Paleoenvironmental reconstruction of a Late Quaternary lagoon system in southern Brazil (Jaguaruna region,Santa Catarina state) based on multi‐proxy analysis

This paper provides a paleoenvironmental reconstruction of a Late Quaternary lagoon system in the Jaguaruna region of Santa Catarina state, southern Brazil. Integrated results of bulk sedimentary organic matter characterization (δ¹³C, δ¹⁵N and C/N), microfossil (pollen and diatom) and grain‐size analysis from three shallow cores (～2.5 m depth) allowed us to propose an evolving paleogeographic scenario in this coastal region for the last ca. 5500 cal a BP. The lagoonal system in this area was more extensive during the mid‐Holocene than today, with a gradual and continuous lagoon–sea disconnection until the present. We add to the debate regarding relative sea‐level (RSL) variations for the Brazilian coast during the Holocene and discuss the importance of sedimentary dynamics for interpreting changes in coastal ecosystems. The multi‐proxy analysis suggests that changes in coastal ecosystems could be directly related to local sedimentary processes, which are not necessarily linked to RSL fluctuations and/or to climatic variations. Copyright © 2011 John Wiley & Sons, Ltd.     

Phytoplankton community structure defined by key environmental variables in Tagus estuary, Portugal

In this work, we analyze environmental (physical and chemical) and biological (phytoplankton) data obtained along Tagus estuary during three surveys, carried out in productive period (May/June/July) at ebb tide. The main objective of this study was to identify the key environmental factors affecting phytoplankton structure in the estuary. BIOENV analysis revealed that, in study period, temperature, salinity, silicate and total phosphorus were the variables that best explained the phytoplankton spatial pattern in the estuary (Spearman correlation, rho=0.803). A generalized linear model (GLM) also identified salinity, silicate and phosphate as having a high explanatory power (63%) of phytoplankton abundance. These selected nutrients appear to be consistent with the requirements of the dominant phytoplankton group, Baccilariophyceae. Apparently, phytoplankton community is adapted to fluctuations in light intensity, as suspended particulate matter did not come out as a key factor in shaping phytoplankton structure along Tagus estuary.     

Linking the Abundance of Estuarine Fish and Crustaceans in Nearshore Waters to Shoreline Hardening and Land Cover

Human alteration of land cover (e.g., urban and agricultural land use) and shoreline hardening (e.g., bulkheading and rip rap revetment) are intensifying due to increasing human populations and sea level rise. Fishes and crustaceans that are ecologically and economically valuable to coastal systems may be affected by these changes, but direct links between these stressors and faunal populations have been elusive at large spatial scales. We examined nearshore abundance patterns of 15 common taxa across gradients of urban and agricultural land cover as well as wetland and hardened shoreline in tributary subestuaries of the Chesapeake Bay and Delaware Coastal Bays. We used a comprehensive landscape-scale study design that included 587 sites in 39 subestuaries. Our analyses indicate shoreline hardening has predominantly negative effects on estuarine fauna in water directly adjacent to the hardened shoreline and at the larger system-scale as cumulative hardened shoreline increased in the subestuary. In contrast, abundances of 12 of 15 species increased with the proportion of shoreline comprised of wetlands. Abundances of several species were also significantly related to watershed cropland cover, submerged aquatic vegetation, and total nitrogen, suggesting land-use-mediated effects on prey and refuge habitat. Specifically, abundances of four bottom-oriented species were negatively related to cropland cover, which is correlated with elevated nitrogen and reduced submerged and wetland vegetation in the receiving subestuary. These empirical relationships raise important considerations for conservation and management strategies in coastal environments.     

Nonpoint pollution load in river catchments with different anthropic impacts: a case study in Southern Brazil

Diffuse or nonpoint source (NPS) pollution results in different pollutant concentrations, which depend on river catchments, land use and precipitation events and may vary along a single event. This study aimed to assess NPS pollution loads of organic matter, nutrients, bacteria and heavy metals in four river catchments associated with different types of land use in Southern Brazil. Cluster analysis was used to identify similarities between basins and main component analysis (PCA) to identify the main variables that characterize diffuse pollution in each basin. The use and occupation of the soil were determinant in the formation of the clusters. The basins with rural characteristics formed one group, whereas the basin with urban characteristic generated another group. PCA suggests that changes in the water quality of the catchments in this study can be explained by organic pollutants and farming activities. The Rancho do Amaral catchment, with 55.8% of native forest, displayed the lowest NPS pollution load for all tested parameters. The Alto da Colina catchment, with the largest urban area and largest agricultural land use (50%), showed the highest NPS for all variables in the study, even though it has the smallest area. The differences in pollutant loads can be attributed to the intense degradation processes associated with anthropic activities, such as urbanization, agricultural activity and the discharge of effluents, which are different for each catchment.     

Identification of the Coronal Sources of the Fast Solar Wind

Starting from the observation that kilohertz quasi-periodic oscillations (kHz QPOs) occur in a very narrow range of X-ray luminosities in neutron star low-mass X-ray binaries, we try to link the kHz QPO observability to variations of the neutron star magnetospheric radius, in response to changing mass inflow rate. At low luminosities, the drop-off of kHz QPO activity may be explained by the onset of the centrifugal barrier, when the magnetospheric radius reaches the corotation radius. At the opposite side, at higher luminosities, the magnetospheric radius may reach the neutron star and the vanishing of the magnetosphere may lead to the stopping of the kHz QPO activity. If we apply these constraints, the magnetic fields of atoll [B approximately 0.3-1x108 G for Aql X-1] and Z [B approximately 1-8x108 G for Cyg X-2] sources can be derived. These limits naturally apply in the framework of beat-frequency models but can also work in the case of general relativistic models.     

