Water Circulation Patterns Research Articles

Accuracy and sensitivity of radium mass balances in assessing karstic submarine groundwater discharge in the stratified Calanque of Port-Miou (Mediterranean Sea)

Abstract Submarine Groundwater Discharge (SGD) has received increased attention in recent years since it was recognized that it may be both volumetrically and chemically important. Around the Mediterranean Sea, 60% of the coastline is composed of karstic aquifers, and to properly estimate the hydrological budget of the Mediterranean Sea it is therefore necessary to better assess the karstic submarine groundwater discharges (KSGD). However, quantifying KSGD is still challenging. Among the methods recently developed to detect and quantify SGD, the mass balance method of the radium quartet 223Ra, 224Ra, 226Ra and 228Ra has proved to be a powerful technique. This approach requires characterizing all the contributing terms and sinks in the coastal water volume affected by SGD, the residence time of coastal waters, as well as a representative concentration of the tracers for both surface water and discharging groundwater. In this study we combine several approaches (223Ra, 224Ra, salinity profiles and Acoustic Doppler Current Profiler (ADCP) measurements) to examine both the accuracy and sensitivity of the radium mass balance method in the case of the cove of Port-Miou (Mediterranean Sea, France) where the main karstic spring discharges locally at 10 m depth. This study benefits from the inland in-situ access to the main karst conduit discharging to the sea which provides a long time series to characterize the brackish submarine groundwater end-member. We show that the composition of the cove water is stratified, with two water bodies: a surface brackish layer and a deeper layer. The mean KSGD value obtained with 223Ra and 224Ra mass balances in the surface water body is precise but significantly lower (0.6 ± 0.1 m3/s) than the karstic spring discharge (4 ± 1 m3/s) estimated within the karst conduit with pressure sensors. The residence time of the cove water estimated using both 224Ra and 223Ra isotopes is very low (1 ± 1 day). Our study shows that the water residence time that we calculated using the Ra mass balance is the key parameter that may impact KSGD. In addition, based on ADCP transects, we suggest that the shape and geometry of the cove, as well as the location of the discharge point of the spring play a key role in explaining these discrepant results. We therefore recommend that in such stratified coves, estimations of KSGD based on short-lived radium isotopes require accurate and independent estimates of the water residence time as well as a good knowledge of the shallow and deep circulation patterns of the cove water.

Effect of an extreme cold event on the metabolism of planktonic microbes in the northernmost basin of the Mediterranean Sea

Abstract In the northern Adriatic Sea (the northernmost basin of the Mediterranean Sea) wind forcing plays a key role in shaping the water column structure, circulation patterns and dense water formation. The latter process might be enhanced during winter by local north-easterly wind, the Bora, responsible for intense and long-lasting episodic outbreaks. Although outbreaks of Bora are extensively studied in the context of thermohaline circulation, little is known about their effects on planktonic microbial communities. From late February to early March 2018, a persistent and strong Bora event caused an unusual drop of seawater temperature (down to 5.7 °C) in the Gulf of Trieste. To investigate the effect of this extreme meteorological event on the coastal planktonic microbes, we evaluated changes in their abundance and cytometric fingerprinting, heterotrophic carbon production rates and the activity of six exoenzymes (β-glucosidase, β-galactosidase, chitinase, lipase, alkaline-phosphatase and leucine aminopeptidase). Additionally, we set up temperature manipulation experiments to investigate the potential limiting effect of the temperature drop on microbial degradation and uptake of organic matter. The dataset clustered in two distinct groups: a cold-affected period (26th February - 8th March), characterised by a reduced particulate organic matter availability and slow metabolic rates, and a recovery one, (12th - 16th March) defined by an overall increase of substrate availability and enhanced heterotrophic carbon production and hydrolysis rates. Our findings revealed that the exoenzymatic activities were constrained at their lower thermal limit during the cold-affected period and that, deviating from the Arrhenius’ linear response to temperature, the prokaryotic growth was limited by the interactive effect of temperature and substrate availability. By limiting the microbial processing of organic matter, extreme meteorological events could alter the functioning of the entire planktonic compartment functioning for several days during and after the onset of the phenomenon, affecting the structure of local trophic webs.

