Episodic riverine influence on surface DIC in the coastal Gulf of Maine

Anomalously high precipitation and river discharge during the spring of 2005 caused considerable freshening and depletion of dissolved inorganic carbon (DIC) in surface waters along the coastal Gulf of Maine. Surface pCO₂ and total alkalinity (TA) were monitored by repeated underway sampling of a cross-shelf transect in the western Gulf of Maine (GOM) during 2004–05 to examine how riverine fluxes, mixing, and subsequent biological activity exert control on surface DIC in this region. Most of the variability in surface DIC concentration was attributable to mixing of low DIC river water with higher DIC, saline GOM waters, but net biological uptake of DIC was significant especially during the spring and summer seasons. The extent and persistence of the coastal freshwater intrusion exerted considerable influence on net carbon dynamics. Integrated over the 10-m surface layer of our study region (∼5 × 10⁴ km²), net biological DIC uptake was 0.48 × 10⁸ mol C during April–July of 2004 compared to 1.33 × 10⁸ mol C during April–July of 2005. We found the temporal signature and magnitude of DIC cycling to be different in adjacent plume-influenced and non-plume regions. Extreme events such as the freshwater anomaly observed in 2005 will affect mean estimates of coastal carbon fluxes, thus budgets based on short time series of observations may be skewed and should be viewed with caution.     

Carbon stock assessment of mangrove ecosystems in Batticaloa Lagoon,Sri Lanka,with different degrees of human disturbances

This article presents a carbon stock assessment to illustrate the organic carbon distribution and storage within mangrove ecosystems in Sri Lanka. The living tree biomass and soil carbon pools were investigated in three sites with varying degree of human disturbance in Batticaloa Lagoon. Soil carbon content was derived by the Walkley Black method from soil samples and mangrove trees were measured for calculations in general allometric equations. The mangroves that were extremely converted into a shrimp farm in Kokkaddicholai recorded a carbon (C) stock of 100.9 kg m‐2. Dominated by the poisonous Excoecaria agallocha stands, the regenerating mangroves in Manmunai Bridge Island hosted the largest C stock measuring 786.4 kg C m‐2. The Kannankudah site—dominated by Avicennia marina, Lumnitzera racemosa and Excoecaria agallocha stands, recorded a C stock of 593.1 kg C m‐2. Cuts and stumps indicated wood harvesting for local livelihoods. The soil C content pool contributed most significantly to the total C stock, with the top 30 cm containing the largest C concentration in all soil profiles. The soil carbon content was highest (5.1 per cent) in Kannankudah, second highest (3.6 per cent) in the disturbed but regenerating forest at Manmunai Bridge Island, and the lowest (0.3 per cent) at the converted site of Kokkaddicholai.     

Larval dispersal and vertical migration behaviour – a simulation study for short dispersal times

Current speed often varies with depth, so vertical movements of larvae are expected to have profound effects on dispersal velocity and therefore dispersal potential. Systematic behaviours are expected to have strong effects on dispersal. However, reliable information on the presence of vertical migrations in larvae is scarce, but the few well investigated empirical examples justify a detailed simulation study and an analysis of potential effects. We present a spatially explicit 3D hydrodynamic model that incorporates biological information in the form of active particles advected in a Lagrangian fashion. The set‐up is designed to analyze the sensitivity of dispersal distances to variation in vertical behaviour of larvae. We simulated short (4 days) pelagic larval durations (PLDs) to determine whether behaviour might be important over short dispersal periods. We found that sinusoidal behaviours (slow vertical migration) in or out of phase with tides did not significantly change the dispersal patterns compared to those of larvae that remained at the surface. By contrast, a quadratic pattern of behaviour resulting in rapid vertical migration, in or out of phase with tides, had dramatic effects on both distance and direction of dispersal. The resulting dispersal kernels were found to be multimodal due to the interaction between tidal and meteorological components in flow. Incorporating biological information on larval migrations in Lagrangian simulation of dispersal will be important in estimates of connectivity and forecasting marine reserve networks.     

A note on the economics of Swedish Baltic Sea fisheries

The cod stocks in the Baltic Sea are important not only for fisheries but for the entire ecosystem utilized by numerous stakeholders around the coast. All such activities have economic values. In this note the economics of the Swedish Baltic Sea cod fishery is estimated in relation to the sector's interaction with other users of the Baltic Sea ecosystem. The results show a negative resource rent for the fishery, € −5 million without public expenses (subsidies and administrative costs), and € −13 million including public expenses. The interactions between the fisheries and tourism, seal population, carbon dioxide emissions, recreational fishing, and discards are discussed, and when monetary estimates are available these are related to the estimated resource rent.     

