Patients with low prognosis in ART: a Delphi consensus to identify potential clinical implications and measure the impact of POSEIDON criteria.

BACKGROUND: Currently, there is no consensus on the optimal management of women with low prognosis in ART. In this Delphi consensus, a panel of international experts provided real-world clinical perspectives on a series of literature-supported consensus statements regarding the overall relevance of the POSEIDON criteria for women with low prognosis in ART. METHODS: Using a Delphi-consensus framework, twelve experts plus two Scientific Coordinators discussed and amended statements and supporting references proposed by the Scientific Coordinators (Round 1). Statements were distributed via an online survey to an extended panel of 53 experts, of whom 36 who voted anonymously on their level of agreement or disagreement with each statement using a six-point Likert-type scale (1 = Absolutely agree; 2 = More than agree; 3 = Agree; 4 = Disagree; 5 = More than disagree; 6 = Absolutely disagree) (Round 2). Consensus was reached if > 66% of participants agreed or disagreed. RESULTS: The extended panel voted on seventeen statements and subcategorized them according to relevance. All but one statement reached consensus during the first round; the remaining statement reached consensus after rewording. Statements were categorized according to impact, low-prognosis validation, outcomes and patient management. The POSEIDON criteria are timely and clinically sound. The preferred success measure is cumulative live birth and key management strategies include the use of recombinant FSH preparations, supplementation with r-hLH, dose increases and oocyte/embryo accumulation through vitrification. Tools such as the ART Calculator and Follicle-to-Oocyte Index may be considered. Validation data from large, prospective studies in each POSEIDON group are now needed to corroborate existing retrospective data. CONCLUSIONS: This Delphi consensus provides an overview of expert opinion on the clinical implications of the POSEIDON criteria for women with low prognosis to ovarian stimulation.

Identify high-risk DOR women ≤ 35 years old following assisted reproduction technology through cutoffs of anti-mullerian hormone and antral follicle counts.

BACKGROUND: Females with diminished ovarian reserve (DOR) have significantly lower cumulative live birth rates (CLBRs) than females with normal ovarian reserve. A subset of young infertile patients, whose ovarian reserve is declining but has not yet met the POSEIDON criteria for DOR, has not received the attention it merited. These individuals have not been identified in a timely manner prior to the initiation of assisted reproductive technology (ART), leading to suboptimal clinical pregnancy outcomes. We categorized this overlooked cohort as the "high-risk DOR" group. OBJECTIVE: The primary aim of this study was to identify high-risk DOR patients through anti-Mullerian hormone (AMH) and antral follicle counts (AFCs). METHODS: A total of 10037 young women (≤ 35 years old) who underwent their first initial oocyte aspiration cycle at a single reproductive medicine center were included and further classified into three groups, based on the thresholds for AMH and AFC established through receiver operating characteristic (ROC) analysis and in alignment with the POSEIDON criteria. Two ROC analyses were performed to identify the cutoff values of AMH and AFC to obtain one viable embryo (one top-quality embryo or one viable blastocyst). The cutoffs of ROC were measured by sensitivity and specificity. The primary outcome was the cumulative live birth rate (CLBR) per oocyte aspiration cycle. The secondary outcomes included the number of oocytes retrieved and the number of viable embryos formed. Pearson's chi-square tests were conducted to compare the clinical outcomes among the three groups. Furthermore, univariate logistic regression analyses were performed to investigate the associations between ovarian reserve and clinical outcomes. All of the above comparisons between the high-risk DOR and NOR were further confirmed by propensity score matching (PSM) (1:1 nearest-neighbor matching, with a caliper width of 0.02). RESULTS: According to the ROC analyses and POSEIDON criteria, the present study identified a population of high-risk DOR patients (1.20 ng/mL < AMH values < 2.50 ng/mL, with 6 ≤ AFC ≤ 10; n = 682), and their outcomes were further compared to those of DOR patients (positive control, AMH values ≤ 1.2 ng/mL, and/or AFC ≤ 5; n = 1153) and of NOR patients (negative control, 2.5 ng/mL ≤ AMH values ≤ 5.5 ng/mL, and 11 ≤ AFC ≤ 20; n = 2649). Patients in the high-risk DOR group had significantly lower CLBRs than those in the NOR group (p < 0.001) but higher CLBRs than those in the DOR group (p < 0.001). Logistic regression further demonstrated that high-risk DOR was associated with a lower likelihood of cumulative live birth chance (OR 0.401, 95% CI: 0.332-0.486, p < 0.001) than NOR was, with a greater likelihood of cumulative live birth chance (OR 1.911, 95% CI:1.558-2.344, p < 0.001) than DOR was. To investigate the effects of embryo development stage, the outcomes of D3 embryos and blastocysts were analyzed separately. Significant differences in pregnancy outcomes were detected only in D3 embryo ET cycles among the three groups (high-risk DOR vs. NOR, all p < 0.05; DOR vs. NOR, all p < 0.05). DOR/high-risk DOR did not influence the pregnancy loss rates or pregnancy outcomes (clinical pregnancy rates and ongoing pregnancy rates) per positive HCG cycle (all p > 0.05). After PSM, the differences in ovarian response and pregnancy outcomes between the high-risk DOR and NOR groups were consistent with the results before PSM. CONCLUSION(S): Our study revealed that the CLBR of the high-risk DOR patients was significantly lower than that of females with normal ovarian reserve and greater than that of females with DOR. The values of AMH ranging from 1.2 to 2.5 and AFC ranging from 6 to 10 appeared to constitute meaningful thresholds in females with mildly reduced ovarian reserve.

