The role of groundwater in CO2 production and carbon storage in Mediterranean peatlands: An isotope geochemistry approach

Peatlands are permanent wetlands recognized for ecosystem services such as biodiversity conservation and carbon storage capacity. Little information is available about their response to global change, the reason why most Earth system climate models consider a linear increase in the release of greenhouse gases (GHG), such as CO₂, with increasing temperatures. Nevertheless, numerous studies suggest that an increase in the temperature may not imply a decrease in photosynthesis and carbon storage rates if water availability is sufficient, the latter being under the control of local hydrology mechanisms. Mediterranean peatlands well illustrate this fact. Since they are groundwater-dependent, they are hydrologically resilient to the strong seasonality of hydroclimatic conditions, especially during the summer drought. In the present study, we demonstrate that, even if such peatlands release CO₂ into the atmosphere, they can maintain a carbon storage capacity. To this end, a geochemical study disentangles the origin and fate of carbon within a Mediterranean peatland at the watershed scale. Field parameters, major ions, dissolved organic and inorganic carbon content and associated δ¹³C values allow for characterizing the seasonality of hydrochemical mechanisms and carbon input from an alluvial aquifer (where rain, river, shallow, and deep groundwater flows are mixing) to the peatland. The inorganic and organic content of peat soil and δ¹³C values of total organic matter and CO₂ complete the dataset, making it possible to provide arguments in favour of lower organic matter oxidation compared to primary production. Overall, this study highlights the groundwater role in the fluxes of CO₂ at the peatland-atmosphere interface, and more broadly the need to understand the interactions between the water and carbon cycles to build better models of the future evolution of the global climate.

Assessing the hydrogeological resilience of a groundwater-dependent Mediterranean peatland: Impact of global change and role of water management strategies

Mediterranean peatlands remain largely under-documented, except for detailed biological data such as fauna and flora taxa lists, and yet are increasingly threatened by water withdrawal and agriculture practices. This lack of information, particularly on their hydrogeological functioning, makes it impossible to evaluate their response to changing climate conditions. A pilot study on a representative Mediterranean peatland on the island of Corsica (France) was conducted to evaluate recharge modalities in the peatland using a coupled water-level monitoring, geochemical and isotope multi-tracing approach (electric conductivity, major ions, δ¹⁸O, δ²H, ³H, ⁸⁷Sr/⁸⁶Sr). The goal was to understand how water budgets in peatland ecosystems were maintained throughout the year, especially during the summer. Despite the remarkable stability of the peatland water level, the recharge contributions of varied water bodies through an alluvial aquifer vary significantly from one season to another. An end-member mixing analysis (EMMA) indicates that the peatland is mainly recharged by an alluvial aquifer. During fall-winter, the alluvial aquifer on which the peatland depends is recharged by the rainfall, a river, and shallow groundwater (colluvium). During spring-summer, water supply is provided mostly by a river, shallow, and deep groundwater (fractured granite). However, this specific hydrogeological functioning is not taken into account by environmental management policies making peatlands vulnerable to anthropogenic and climatic pressures. Thus, their actual status regarding water and aquatic environment management policies is discussed to provide recommendations for better consideration and preservation.

Seasonal influences on groundwater arsenic concentrations in the irrigated region of the Cambodian Mekong Delta

Similar to many southern and southeast Asian regions, the mobilisation of arsenic (As) from sediments has driven a widespread contamination problem for groundwater resources in the Cambodian Mekong Delta. For the first time, the seasonal changes in As concentrations and potential links to groundwater pumping for irrigation in shallow aquifers of the Cambodian Mekong Delta are investigated. Using environmental tracers (δ¹⁸O, δ²H, ³H, major/trace ions and rare earth elements) the natural and pumping-induced changes in hydrogeological processes are identified. Three conceptual models are proposed: Model 1, where there is limited local recharge or low recharge rates (³H mean residence time > 60 years) and groundwater has a large range in As concentrations (0.2 to 393.8 μg/L). In this semi-confined aquifer, only one of the six groundwater sites has As concentrations that increase (by 10.9 μg/L) potentially due to groundwater pumping and resultant mixing with high-As and low (Pr/Sm)_NASC groundwater. However, data on groundwater extraction volumes is required to verify the link with irrigation practices. Model 2, where groundwater is recharged by evaporated surface waters (fractionated δ¹⁸O and δ²H). There are moderate As concentrations (64.1-106.1 μg/L) but no significant seasonal changes even though the recharging waters have relatively greater organic carbon contents during the dry season (reduced Ce/Ce*anomaly). Finally model 3, where groundwater is significantly recharged by wet season rainfall (~50% from δ¹⁸O data). There is a minor increase in As concentrations with recharge (by 6. μg/L). These combined results highlight an aquifer system in the irrigated region of the Cambodian Mekong Delta where As concentrations are largely impacted by natural rather than irrigation processes. Seasonal-scale recharge processes control As processes where the aquifer is not confined by shallow clay layers, and where the aquifer is semi-confined As concentrations largely reflect longer-term natural processes.

