Although the Indian population is largely vegetarian, not much attention has been given to the cultivation of vegetables, as compared to other crops like cereals, pulses and oil seeds. Therefore, the present study was conducted on two leafy vegetables, spinach (Spanacia oleracea L.) and methi (Trigonella foenum graecum L.) commonly grown in Aligarh, as the two popular vegetables of Indian diet. The study was conducted for two successive years and during the first year, phosphorus and fly ash interactions with a uniform dose of nitrogen and potassium on both vegetables was observed. During the second year, while keeping nitrogen and phosphorus uniform, potassium and fly ash combinations were studied again with both vegetables, to determine the optimum dose of inorganic fertilizers and fly ash combination. It was observed that fly ash applied at the rate of 15 t ha-1 along with N40P15K20, proved optimum for spinach while in the case of methi, N20P30K40 + FA10 was sufficient. Therefore, both vegetables can safely be grown with 10 to 15 t ha-1 of fly ash and a comparatively lower quantity of NPK.

Arsenic (As) contamination and bioaccumulation are a serious threat to agricultural plants. To address this issue, we checked the efficacy of As tolerant plant growth promoting bacteria (PGPB), zinc oxide nanoparticles (ZnO NPs) and oxalic acid (OA) in Luffa acutangula grown on As rich soil. The selected most As tolerant PGPB i.e Providencia vermicola exhibited plant growth promoting features i.e solubilzation of phosphate, potassium and siderophores production. Innovatively, we observed the synergistic effects of P. vermicola, ZnO NPs (10 ppm) and OA (100 ppm) in L. acutangula grown on As enriched soil (150 ppm). Our treatments both as alone and in combination alleviated As toxicity exhibited by better plant growth and metabolism. Results revealed significantly enhanced photosynthetic pigments, proline, relative water content, total sugars, proteins and indole acetic acid along with As amelioration in L. acutangula. Furthermore, upregulated plant resistance was manifested with marked reduction in the lipid peroxidation and electrolyte leakage and pronounced antagonism of As and zinc content in leaves under toxic conditions. These treatments also improved level of nutrients, abscisic acid and antioxidants to mitigate As toxicity. This marked improvement in plants’ defense mechanism of treated plants under As stress is confirmed by less damaged leaves cell structures observed through the scanning electron micrographs. We also found substantial decrease in the As bioaccumulation in the L. acutangula shoots and roots by 40 and 58% respectively under the co-application of P. vermicola, ZnO NPs and OA in comparison with control. Moreover, the better activity of soil phosphatase and invertase was assessed under the effect of our application. These results cast a new light on the application of P. vermicola, ZnO NPs and OA in both separate and combined form as a feasible and ecofriendly tool to alleviate As stress in L. acutangula.

Private wells in Ireland and elsewhere have been shown to be prone to microbial contamination with the main suspected sources being practices associated with agriculture and domestic wastewater treatment systems (DWWTS). While the microbial quality of private well water is commonly assessed using faecal indicator bacteria, such as Escherichia coli, such organisms are not usually source-specific, and hence cannot definitively conclude the exact origin of the contamination. This research assessed a range of different chemical contamination fingerprinting techniques (ionic ratios, artificial sweeteners, caffeine, fluorescent whitening compounds, faecal sterol profiles and pharmaceuticals) as to their use to apportion contamination of private wells between human wastewater and animal husbandry wastes in rural areas of Ireland. A one-off sampling and analysis campaign of 212 private wells found that 15% were contaminated with E. coli. More extensive monitoring of 24 selected wells found 58% to be contaminated with E. coli on at least one occasion over a 14-month period. The application of fingerprinting techniques to these monitored wells found that the use of chloride/bromide and potassium/sodium ratios is a useful low-cost fingerprinting technique capable of identifying impacts from human wastewater and organic agricultural contamination, respectively. The artificial sweetener acesulfame was detected on several occasions in a number of monitored wells, indicating its conservative nature and potential use as a fingerprinting technique for human wastewater. However, neither fluorescent whitening compounds nor caffeine were detected in any wells, and faecal sterol profiles proved inconclusive, suggesting limited suitability for the conditions investigated.

One of the strategies to realize a nitrogen cycle society, we attempted to recover ammonium ions from industrial wastewater, especially sewage water with adsorbent materials. We have developed an adsorbent with high ammonium selectivity based on copper hexacyanoferrate and granulated it as pellets. Using a compact column system filled with this granule adsorbent, ammonium ions were recovered from sewage containing 1000–1500 mg-NH₄⁺/L ammonium ions. Despite the coexistence of many metal ions, the adsorbent selectively and stably adsorbed ammonium ions. Furthermore, it was shown that the saturated adsorbent can be regenerated by flowing a potassium ion solution through a column adsorbent to desorb ammonium ions. In other words, the column can be used repeatedly, and there was almost little deterioration in adsorption even after 250 cycles. In addition, it was shown that by increasing the number of stages of this column, it is possible to sufficiently reduce the ammonium in the adsorbent solution and recover the concentrated ammonium solution.