Impact of dehydroepiandrosterone sulfate and free androgen index on pregnancy and neonatal outcomes in PCOS patients.

BACKGROUND: Polycystic ovary syndrome (PCOS) is a prevalent endocrine disorder associated with infertility and pregnancy complications. The pathogenesis of PCOS and its impact on reproductive function may be influenced by the source of androgens, including testosterone, free androgen, dehydroepiandrosterone sulfate (DHEAS). However, the differential effects of these androgen on pregnancy and neonatal outcomes and the cut-off value of East Asian population with PCOS remain unclear. METHODS: A retrospective cohort study was conducted at the Reproductive Medicine Center of the First Affiliated Hospital of Sun Yat-sen University from January 2015 to November 2022, involving 636 cycles of in vitro fertilization/intracytoplasmic sperm injection (IVF/ICSI). Subgroup analyses were performed using cut-off values of 6.4 for free androgen index (FAI), 9.5 µmol/L for DHEAS. Pregnancy and neonatal outcomes were compared between groups. Restricted cubic spline (RCS) was used to identify significant cut-off values affecting pregnancy. RESULTS: Higher FAI levels (> 6.4) were associated with decrease in clinical pregnancy rate (PR) (50.61% vs. 41.66%, p = 0.024), live birth rate (LBR) (42.42% vs. 32.35%, p = 0.011). When DHEAS levels exceeded 9.5 µmol/L, there was a significant decrease in clinical PR (51.27% vs. 42.73%, P = 0.039), LBR (42.73% vs. 32.73%, P = 0.012). Negative correlations were also observed between DHEAS levels and cumulative pregnancy rate (70.57% vs 56.62% p = 0.002) and cumulative live birth rate (CLBR) (59.35% vs 43.37%, p = 0.0007). Both FAI and DHEAS elevated is associated with the lowest clinical pregnancy rate (37.84%). Conversely, when solely FAI is elevated, the pregnancy rate increases to 52.38%, while an elevation in DHEAS alone is associated with a pregnancy rate of, both of which are lower than when neither FAI nor DHEAS are elevated (60.68%). The live birth rates exhibit a similar trend (30.00% vs 40.00% vs 41.83% vs 44.48%). RCS revealed a significant decrease in CPR and CLBR when DHEA levels exceeded 7.69 umol/L, while the cut-off value of FAI was 6.36 for CPR and CLBR. CONCLUSION: In conclusion, PCOS patients with biochemical hyperandrogenism show unsatisfactory clinical PR and CLBR when undergoing assisted reproductive technology (ART). This may be attributed to the influence of both adrenal-derived DHEAS and ovarian-derived FAI on the unfavorable pregnancy outcomes.

A heatmap for expected cumulative live birth rate in preimplantation genetic testing for monogenic disorders and chromosomal structural rearrangements.