Impact of irrigated agriculture on groundwater resources in a temperate humid region

The groundwater irrigation expansion, and its multiple potential impacts on the quantity and quality of water resources, is not just restricted to areas that are water limited. In this study we present the seasonal impacts irrigation practices can have on groundwater resources in a temperate humid region, where the average annual rain/PET ratio is 1.0. In this system the irrigation expansion is solely supported by groundwater pumping, but despite this only 5 boreholes are monitored for hydraulic head data. In this study, we compensate the scarce hydrophysical dataset by incorporating environmental tracers (major ions, δ¹⁸O, δ²H and δ¹³C) and dating tracers (³H, CFC, SF₆ and ¹⁴C). Results indicate that at 9 of the 15 irrigation sites investigated, groundwater pumping for irrigation has induced the mixing of recent groundwater (up to <1year) with older waters. The origin of the older waters was from either the deeper marl aquifer, or the shallow sand-clay aquifer (SCB) that has a ¹⁴C mean residence time (MRT) of up to 9700years. Secondly, although high nitrate loads in infiltrating waters were being diverted via the artificial subsurface drainage system, increases in fertiliser loads have resulted in higher NO₃ concentrations in younger groundwater (NO₃: 9-45mg/L, MRT <20years), compared with older groundwater (NO₃≤9mg/L, MRT>20years). The changes in flow pathways, induced by irrigation, also results in seasonal declines in groundwater NO₃ concentrations due to mixing with older waters. In temperate humid areas, such evaluations of the seasonal evolution of water residence time, mixing process, and agrochemical contaminants are an important contribution to real water resources management in irrigated catchments.

Reproducibility of the water drinking test in treated glaucomatous patients

BACKGROUND

To evaluate the reproducibility of intraocular pressure peaks and fluctuation elicited during the water drinking test in treated glaucomatous patients with a long follow-up interval.

DESIGN

Retrospective cohort study in a tertiary care practice.

PARTICIPANTS

Thirty-four treated primary open-angle glaucoma patients.

METHODS

All patients underwent the water drinking test performed in two consecutive visits without any change in the therapeutic regimen. The mean interval between tests was 4.85 (range: 3-6) months. Reproducibility of peak and fluctuation during the water drinking test was assessed using intraclass correlation coefficients. Bland-Altman analysis was used to assess the agreement of intraocular pressure peaks and fluctuation measured between two consecutive tests.

MAIN OUTCOME MEASURES

Intraclass correlation and agreement of intraocular pressure peaks and fluctuation between visits.

RESULTS

There were no significant differences in baseline intraocular pressure values (mean ± standard deviation, 11.73 ± 2.36 and 11.61 ± 2.71 mmHg; P = 0.72) and peaks (14.55 ± 3.41 and 15.02 ± 3.66 mmHg, respectively; P = 0.163) detected during the water drinking test between the first and second visits. There was also no significant difference between the average intraocular pressure fluctuation values (2.82 ± 1.99 and 3.41 ± 2.54 mmHg, respectively; P = 0.135). Intraocular pressure peaks and fluctuation presented intraclass correlation coefficients of 0.85 (P < 0.001) and 0.50 (P < 0.001), respectively.

CONCLUSIONS

Our results demonstrate excellent reproducibility of intraocular pressure peaks during the water drinking test. Intraocular pressure fluctuation did not reveal good reproducibility, though. These results emphasize the applicability of this test to assess treatment efficacy in daily practice and interventional studies.

