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PubMed2001

Differences in the effects of flooding the soil early and late in the photoperiod on the water relations of pot-grown tomato plants.

The water relations of potted tomato plants (Lycopersicon esculentum Mill. cv INCA 9(1)) submitted to two flooding/recovery cycles imposed at the beginning and at the end of photoperiod were studied under controlled conditions. In both experiments, flooding induced stomatal closure due to leaf dehydration linked to a lowered root hydraulic permeability. Thus, during the early hours of flooding there was an effective negative hydraulic message from O(2) deficient roots. However, when the soil was drained stomata did not re-open until some time after leaf water potential and leaf turgor potential returned to normal, supporting the view that chemical messages predominate. Flooding imposed at the end of photoperiod induced a delay in g(l), Psi(l), and Psi(p,) recovery.

Journal Article↗
PubMed1999

Flow and oxygenation dependent (FLOOD) contrast MR imaging to monitor the response of rat tumors to carbogen breathing.

Gradient recalled echo (GRE) images are sensitive to both paramagnetic deoxyhaemoglobin concentration (via T2*) and flow (via T1*). Large GRE signal intensity increases have been observed in subcutaneous tumors during carbogen (5% carbon dioxide, 95% oxygen) breathing. We term this combined effect flow and oxygenation-dependent (FLOOD) contrast. We have now used both spin echo (SE) and GRE images to evaluate how changes in relaxation times and flow contribute to image intensity contrast changes. T1-weighted images, with and without outer slice suppression, and calculated T2, T2* and "flow" maps, were obtained for subcutaneous GH3 prolactinomas in rats during air and carbogen breathing. T1-weighted images showed bright features that increased in size, intensity and number with carbogen breathing. H&E stained histological sections confirmed them to be large blood vessels. Apparent T1 and T2 images were fairly homogeneous with average relaxation times of 850 ms and 37 ms, respectively, during air breathing, with increases of 2% for T1 and 11% for T2 during carbogen breathing. The apparent T2* over all tumors was very heterogeneous, with values between 9 and 23 ms and localized increases of up to 75% during carbogen breathing. Synthesised "flow" maps also showed heterogeneity, and regions of maximum increase in flow did not always coincide with maximum increases in T2*. Carbogen breathing caused a threefold increase in arterial rat blood PaO2, and typically a 50% increase in tumor blood volume as measured by 51Cr-labelled RBC uptake. The T2* increase is therefore due to a decrease in blood deoxyhaemoglobin concentration with the magnitude of the FLOOD response being determined by the vascular density and responsiveness to blood flow modifiers. FLOOD contrast may therefore be of value in assessing the magnitude and heterogeneity of response of individual tumors to blood flow modifiers for both chemotherapy, antiangiogenesis therapy in particular, and radiotherapy.

Animals↗
PubMed2001

A flood-related outbreak of carbon monoxide poisoning--Grand Forks, North Dakota.

Post-disaster carbon monoxide (CO) poisoning is a growing problem in the United States. This study describes a documented outbreak of CO poisoning associated with flooding. Health department staff investigated cases of CO poisoning following the severe flood of 1997 in Grand Forks, North Dakota. Thirty-three laboratory-confirmed cases were identified, involving 18 separate incidents. Patients ranged in age from 7 to 67 years, and most were men. One patient lost consciousness and was admitted to the hospital; all others were released after receiving supplemental oxygen. Every incident involved gasoline-powered pressure washers being used in basements. Five incidents among professional cleaners accounted for 16 cases; the remaining incidents involved noncommercial use. Thirty patients, from 15 incidents, reported the basement was ventilated while the pressure washer was in use. CO poisoning must be considered a potential hazard after major floods.

Adolescent↗
PubMed2005

Modeling of the solid-solution partitioning of heavy metals and arsenic in embanked flood plain soils of the rivers Rhine and Meuse.

The aim of this study is to predict the solid-solution partitioning of heavy metals in river flood plain soils. We compared mechanistic geochemical modeling with a statistical approach. To characterize the heavy metal contamination of embanked river flood plain soils in The Netherlands, we collected 194 soil samples at 133 sites distributed in the Dutch part of the Rhine and Meuse river systems. We measured the total amounts of As, Cd, Cr, Cu, Ni, Pb, and Zn in the soil samples and the metal fraction extractable by 2.5 mM CaCl2. We found a strong correlation between heavy metal contamination and organic matter content, which was almost identical for both river systems. Speciation calculations by a fully parametrized model showed the strengths and weaknesses of the mechanistic approach. Cu and Cd concentrations were predicted within one log scale, whereas modeling of Zn and Pb needs adjustment of some model parameters. The statistical fitting approach produced better results but is limited with regard to the understanding it provides. The log RMSE for this approach varied between 0.2 and 0.32 for the different metals. The careful modeling of speciation and adsorption processes is a useful tool for the investigation and understanding of metal availability in river flood plain soils.

