Interactions between groundwater and surface water at river banks and the confluence of rivers

Riparian vegetation depends on hydrological resources and has to adapt to changes in water levels and soil moisture conditions. The origin and mixing of water in the streamside corridor were studied in detail. The development of riparian woodland often reflects the evolution of hydrological events. River water levels and topography are certainly the main causes of the exchange between groundwater and river water through the riverbank. Stable isotopes, such as 18O, are useful tools that allow water movement to be traced. Two main water sources are typically present: (i) river water, depleted of heavy isotopes, originating upstream, and (ii) groundwater, which comes mainly from the local rainfall. On the Garonne River bank field site downstream of Toulouse, the mixing of these two waters is variable, and depends mainly on the river level and the geographical position. The output of the groundwater into the river water is not diffuse on a large scale, but localised at few places. At the confluence of two rivers, the water-mixing area is more complex because of the presence of a third source of water. In this situation, groundwater supports the hydrologic pressure of both rivers until they merge, this pressure could influence its outflow. Two cases will be presented. The first is the confluence of the Garonne and the Ariège Rivers in the south-west of France, both rivers coming from the slopes of the Pyrénées mountains. Localised groundwater outputs have been detected about 200 m before the confluence. The second case presented is the confluence of the Ganges and the Yamuna Rivers in the north of India, downstream of the city of Allahabad. These rivers are the two main tributaries of the Ganges, and both originate in the Himalayas. A strong stream of groundwater output was measured at the point of confluence

Daily variations of water use with vapor pressure deficit in a plantation of I214 poplars.

Daily rates of whole tree water use were measured in a homogeneous 7-year-old plantation over 84 days. Two trees were selected in the two most contrasting ends, i.e., with mean water table at -1.5 m and -3.5 m. Results showed that the mean tree water use was close to 80 dm3 day–1 with a small mean difference between the two sites (5.4 dm3 day–1, about 7%). Higher daily variations were observed on a single tree over the season (from 17 to 138 dm3 day–1). These fluctuations could be modeled using linear regressions on the vapor pressure deficit (VPD). Results also indicated decreasing sap flux densities with radial sapwood depth and that the whole tree water use could be estimated from the sap flux densities measured at the 0–2 cm depth

Sap flow and water transfer in the Garonne river riparian woodland, France : first results on poplar and willow

This work is the first attempt at using Granier sap sensors on Populus nigra, Populus x euramericana cv I45/51 and Salix alba for the monitoring of sap flows in an active floodplain over two consecutive years. The main characteristic of these diffuse porous trees is their capacity to use several tree rings for xylem sap transfer. Results showed that the sap flux densities remained homogeneous on the external 4 cm of the trunk, then decreased with depth. For young trees, the active sapwood can represent half of the trunk. Results indicated that in the same environment and at the same age, daily differences existed between the two major native riparian tree species, the black poplar and the white willow. Their maximal sap flux density (2.6-3.6 dm 3 dm -2 h -1) was similar to other fast growing trees. The influence of age was the third important screened factor. Sap flow measurements over several months indicated that water uptake was variable throughout the season, depending on water availability, and was more pronounced for older trees. The sap flux densities for the planted poplar (I45/51) ranged from 2.2-2.6 dm 3 dm -2 h -1 (about 90 dm 3 day -1) in the wetter spring conditions and dropped to 1.6-1.7 dm 3 dm -2 h -1 (about 60 dm 3 day -1) in less favourable conditions. Under the worst conditions, e.g., the especially long drought in the summer of 1998, these values dropped to 1.0-1.2 (about 40 dm 3 day -1), and even to 0.35 dm 3 dm -2 h -1 (about 12 dm 3 day -1) for a few days. Complementary long-term studies are needed to better understand the complex sap flow changes and to be able to relate them to significant environmental factors. Priority should be given to the long-term monitoring of sap flows at different depths for a correct estimation of actual daily water uptakes by riparian softwood trees

Isotopic characteristics of the Garonne River and its tributaries

The Garonne is the largest river in the south-west of France, and its drainage basin stretches between the Pyrenees and the Massif Central mountains. Until now, no water stable isotope study has been performed on the whole Garonne river basin which is composed of different geological substrata, and where the water resources are limited during the dry summer period. This study focuses on the Garonne river and its tributaries from the Pyre´ne´es foothill upstream to its confluence with the Lot River downstream. The aim of the study is to determine the origins of the surface waters using their chemical and stable isotopic compositions (18O, D and 13C), to better understand their circulation within the drainage basin and to assess the anthropogenic influences. The Garonne displays a specific 18O seasonal effect, and keeps its Pyre´nean characteristics until its confluence with the Tarn River. The difference in the dissolved inorganic carbon (DIC) comes mainly from the change in lithology between the Pyre´ne´es and the Massif Central mountains. Agriculture activity is only detected in the small tributaries