PURPOSE: Our objective is to predict the cumulative live birth rate (CLBR) and identify the specific subset within the population undergoing preimplantation genetic testing for monogenic disorders (PGT-M) and chromosomal structural rearrangements (PGT-SR) which is likely to exhibit a diminished expected CLBR based on various patient demographics. METHODS: We performed a single-centre retrospective cohort study including 1522 women undergoing 3130 PGT cycles at a referral centre for PGT. A logistic regression analysis was performed to predict the CLBR per ovarian stimulation in women undergoing PGT-M by polymerase chain reaction (PCR) or single-nucleotide polymorphism (SNP) array, and in women undergoing PGT-SR by SNP array, array comparative genomic hybridization (CGH) or next-generation sequencing (NGS). RESULTS: The mean age of women was 32.6 years, with a mean AMH of 2.75 µg/L. Female age and AMH significantly affected the expected CLBR irrespective of the inheritance mode or PGT technology. An expected CLBR < 10% was reached above the age of 42 years and AMH ≤ 1.25 µg/L. We found no significant difference in outcome per ovarian stimulation between the different PGT technologies, i.e. PCR, SNP array, array CGH and NGS. Whereas per embryo transfer, we noticed a significantly higher probability of live birth when SNP array, array CGH and NGS were used as compared to PCR. CONCLUSION: In a PGT-setting, couples with an unfavourable female age and AMH should be informed of the prognosis to allow other reproductive choices. The heatmap produced in this study can be used as a visual tool for PGT couples.

Sunlight-activated 3D-mesoporous-flowerlike Cl-Br bismuth oxides nanosheet solid solution: In situ EG-thermal-sonication synthesis with excellent photodecomposition of ciprofloxacin.

In this research, a group of BiOX (Cl:Br) nanosheet solid solution with various Cl/Br molar ratios have been fabricated using a facile one-pot in-situ thermal-sonication method. The crystal phases structure, elemental composition, morphology, specific surface area and optical features of as-synthesized photocatalyst were explored by XRD, EDX, FESEM, HRTEM, AFM, BET-BJH, and DRS techniques. The photocatalytic activity of nanophotocatalysts was investigated by photodegradation of ciprofloxacin as a model pharmaceutical pollutant under simulated solar light illumination. The scavenging effect was studied by using tTriethanolamine and 2-propanol to evaluate the roles of holes and hydroxyl radicals as main active species. All the samples showed higher photocatalytic activity compared to pristine BiOCl and BiOBr. Among the solid solutions, BiOX (Cl:Br = 1:3)-U sample exhibited excellent photocatalytic performance by 100% degradation efficiency of ciprofloxacin within 120 min. The outstanding photocatalytic activity of BiOX (Cl:Br = 1:3)-U might be ascribed to the large specific surface area, suitable morphology and band gap, effective separation of the photo-generated electron-hole pairs and the existence of the meso-size pores in structure. Moreover, results demonstrated that the presence of ultrasound irradiations and generated microjets during the synthesis step could appreciably improve the photocatalytic performance. After 4 cycles, there was no significant change in photocatalytic activity that confirms the high stability of BiOX (Cl:Br = 1:3)-U mesoporous nanophotocatalyst. Besides, the influence of operating parameters on the degradation efficiency and the possible photocatalytic mechanism was examined.

Effects of clbR overexpression on enzyme production in Aspergillus aculeatus vary depending on the cellulosic biomass-degrading enzyme species.

ClbR is a Zn(II)2Cys6 transcriptional activator that controls the expression of cellulase-related genes in response to Avicel and cellobiose in Aspergillus aculeatus. A clbR-overexpressing strain (clbR-OE) that expresses the clbR gene at levels sevenfold higher than the control strain sustainably produced xylanolytic and cellulolytic activities during 10-day cultivation of A. aculeatus, enabling synchronization of xylanolytic and cellulolytic activities at a maximum level. However, clbR overexpression did not simultaneously increase levels of all xylanolytic and cellulolytic enzymes. Peptide mass fingerprint analysis revealed markedly increased production of FIa-xylanase in clbR-OE, whereas expression of FIII-avicelase and FII-carboxymethyl cellulase was unaffected and expression of hydrocellulase was lower in clbR-OE than in the control. Northern blot analysis confirmed that these effects of clbR overexpression on enzyme production were mediated at the transcriptional level. These data suggest that ClbR participates in diverse signaling pathways to control the expression of cellulosic biomass-degrading enzymes in A. aculeatus.

