Unprecedented summer-season sampling of the Arctic Ocean during the period 2006–2008 makes possible a quasi-synoptic estimate of liquid freshwater (LFW) inventories in the Arctic Ocean basins. In ...comparison to observations from 1992 to 1999, LFW content relative to a salinity of 35 in the layer from the surface to the 34 isohaline increased by 8400±2000
km
3 in the Arctic Ocean (water depth greater than 500
m). This is close to the annual export of freshwater (liquid and solid) from the Arctic Ocean reported in the literature.
Observations and a model simulation show regional variations in LFW were both due to changes in the depth of the lower halocline, often forced by regional wind-induced Ekman pumping, and a mean freshening of the water column above this depth, associated with an increased net sea ice melt and advection of increased amounts of river water from the Siberian shelves. Over the whole Arctic Ocean, changes in the observed mean salinity above the 34 isohaline dominated estimated changes in LFW content; the contribution to LFW change by bounding isohaline depth changes was less than a quarter of the salinity contribution, and non-linear effects due to both factors were negligible.
► Unprecedented Arctic-basin-wide sampling in 2006 – 2008 enables freshwater budgets. ► Liquid freshwater content increased by 8400±2000 km
3 (20%), relative to the 1990s. ► Changes largely due to freshening of upper Arctic Ocean (river input and ice-melt). ► Changes partly due to regional Ekman Pumping. ► Results from ice-ocean model (NAOSIM) compare well on basin scales.
Dew Water Beysens, Daniel
2022, 2018, 2022-09-01, 2018-08-01
eBook
The world's ever-increasing need for fresh water has led to the use of non-conventional sources such as rain and fog water collection. Although rain water collection is relatively simple, the supply ...is often erratic. Passive fog water collection has been used in several parts of the world but is only relevant to certain geographical locations. Dew occurrence, however, is far more widespread, can form in most climates and geographic settings, show high frequency and prevalence throughout the year. During the past 20 years, dew collection has therefore been investigated as a serious supplemental source of fresh water. Dew Water offers a thorough review of dew, its formation characteristics and potential for dew collection, for audiences that include policy-makers, non-governmental organizations involved in development aid and sustainable development, engineers, urban planners, researchers and students. After providing a background on atmospheric water, humid air, and sky and materials emissivity, the book deals with dew formation and its estimation with a focus on the use of meteorological data. Dew measurement techniques are reviewed and discussed as well as dew collection by passive means. Computational fluid dynamics technique is described for better design of dew collectors. Dew quality (chemistry, biology) is assessed in view of potable water quality. Costs and economic aspects are also considered.
Eight organic UV filters and stabilizers were quantitatively determined in wastewater sludge and effluent, landfill leachate, sediments, and marine and freshwater biota. Crab, prawn and cod from ...Oslofjord, and perch, whitefish and burbot from Lake Mjøsa were selected in order to evaluate the potential for trophic accumulation. All of the cod livers analysed were contaminated with at least 1 UV filter, and a maximum concentration of almost 12μg/g wet weight for octocrylene (OC) was measured in one individual. 80% of the cod livers contained OC, and approximately 50% of cod liver and prawn samples contained benzophenone (BP3). Lower concentrations and detection frequencies were observed in freshwater species and the data of most interest is the 4 individual whitefish that contained both BP3 and ethylhexylmethoxycinnamate (EHMC) with maximum concentrations of almost 200ng/g wet weight. The data shows a difference in the loads of UV filters entering receiving water dependent on the extent of wastewater treatment. Primary screening alone is insufficient for the removal of selected UV filters (BP3, Padimate, EHMC, OC, UV-234, UV-327, UV-328, UV-329). Likely due in part to the hydrophobic nature of the majority of the UV filters studied, particulate loading and organic carbon content appear to be related to concentrations of UV filters in landfill leachate and an order of magnitude difference in these parameters correlates with an order of magnitude difference in the effluent concentrations of selected UV filters (Fig. 2). From the data, it is possible that under certain low flow conditions selected organic UV filters may pose a risk to surface waters but under the present conditions the risk is low, but some UV filters will potentially accumulate through the trophic food chain.
•Total organic UV filter wastewater effluent loadings were up to 800ng/day/1000 population.•The occurrence of BP3, EHMC, Padimate, OC, UV-327 and UV-238 in selected biota suggests the potential to bioaccumulate.•Risk quotients were <1 for BP3, EHMC, OC, UV-327 and UV-328, indicating low risk to receiving waters.