Twenty-four-hour repeatability of diurnal intraocular pressure patterns in glaucomatous and ocular hypertensive individuals

OBJECTIVE

To verify the 24-hour repeatability of diurnal intraocular pressure patterns in glaucomatous and ocular hypertensive individuals.

METHODS

A prospective analysis of 88 eyes from 88 ocular hypertensive or open-angle glaucoma patients was conducted on diurnal tension curves obtained by the same examiner on two consecutive days. The intraclass correlation coefficient test was used for statistical analysis.

RESULTS

Eighty-eight eyes from 88 patients were analyzed. Fifty-seven patients (64.8%) were female. The mean age of all participants was 68.7 (SD 10.8, range 51-79) years. The intraclass correlation coefficient values for measurements at 8 AM, 11 AM, 2 PM, and 4 PM were 0.80, 0.82, 0.83, and 0.86, respectively (all intraclass correlation coefficient values, p<0.001).

CONCLUSION

Diurnal intraocular pressure data collected on a single day characterize the diurnal intraocular pressure variability over 24 hours in primary open-angle glaucoma and ocular hypertensive patients.

Neurologic and histologic outcome after intraneural injections of lidocaine in canine sciatic nerves

BACKGROUND

Inadvertent intraneural injection of local anesthetics may result in neurologic injury. We hypothesized that an intraneural injection may be associated with higher injection pressures and an increase in the risk of neurologic injury.

METHODS

The study was conducted in accordance with the principles of laboratory animal care, and was approved by the Laboratory Animal Care and Use Committee. Fifteen dogs of mixed breed (16-21 kg) were studied. After general endotracheal anesthesia, the sciatic nerves (n= 30) were exposed bilaterally. Under direct vision, a 25-gauge, long-beveled needle (30 degrees) was placed either epineurally (n= 10) or intraneurally (n= 20), and 4 ml of preservative-free lidocaine 20 mg/ml was injected using an automated infusion pump (4 ml/min). Injection pressure data were acquired using an in-line manometer coupled to a computer via an analog-to-digital conversion board. After injection, the animals were awakened and subjected to serial neurologic examinations. One week later, the dogs were killed, the sciatic nerves excised and histologic examination was performed by pathologists blind to the purpose of the study.

RESULTS

All perineural injections resulted in low pressures (< or = 5 psi). In contrast, eight of 20 intraneural injections resulted in high pressures (20-38 psi) at the beginning of the injection. Twelve intraneural injections, however, resulted in pressures of less than 12 psi. Neurologic function returned to baseline within 3 h after perineural injections and within 24 h after intraneural injections, when the measured injection pressures were less than 12 psi. Neurologic deficits persisted throughout the study period after all eight intraneural injections that resulted in high injection pressures. Histologic examination of the affected nerves revealed fascicular axonolysis and cellular infiltration.

CONCLUSIONS

The data in our canine model of intraneural injection suggest that intraneural injections do not always lead to nerve injury. High injection pressures during intraneural injection may be indicative of intrafascicular injection and may predict the development of neurologic injury.

Dynamic contour tonometry and goldman applanation tonometry in eyes with keratoconus

PURPOSE

The dynamic contour tonometer is a nonapplanation contact tonometer designed to be largely independent of the structural properties of the cornea. Theoretically, it may measure intraocular pressure most accurately in abnormally thinner corneas. This study compares intraocular pressure measurements by dynamic contour tonometry with Goldman applanation tonometry in eyes with normal corneas and eyes with advanced keratoconus.

METHODS

A comparative case series. Subjects underwent intraocular pressure measurements by dynamic contour tonometry, Goldman applanation tonometry, ultrasonic pachymetry, and slit scanning topography.

EXCLUSION CRITERIA

any ocular pathology other than keratoconus, previous corneal or refractive surgery, stromal scarring due to acute hydrops, or any other corneal opacities.

RESULTS

Ten patients with keratoconus were included in Group A, and 12 normal patients composed Group B according to the pre-established criteria. The mean Goldman tonometry measurement in group A was 10.3 +/- 1.8 mm Hg and group B was 14.3 +/- 0.75 mm Hg. (P = 0.024). In group A, the mean measurement with the dynamic contour tonometer was 14.6 +/- 2.09 mm Hg, and in group B, it was 17.4 +/- 3.1 mm Hg (P = 0.026). The difference between both methods of measurement in group A was statistically significant (P < 0.0002).