Progestin-primed ovarian stimulation with letrozole using different doses of medroxyprogesterone acetate per day: a retrospective cohort study.

Background: In the progestin-primed ovarian stimulation protocol, the oral administration of medroxyprogesterone acetate has been observed to effectively inhibit the LH surge during ovarian stimulation in patients experiencing infertility. Nevertheless, the use of utilizing medroxyprogesterone acetate during ovarian stimulation can result in more pronounced pituitary suppression, potentially necessitating increased doses of gonadotropins and extended treatment durations. Therefore, it is necessary to determine the optimal dose of medroxyprogesterone acetate, aiming to use relatively lower concentrations of medroxyprogesterone acetate to effectively and safely suppress early LH surges. Method: This retrospective cohort study included 710 patients who underwent cycles of in vitro fertilization or intracytoplasmic sperm injection and were subjected the progestin-primed ovarian stimulation protocol utilizing letrozole between from 1st January 2021 to 31st December 2021. The study population was divided into low, medium, and high concentration groups based on the daily dosage of medroxyprogesterone acetate.The primary focus of this investigation was on the cumulative live birth rate. Secondary outcomes encompassed the occurrence of a premature surge in luteinizing hormone, the quantity of retrieved oocytes, viable embryos, and high-quality embryos, as well as clinical pregnancy rate, abortion rate, ectopic pregnancy rate, and multiple pregnancy rate. Results: In this study, significant differences were observed among three groups in various parameters including body mass index, baseline levels of Anti-Müllerian hormone and luteinizing hormone, antral follicle count, total dose of gonadotropin, and duration of gonadotropin administration (p<0.05). The number of oocytes and viable embryos were significantly higher in medium group and higher than those in the low dose group. Following adjustments for confounding factors related to medroxyprogesterone acetate for various outcome measures, we conducted multiple regression analysis to investigate the independent effects of daily medroxyprogesterone acetate dosage within the combined progestin-primed ovarian stimulation and letrozole protocol. Following multivariable regression analysis, no disparities were found in embryo characteristics (number of oocytes retrieved, number of available embryos, number of high-quality embryos) or pregnancy outcomes (clinical pregnancy rate, cumulative live birth rate) among the three groups. Conclusion: Progestin-primed ovarian stimulation with letrozole using different dose of medroxyprogesterone acetate per day was comparable in terms of the number of oocytes retrieved, the number of high-quality embryos, clinical pregnancy rate and cumulative live birth rate after frozen embryo transfer.

'Candidatus Liberibacter brunswickensis' colonization has no effect to the early development of Solanum melongena.

This study is the first to investigate the presence and movement of the novel Liberibacter species 'Candidatus Liberibacter brunswickensis' (CLbr) in eggplant, Solanum melongena. The psyllid, Acizzia solanicola can transmit CLbr to eggplant and CLbr can be acquired by CLbr-negative A. solanicola individuals from CLbr-positive eggplants. In planta, CLbr can replicate, move and persist. Investigation into the early development of eggplants showed that CLbr titres had increased at the inoculation site at 14 days post inoculation access period (DPIAP). CLbr had become systemic in the majority of plants tested by 28 DPIAP. The highest bacterial titres were recorded at 35 DPIAP in all samples of the inoculated leaf, the roots, stems and the midrib and petiole samples of the newest leaf (the top leaf). This finding strongly suggests that CLbr movement in planta follows the source to sink relationship as previously described for 'Ca. Liberibacter asiaticus' (CLas) and 'Ca. Liberibacter solanacearum' (CLso). No symptoms consistent with Liberibacter-associated diseases were noted for plants colonised by CLbr during this study, consistent with the hypothesis that CLbr does not cause disease of eggplant during the early stages of host colonisation. In addition, no significant differences in biomass were found between eggplant colonised with CLbr, compared to those that were exposed to CLbr-negative A. solanicola, and to control plants.

Cl/Br mass ratio and water quality index from the Quaternary aquifer of south Bengal Basin in India.