A double structure generalized plasticity model for expansive materials

The constitutive model presented in this work is built on a conceptual approach for unsaturated expansive soils in which the fundamental characteristic is the explicit consideration of two pore levels. The distinction between the macro‐ and microstructure provides the opportunity to take into account the dominant phenomena that affect the behaviour of each structural level and the main interactions between them. The microstructure is associated with the active clay minerals, while the macrostructure accounts for the larger‐scale structure of the material. The model has been formulated considering concepts of classical and generalized plasticity theories. The generalized stress–strain rate equations are derived within a framework of multidissipative materials, which provides a consistent and formal approach when there are several sources of energy dissipation. The model is formulated in the space of stresses, suction and temperature; and has been implemented in a finite element code. The approach has been applied to explaining and reproducing the behaviour of expansive soils in a variety of problems for which experimental data are available. Three application cases are presented in this paper. Of particular interest is the modelling of an accidental overheating, that took place in a large‐scale heating test. This test allows the capabilities of the model to be checked when a complex thermo‐hydro‐mechanical (THM) path is followed. Copyright © 2005 John Wiley & Sons, Ltd.     

International borders, ground water flow, and hydroschizophrenia

A substantial body of research has been conducted on transboundary water, transboundary water law, and the mitigation of transboundary water conflict. However, most of this work has focused primarily on surface water supplies. While it is well understood that aquifers cross international boundaries and that the base flow of international river systems is often derived in part from ground water, transboundary ground water and surface water systems are usually managed under different regimes, resulting in what has been described as "hydroschizophrenia." Adding to the problem, the hydrologic relationships between surface and ground water supplies are only known at a reconnaissance level in even the most studied international basins, and thus even basic questions regarding the territorial sovereignty of ground water resources often remain unaddressed or even unasked. Despite the tensions inherent in the international setting, riparian nations have shown tremendous creativity in approaching regional development, often through preventive diplomacy, and the creation of "baskets of benefits," which allow for positive-sum, integrative allocations of joint gains. In contrast to the notion of imminent water wars, the history of hydropolitical relations worldwide has been overwhelmingly cooperative. Limited ground water management in the international arena, coupled with the fact that few states or countries regulate the use of ground water, begs the question: will international borders serve as boundaries for increased "flows" of hydrologic information and communication to maintain strategic aquifers, or will increased competition for shared ground water resources lead to the potential loss of strategic aquifers and "no flows" for both ground water users?     

Particle accumulation in a cylindrical sediment trap under laminar and turbulent steady flow: An experimental approach

The hydrodynamical, fluid and particle parameters which control flushing rates, flow cells, and accumulation rates of particulate matter in cylindrical (MultiPIT) sediment traps were quantified in a flume simulation using a seeding technique for 25–45 µm particles. Particle collection was found to be a trap- and particle-specific filtering process encompassing advective and gravitational entry of particles over a reduced trap aperture area, and gravitational-turbulent removal of particles at the bottom of the internal flow cell. Trapping efficiency increased up to 10-fold with increasing horizontal flow velocity (1–30 cm · s^–1). For given flow velocity, the trap over-and undercollected particles relative to their weight, i.e. (theoretical) Stokes settling velocity. The trapping efficiency increased with increasing trap Reynolds number Re_T, changed by the approaching velocity in our experiments. Opposite findings from earlier experiments using the flume seeding technique and changing Re_T by altering the trap diameter (Butman, 1986) are discussed. Semi-empirical equations are derived for the accumulation process of light, heavy and intermediate particles. From these, measured trap fluxes can be converted into in-situ verticle particle flux except for light particles.     

Nation building and resource management: The politics of ‘nature’ in Timor Leste

This paper examines the role of custom and tradition in the process of nation building and resource management in post-independence Timor Leste (East Timor). While customary land tenure is alluded to but not explicitly recognized under the Timorese Constitution, it is clearly stated that all natural resources are owned by the State. However, this paper argues that rather than waiting for the government to create land and resource management related laws, local people in Timor Leste are making and remaking their own laws, mobilizing their customary practices and, increasingly, ‘performing’ their traditions in public demonstrations of their extant capacities. In part, this process can be read as a way of enticing in outsiders, making them a party to the law making process, a witness to its legitimacy. Often critical to such processes, is the ability of local level leaders to draw in outsiders through their engagements with the idea of ‘nature’ – a concept which allows diverse interests to come together in conversation and build relationships despite what is often a dissonance in the meanings and priorities attributed to the concept (see Tsing, A.L., 2005. Friction: An Ethnography of Global Connection. Princeton University Press, Princeton and Oxford). The paper focuses on a view from the margins – Tutuala in the far east of the country – and ways in which this community is attempting to both resist and embrace the developmental hegemony of a centrist state. This, it is argued, is a case which demonstrates the power of the local (both ritually and politically) to shape and intervene in the national development process and the associated discourses of nature preservation.