This study investigates the application of sulphur isotope ratios (δ
34S) in combination with carbon (δ
13C) and nitrogen (δ
15N) ratios to understand the influence of environmental sulphur on the ...isotopic composition of archaeological human and faunal remains from Roman era sites in Oxfordshire, UK. Humans (
n
=
83), terrestrial animals (
n
=
11), and freshwater fish (
n
=
5) were analysed for their isotope values from four locations in the Thames River Valley, and a broad range of δ
34S values were found. The δ
34S values from the terrestrial animals were highly variable (−13.6‰ to +0.5‰), but the δ
34S values of the fish were clustered and
34S-depleted (−20.9‰ to −17.3‰). The results of the faunal remains suggest that riverine sulphur influenced the terrestrial sulphur isotopic signatures. Terrestrial animals were possibly raised on the floodplains of the River Thames, where highly
34S-depleted sulphur influenced the soil. The humans show the largest range of δ
34S values (−18.8‰ to +9.6‰) from any archaeological context to date. No differences in δ
34S values were found between the males (−7.8
±
6.0‰) and females (−5.3
±
6.8‰), but the females had a linear correlation (
R
2
=
0.71;
p
<
0.0001) between their δ
15N and δ
34S compositions. These δ
34S results suggest a greater dietary variability for the inhabitants of Roman Oxfordshire than previously thought, with some individuals eating solely terrestrial protein resources and others showing a diet almost exclusively based on freshwater protein such as fish. Such large dietary variability was not visible by analysing only the carbon and nitrogen isotope ratios, and this research represents the largest and most detailed application of δ
34S analysis to examine dietary practices (including breastfeeding and weaning patterns) during the Romano-British Period.
The acute toxicity of Tl(I) to the microalga, Pseudokirchneriella subcapitata, the planktonic crustaceans, Daphnia magna and Daphnia pulex, and early-life stage of the zebrafish, Danio rerio, has ...been studied according to OECD protocols. Toxicological end-point concentrations for the microalga ranged from 17μgl−1 for a 72h EyC25 (yield inhibition) to 80μgl−1 for a 72h ErC50 (growth inhibition). Daphnia were less sensitive to Tl, with 48h EC50s of about 1000μgl−1 and 1200μgl−1 for D. magna and D. pulex, respectively; however, end-point concentrations were reduced considerably (to about 510μgl−1 and 730μgl−1, respectively) when experiments were repeated in dechlorinated Plymouth tap water (rather than OECD medium). The 96h LC50 for D. rerio was 870μgl−1 but a variety of sub-lethal effects, including enlargement of yolk sac and reduction in heart beat rate, were observed when larvae were exposed to lower concentrations. Based on these results, a predicted no effect concentration (PNEC) for Tl in freshwaters of 0.087μgl−1 is proposed. The PNEC is an order of magnitude lower than the only (Canadian) water quality guideline for Tl that appears to exist, and is lower than Tl concentrations reported in freshwaters impacted by historical or contemporary metal mining. Our results are also consistent with previous studies that employ different organisms and end-points in that Tl toxicity is dependent on the concentration of K+, the biogeochemical analogue of Tl+. Accordingly, regulation of Tl in the freshwater environment should factor in the relative abundance of K.
•The toxicity of thallium to four freshwater organisms has been studied.•The microalga, Pseudokirchneriella subcapitata, was most sensitive to Tl.•Tl toxicity to Daphnia was greater in tap water than in artificial water.•Various sub-lethal effects were observed in early-life stage Danio rerio.•A PNEC for Tl of 0.087μgl−1 is proposed.
The aim of this study is to investigate the importance of freshwater discharge as a physical forcing in Patos Lagoon at timescales longer than one year, as well as identify the temporal variability ...of the dominant processes in freshwater discharge and water levels along the Patos Lagoon. Due to its proximity to the mouth, the water level at the estuary is influenced by the remote effects associated with the adjacent ocean circulation and wave climatology, reducing the observed correlation. At the lagoonar region a high correlation is expected because interannual data is being used, reducing the influence of the wind. Cross wavelet technique is applied to examine the coherence and phase between interannual time-series (South Oscillation Index, freshwater discharge and water levels). The freshwater discharge of the main tributaries and water levels in Patos Lagoon are influenced by ENSO on interannual scales (cycles between 3.8 and 6 years). Therefore, El Niño events are associated with high mean values of freshwater discharge and water levels above the mean. On the other hand, La Niña events are associated with low mean values of freshwater discharge and water levels below the mean.
Upstream migration of the Atlantic blue crab Callinectes sapidus is well described in its native range, but it is little known in invaded areas.