CONCLUSION

Intraocular pressure readings with dynamic contour tonometry in the keratoconus group were significantly higher than Goldman measurements and lower when compared to the control group. As there are no published manometric studies in eyes with keratoconus, these lower intra-ocular readings with the dynamic contour tonometry could be related to the discrepancy between the radius of corneal curvature and its tip, the significant thinning of the cornea, or other corneal biomechanical abnormalities related to advanced keratoconus.

Correlation of high-molecular cytokeratin in tissue of prostatic cancer with Gleason score and PSA

The absence of basal cell layer of prostatic acini containing high-molecular cytokeratin, which is immunohistochemically detected by monoclonal antibody 34betaE12, is an essential diagnostic characteristic of prostatic cancer. The absence of immunohistochemical reaction in 3 or more pseudoglandular structures of prostatic tissue indicates malignant process. The percentage of immunohistochemically completely negative glandular structures was determined by semiquantitative measurement in tissue specimens obtained by TRUS biopsy of the prostate, and it was correlated with serum PSA concentration and Gleason score. The increase of percentage of glandular prostatic formations completely negative to high-molecular cytokeratin detected by 34betaE12 led to simultaneous rise of mean value of Gleason prostatic cancer score (p < 0.001) as well as the average serum PSA concentration in subjects (p < 0.05).

[Role of the Swan-Ganz pulmonary artery (PA) catheter in evaluation of hemodynamic changes during myocardial revascularization in patients with low left ventricular function]

Coronary artery bypass surgery in patient with bad left ventricular function is a challenge for surgical time. Specially important is monitoring of haemodynamics. We performed this open, prospective, randomized study with the aim to assess haemodynamics and oxygen profile monitoring. 34 pts for coronary surgery (EF < 40%) were divided in two groups. Group A, 17 pts. Received glucose-insulin-potassium (GIK) solution. Group B, 127 pts. Received Ringer solution. Haemodynamic and oxygen metabolism parameters were measured in four time points. I after the induction in anesthesia; II after the operation; III 6 hours post op.; IV 24 hour post op. Data are expressed as mean +/- SD, Anova for repeated measures followed by Newman-Keuls testing were used. In both groups were evident deterioration of cardiac function during first 6 h as well as VO2 and DO2, more prominent in Group B. Significant recovery and improvement of cardiac function were evident in Group A after 24 h. CI during the time in Group A improves significantly (2.14 +/- 0.36 v. 3.05 +/- 0.55; p = 0.0002) and difference during the time between groups was p = 0.005. LVSWI improved significantly during the time him Group A (AIII vs. AIV) p = 0.007. Simultaneously. VO2 improves significantly in Group A (103 +/- 21 vs. 164 +/- 30, p = 0.00001) while difference between groups in DO was p = 0.037. Importance of oxygen metabolism monitoring for both, left ventricular function and haemodynamics assessment was evident in our study.

Manual percutaneous method for diagnosis of spinal tumors

Summary. In a patient with malignant tumors of bone it is common to perform biopsy prior to surgery. There are a number of alternatives available for obtaining a specimen for pathological examination. We have introduced the technique of manual percutaneous discectomy (MPD), as a method for taking material for analysis. In a series of 13 symptomatic patients harbouring suspected spinal tumors the MPD was done and the accurate diagnosis was confirmed in all of them. Only three patients had a minor transient complication. This method enables us to obtain sufficient pathological material for analysis and has minimal morbidity and it could have priority over the other methods.

[Renal cancer presenting as parietal-temporal cerebral metastasis and a persistent fever]

SUMMARY

The authors report the clinical case of a 48-year-old man presenting with persistent fever, in whom a brain tumour was detected. Histological examination of the resection specimen revealed metastasis from a renal cell carcinoma. The primary tumour was discovered on the right kidney which was then resected. The early postoperative course was favourable, but no long-term follow-up is available.

A 200-kHz ultrasonic transducer coupled to the air with a radiating membrane

The development of a 200-kHz air ultrasonic transducer that consists of a piezoceramic disc and metal housing, the latter acting as a radiating membrane, is discussed. Theoretical analysis of the axially symmetric transducer structure is based upon the finite-element method. Calculations of the resonance frequencies, corresponding transducer deformations and input electrical admittance are performed using triangular ring elements with six degrees of freedom. Measured values on experimentally built transducers show good agreement with theory.