Winter study of Antarctic zone of the Southern Ocean (to the 25-th anniversary of the Soviet-Russian-American drift station “Weddell-1”)

The information concern oceanographic investigations in 1980-90 within Antarctic sea-ice formation area together with “International oceanographic study of Antarctic Zone” ( “iAnZone”) program is given. The supreme component of these investigations became the soviet-american winter expedition “Ice Station Weddell-1” (ISW-1), supported by “Academic Fedorov”(SU), “Nathaniel Palmer” (US) and drift station (3.02.92–9.06.92). The water mass structure and circulation patterns in most remote part of the Weddell Gyre, including Western boundary current parameters and bottom water from the shelf were for the first time defined.

Regional circulation patterns of Mediterranean Outflow Water near the Iberian and African continental slopes

Abstract. The Mediterranean Outflow Water (MOW) is a dense water mass originated in the Strait of Gibraltar. Downstream of the Gulf of Cádiz, the MOW forms a reservoir region west of the Iberian continental slopes at a buoyant depth of approximately 1000 m. This region plays a key role as the main centre where the MOW is mixed and distributed into the North Atlantic. The seafloor in this area is characterized by the presence of a complex bathymetry with three abyssal plains separated by mountain chains. Although the topographic features do not reach the surface, they influence ocean flows at intermediate and deep ocean layers, conditioning the distribution and circulation of MOW. The Copernicus Marine Environmental Monitoring Service (CMEMS) Iberian–Biscay–Ireland (IBI) ocean reanalysis is used to provide a detailed view of the circulation and mixing processes of MOW near the Iberian and African continental slopes. This work emphasizes the relevance of the complex bathymetric features defining the circulation processes of MOW in this region. The high resolution of the IBI reanalysis allows us to make a description of the mesoscale features forced by the topography. The temperature, salinity, velocity, transport, and vorticity fields are analysed to understand the circulation patterns of MOW. The high-resolution circulation patterns reveal that Horseshoe Basin and the continental slope near Cape Ghir (a.k.a. Cap Rhir or Cabo de Aguer) are key areas controlling the mixing processes of MOW with the surrounding water masses, mainly North Atlantic Central Water (NACW) and Antarctic Intermediate Water (AAIW). The water mass variability is also analysed by means of composite analysis. Results indicate the existence of a variability in the MOW tongue which retracts and expands westwards in opposition to the movement of the underlying North Atlantic Deep Water.

Application of environmental isotopes to identify recharge source, age, and renewability of phreatic water in Yinchuan Basin

AbstractThe accurate understanding of groundwater circulation pattern and its renewable capacity is vital for groundwater resource assessment and the rational exploitation and utilization of groundwater. Estimation of groundwater recharge is difficult in arid or semiarid area due to the low amount and variability of recharge. A combination of isotope investigation with hybrid model allows a direct calculation of renewability of the aquifer. In this paper, the phreatic water circulation pattern and its renewable capacity of phreatic water in Yinchuan Basin, a semiarid area located at the northwest China, are investigated by the application of environmental isotope method, which mainly focusses on the isotope characteristics of different water bodies, phreatic water isotope age, phreatic water circulation pattern, and phreatic water renewal rate. The results demonstrate that the two dominant recharge sources of groundwater in Yinchuan Basin, local atmospheric precipitation and Yellow River, account for 13% and 87%, respectively. The average residence time of phreatic water in Yinchuan Basin is about 48 years, and the average renewal rate is 3.38%/a. The results indicate that the phreatic water has a strong renewable capacity and the regeneration rate distribution is consistent with that indicated by isotope age.

