Predicting groundwater phosphate levels in coastal multi-aquifers: A geostatistical and data-driven approach.

The groundwater (GW) resource plays a central role in securing water supply in the coastal region of Bangladesh and therefore the future sustainability of this valuable resource is crucial for the area. However, there is limited research on the driving factors and prediction of phosphate concentration in groundwater. In this work, geostatistical modeling, self-organizing maps (SOM) and data-driven algorithms were combined to determine the driving factors and predict GW phosphate content in coastal multi-aquifers in southern Bangladesh. The SOM analysis identified three distinct spatial patterns: K+Na+pH, Ca2+Mg2+NO3-, and HCO3-SO42-PO43-F-. Four data-driven algorithms, including CatBoost, Gradient Boosting Machine (GBM), Long Short-Term Memory (LSTM), and Support Vector Regression (SVR) were used to predict phosphate concentration in GW using 380 samples and 15 prediction parameters. Forecasting accuracy was evaluated using RMSE, R2, RAE, CC, and MAE. Phosphate dissolution and saltwater intrusion, along with phosphorus fertilizers, increase PO43- content in GW. Using input parameters selected by multicollinearity and SOM, the CatBoost model showed exceptional performance in both training (RMSE = 0.002, MAE = 0.001, R2 = 0.999, RAE = 0.057, CC = 1.00) and testing (RMSE = 0.001, MAE = 0.002, R2 = 0.989, RAE = 0.057, CC = 0.998). Na+, K+, and Mg2+ significantly influenced prediction accuracy. The uncertainty study revealed a low standard error for the CatBoost model, indicating robustness and consistency. Semi-variogram models confirmed that the most influential attributes showed weak dependence, suggesting that agricultural runoff increases the heterogeneity of PO43- distribution in GW. These findings are crucial for developing conservation and strategic plans for sustainable utilization of coastal GW resources.

Hexavalent chromium removal from aqueous medium by ternary nanoadsorbent: A study of kinetics, equilibrium, and thermodynamic mechanism.

Although many studies have focused on chromium removal from aqueous media by ternary Nano adsorbents, still the integrated kinetics, equilibrium, and thermodynamic mechanisms of chromium removal remain unknown. Thus in this study, we have synthesized a novel ternary oxide nanocomposite comprising iron, manganese, and stannous (Fe2O3-MnO2-SnO2) in a facile method as a promising adsorbent for the removal of Cr(VI) from an aqueous medium. The Fe2O3-MnO2-SnO2 system was firstly characterized by FTIR, XRD, TGA, BET, and SEM/EDX. The effect of parameters, for instance, pH, temperature, initial Cr(VI) intensity, and adsorbent dose, have been examined to optimize the Cr(VI) adsorption performance. The adsorption of Cr(VI) onto Fe2O3-MnO2-SnO2 nanoadsorbent is associated with an adsorption/reduction mechanism. Using an initial Cr(VI) intensity of 50 mg L-1, 200 rpm agitation, 2.5-g L-1 of adsorbent, pH 2, 90 minutes adsorption time, and 298 K temperature, a maximum adsorption capability of 69.2 mg Cr(VI) g-1 for Fe2O3-MnO2-SnO2 was obtained. Models of pseudo-2nd-order kinetics and Langmuir's isotherm were best suited to the investigated data. Besides, thermodynamic parameters show that Cr(VI) adsorption onto Fe2O3-MnO2-SnO2 was random and dominated by entropy. The reusability of Fe2O3-MnO2-SnO2 was found to be consistently high (remaining above 80% for Cr(VI)) over four adsorption-desorption cycles. Chromium adsorption from the tannery wastewater was achieved 91.89% on Fe2O3-MnO2-SnO2. Therefore, Fe2O3-MnO2-SnO2 nanoparticles, being easy to be synthesized, reusable and having improved adsorption capability with higher surface area, could be a desirable option for removing Cr(VI) from aqueous environments.

Sediment-bound hazardous trace metals(oid) in south-eastern drainage system of Bangladesh: First assessment on human health.

Despite the beneficial aspect of a natural drainage system, increasing human-induced activities, which include urbanization and growth in industrialization, degrade the ecosystem in terms of trace metal contamination. In response, given the great importance of the south-eastern drainage system in Bangladesh, a detailed evaluation of the human health risk as well as the potential ecological risk of trace metals (Be, Cd, Co, Cr, Cu, Hg, Ni, Pb, Se, V, Zn, and As) in Karnaphuli riverbed sediment was conducted. Mean levels of the elements in mg/kg were As (5.62 ± 1.47); Se (0.84 ± 0.61); Hg (0.37 ± 0.23); Be (1.17 ± 0.49); Pb (15.62 ± 8.42); Cd (0.24 ± 0.33); Co (11.59 ± 4.49); Cr (112.75 ± 40.09); Cu (192.67 ± 49.71); V (27.49 ± 10.95); Zn (366.83 ± 62.82); Ni (75.83 ± 25.87). Pollution indicators, specifically contamination factor (CF), pollution load index (PLI), degree of contamination (Cd), enrichment factor (EF), geo-accumulation index (Igeo), and potential ecological risk index (RI), were computed to assess sediment quality. For the first observation of health risk, chronic daily intake (CDI), hazard quotient (HQ), hazard index (HI), carcinogenic risk (CR) and total carcinogenic risk (TCR) indices were calculated. According to the results, CDI values through the ingestion route of both the adult and child groups were organized in the following descending mode respectively: Zn > Cu > Cr > Ni > V > Pb > Co > As > Se > Be > Cd > Hg. The non-carcinogenic risks were generally low for all routes of exposure, except HQingestion was slightly higher for both adults and children. The calculated hazard index (HI) was, nevertheless, within the permitted range (HI < 1). Similarly, none of the metals exhibited any carcinogenic risks, as all CR values were within the 10-4-10-6 range. The need for authoritative efforts and water policy for the sake of the surrounding ecosystem and human health in the vicinity of the examined watershed is strongly felt as an outcome of this study. The purpose of this study is to protect public health by identifying trace metal sources and reducing industrial and domestic discharge into this natural drainage system.