Here, we report several long‐distance migration events ...of the blue crab in the Iberian Peninsula and use a global database to calculate the probability of occurrence of the species in relation to distance to sea. We then exemplify the potential of blue crab impacts on freshwaters by overlapping its probability of occurrence with that of the critically endangered European eel Anguilla anguilla. Finally, we evaluate the extent to which dam barriers can halt the upstream migration of the blue crab.
Invasive blue crab has been detected at 108 km from the sea in the Guadalquivir River (the farthest distance reported in the non‐native range), at 71 km in the Guadiana River and at 53 km in the Ebro River. The probability of occurrence decreased steeply in the first upstream kilometres, but it is still concerning at a dozen kilometres from the river mouth (50% at 19 km, 25% at 38 km, and 3% at 100 km). The blue crab invasive potential widely overlaps (63%) with the Iberian range of the European eel. The blocking effect of dams on the potential invasion of freshwater systems by the blue crab was limited (13%).
Our study highlights the need to study the upstream migration of the blue crab within its non‐native range, since it could involve serious impacts in reachable river and stream habitats.
Runoff and nutrient transport by rivers were analysed in the Northern Adriatic continental shelf, in order to evaluate their interannual and multidecal variability, as well as their current ...contribution to determine freshwater and nutrient budgets in this marine region. During the years 2004–2007, the runoff in the basin (34.1–64.6
km
3
yr
−1) was highly imbalanced, being 84% of freshwater discharged along the western coast, because of the contributions of Po, Adige and Brenta rivers. In the northern and eastern sections of the coast, freshwater discharge by rivers was less important (10 and 6%, respectively), but not negligible in determining the oceanographic properties at sub-regional scales. The oscillations of the transport of biogenic elements (124–262×10
3
t
N
yr
−1 for TN, 72–136×10
3
t
N
yr
−1 for DIN, 4.5–11.1×10
3t
P
yr
−1 for TP, 2.2–3.5×10
3
t
P
yr
−1 for PO
4 and 104–196×10
3
t
Si
yr
−1 for SiO
2) were strictly dependant to the differences in the annual runoff. A strong excess of N load in comparison to P load characterised all rivers, both in inorganic nutrient (DIN/PO4=37–418) and total (TN/TP=48–208) pools, particularly in the northern and eastern areas of the basin.
The annual runoff showed significant oscillations for Po on multidecadal time scale, whereas a general decrease (−33%) was observed for the other N Adriatic rivers as the recent discharges were compared to those before the 1980s. During the dry years 2005–2007, a strong reduction of river water flows and nutrient loads was experienced by the N Adriatic ecosystem with respect to years characterised by medium-high regimes. An increased frequency of similar drought periods, due to ongoing climate changes or to a larger human usage of continental waters, would be easily able to significantly change the biogeochemistry of this basin.
► A strong decrease of minor river loads is taking place in the N Adriatic. ► Po load shows long term oscillations and recurrent periods of drought of 2–3
yr. ► River nutrient transport depends on water load and highly varies on interannual scale. ► Periods of scarce river load affect the biogeochemistry of N Adriatic. ► Decreasing riverine inputs of phosphorus might enhance oligotrophy of N Adriatic.
Fish can become stranded when water levels decrease, often rapidly, as a result of anthropogenic (e.g., canal drawdown, hydropeaking, vessel wakes) and natural (e.g., floods, drought, winter ice ...dynamics) events. We summarize existing research on stranding of fish in freshwater, discuss the sources, consequences, and mitigation options for stranding, and report current knowledge gaps. Our literature review revealed that ∼65.5% of relevant peer-reviewed articles were found to focus on stranding associated with hydropower operations and irrigation projects. In fact, anthropogenic sources of fish stranding represented 81.8% of available literature compared to only 19.9% attributed to natural fish stranding events. While fish mortality as a result of stranding is well documented, our analysis revealed that little is known about the sublethal and long-term consequences of stranding on growth and population dynamics. Furthermore, the contribution of stranding to annual mortality rates is poorly understood as are the potential ecosystem-scale impacts. Mitigation strategies available to deal with stranding include fish salvage, ramping rate limitations, and physical habitat works (e.g., to contour substrate to minimize stranding). However, a greater knowledge of the factors that cause fish stranding would promote the development and refinement of mitigation strategies that are economically and ecologically sustainable.
► When water levels decrease in freshwater ecosystems, fish can become stranded. ► It is unknown whether fish stranding contributes significantly to mortality rates. ► We summarize the sources, consequences, and mitigation options for fish stranding. ► Generalized statements can be made about the factors associated with stranding. ► It is difficult to assess effectiveness of mitigation strategies.
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