The purpose of this study is to identify suitable areas for the exploitation of groundwater for human consumption by analysing Cl/Br and other indicators of wastewater influence on groundwater quality in and around the twin megacities of Kolkata and Howrah, located on the complex deltaic system of south Bengal Basin in India. About 18%, 56.5%, 28% and 35.5% of the 287 groundwater samples comply with the Indian acceptable limits (ALs) of TDS, Cl, Fe and Mn, respectively. About 29% of the 279 samples analysed have Cl/Br < 268 where the excess Br is derived from organic degradation. About 30% samples have Cl/Br > 308 clustering mainly around a palaeo-channel indicating wastewater contamination. In addition to these, many samples have NO3/Cl > 0.0002 and SO4/Cl > 0.014, indicating that the groundwater is contaminated by wastewater from sewage and septic tank leakage. The concentrations of metals (Fe, Mn) and As are also higher than AL particularly on either side of the palaeo-channel, which may affect the human body functions. The localised recharge of wastewater also contains high SO4. Sulphate reduction in the aquifer sequesters the As in groundwater into the neo-formed arsenopyrite. Based on the estimated water quality index, the groundwater samples have been classified into four types-highly suitable (28.17%), moderately suitable (23.94%), doubtful (15.85%) and unsuitable (32.04%) for drinking purpose. The first two types cover about 62% of the study area. But the highly urbanised area of Kolkata and Howrah city and the industrial areas in the southern fringe of Kolkata city have the latter two types of groundwater. The over-withdrawal of groundwater may expedite the quality deterioration of 'highly and 'moderately suitable water' of the study area into 'doubtful' and 'unsuitable for drinking' categories through mixing mechanism in the aquifer.

Natural background levels in groundwater in the Pearl River Delta after the rapid expansion of urbanization: A new pre-selection method.

Establishment of natural background levels (NBL) of groundwater in urbanized areas such as the Pearl River Delta (PRD) is challenging. Pre-selection methods are the most common approaches for NBL assessment, but it will overestimate (or underestimate) contaminated groundwater in urbanized areas by using present pre-selection methods with empirical definite values because of complicated human activities. Unlike present pre-selection methods, this study aims to establish a new pre-selection method with the indicative of Cl/Br ratios to identify contaminated groundwaters with convincing evidences. Specifically, this new method consists of indicatives of the oxidation capacity and the Cl/Br ratio combining with contaminated-markers. In addition, factors controlling NBL of Cl and NO3 in groundwater in various hydrogeological units in the PRD were also discussed. Main procedures of this new method: contaminated-markers in various hydrogeological units are extracted by a hierarchical cluster analysis, thereby determining threshold values of Cl/Br ratios and Cl concentration in various hydrogeological units for identifying contaminated groundwater; After that, groundwater chemical datasets was selected by the oxidation capacity, and then tested by Grubbs' test until normal distributions. Groundwater Cl and NO3 concentrations in datasets before and after this new method are dependent and independent of urbanization levels, respectively, indicating that the new method is useful for groundwater NBL assessment in urbanized areas such as the PRD. Both the seawater intrusion and the diffusion of Cl from marine deposits are likely to be responsible for the much higher NBL-Cl in coastal-alluvial and marine aquifers than in other hydrogeological units. Groundwater Cl enrichment resulted from groundwater recharge and evaporation is mainly responsible for the higher NBL-Cl in alluvial-proluvial aquifers than in lacustrine aquifers, fissured aquifers, as well as karst aquifers. More than double times NBL-NO3 in alluvial-proluvial and fissured aquifers than in other hydrogeological units is probably attributed to more oxidizing conditions of their vadose zones and groundwaters.

(Chlorido/bromido)[(1,2,5,6-η)-cyclo-octa-1,5-diene](4-isopropyl-1-methyl-1,2,4-triazol-5-yl-idene)rhodium(I).

A new triazole-based neutral RhI complex, [Rh(Cl0.846Br0.154)(C6H11N3)(C8H12)], has been synthesized and structurally characterized. The RhI atom has a distorted square-planar coordination environment, formed by a bidentate cyclo-octa-1,5-diene (COD) ligand, an N-heterocyclic carbene and a halide ligand that shows substitutional disorder (Cl:Br = 0.846:0.154). No significant inter-molecular inter-actions other than van der Waals forces are found in the crystal structure. Diffraction data indicated a two-component inversion twin with a ratio of 0.95 (5):0.05 (5).

The effects of irrigation on groundwater quality and quantity in a human-modified hydro-system: The Oglio River basin, Po Plain, northern Italy.