A Region on Chromosome 7 Related to Differentiation of Rice (Oryza sativa L.) Between Lowland and Upland Ecotypes.

Due to global population expansion and climate change impacts, the development of a stable yielding variety that adapts well to unfavorable conditions for rice cultivation, can contribute to sustainable and stable production in rice (Oryza sativa L.). Understanding genetic differentiations to ecotypes for rice cultivations, such as upland, rainfed lowland, and irrigated lowland, is very important to develop the breeding materials for adapting to each environmental condition. The upland landrace variety basically has low tiller/panicle numbers and a large panicle, and the plant architecture is different from that of the lowland variety. The tiller and panicle numbers have been considered as one of the most difficult traits for genetic changes artificially in rice breeding. A low tiller recessive gene ltn2 originated from a New Plant Type variety, IR 65600-87-2-23, harboring segments from an upland variety, Ketan Lumbu (Tropical Japonica Group), was found on chromosome 7, and the other QTLs for culm length, culm weight, panicle length, panicle weight, seed fertility, harvest index, and soil surface rooting were also detected in the same chromosome region. These low tiller genes and the other QTLs were estimated to play an important role in developing the architecture for upland rice. Some QTLs for root growth angle, DRO3 and qSFR7, were also found in the same chromosome region from upland varieties categorized into the Tropical Japonica Group, and the QTLs may also be relevant to upland adaptation together with other traits. Previous studies using high throughput re-sequencing (whole genome variation data) of a large batch of rice accessions could identify the ecotype differentiated genomic regions (EDRs) and Ecotype differentiated genes (EDGs) such as Os07g0449700, a type response regulator, which is critical in upland adaptation in the same region of chromosome 7. Two selective loci, E3735 and E4208, for upland and lowland differentiation, and their corresponding genes Os07g0260000 and Os07g0546500 were also detected on chromosome 7 by drought-responding EST-SSRs. These findings indicate that the region on chromosome 7 is highly possible to related to the plant shoot and root architecture in the upland rice variety that has an important role and differentiates between upland and lowland ecotypes.

Assisting Phytoremediation of Heavy Metals Using Chemical Amendments.

Phytoremediation is one of the safer, economical, and environment-friendly techniques in which plants are used to recover polluted soils, particularly those containing toxic organic substances and heavy metals. However, it is considered as a slow form of remediation, as plants take time to grow and flourish. Various amendments, including the augmentation of certain chemical substances i.e., ethylenediamine tetraacetic acid (EDTA), ethylene glycol tetra acetic acid (EGTA), and sodium dodecyl sulfate (SDS) have been used to induce and enhance the phytoextraction capacity in plants. Several reports show that chemical amendments can improve the metal accumulation in different plant parts without actually affecting the growth of the plant. This raises a question about the amount and mechanisms of chemical amendments that may be needed for potentially good plant growth and metal phytoremediation. This review provides a detailed discussion on the mechanisms undertaken by three important chemical amendments that are widely used in enhancing phytoremediation (i.e., EDTA, EGTA, and SDS) to support plant growth as well as soil phytoremediation. A core part of this review focuses on the recent advances that have been made using chemical amendments in assisting metal phytoremediation.

Identification of a low tiller gene from a new plant type cultivar in rice (Oryza sativa L.).

We characterized a rice introgression line, YTH34, harboring a chromosome segment from a New Plant Type (NPT) cultivar, IR65600-87-2-2-3, in the genetic background of an Indica Group elite rice cultivar, IR 64, under upland and irrigated lowland conditions in Japan. The number of panicles (as an indicator of tiller number) and number of spikelets per panicle of YTH34 were lower than those of IR 64 under irrigated lowland conditions, but both of those as well as culm length, panicle length, seed fertility, panicle weight, whole plant weight, and harvest index were dramatically reduced under upland conditions. And the low tiller of YTH34 was confirmed to start after the maximum tiller stage. In particular, the decrease of panicle number was remarkable in upland, so we tried to identify the chromosome location of the relevant gene. Through segregation and linkage analyses using F3 family lines derived from a cross between IR 64 and YTH34, and SSR markers, we found that low tiller number was controlled by a single recessive gene, ltn2, and mapped with the distance of 2.1 cM from SSR marker RM21950, in an introgressed segment on chromosome 7. YTH34 harboring ltn2 and the genetic information for DNA markers linked will be useful for genetic modification of plant architectures of Indica Group rice cultivar.