Upper circulation in Bone Bay and its relation to biogeochemical distribution: from observation and model

The surrounding waters and the physical mechanisms within the ocean are playing a major role to bring nutrients to Bone Bay, field observation in October 2014 and analysis of numerical modeling were conducted in order to understand the pattern of water circulation, as well as the variability of seawater transport and its impacts to the biogeochemical distribution. The results of the observation show that the distribution of salinity is lower in locations closest to the gulf (Transect A) and higher towards the furthest locations from the gulf (Transect D), followed by the pattern of other parameters (temperature, dissolved oxygen, and chlorophyll-a). This happened due to the low current speed in the Flores Sea during the time of observation hence no water flowed into the gulf which was dominated by freshwater from rivers. It is confirmed by the transport model that shows that seawater is transported strongly to the north from January to March and due to the topography at the mouth of the gulf, the water accumulates and forms an eddy which transports water to the south in April until the next few months. This explains the distribution of phytoplankton and zooplankton inside the gulf from January to March.

Distribution and source apportionment of hydrocarbons in sediments of oil-producing continental margin: a fuzzy logic approach.

Investigation were carried out targeting distribution and source apportioning of hydrocarbons in surface sediments from shallow to deep waters in the Campos Basin, one of the most important oil-producing provinces in Brazil. The observed levels of aliphatic (≤ 124μgg-1) and polycyclic aromatic hydrocarbons (PAHs ≤ 599ngg-1) are lower than those considered relevant for environmental risk to the benthic habitats. Higher median concentrations of aliphatic hydrocarbons (8.49μgg-1) and PAHs (84.8ngg-1) in the middle slope sediments (700-1000-m water depths) showed the influence of hydrodynamics upon hydrocarbon accumulation in the sediments. Diagnostic ratios and conventional statistical analysis applied to hydrocarbon data produced insufficient information on the contribution of different sources. These traditional approaches do not consider the potential changes affecting source assignment and therefore cannot deal with the uncertainties. The fuzzy logic applied as an alternative method for data treatment successfully incorporated the uncertainties in the differentiation between petrogenic and pyrolytic sources, including those due to degradation. Moreover, by using fuzzy logic, it was possible to identify that water circulation patterns, mass transport, deposition, and degradation processes are more relevant factors in determining hydrocarbon composition than source proximity.

The Effect of Sidewall Friction on Complex Channel Geometry using LABSWETM

Lattice Boltzmann Model for Shallow Water Equation with Turbulence Modeling (LABSWETM) is used to study the flow patterns of sidewall friction effects. The lattice Boltzmann method (LBM) approach in recovery the macroscopic governing equation which is shallow water equation from the microscopic flow behavior of particle movement as described by kinetic theory is explored. With the solution of force term to be used in lattice Boltzmann equation, the boundary condition of LBM is explored. With the use of bed and wall friction coefficients, the importance of Manning’s coefficient in determining the outcome of flow patterns simulation is explained. For model verification, the model represents a straight channel with a circular cavity attached to it. The result of this simulation includes the water circulation patterns, cross-section of average velocity distribution, and water depth. For validation, the cross-sections of the model in term of velocity vectors are compared against alternative numerical and experimental data.

Modelirovanie rasprostraneniya zagryaznyayushchey primesi v Sevastopol'skoy bukhte