Adsorption↗
PubMed2005

Spatial variability and uncertainty in ecological risk assessment: a case study on the potential risk of cadmium for the little owl in a Dutch river flood plain.

This paper outlines a procedure that quantifies the impact of different sources of spatial variability and uncertainty on ecological risk estimates. The procedure is illustrated in a case study that estimates the risks of cadmium for a little owl (Athene noctua vidalli) living in a Dutch river flood plain along the river Rhine. A geographical information system (GIS) was used to quantify spatial variability in contaminant concentrations and habitats. It was combined with an exposure and effect model that uses Monte Carlo simulation to quantify parameter uncertainty. Spatial model uncertainty was assessed by the application of two different spatial interpolation methods (classification and kriging) and foraging ranges. The results of the case study show that parameter uncertainty is the main type of uncertainty influencing the risk estimate, and to a lesser extent spatial variability, while spatial model uncertainty was of minor importance. Compared to the deterministically calculated hazard index for the little owl (0.9), inclusion of spatial variability resulted in a median hazard index that can vary between 0.8 and 1.4. It is concluded that a single estimator for a whole flood plain may over- or underestimate risks for specific parts within the flood plain. Further research that expands the procedure presented in this paper is necessary to improve the incorporation of spatial factors in ecological risk assessment.

Animals↗
PubMedDate not supplied

Field studies on 32P movement and P leaching from flooded paddy soils in the region of Taihu Lake, China.

Field experiments were done in two sites, Yixing and Changshu, Jiangsu province, China, to study P movement and leaching in flooded paddy soils. P movement in soil was investigated by using the KH2 32PO4 tracker method, and the amount of P leached from the soil layer in different depths was estimated by measuring P concentrations in the soil solution and saturated hydraulic conductivities in field. Determination was done about one month after P application. There was 46% and 42% of total 32P retained in the 0-5cm layer of soil in the Yixing site and in the Changshu site respectively. The 32P retained in the 25-30 cm layer was only about 1-2% of the total 32P added. Furthermore, 8.01% of 32P in the soil of Yixing site and 16.8% of 32P in the soil of Changshu site was lost from the layer 0-30 cm soil. The seasonal amounts of P leached from the top soil layer and from bottom layer are about 4.5-5.8% and 1.6-2.1% of the total P application, respectively. Changes of total P concentrations in soil solutions during rice growth showed that the fertilizer P applied before flooding of the paddy fields suffered a flash leaching loss and a slow leaching loss. We concluded that the fertilizer P could quickly move in the flooded paddy rice field and parts of it can enter into surface water and ground water. Unless the P application is well managed the risk of P loss and consequently environmental pollution exist.

Agriculture↗
PubMed2003

Assessment of exposure to a flood disaster in a mental-health study.

The lasting psychological consequences of disasters are an important public health issue, especially for determining the support needed by victims. One important question in evaluating psychological consequences remains the assessment of individual disaster-related experiences or stressors. This article proposes two approaches towards the construction of cumulative exposure indicators (CEIs) for a disaster and discusses their relevance for other disasters. In 1997, we carried out a cross-sectional study of the association between the severity of exposure to a 1992 flood in southeastern France and the prevalence of psychological symptoms 5 years later. We interviewed 500 randomly selected subjects residing in one of the most affected municipalities and constructed two CEIs: one based on relevant articles in the literature and the second based on the results of a principal component analysis (PCA) of all the items exploring exposure to the flood. We compared these CEIs with a map of flood damage and tested the association between these indicators and a score of post-traumatic stress symptoms. Most of the subjects (79.1%) had been exposed to at least one stressor besides physical presence. The two CEIs were significantly correlated with one another; comparisons with the map showed that both had good ability to discriminate between mild and severe exposure. Multiple regression analyses showed a significant exposure-effect relation, of the same level of magnitude and significance, between the post-traumatic stress disorder score and each CEI. Our results show the appropriateness of such indicators in assessing the effect of cumulative stress from natural disasters. Guidelines should be developed to improve the comparability of instruments and help standardize methods for evaluating cumulative stress from disasters insofar as possible. Further research is nonetheless necessary to assess the consistency and reproducibility of the data collected.

Adult↗
PubMed1991

Measurement of protein synthesis in human skeletal muscle: further investigation of the flooding technique.