For several hundred years, farming in the Po Plain of Italy (46,000 km2, 20 million inhabitants) has been supported by intensive surface irrigation with lake and river water. Despite the longevity of irrigation, its effects on the quality and quantity of groundwater is poorly known and so is investigated here through seasonal measurements of hydraulic heads and water quality in groundwaters, rivers, lake, springs and rainwaters. In the north of the study region, an unconfined coarse-grained alluvial aquifer, infiltration of surface irrigation water, sourced from the Oglio River and low in NO3, contributes much to aquifer recharge (up to 88%, as evidenced by a δ2H-Cl/Br mixing model) and has positive effects on groundwater quality by diluting high concentrations of NO3 (decrease by 17% between June and September). This recharge also helps to maintain numerous local springs that form important local micro-environments. Any increase in water-use efficiency in irrigation will reduce this recharge, imperil the spring environments, and lessen the dilution of NO3 leading to increasing NO3 concentrations in groundwater. These findings can be extended by analogy to the entire Po Plain region and other surface-water-irrigated systems worldwide where inefficient irrigation methods are used and similar hydrogeological features occur.

Changing recharge pathways within an intensively pumped aquifer with high fluoride concentrations in Central Mexico.

Fluoride (F), naturally found in aquifers around the world at toxic concentrations, causes disease in millions of people. The long-term stability, however, of those concentrations within intensively pumped aquifers is poorly characterized. We assessed long-term stability in the spatial distribution of F concentrations in an intensively pumped aquifer within the semi-arid, inter-montane Independence Basin in central Mexico between 1999 and 2016. Although stable in 16 re-sampled wells, F concentrations increased in some localities across the basin by as much as 4mg/L. Changes in recharge pathways to the deep aquifer were identified by analyzing changes in δ2H, δ18O and Cl/Br mass ratios. In 1999, δ2H and δ18O values suggested the aquifer was recharged in the mountains. In 2016, however, substantial increases in δ18O values in the center of the basin suggest recharge water is derived from rainfall that had experienced increased evaporation. In 1999, the mass ratio Cl/Br in groundwater was slightly enriched over local rainfall, and followed a single mixing line on a plot of Cl. vs. Cl/Br. In 2016, however, three distinct groupings of wells were evident, all following different mixing lines. These changes suggest input from new sources including urban sewage, evaporate dissolution, connate sea water and geothermal waters. Step-wise multiple regression was used to quantify the impact of physical and chemical parameters on F concentrations. In 1999, Li (6.8±1.7) and Na (0.01±0.004) drove F concentrations (R2=0.54). In 2016, Na (0.013±0.0018), HCO3 (0.004±0.001), Ca (-0.0018±0.00045), and Mg (-0.055±0.023) drove F concentrations (0.78). Irrigation pumping and urban expansion within semi-arid, groundwater-dependent, inter-montane basins drive mixing of disparate groundwater chemistries and introduces new sources of recharge to aquifers inducing changes in aquifer chemistry including increasing concentrations of geogenic toxic elements.

Pollutant sources in an arsenic-affected multilayer aquifer in the Po Plain of Italy: Implications for drinking-water supply.

In aquifers 160 to 260m deep that used for public water-supply in an area ~150km2 around the town of Cremona, in the Po Plain of Northern Italy, concentrations of arsenic (As) are increasing with time in some wells. The increase is due to drawdown of As-polluted groundwater (As ≤144µg/L) from overlying aquifers at depths 65 to 150m deep in response to large-scale abstraction for public supply. The increase in As threatens drinking-water quality locally, and by inference does so across the entire Po Plain, where natural As-pollution of groundwater (As >10µg/L) is a basin-wide problem. Using new and legacy data for Cl/Br, δ18O/δ2H and other hydrochemical parameters with groundwater from 32 wells, 9 surface waters, a sewage outfall and rainwater, we show that the deep aquifer (160-260m below ground level), which is tapped widely for public water-supply, is partly recharged by seepage from overlying aquifers (65-150m below ground level). Groundwater quality in deep aquifers appears free of anthropogenic influences and typically <10µg/L of As. In contrast, shallow groundwater and surface water in some, not all, areas are affected by anthropogenic contamination and natural As-pollution (As >10µg/L). Outfalls from sewage-treatment plants and black water from septic tanks firstly affect surface waters, which then locally infiltrate shallow aquifers under high channel-stages. Wastewater permeating shallow aquifers carries with it NO3 and SO4 which suppress reduction of iron oxyhydroxides in the aquifer sediments and so suppress the natural release of As to groundwater.