Introduction. Tracking of spread of various contaminations and elaboration of the operational systems to control wrecking discharges are among the important tasks of marine environment monitoring. The processes of transport of the contaminating impurity inflowing from different sewers were modeled based on the diagnostic calculations of water circulation in the Sevastopol Bay. Data and Methods. The currents field was calculated using the sigma-coordinate version of the Princeton Ocean Model adapted for the regional conditions in the Sevastopol Bay. To calculate the polluting impurity transport, the model of the matter transfer and diffusion was incorporated into the circulation model. The data on the wind speed and direction obtained at the Sevastopol met office, the temperature, salinity and density climatic fields calculated using the information of 2.7 thousands hydrological stations in the Sevastopol Bay, average seasonal variations of the River Chernaya water discharge and the digital bottom relief with spatial resolution 68 m were used in the model. Analysis of Results. Numerical experiments on the contaminant propagation from the point of possible discharge in the Gollandiya Bay reveal that dependence of the pollutant movement trajectory (direction) upon the pattern of water circulation is most evident in the Yuzhnaya Bay and less manifested in the central part of the Sevastopol Bay. In case of a wrecking discharge in the River Chernaya mouth, a contaminant spot, regardless of wind conditions, moves to the northwest and reaches the Gollandiya Bay. Further evolution of the polluted water volume is similar to the process developing after a sewage discharge directly within the Gollandiya Bay. Discussion and Conclusions. The carried out numerical calculations confirm operational capability of the model and its adequate reproduction of the physical processes under study. It permits both to model the circulation seasonal variation and the thermohaline structure of the Sevastopol Bay waters, and to describe more accurately trajectories of the contaminants’ spread.

Oceanographic characteristics of the Adriatic Sea – Support to secondary HAOP spread through natural dispersal

Vessels, specifically ballast water and hull fouling, are a major vector for the introduction of non-indigenous species (NIS) in European seas. The Mediterranean is one of the world's marine regions where their invasion is heaviest. The shallow Adriatic basin is a highly sensitive area that is already experiencing its consequences. The secondary spread of NIS over a wider area through natural dispersion is a complex process that depends on a wide range of oceanographic factors. This work analysed the dataset of the BALMAS project, in whose framework twelve ports in the Adriatic Sea were subjected to a Port Baseline Survey (PBS), to estimate the natural spread of NIS organisms from their port of arrival to the wider Adriatic basin. Its findings indicate that the prevailing water circulation patterns facilitate the natural dispersal of harmful aquatic organisms and pathogens (HAOP).

Decoupling of Macromolecular Compositions of Particulate Organic Matters between the Water Columns and the Sediment in Geoje-Hansan Bay, South Korea

The biochemical composition of particulate organic matter (POM) is very important to understand in relation to the trophic conditions of marine ecosystems since it forms the primary trophic base. The present study investigated the biochemical compositions (i.e., carbohydrates, proteins, and lipids) of POM monthly from January to December 2015 in Geoje-Hansan Bay to determine if the macromolecular composition of POM is coupled between the water columns and sediment. A spatial difference in the macromolecular compositions was observed in the water columns between the inner and outer bays, which may be caused by the different physiological conditions of phytoplankton growth that are due to the water circulation pattern in the bay. In contrast, no distinctive spatial difference in the macromolecular compositions was found in the sedimentary organic matter. Overall, while carbohydrates were the dominant (45.7%) macromolecules of the POM in the water columns, proteins were dominant (47.9%) in the sedimentary organic matter during our observation period. Decoupling of the macromolecular compositions between the water columns and underneath the sediment in Geoje-Hansan Bay appears to be a result of the various effects of selective filter feeding by oysters and protein-dominant benthic microalgae and fouling organisms.

Domoic Acid-Producing Diatoms of the Genus Pseudo-nitzschia H. Peragallo, 1900 (Bacillariophyta) from the North Pacific

Information on diatoms of the genus Pseudo-nitzschia, known as producers of domoic acid (DA), from the North Pacific is summarized. The differences in the negative impact of toxic diatoms on ecosystems in the western and eastern North Pacific are shown. The possible causes that determine the degree of these different impacts are discussed: a different composition of dominant species; a difference in the intracellular DA concentration in bloom-forming species; the hydrological, climatic, and hydrochemical factors that are responsible for the formation of toxic blooms (upwelling events, patterns of water circulation, concentration of iron compounds in sea water, etc.). The conclusion is made that the prospects of further studies of toxic diatoms are based on comparative investigations into the species and genetic diversity of Pseudo-nitzschia and associated bacteria, as well as the environmental parameters that control the formation of toxic blooms and the accumulation of DA in microalgae and other marine organisms in the eastern and western North Pacific.