1. The rate of protein synthesis in quadriceps muscle of healthy subjects estimated from the incorporation of L-[1-13C]leucine given by continuous infusion was 1.1%/day. The estimate of protein synthesis from the incorporation of a flooding amount of labelled leucine was 1.8%/day (SD 0.65). The possibility that the higher rate obtained with the flooding technique arose from stimulation of protein synthesis by the large amount of leucine is unlikely. 2. The same rate of protein synthesis (1.7%/day, SD 0.3) was obtained with a flooding amount (0.05 g/kg) of a different amino acid, L-[1-13C]phenylalanine, as was obtained with leucine. 3. Incorporation of L-[1-13C]phenylalanine was not affected by simultaneous injection of leucine (1.7%/day, SD 0.7) or valine (1.6%/day, SD 0.4). 4. Protein synthesis, assessed in a completely different way from the proportion of polyribosomes isolated from the skeletal muscle, was unaltered by the injection of 0.05 g of L-leucine/kg (44.6%, SD 8.5 versus 43.8%, SD 7.7). 5. Good agreement in estimates of protein synthesis was observed in subjects in whom both legs were measured with both L-[1-13C]leucine (mean difference 0.16%/day) and L-[1-13C]phenylalanine (mean difference 0.2%/day).

Adult↗
PubMed1979

Neodymium isotopes in flood basalts from the Siberian Platform and inferences about their mantle sources.

The initial isotopic compositions of Nd and Sr in basalts from the Central Siberian Plateau and other major continental flood basalts are reported. The continental flood basalts appear to be the product of partial melting of mantle sources that consist of relatively primitive undifferentiated material and are clearly distinct from midocean ridge basalts, which sample mantle reservoirs that have been modified by extraction of continental crust earlier in earth history. These observations provide fundamental constraints on models of mantle structure and dynamics. Isotopic effects of crustal contamination are clearly recognizable in some continental flood basalts, but these effects can be distinguished from isotopic patterns inherited from the mantle magma sources.

Journal Article↗
PubMed2001

The consequences of the Odra flood (summer 1997) for the Odra lagoon and the beaches of Usedom: what can be expected under extreme conditions?

The exceptional flood of the river Odra in July/August 1997 caused severe damage, especially on the Polish side of the Odra valley. An additional 5 km3 of water were discharged during the flood. This represents about a third of the normal annual Odra discharge of 17 km3. Large agricultural and industrial areas were submerged, as well as towns and villages. However, as regards the Odra lagoon and the beaches of the Isle of Usedom, the substances transported, such as nutrients and pollutants, did not cause much damage, due to strong dilution. Hygienic investigations (human pathogenic bacteria and viruses) showed that the water had bathing quality during the whole flood.

Agriculture↗
PubMed2003

The use of stable isotopes to evaluate water mixing and water use by flood plain trees along the Garonne valley.

Before the confluence of the Tarn, the Garonne valley was the driest area in the entire south-west of France, due to the relatively low rainfall and low summer discharge of the Garonne River and its tributaries. The natural abundance of the stable isotope of oxygen (18O) and ionic charge of surface and ground water were used to estimate the water source for the Garonne River and phreatic subsurface water. We also measured these constituents in the sap of trees at several flood plain sites to better understand the source of water used by these trees. 18O signatures and conductivity in the Garonne River indicated that the predominance of water was from high altitude surface runoff from the Pyrenees Mountains. Tributary inputs had little effect on isotopic identity, but had a small effect on the conductivity. The isotopic signature and ionic conductivity of river water (delta18O: -9.1 per thousand to -9.0 per thousand, conductivity: 217-410 microS/cm) was distinctly different from groundwater (delta18O: -7.1 per thousand to -6.6 per thousand, conductivity: 600-900 microS/cm). Isotopic signatures from the sap of trees on the flood plain showed that the water source was shallow subsurface water (<30 cm), whereas trees further from the river relied on deeper ground water (>1 m). Trees at both locations maintained sap with ionic charges much greater (2.3-3.7x) than that of source water. The combined use of 18O signatures and ionic conductivity appears to be a potent tool to determine water sources on geographic scales, and source and use patterns by trees at the local forest scale. These analyses also show promise for better understanding of the effects of anthropogenic land-use and water-use changes on flood plain forest dynamics.

Disasters↗
PubMed2006

Flooding of lignite mines: isotope variations and processes in a system influenced by saline groundwater.