Geochemical processes controlling groundwater quality under semi arid environment: A case study in central Morocco.

Bahira plain is an important area for Morocco due to its agriculture and mining activities. Situated in a sub-arid to arid climate, this plain hosts an aquifer system that represents sequences of carbonates, phosphates, evaporates and alluvial deposits. Groundwater flows from Ganntour plateau (recharge area) to the basin-fill deposits and Zima Lake and Sed Elmejnoun where water evaporates. The objective of this study was to characterize the chemical properties of the groundwater and to assess the processes controlling the groundwater's chemistry. We can divide water samples into three hydrochemical water groups: recharge waters (Ca/Mg-HCO3), transition zone waters (Ca-HCO3-SO4/Cl) and discharge waters (Na-Cl/SO4). Accordingly, compositions of waters are determined by the availability of easily soluble minerals like calcite (Ca-HCO3 dominant), halite (Na-Cl dominant) and gypsum (Ca-SO4 dominant). Cl/Br ratios show that Cl concentration increases from dissolution of natural halite. When groundwater is affected by extreme evaporation Cl/Br ratios may increase up to 1900. High fluoride concentrations are associated with low Ca2+ concentrations (<100mg/L). That means when recharge waters enter the aquifer, it starts dissolving fluorite since the Ca2+ concentration is low. Once groundwater becomes saturated with Ca2+, the immobilization of fluoride is occurring by precipitation of fluoride-rich minerals like fluoro-apatite. According to the environmental isotope (18O and 2H) analyses, they are three potential processes affecting groundwater: 1. Evaporation as verified by low slope value, 2. Water-rock interaction, 3. admixture of waters showed different stable isotope compositions and salinities.

Sources of groundwater salinity and potential impact on arsenic mobility in the western Hetao Basin, Inner Mongolia.

The quality of groundwater used for human consumption and irrigation in the Hetao Basin of Inner Mongolia, China is affected by elevated salinity as well as high arsenic (As) concentrations. However, the origin of high salinity and its potential impact on As mobility in the Basin remain unclear. This study explores both issues using stable isotopic compositions and Cl/Br ratios of groundwater as well as the major ions of both groundwater and leachable salts in aquifer sediments. Limited variations in δ18O and δ2H (-11.13 to -8.10, -82.23 to -65.67) with the wide range of Total Dissolved Solid (TDS, 351-6734mg/L) suggest less contribution of direct evaporation to major salinity in groundwater. Deuterium excess shows that non-direct evaporation (capillary evaporation, transpiration) and mineral/evaporite dissolution contribute to >60% salinity in groundwater with TDS>1000mg/L. Non-direct evaporation, like capillary evaporation and transpiration, is proposed as important processes contributing to groundwater salinity based on Cl/Br ratio and halite dissolution line. The chemical weathering of Ca, Mg minerals and evaporites (Na2SO4 and CaSO4) input salts into groundwater as well. This is evidenced by the fact that lacustrine environment and the arid climate prevails in Pleistocene period. Dissolution of sulfate salts not only promotes groundwater salinity but affects As mobilization. Due to the dissolution of sulfate salts and non-direct evaporation, groundwater SO42- prevails and its reduction may enhance As enrichment. The higher As concentrations (300-553µg/L) are found at the stronger SO42- reduction stage, indicating that reduction of Fe oxide minerals possibly results from HS- produced by SO42- reduction. This would have a profound impact on As mobilization since sulfate is abundant in groundwater and sediments. The evolution of groundwater As and salinity in the future should be further studied in order to ensure sustainable utilization of water resource in this water scarce area.

Spatio-temporal assessment and trend analysis of surface water salinity in the coastal region of Bangladesh.