Water circulation in Toronto Harbour

We present an overview of physical processes that drive water circulation within the extended system of coastal embayments in the Toronto Harbour. The different water circulation patterns occur at various spatial and temporal scales, and our article provides context for the various efforts to improve water quality by the Toronto and Region Remedial Action Plan. Velocity profiles and water level measurements showed that the harbour’s Helmholtz pumping mode drives a 1-h period oscillation, which can influence flushing of the shallow embayments. This process likely persists year-round and would lead to flushing time-scales of between 1–11 days for these shallow embayments. If this ubiquitous pumping is combined with solar heat fluxes, it partially explains the persistent temperature gradients amongst the shallow embayments. In the larger and deeper (∼10 m) Inner Harbour, the prevailing westerly winds drive most of the mean circulation, with a current entering through the Western Gap and leaving through the Eastern Gap. This wind driven circulation leads to a residence time of water in the Inner Harbour between 7–14 days. In addition, periodic strong and sustained westerly winds can induce frequent upwelling events in Lake Ontario (between 4 to 10 times during the stratified season) that mildly increase the exchange flow and help maintain good water quality by exchange nearshore waters with cleaner hypolimentic waters. The intrusion of cold water into the harbour can also lead to highly variable temperature regimes with sudden drops in temperature that could have negative effects on aquatic organisms.

Distribution and Variability of the Meiobenthic Assemblages near the Korean Polymetallic Nodule Claim Area of the Clarion-Clipperton Fracture Zone (Subequatorial NE Pacific)

This study was carried out as part of a baseline long-term environmental project in the proposed mining areas for an environmental impact assessment of future mining in the Clarion-Clipperton Fracture Zone (CCFZ). The community structure and distributional pattern of meiobenthos were investigated in the deep-sea bottom of the Clarion-Clipperton Fracture Zone of the northeastern Pacific in July 1998, 1999, 2001, 2003 and August 2004, 2005. Twenty one meiobenthic groups were found at the stations in the study area. The most abundant meiobenthos comprised nematodes followed by benthic foraminiferans and harpacticoid copepods. The maximum density of meiobenthos was 306 ind/10 cm2 at the station located at 11°N (water depth, 4833 m), and the minimum density was 6 ind/10 cm2 at the station located at 14°N (water depth, 5037 m). Oligotrophic conditions in the CCFZ seem to directly reflect the lower standing stocks of meiobenthos in the CCFZ compared to other deep-sea plains of similar depth. The latitudinal distribution pattern of meiobenthos in the study area seemed to be related with surface water primary productivity, which was connected to the water circulation pattern of the Pacific Ocean near the Equator, diverging at 8oN latitude and converging at 5°N. The horizontal distribution of meiobenthic organisms in the study area showed high densities at the stations within 135–136°W. The densities of meiobenthic organismas within the CCFZ were high at stations with few manganese nodules on the sediment surface at low-latitude sites. In 1998, the observed relative high values of meiobenthic abundance were at stations from 5° to 6°N. Other stations from 7° to 10°N showed no significant fluctuations during the interannual sampling periods. It is considered that the inter-annual fluctuation of meiobenthos abundance is intimately related with a regime shift that may have occurred in the north Pacific between 1998 and 1999, the El Nino period. Vertical distribution of meiobenthic organisms showed the highest individual numbers in the surface sediment layers of 0∼2 cm depth and a steep decreasing trend as sediment becomes deeper at the stations of high latitude located in 16∼17°N. Size distribution analyses showed that organisms that fit into the sieve mesh size of 0.063 mm were abundant.

