Nitrate distribution and dynamics as indicators to characterize karst groundwater flow in a mined mineral deposit in southwestern China

Groundwater recharge source and flowpaths, along with aquifer medium characteristics, are identified based on nitrate distribution and dynamics. These are significant factors in long-term water-resources management of the Sichuan-Yunnan-Guizhou lead-zinc mining deposits, southwestern China. The results show that high nitrate concentration correlates with lower temperature and heavy isotope enrichment, indicating groundwater recharge from the eastern karst depression area (situated at higher elevation), which has intensive agriculture. Higher NO3- concentration corresponds to higher Ca/Mg ratio in the Carboniferous karst aquifer, both indicating the preferential groundwater flowpath, while the lateral nitrate distribution signifies hydraulic connection with the northern Devonian aquifer passing through the aquitard via NE–SW and N–S trending faults. Nitrate pollution has reached deep sections of the karst aquifers and generated a wide vertical distribution, with the lowest elevation of significant nitrate concentration at –28 m relative to sea level, far lower than the recharge area by over 1,500 m. The variations in groundwater temperature, electrical conductivity and partial pressure of CO2 in the early rainy season are associated with enhanced dissolution capacity of the carbonate minerals, controlled by the soil CO2 effect, hence characterizing the mining area as a fissure-dominant karst groundwater system. Under such conditions, nitrate concentration rises and recedes subsequent to recharge events, and these processes characterize nitrate leaching. Overall, the current nitrate distribution is the result of increased agricultural productivity, intensive mine dewatering works and intrinsic media heterogeneity. Nitrate functions as an artificial, stable and cost-effective tracer for groundwater-system characterization in this mining area

Control of Contaminant Transport Caused by Open-Air Heavy Metal Slag in Zhehai, Southwest China

Slag heaps are formed by mining waste materials, and the improper treatment of leachate from such heaps can threaten nearby aquifers. The Zhehai slag heap in Yunnan Province, China, contains 2.7 million tons of zinc and cadmium slag, and is considered a heavy metal source threatening the local groundwater safety, however, the severity of contamination remains unknown. In this study, numerical modeling was used to predict the groundwater flow and contaminant transport in this area based on field data. The results show that the atmospheric precipitation infiltration recharge at the top of the heap is 81.8 m3/d, accounting for 93.76% of total infiltration. The south and east sides of the area are the main outflow channels for contaminants, accounting for 93.25% of the total discharge around the heap. To reduce aquifer contamination, an in situ system involving a “controlling the source, ‘breaking’ the path, and intercepting the flow„ (CSBPIF) strategy is established. The results indicate that the system performs well because it not only decreases the flow velocity but also reduces the concentrations of contaminants adsorbed by clay media. Moreover, the equivalent bottom liner thicknesses of the clay layers were calculated to improve the applicability of the CSBPIF system. Compared with ex situ disposal, this scheme provides an economic and effective solution and can be used to prevent and control groundwater pollution in China

Correction: Wu et al. Homologous Drought-Induced 19 Proteins, PtDi19-2 and PtDi19-7, Enhance Drought Tolerance in Transgenic Plants. Int. J. Mol. Sci. 2022, 23, 3371

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The poplar <i>VQ1</i> gene confers salt tolerance and pathogen resistance in transgenic <i>Arabidopsis</i> plants via changes in hormonal signaling

AbstractThe VQ protein family is plant-specific, and is involved in growth, development, and biotic and abiotic stress responses. In this study, we found that the gene expression of poplar VQ1Populus trichocarpaVQ1Arabidopsis thalianaArabidopsisMPK6NPR1PDF1.2WRKY70ABI1KUP6NCED2Pseudomonas syringaeVQ1Arabidopsi

Homologous Drought-Induced 19 Proteins, PtDi19-2 and PtDi19-7, Enhance Drought Tolerance in Transgenic Plants

Drought-induced 19 (Di19) proteins play important roles in abiotic stress responses. Thus far, there are no reports about Di19 family in woody plants. Here, eight Di19 genes were identified in poplar. We analyzed phylogenetic tree, conserved protein domain, and gene structure of Di19 gene members in seven species. The results showed the Di19 gene family was very conservative in both dicotyledonous and monocotyledonous forms. On the basis of transcriptome data, the expression patterns of Di19s in poplar under abiotic stress and ABA treatment were further studied. Subsequently, homologous genes PtDi19-2 and PtDi19-7 with strong response to drought stress were identified. PtDi19-2 functions as a nuclear transcriptional activator with a transactivation domain at the C-terminus. PtDi19-7 is a nuclear and membrane localization protein. Additionally, PtDi19-2 and PtDi19-7 were able to interact with each other in yeast two-hybrid system. Overexpression of PtDi19-2 and PtDi19-7 in Arabidopsis was found. Phenotype identification and physiological parameter analysis showed that transgenic Arabidopsis increased ABA sensitivity and drought tolerance. PtDi19-7 was overexpressed in hybrid poplar 84K (Populus alba &times; Populus glandulosa). Under drought treatment, the phenotype and physiological parameters of transgenic poplar were consistent with those of transgenic Arabidopsis. In addition, exogenous ABA treatment induced lateral bud dormancy of transgenic poplar and stomatal closure of transgenic Arabidopsis. The expression of ABA/drought-related marker genes was upregulated under drought treatment. These results indicated that PtDi19-2 and PtDi19-7 might play a similar role in improving the drought tolerance of transgenic plants through ABA-dependent signaling pathways