,and government and non-government agencies.Government agencies operate in a largely top-down,engineering mode, their larger projects limited to villages suffering water scarcity. The local government provides small funds for renovation work of FMIS,though allocation of funds is highly politicized. Nongovernment agencies, for a variety of reasons including donor-funding cycles, apply a one-size-fitsall ‘participatory' model in an attempt to socially engineer rules and institutions. In communities divided by factionalism the use of such external models that stress formation of committees are unlikely to yield positive results, and could instead contribute to undermining the very systems they seek to support. This research argues that irrigation interventions should take care to build upon the rich and complex social arrangements that have sustained FMIS through the centuries.