The Açu Reef morphology, distribution, and inter reef sedimentation on the outer shelf of the NE Brazil equatorial margin

Abstract Submerged reefs, referred to as the Acu Reefs, have been newly observed on both sides of the Acu Incised Valley on the northeastern equatorial Brazilian outer shelf. This study aims to understand the roles of shelf physiography, its antecedent morphologies, and its inter reef sedimentation on the different development stages of the biogenic reef during last deglacial sea-level rise. The data sets consist of side-scan sonar imagery, one sparker seismic profile, 76 sediment samples, and underwater photography. Seven backscatter patterns (P1 to P7) were identified and associated with eleven sedimentary carbonate and siliciclastic facies. The inherited relief, the mouth of the paleo incised valley, and the interreef sediment distribution play major controls on the deglacial reef evolution. The reefs occur in a depth-limited 25–55 m water depth range and in a 6 km wide narrow zone of the outer shelf. The reefs crop out in a surface area over 100 km2 and occur as a series of NW-SE preferentially orientated ridges composed of three parallel ridge sets at 45, 35, and 25 m of water depth. The reefs form a series of individual, roughly linear ridges, tens of km in length, acting as barriers in addition to scattered reef mounds or knolls, averaging 4 m in height and grouped in small patches and aggregates. The reefs, currently limited at the transition between the photic and mesophotic zones, are thinly covered by red algae and scattered coral heads and sponges. Taking into account the established sea-level curves from the equatorial Brazilian northeastern shelf / Rochas Atoll and Barbados, the shelf physiography, and the shallow bedrock, the optimal conditions for reef development had to occur during a time interval (11–9 kyr BP) characterized by a slowdown of the outer shelf flooding, immediately following Meltwater Pulse-1B. This 2 kyr short interval provided unique conditions for remarkable reef backstepping into distinct parallel ridge sets. Furthermore, the Acu Reefs have trapped relict siliciclastic sediments within the three sets of reefs, west of the Acu Incised Valley and adjacent coasts. Lines evidence of easterly nearshore currents carried sediments from the old Acu Incised Valley and adjacent coasts. These incipiently drowned reefs influence the water circulation patterns of the modern shelf system, its carbonate sedimentation, and sediment transport. This study provides a new example of reef occurrence which might be more commonly observed on similar equatorial continental shelves.

The experimental new hybrid solar dryer and hot water storage system of thin layer coffee bean dehumidification

Abstract The thin layer coffee beans dehumidification and hot water storage were investigated in solar greenhouse dryer simultaneously. The thermal energy was stored for use in the absence of sunlight. The conditions were studied the flow rate of water circulating, model of installation for solar collector assistance, the area ratio of product dehumidification to solar hot water producing (Ad:Ac), flow pattern of water circulation and capacity tank of water circulating in the system. The experiments were found the flow pattern of water circulation within the force flow 0.20 kg/s-mˆ2, tray products temperature (45 deg. C) at (Ad:Ac) 1:1, capacity tank of water circulating (60 L). The thermal energy can be used and stored in the form of hot water and reused at a time without sunlight as well. The initial coffee beans moisture content was dropped from 55 to below 12 (%w.b.) in 12 h drying time. The optimum of mathematical equations for thin layer coffee beans drying based on Midilli mathematical model i.e. (MR = a exp(-ktˆn) – bt); k = 0.03838, n = 1.56771, a = 1.03046, b = −0.00477, R2 = 0.9896, RMSE = 0.0420. Moreover, the effective moisture diffusivity coefficient of 9.754 × 10ˆ-11 mˆ2/s.