Monitoring of water from the underground to the tree: first results with a new sap extractor on a riparian woodland

Riparian woodlands are characterized by variable hydrological conditions. Following the mapping of the complex underground water circulation of the wetlands, we studied the water uptake by trees. Although there are numerous analytical techniques available to monitor the water origin and water fluxes, no rapid technique for the extraction of xylem sap exists on the market. For this reason we designed and built a unique machine able to extract sap directly in the field from wood cores in a few minutes. A short description of the machine and its performance is given, prior to reporting the first experimental results obtained in a young riparian woodland along the Garonne River. The results compare the vertical water profile of the soil and the corresponding xylem sap at different roots horizons and in the trunk

Effect of various inspired oxygen concentrations on pulmonary and systemic hemodynamics and oxygenation during resuscitation in a transitioning preterm model.

BackgroundThe Neonatal Resuscitation Program recommends initial resuscitation of preterm infants with low oxygen (O2) followed by titration to target preductal saturations (SpO2). We studied the effect of resuscitation with titrated O2 on gas exchange, pulmonary, and systemic hemodynamics.MethodologyTwenty-nine preterm lambs (127 d gestation) were randomized to resuscitation with 21% O2 (n = 7), 100% O2 (n = 6), or initiation at 21% and titrated to target SpO2 (n = 16). Seven healthy term control lambs were ventilated with 21% O2.ResultsPreductal SpO2 achieved by titrating O2 was within the desired range similar to term lambs in 21% O2. Resuscitation of preterm lambs with 21% and 100% O2 resulted in SpO2 below and above the target, respectively. Ventilation of preterm lambs with 100% O2 and term lambs with 21% O2 effectively decreased pulmonary vascular resistance (PVR). In contrast, preterm lambs with 21% O2 and titrated O2 demonstrated significantly higher PVR than term lambs on 21% O2.Conclusion(s)Initial resuscitation with 21% O2 followed by titration of O2 led to suboptimal pulmonary vascular transition at birth in preterm lambs. Ventilation with 100% O2 in preterm lambs caused hyperoxia but reduced PVR similar to term lambs on 21% O2. Studies evaluating the initiation of resuscitation at a higher O2 concentration followed by titration based on SpO2 in preterm neonates are needed

Alternative forage crops for finishing lambs

Alternative forage crops offer a number of benefits for farmers including a cheap finishing system for lambs, benefits for soil condition, fertility building for rotations and providing a cover crop. Certain forages have also been demonstrated to have some anthelmintic benefits for lambs. A demonstration study was undertaken to investigate the potential of six crops used in the horticulture industry (fertility building crops) as forage crops for weaned growing lambs. The crops include white mustard, Nemat (form of Rocket), Crimson Clover, Sweet Clover , Caliente 119 and Caliente 99 (Cruciferae). The grazing field was split into three blocks and two crops were sown in solid strips in each block. Each block also had grass headlands. 10 ewe lambs were randomly allocated (balanced for liveweight) to each block. Lambs were introduced to the blocks 1 week after crop emergence. Lambs were weighed fortnightly for 8 weeks. Mob faecal samples were also taken from each group on a fortnightly basis. Grazing behaviour assessments were also undertaken. Lambs grazing the mustard treatment had the least liveweight gain of the three groups over the grazing period (average of 58g/day). Whereas lambs grazing the clover treatment had the greatest liveweight gain (average of 110g/day). Lambs grazing the Caliente treatment were intermediate (average of 92g/day). However, in the third grazing period lambs on the Caliente treatment had negative liveweight gains (-50 g/day). Although activity varied throughout the day, on average 75% of lambs were grazing at any given time. For the Caliente treatment group on average at anytime 33% of lambs were grazing the Caliente 99 variety compared to 23% grazing the Caliente 119 variety. Only 16% of lambs were on average grazing the grass areas at any one time. In the clover treatment group 45% of lambs were to be found grazing the Crimson clover sward at any one time on average, 22% were grazing the Sweet clover sward and only 3% grazing the grass areas. For the mustard treatment 33% of lambs on average were grazing the Nemat sward at any time, with 22% grazing the white mustard sward and the grass areas. This study suggests that fertility building crops such as Caliente, clover and mustard can be utilised as a grazed forage crops. However, it may be more appropriate to sow the crops as a mixed crop for grazing rather than as monoculture. This would also increase any environmental benefits such as an increase in biodiversity

The behaviour and health of dairy lambs reared artificially with and without early access to meal : a thesis presented in partial fulfilment of the requirements for the degree of Master of Science in Animal Science at Massey University.