Drought is the major limiting factor for tree-ring growth of high-altitude Canary Island pines on Tenerife

This is a detailed study of 50 wood cores sampled from 25 Canary Island pines ( Pinus canariensis ) growing in a subtropical climate close to the tree limit (at Lomo de Retamar, 2000–2100 m a.s.l.) on the southern, leeward side of Tenerife.
The Canary Island pines form tree-rings and, similarly to temperate pines, earlywood is formed during spring. But many pines fail to form tree-rings every year and one purpose for this paper has been to find a way to overcome this problem. Another purpose has been to see what correlations, if any, exist between the ring widths and meteorological data. Meteorological data have been collected since 1916 at the nearby Izaña meteorological observatory. It was also important to find the limiting factor for growth of Canary Island pines close to the tree limit.
Through cross-dating, missing rings were found to be typical for younger parts of older trees; in the same years younger trees instead had low growth. Some trees lacked more than 20 rings in a century. This study shows that it is possible to compensate for missing rings, at least when the number of missing rings is less than 10%.
Correlation studies showed that the growth of the tree rings was mainly due to the precipitation factor, particularly the annual precipitation one year before the ring formation, but also due to temperature. Strangely enough, multiple linear regression gave the highest correlation coefficient (0.50) for a combination of annual precipitation one year earlier and temperature four years earlier.     

A new approach to oscillatory rough turbulent boundary layers

Velocity measurements have been performed in an oscillatory turbulent boundary layer over a rough wall, using a large oscillating water tunnel. These together with measurements by Kalkanis (1964) over an oscillating wall indicate the existence of universal wall and defect laws for velocity. A logarithmic overlap layer is predicted and observed as in a steady turbulent boundary layer, and this results in a new relationship between friction factor and relative boundary layer thickness. The phase lead of the defect velocity relative to the wall ditto seems to follow a universal law over the whole defect layer. A method is suggested for the calculation of the phase lead of wall shear stress over velocity in the free stream for large amplitude to roughness ratios. Apart from the inner layer, it is in principle possible to construct the velocity profiles in a turbulent oscillatory boundary layer at a rough wall, using the findings of this report. A review of experimental and theoretical investigations of the stability of the oscillatory boundary layer is also given.     

Energy properties and shoaling of higher-order stokes waves on a current

The energy density, the energy flux, the set-down, the radiation stress, and some wave energy velocities have been derived correct to fourth order in wave steepness for waves on a vorticity-free current. The energy flux and the set-down have been used for shoaling predictions for finite amplitude waves with and without a net volume flux. The results with a zero volume flux are compared with more accurate shoaling predictions showing rather good accordance, except for large steepnesses. This also applies to the deep water wave energy transport velocity. The results with a net volume flux show that the steepness of the waves reduces the influence of this flux on the wave evolution. Some problems in connection with the orders in Stokes waves are discussed, among others concerning the dispersion relation and the orders of integral properties. Bed shear and accompanying dissipation is neglected.     

Aerosol Chemistry, and Light-Scattering and Hygroscopicity Budgets during Outflow from East Asia

During the ACE-Asia field campaign, 41 aerosol filter samples were obtained by airborne sampling over the ocean to the north, south and west of Japan, generally under conditions of outflow from the Asian continent. These samples were analyzed for their water-soluble chemical components, particularly organic species. Suites of inorganic anions, carbohydrates, organic acids and metallic elements were identified and quantified (21 distinct species). Simultaneously, measurements were made of the aerosol hygroscopicity and light scattering. A factor analysis performed on the compositional data identified several sources for the aerosols sampled during the field campaign. Regression of the light-scattering data onto tracers for each of these factors suggests that the aerosol light scattering could be largely attributed to three of these factors: anthropogenic emissions, biomass burning, and soil dust. Similarly, the aerosol hygroscopicity was largely consistent with an empirical mixing model based on past measurements of the hygroscopicity of these individual aerosol types. Limited size-resolved , aerosol composition measurements were also obtained and suggested different sources for various chemical species.     

Laser microprobe sulphur isotope analysis of arsenopyrite: experimental calibration and application to the Boliden Au–Cu–As massive sulphide deposit

Metamorphic remobilization of arsenopyrite-rich ores is a globally important process which can lead to significant concentrations of gold. In order to understand this and related processes, relations of sulphur isotopes can give a number of important clues. To resolve such relations in detail, we have successfully calibrated and applied a laser combustion system for in situ analysis of sulphur isotopic compositions of arsenopyrite. Experimental calibration of the laser fractionation factor (+0.4‰) was obtained by using compositionally and isotopically homogeneous natural samples from ore deposits at Boliden (Sweden) and Freiberg (Germany); subsequent to detailed microscopic study, the S isotope ratios of these samples were measured by conventional and laser combustion techniques.The present application to different types of arsenopyrite in the Palaeoproterozoic metamorphosed VHMS ores of the Boliden Au–Cu–As deposit, Skellefte district, northern Sweden, shows that the sulphur isotope composition of arsenopyrite is essentially unmodified during medium-grade metamorphic recrystallization and remobilization. Here, massive arsenopyrite ore is crosscut by later veins that carry a complex quartz–sulphosalt–sulphide assemblage. The latter ore type is markedly Au-rich compared to the host ore, and thus of significant economic interest. We find that both ore types exhibit very similar sulphur isotope compositions, ca. +2‰ to +3‰ (V-CDT), which is similar to most massive sulphide deposits in the Skellefte district. Thus, the crosscutting Au-rich vein ore has inherited the sulphur isotope composition from sulphur liberated by metamorphic reactions affecting the massive ore, and most likely also inherited the Au through this mechanism. The latter finding clearly has important implications both for the general discussion on, and the prospecting for, similar high-grade Au ores in this world-class mining region.