Localised hydrodynamics influence vulnerability of coral communities to environmental disturbances

The movement of water can have a significant influence on the vulnerability of hermatypic corals to environmental disturbances such as cyclone damage, heat stress and anoxia. Here, we explore the relationship between small reef-scale water circulation patterns and measured differences in the abundance, composition and vulnerability of coral assemblages over decades. Changes in coral cover and community structure within Bill’s Bay (Ningaloo Reef, Western Australia) over a 22-yr period, during which multiple disturbance events (including mass bleaching, anoxia, and tropical cyclones) have impacted the area, were compared with spatial variation in water residence times (WRT). We found that reef sites associated with longer water residence times (WRT >15 h) experienced higher rates of coral mortality during acute environmental disturbances compared to reef sites with shorter WRT. Shifts in coral community composition from acroporid to faviid-dominated assemblages were also more prominent at sites with long WRT compared to reef sites with shorter WRT, although shifts in community composition were also observed at sites close to shore. Interestingly, these same long-WRT sites also tended to have the fastest recovery rates so that coral cover was returned to original levels of approximately 20% over two decades. This study provides empirical evidence that spatial patterns in water circulation and flushing can influence the resilience of coral communities, thus identifying areas sensitive to emerging threats associated with global climate change.

Research with radiation and radioisotopes to better understand plant physiology and agricultural consequences of radioactive contamination from the Fukushima Daiichi nuclear accident

Research carried out by me and my group over the last almost four decades are summarized here. The main emphasis of my work was and continues to be on plant physiology using radiation and radioisotopes. Plants live on water and inorganic elements. In the case of water, we developed neutron imaging methods and produced 15O-labeled water (half-life 2 min) and applied them to understand water circulation pattern in the plant. In the case of elements, we developed neutron activation analysis methods to analyze a large number of plant tissues to follow element specific distribution. Then, we developed real-time imaging system using conventional radioisotopes for the macroscopic and microscopic observation of element movement. After the accident in Fukushima Daiichi nuclear power plant, we, the academic staff of Graduate School, have been studying agricultural effects of radioactive fallout; the main results are summarized in two books published by Springer.

Circling the Seas: Design of Lagrangian Drifters for Ocean Monitoring

Lagrangian drifters are oceanographic devices used to study circulation patterns in the ocean. The devices are typically passive, which means that they have no actuators to initiate motion. They are mainly driven by the ocean currents. A drifter, as depicted in Figure 1, in principle, consists of a surface float and a drogue connected via a tether. The surface float provides the necessary buoyancy to hold the drogue at a certain depth, whereas the drogue (and, thus, the whole drifter) is carried by the currents prevailing at that depth of the ocean. A main focus of oceanographers' and marine biologists' research is the complex dynamics of the ocean, the circulation patterns of water, and the induced movements of effluents, larvae, and other microorganisms [1]. Drifters are used to tag and track the ocean currents and can help to better explain both oceanographic as well as biological phenomena. Our particular interest is the monitoring task of tracking wastewater plumes in the coastal ocean. In this article, we describe the design of low-power, low-cost Lagrangian drifters for ocean monitoring, developed at the Robotic Embedded Systems Laboratory (RESL) at the University of Southern California (USC). We discuss the design challenges and present the overall system characteristics of the RESL drifters. The drifters are augmented by radio communication, which simplifies the task of drifter recovery by a research vessel and enables setting up a bidirectional wireless sensor network between drifters, autonomous underwater vehicles (AUVs), vessels, and base stations.

Water circulation and recharge pathways of coastal lakes along the southern Baltic Sea in northern Poland

AbstractThe purpose of this paper is to describe water circulation patterns for selected lakes found along the Baltic coast in northern Poland and to determine primary recharge mechanisms or pathways that produce an influx or loss of lake water. A secondary purpose of the paper is to determine the magnitude of recharge for each studied source of water – river water influx, surface runoff from direct catchments, forced influx from polders surrounding lakes, and periodic marine water intrusions from the nearby Baltic Sea. It is also important to determine the magnitude of water outflow from lakes to the sea via existing linkages as well as to compare horizontal influx and outflow data. The study area consisted of five lakes located along the Baltic Sea in northern Poland: Łebsko, Gardno, Bukowo, Kopań, Resko Przymorskie. The main driving force of the studied lakes are large rivers that drain lake catchment areas and periodic brackish water intrusions by the Baltic Sea.