Many large-scale dairy sheep producers use lamb-rearing systems and provide lambs with milk replacer (MR) ad libitum and grain-based meal to accelerate rumen development to support early weaning methods. Lambs are raised inside for three weeks before being relocated to a pasture paddock and weaned off MR, followed by weaning off meal 3-4 weeks later onto a pasture-only diet. The potential to replace the early provision of meal with early access to good quality pasture before weaning has not been evaluated and may have effects on the development of feeding behaviour. Studies on feeding behaviour in lambs have focused on differences between restricted and ad libitum quantities of MR, with little research on differences in use of solid feed before weaning. Sixty East Friesian crossbred ewe lambs aged 3-4 days were randomly allocated to one of two treatment groups; MR ad libitum with access to meal (M) or MR ad libitum without meal (NM). Both groups had access to pasture at the beginning of week 4, and were abruptly weaned off MR at week 6 and gradually weaned off meal (M lambs only) beginning in the middle of week 8 until the end of week 10. It was hypothesised that; (1) while lambs were being reared inside, M lambs would initiate rumination earlier due to their early access to meal. (2) There would be no difference in the milk feeding behaviour between lambs on the two diets. (3) There would be no difference in the health of the lambs and lastly (4), once outside, M lambs would spend more time grazing and subsequently ruminating as a result of their earlier rumen development. All lamb behaviours were visually recorded during weeks 2, 3, 5, 7, 10 and 12 (nine hours/week). Milk feeding behaviour traits were automatically recorded hourly through the automatic MR dispenser while being reared inside for 23 days. Health scores were recorded twice daily and total days health incidences were recorded. Meal access accelerated onset of rumination, while NM lambs spent more time consuming wood shavings during week 3 (P<0.001). Once outside, NM lambs spent more time grazing during weeks 5 (P<0.05), 7 and 12 (P<0.001), and increased rumination time compared to M lambs by week 12 (P<0.001). Lambs with meal access on average had a greater number of rewarded meals (meals in which lambs consumed more than 1 ml), with a greater intake of MR per meal than lambs without meal access (P<0.001). There were no mortalities of lambs fed either diet. Loose faeces (mild scours), pink eye and navel infections were observed in both M and NM lambs. These findings may allow refinement of lamb-rearing practices by adjustments to the provision of meal to lambs since no adverse behavioural or health effects were observed in lambs without meal access

Postnatal β2 adrenergic treatment improves insulin sensitivity in lambs with IUGR but not persistent defects in pancreatic islets or skeletal muscle

Placental insufficiency causes intrauterine growth restriction (IUGR) and disturbances in glucose homeostasis with associated β adrenergic receptor (ADRβ) desensitization. Our objectives were to measure insulin-sensitive glucose metabolism in neonatal lambs with IUGR and to determine whether daily treatment with ADRβ2 agonist and ADRβ1/β3 antagonists for 1 month normalizes their glucose metabolism. Growth, glucose-stimulated insulin secretion (GSIS) and glucose utilization rates (GURs) were measured in control lambs, IUGR lambs and IUGR lambs treated with adrenergic receptor modifiers: clenbuterol atenolol and SR59230A (IUGR-AR). In IUGR lambs, islet insulin content and GSIS were less than in controls; however, insulin sensitivity and whole-bodyGUR were not different from controls.Of importance, ADRβ2 stimulation with β1/β3 inhibition increases both insulin sensitivity and whole-body glucose utilization in IUGR lambs. In IUGR and IUGR-AR lambs, hindlimb GURs were greater but fractional glucose oxidation rates and ex vivo skeletal muscle glucose oxidation rates were lower than controls. Glucose transporter 4 (GLUT4) was lower in IUGR and IUGR-AR skeletal muscle than in controls but GLUT1 was greater in IUGR-AR. ADRβ2, insulin receptor, glycogen content and citrate synthase activity were similar among groups. In IUGR and IUGR-AR lambs heart rates were greater, which was independent of cardiac ADRβ1 activation. We conclude that targeted ADRβ2 stimulation improved whole-body insulin sensitivity but minimally affected defects in GSIS and skeletal muscle glucose oxidation. We show that risk factors for developing diabetes are independent of postnatal catch-up growth in IUGR lambs as early as 1 month of age and are inherent to the islets and myocytes

The Guianese paradox: How can the freshwater outflow from the Amazon increase the salinity of the Guianan shore?

French Guiana is notable for the extent of its rain forests, which occupy 97% of the country, and the influence of the Amazon along its shores. In fact, the shores and estuaries support a mangrove forest typical of saline conditions. This paper reports the chemical characteristics, conductivity and salinity and the stable isotopes (oxygen and deuterium) of the rivers and shores between the Cayenne area and the border with Surinam. The results show a quite homogenous freshwater pool over the country. However, the low slope of the coast, a result of the wide mud banks deposited by the Amazonian plume, have turned the mouths of the smaller rivers to the northwest, creating large salty areas where mangroves grow several kilometers inland. Despite the large amount of Amazonian water, the Guianan coast exhibits high salinity. In fact, the freshwater itself remains far from the shore, following the north Brazilian current, while only the mud plume arrives at the coast, creating this paradox