There is limited information regarding the toxicity of the trace element thallium (Tl) to aquatic biota, most of which assesses acute toxicity and bioaccumulation. The relative lack of chronic Tl toxicity data compromises the establishment of water quality criteria for this trace metal. In the presented work, chronic toxicity endpoints (final body weight (a proxy measure of growth), survival, and reproduction) and Tl body burden were measured in the freshwater crustacean Daphnia magna during a 21-day exposure to dissolved Tl. Thallium caused complete mortality in daphnids between exposure concentrations of 424 and 702 μg L⁻¹. In contrast with previously published work examining acute Tl toxicity, exposure to Tl for 21 days was not associated with changes in whole-body potassium concentration. This was despite a 710-fold increase in Tl body burden in animals exposed to 424 μg L⁻¹ relative to the control. Median effect concentrations (EC₅₀’s) for growth and reproduction (total neonates produced), were 1.6 (95% confidence interval: 1.0–3.1) and 11.1 (95% confidence interval: 5.5–21.8) μg Tl L⁻¹, respectively. A no observable effect concentration (NOEC) of 0.9 μg Tl L⁻¹ for growth, and a NOEC range of 0.9–83 μg Tl L⁻¹ for a variety of reproductive metrics, was measured. A lowest observable effect concentration (LOEC) of 8.8 μg Tl L⁻¹ was determined for the effects of Tl on growth and most of the reproductive endpoints examined. These data indicate that under controlled laboratory conditions D. magna is significantly less sensitive to Tl than the species on which the current Canadian Council of Ministers of the Environment regulatory guideline value of 0.8 μg L⁻¹ is based.

We investigated the in vitro effects of pyriproxyfen on ionic balance in the testis of the zebrafish by measuring ⁴⁵Ca²⁺ influx. In vivo pyriproxyfen treatment was carried out to study oxidative stress, and conduct morphological analysis of the testis and liver. Whole testes were incubated in vitro with/without pyriproxyfen (10⁻¹², 10⁻⁹ or 10⁻⁶ M; 30 min) and ⁴⁵Ca²⁺ influx determined. To study pyriproxyfen’s mechanism of action, inhibitors/activators of ionic channels or pumps/exchangers, protein kinase inhibitors or a calcium chelator were added 15 min before the addition of ⁴⁵Ca²⁺ and pyriproxyfen. We evaluated the in vivo effects of 7 day exposure to waterborne pyriproxyfen (10⁻⁹ M) on reactive oxygen species (ROS) formation, lipid peroxidation, and reduced glutathione content (GSH), glutathione S-transferase (GST), superoxide dismutase (SOD), catalase (CAT) and γ-glutamyltransferase (GGT) activity. Morphological analyses of the testis and liver were carried out after in vivo exposure of D. rerio to pyriproxyfen. Pyriproxyfen increased ⁴⁵Ca²⁺ influx by opening the voltage-dependent T-type channels (T-type VDCC), inhibiting sarco/endoplasmic reticulum ⁴⁵Ca²⁺-ATPase (SERCA) and the NCX exchanger (forward mode) and by mobilizing calcium from stores. The involvement of potassium channels and protein kinase C (PKC) was also demonstrated in pyriproxyfen-induced intracellular calcium elevation. In vivo pyriproxyfen treatment of D. rerio increased lipid peroxidation, decreased GSH content and increased GST activity in testes, in addition to increasing the number and size of spermatogonia cysts and inducing hepatocyte basophilia and dilation of blood vessels in the liver. The toxicity of pyriproxyfen is mediated by calcium overload, increased lipid peroxidation, and a diminished antioxidant capacity in the testis, due to GSH depletion, and altered spermatogenesis. The development of high basophilia in the liver suggests that pyriproxyfen may have estrogenic activity, possibly acting as an endocrine-disruptor. These findings indicate that these alterations may contribute to pyriproxyfen toxicity and spermatogenesis disruption.

Potassium (K⁺) is the most abundant cation in phytoplankton cells, but its impact on Microcystis aeruginosa (M. aeruginosa) has not been fully documented. This study presents evidence of how K⁺ availability affects the growth, oxidative stress and microcystin (MC) production of M. aeruginosa. The iTRAQ-based proteomic analysis revealed that during K⁺ deficiency, serious oxidative damage occurred and the photosynthesis-associated and ABC transporter-related proteins in M. aeruginosa were substantially downregulated. In the absence of K⁺, a 69.26% reduction in cell density was shown, and both the photosynthesis and iron uptake were depressed, which triggered a declined production of ATP and expression of MC synthetases genes (mcyA, B and D), and MC exporters (mcyH). Through the impairment of both the MC biosynthesis and MC transportation out of cells, K⁺ depletion caused an 85.89% reduction of extracellular MC content at the end of the study. However, with increasing in the available K⁺ concentrations, photosynthesis efficiency, the expression of ABC-transporter proteins, and the transcription of mcy genes displayed slight differences compared with those in the control group. This work represents evidence that K⁺ availability can regulate the physiological metabolic activity of M. aeruginosa and K⁺ deficiency leads to depressed growth and MC production in M. aeruginosa.

Porous carbon, which can be functionalized, is considered as a potential carbon material. Herein, two-dimensional (2D) nitrogen-doped magnetic Fe₃C/C (NMC) was prepared by a simple carbonization method using potassium humate (HA-K) as raw material. Remarkably, two templates, g-C₃N₄ and KCl, were formed in situ during the carbonization process, which provide the necessary conditions for the formation of 2D NMC. The NMC was comprehensively studied by different characterization methods. The results show that NMC has a large surface area and mesoporous structure. The prepared NMC-0.50 was used to test the removal performance of Cr(VI). The effects of pH value, coexisting ions and time on Cr(VI) removal performance were investigated, and the adsorption kinetics, isotherm and thermodynamics were studied. The results showed that the adsorption isotherm model of NMC-50 accorded with the Langmuir model, and the maximum adsorption capacity was 423.73 mg g⁻¹. The reaction mechanism of Cr(VI) is adsorption and redox reaction. In addition, NMC-0.50 exhibit high selectivity, separability and regeneration performance. A convenient means for the synthesis of NMC was designed in this work, and demonstrate that NMC has practical value as an adsorbent.