The quality of both groundwaters and surface waters that arise during flooding of abandoned lignite open pits are influenced by regional and local factors. A typical regional factor is due to oxidised sedimentary sulfides. A more local factor is the interaction of shallow water with highly saline groundwater, which is important in Merseburg-Ost (Germany). Investigation of this system is aided by the use of many environmental isotope tracers but special problems can arise. In order to reveal processes in the mine environment (shallow groundwater, lake water) and to characterise mixtures with saline groundwater results are described using the tracers deltaD, delta18O, delta13C, delta34S, 87Sr/86Sr, 3H, 14C, 39Ar, and 222Rn. Deep highly saline groundwater had a radiocarbon concentration typically below 10 pMC. The values of delta13C(DIC) are around-5 per thousand. As delta13C of the aquifer rock samples (Permian, Zechstein carbonates) was in the range of-6...+5 per thousand, residence time corrections based on delta13C are questionable. Additional checks with 39Ar, as well as results from the variationof delta18O (or deltaD) with respect to the salinity, emphasise a Holocene age; as is also the case for most mineralised groundwaters and also for water having a low delta18O (and deltaD). For saline groundwater residing in the Zechstein aquifer the measured delta34S values of about 12 per thousand are close to those expected from the literature. In contrast, the 87Sr/86Sr ratio of dissolved strontium is far from the values anticipated for the aquifer rocks despite there being proportionality between the chloride concentration and the strontium concentration. Furthermore, the proportionality is not valid in lower mineralised water. The 87Sr/86Sr ratio can, therefore, hardly be used as a tracer for the distribution of ascending saline water. The amount of salt-water coming from below into the residual quarry basins is an essential contribution to the lake inventories. Therefore, 222Rn was used to assist in determining the renewal of salt-water layers that formed in deep lake locations. In the deep zones 222Rn concentrations up to 6 Bq/l were measured but were dominantly in equilibrium with 226Ra, which was found in all higher mineralised groundwater samples. Excess radon was limited to just a few decimetres above the lake sediment surface but does not appear to be caused by continuous groundwater discharge. Hydrochemical investigations of groundwater from the Quaternary aquifer were carried out over the last six years before flooding was complete. Apart from a slight downward shift of the average sulfate concentration, other changes showed virtually no trends. An increase of the sulfate concentration was mostly correlated with a decrease of delta34S for individual sites only, but not for the whole ensemble of sampling locations. Sulfate from pyrite oxidation plays an important role but cannot be attributed unequivocally to coal mining. There are hints that the conditions closer to the basin edges may differ from those remoter parts of the flood plain.

Coal↗
PubMed2002

The aerenchymatous phellem of Lythrum salicaria (L.): a pathway for gas transport and its role in flood tolerance.

While the importance of cortical aerenchyma in flood tolerance is well established, this pathway for gaseous exchange is often destroyed during secondary growth. For woody species, therefore, an additional pathway must develop for oxygen to reach submerged tissues. In this paper we examine the potential for the aerenchymatous phellem (cork) of Lythrum salicaria L. to provide a pathway for gas transport from shoots to roots and assess its importance in flood tolerance. Plants in which the continuity of the aerenchymatous phellem between shoots and roots was broken showed a significant reduction in oxygen levels in roots, but no difference in carbon dioxide levels compared with controls that retained an intact phellem. These plants also had a greater total shoot height and shoot dry weight, and an increase in shoot/root dry mass ratios compared with controls. Total dry weight was not significantly affected by this treatment. This study is the first to show that the aerenchymatous phellem can provide a pathway for gaseous exchange between roots and shoots and can influence plant morphology and patterns of resource allocation. This suggests that this tissue may play a significant role in the flood tolerance of a woody plant.

Adaptation, Physiological↗
PubMed2003

Molecular and cellular adaptations of maize to flooding stress.

Anaerobic treatment dramatically alters the patterns of gene expression in maize (Zea mays L.) seedlings. During anaerobiosis there is an immediate repression of pre-existing protein synthesis, with the concurrent initiation of a selective synthesis of approx. 20 proteins. Among these anaerobic proteins are enzymes involved in glycolysis and related processes. However, inducible genes that have different functions were also found; these may function in other, perhaps more long-term, processes of adaptations to flooding, such as aerenchyma formation and root-tip death. In this article we review our recent work on maize responses to flooding stress, which has addressed two questions: how are these gene expression changes initiated and how do they lead to adaptation to flooding stress? Our results indicate that an early rise in cytosolic Ca(2+), as well as a quick establishment of ionic homeostasis, may be essential for the induction of adaptive changes at the cellular as well as organismal level.

Adaptation, Physiological↗
PubMed2006

Apoptosis-like programmed cell death occurs in procambium and ground meristem of pea (Pisum sativum) root tips exposed to sudden flooding.