The study was designed to collect water samples over two seasons-wet-monsoon season (n = 96) (March-April) and dry-monsoon season (n = 44) (September-October)-to understand the seasonal variation in anion and cation hydrochemistry of the coastal rivers and estuaries contributing in the spatial trend in salinity. Hydrochemical examination of wet-monsoon season primarily revealed Ca-Mg-HCO3 type (66%) and followed by Na-Cl type (17.70%) water. In the dry-monsoon season, the scenario reversed with primary water being Na-Cl type (52.27%) followed by Ca-Mg-HCO3 type (31.81%). Analysis of Cl/Br molar ratio vs. Cl (mg/L) depicted sampling area affected by seawater intrusion (SWI). Spatial analysis by ordinary kriging method confirmed approximately 77% sample in the dry-monsoon, and 34% of the wet-monsoon season had shown SWI. The most saline-intruded areas in the wet-monsoon seasons were extreme south-west coastal zone of Bangladesh, lower Meghna River floodplain and Meghna estuarine floodplain and south-eastern part of Chittagong coastal plains containing the districts of Chittagong and Cox's Bazar adjacent to Bay of Bengal. In addition, mid-south zone is also affected slightly in the dry-monsoon season. From the analyses of data, this study could further help to comprehend seasonal trends in the hydrochemistry and water quality of the coastal and estuarine rivers. In addition, it can help policy makers to obligate some important implications for the future initiatives taken for the management of land, water, fishery, agriculture and environment of coastal rivers and estuaries of Bangladesh.

Cl/Br ratios and chlorine isotope evidences for groundwater salinization and its impact on groundwater arsenic, fluoride and iodine enrichment in the Datong basin, China.

In order to identify the salinization processes and its impact on arsenic, fluoride and iodine enrichment in groundwater, hydrogeochemical and environmental isotope studies have been conducted on groundwater from the Datong basin, China. The total dissolved solid (TDS) concentrations in groundwater ranged from 451 to 8250 mg/L, and 41% of all samples were identified as moderately saline groundwater with TDS of 3000-10,000 mg/L. The results of groundwater Cl concentrations, Cl/Br molar ratio and Cl isotope composition suggest that three processes including water-rock interaction, surface saline soil flushing, and evapotranspiration result in the groundwater salinization in the study area. The relatively higher Cl/Br molar ratio in groundwater from multiple screening wells indicates the contribution of halite dissolution from saline soil flushed by vertical infiltration to the groundwater salinization. However, the results of groundwater Cl/Br molar ratio model indicate that the effect of saline soil flushing practice is limited to account for the observed salinity variation in groundwater. The plots of groundwater Cl vs. Cl/Br molar ratio, and Cl vs δ(37)Cl perform the dominant effects of evapotranspiration on groundwater salinization. Inverse geochemical modeling results show that evapotranspiration may cause approximately 66% loss of shallow groundwater to account for the observed hydrochemical pattern. Due to the redox condition fluctuation induced by irrigation activities and evapotranspiration, groundwater salinization processes have negative effects on groundwater arsenic enrichment. For groundwater iodine and fluoride enrichment, evapotranspiration partly accounts for their elevation in slightly saline water. However, too strong evapotranspiration would restrict groundwater fluoride concentration due to the limitation of fluorite solubility.

Experimental and theoretical studies of solvent effects on the hydrogen bonds in homoconjugated cations of substituted 4-halo (Cl, Br) pyridine N-oxide derivatives.

Hydrogen bond OHO-type bridges formed between six substituted 4-halo (Cl, Br) pyridine N-oxide systems and their simple cations have been investigated by using the potentiometric titration method. The formation constants of these complexes (expressed as lg K BHB + ) have been determined in two non-aqueous aprotic solvents with different polarity, i.e., acetone (AC) and acetonitrile (AN). It has been observed that tri- and tetra-substituted pyridine N-oxides [B] and their cationic acids [BH+] form stable homocomplexed cations [BHB+] stabilized by O⋯H⋯O bridges in both solvents used. It has been found that the most stable homocomplexed system is formed by 3,5-dimethyl-4-chloropyridine N-oxide (3,5Me24ClPyO). The lg K BHB + values for this compound in acetone and acetonitrile are 3.15 and 2.82, respectively. Furthermore, by using ab initio methods at the RHF and MP2 levels utilizing the Gaussian 6-31++G∗∗ basis set, the energies of formation of the homocomplexed cations and Gibbs free energies have been determined in vacuo. The calculated energy parameters in vacuo have been compared with the cationic homoconjugation constants determined potentiometrically in acetone and acetonitrile to establish a correlation between these magnitudes. Additionally, the results of potentiometric measurements have been used to determine the acidity constants of the conjugate acids of N-oxides.