BACKGROUND AND AIMS: Pea (Pisum sativum) primary roots form long vascular cavities when grown under wet or flooded conditions at 25 degrees C. It is thought that the cavities are a form of aerenchyma. At 25 degrees C short roots continue to grow after flooding. After roots reach 10 cm long flooding causes rapid cessation of growth, and root tips often become curled. In longer roots the cavities do not extend into the base of the roots, perhaps rendering them ineffective as aerenchyma. It was hypothesized that the resulting growth arrest was due to programmed cell death (PCD) rather than necrosis. METHODS AND KEY RESULTS: Histological examination by light microscope showed that some cells in the primary meristem (elongation) zone of the primary root tips had morphological abnormalities, including misshapen and fragmented nuclei, and cytoplasmic shrinking and fragmentation. Transmission electron microscopy revealed lobing, invagination and chromatin aggregation in nuclei. The affected cells were positive for terminal deoxynucleotidyl transferase-mediated dUTP nick-end labelling. Extracted DNA formed a "DNA ladder" during electrophoresis. Cell death usually began in procambium at one or two protoxylem poles and seemed to spread out to nearby tissues, which asymmetrically inhibited growth and resulted in tip curling. CONCLUSIONS: The above are symptoms of apoptosis-like PCD. Programmed root tip death may rapidly reduce oxygen demand and sink strength, allowing more rapid diversion of resources to lateral roots growing in more permissive conditions.

Cell Death↗
PubMed2003

Internal oxygen transport in cuttings from flood-adapted várzea tree species.

Tree species from the Central Amazon inundation areas are subjected to extreme flooding, with trees being partially submerged for up to 10 months. The rapidly advancing floodwater table at the onset of the aquatic phase interrupts the inward diffusion of oxygen from the atmosphere to submerged plant parts. Salix martiana (Leyb.) (Salicaceae) and Tabernaemontana juruana ((Markgr.) Schumann ex J. F. Macbride) (Apocynaceae), tree species typical of Amazon floodplains, respond to low oxygen concentrations by forming adventitious roots capable of longitudinal oxygen transport. Cuttings of these tree species were subjected to simulated flooding and the oxygen concentration of the root cortex was temporally monitored by oxygen microelectrodes that penetrated the roots. Changes in the floodwater table made it possible to localize precisely the entry points of atmospheric oxygen. Under experimental conditions, mathematical description of the transport kinetics revealed that longitudinal transport of O2 in both species was mainly attributable to diffusion. Based on the finding that diffusion was inhibited by a small increase in the floodwater table, we conclude that internal oxygen transport during a rising water table is only attainable when adventitious roots are continuously and rapidly developed, as is the case in S. martiana. In T. juruana, slow growth of adventitious roots and low root porosity suggest that other adaptations are required to overcome long flooding periods.

Adaptation, Physiological↗
PubMed1985

Distribution of gamma exposure rates in a reactor effluent stream flood plain system.

Ground-level gamma dosimetry surveys were conducted along the length of a radiocesium-contaminated reactor effluent stream flood plain system to determine the extent and patterns of isotope distribution over a decade after reactor releases were stopped. The maximum mean exposure rates were found at upstream locations near the source of the contamination and in a downstream sedimentary delta. Gamma exposure rates were not uniformly distributed and high exposure rates were generally restricted to small areas of the flood plain. There was little similarity in either the spatial distribution or magnitudes of maximum gamma exposure rates across flood plains along the stream. Frequency the measured exposure rates tended to be highly skewed and most closely approximated the log-normal distribution in most areas along the stream. However, the complex and changing patterns of dose distributions strongly affected the ability to predict the probability of encountering unusually high exposure rates. Complex statistical and distributional models are required to provide precise descriptions of the dosimetry environment in such complex ecosystems and different models could be required on a site-by-site basis.

Cesium Radioisotopes↗
PubMed1979

Mood changes and flooding outcome in obsessive-compulsive patients. Report of a 2-year follow-up.

Twenty-five chronic obsessive-compulsive patients treated with flooding were investiaged retrospectively after 2 years by an independent assessor for the presence of depressive mood fluctuations during their life histories using a five-point rating scale. Patients themselves also completed rating scales for obsessional phenomena during the pre-, post-treatment, and follow-up assessment. Fifteen patients were characterized as not having exhibited mood changes and 10 as having such changes. Patients without changes responded promptly to flooding treatment and showed further improvement during follow-up. Patients with mood changes, although responding well to initially delivered flooding sessions, showed significant relapse at follow-up.

Adult↗