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Gum rejuvination: can it be even now a goal inside specialized medical periodontology?
that biochar can improve the physical and chemical properties of soil, increase soil fertility, and enhance the soil's ability to retain water and fertilizer after twelve months. The findings of this study can be used as a reference in practical applications for soil improvement and sustainable management of Eucalyptus plantations.A field experiment with an orthogonally designed experiment L9(34) was designed to investigate the effect of different N, P, and K levels on plant growth and Cd uptake by Hylotelephium spectabile. The results showed that the biomass of H. spectabile significantly increased with the N application rate. The highest dry weight in the shoot occurred in the treatments with a high level of N (337.5 kg ·hm-2), which was 0.86-2.00 times higher than the value with no fertilizer treatment. The addition of K contributed to promoting the Cd absorption of H. spectabile, while no effect was observed when N and P were added. Consequently, NPK fertilizers contribute to increasing the Cd uptake of H. spectabile, and the N and K fertilizer play important role in plant growth and Cd absorption respectively. Moreover, the effect of fertilizers on Cd uptake of H. spectabile was in the order of N > K > P, which indicated that N fertilizer was the main factor for promoting the Cd phytoextraction efficiency of H. spectabile by increasing the biomass. Therefore, the application of high levels of N combined with moderate levels of P and K will be an effective approach to improve the Cd phytoremediation efficiency of H. spectabile by promoting its growth, and the Cd uptake can be increased by a factor of 0.9-2.2 compared to no fertilizer treatment condition.Pb accumulation in rice varies significantly at different growth stages. In this study, a hydroponic experiment was conducted to study the effects of exogenous Pb stress on Pb accumulation and transportation in rice plants and determine the key rice growth stages of Pb accumulation and their contribution to the Pb content in brown rice. For the hydroponic experiment, 0.5 mg ·L-1 of exogenous Pb was added to rice at different growth stages, including the tillering stage, jointing stage, booting stage, filling stage, dough stage, maturing stage, and whole growth stage (103 d) of the rice plant. Another treatment of the whole growth stage without Pb stress was established as the control. The results showed that ① There were no significant effects of Pb stress in any single stage on the plant height, tiller number, and biomass, but the rice plant height and biomass significantly decreased under the Pb stress for the whole growth period. ② Pb contents in different tissues at the maturing stage of the rice plant weaf resistance control techniques should be applied appropriately at the booting stage of the rice plants to reduce Pb accumulation in brown rice and to realize the safe use of rice paddies polluted with Pb.A field investigation in the abandoned lead-zinc mines in Yunan Province was conducted to assess the accumulation potential of dominant plant species and six heavy metals in mine soils. Eighteen types of plants were selected for the analysis. Local plants and soil were sampled and analyzed for cadmium (Cd), chromium (Cr), copper (Cu), nickel (Ni), lead (Pb), and Zn (zinc) concentrations. Bioconcentration and translocation factors were calculated. Cluster analysis was performed to calculate the accumulation potential. The results showed that all dominant plants (18 species and 13 families) were herbaceous plants. The content of heavy metals in these plants was higher than their normal content in plants. The above-ground Cd content of Corydalis yanhusuo, Carum bretschneideri, and Picris hieracioides reached 62.29, 76.49, and 85.09 mg ·kg-1. The bioconcentration factors of Cd in these three plants were 0.57, 0.58, and 0.66, and the translocation factors were 0.89, 0.45, and 1.48, respectively. These plants have a strong ability to absorb and transfer Cd in soil; hence, they have the potential to remediate the Cd-contaminated soil. The above-ground Cd content of Euphorbia fischeriana and Cynoglossum amabile were 0.46 mg ·kg-1and 0.23 mg ·kg-1, respectively, and the bioconcentration factors were less than 0.01. These two plants accumulate low levels of heavy metals and thus, are suitable for growth in high altitude areas of Southwest China. They are considered economic plants for safe use in Cd-contaminated farmlands and have high application value. To protect the ecological environment of the mining areas, the other 13 plants having good tolerance to heavy metal pollution can be used as vegetation restoration plants in mining areas.Heavy metals (HMs) are naturally occurring elements that have high natural background levels in the environment. Therefore, it is important to conduct ecological risk assessment and identify potential sources of HMs. In the past, studies were conducted at the regional scale. The accuracy of those studies could not meet the needs of spatial planning and natural resource management. Therefore, it is necessary to conduct ecological risk assessment at the township scale. In this study, 1092 soil samples (from 0-20 cm depth) were collected in the town of Reshui, an area with high background levels of soil HMs with the parent material of carbonatite, which is commonly found in Southwest China. The town of Reshui is a multi-ecological risk superimposed area where the ecological risk is high. ML351 In this study, concentrations of HMs (Cd, Cr, As, Hg, Pb, Cu, Zn, and Ni) in the topsoil were analyzed, and statistical analysis (SA), geographic information system (GIS) modeling, and positive matrix factorization (PMF) analysi have higher levels, but the total amount of Hg and its pollution risk are lower. Cd has a high bioavailability ratio, is easy to enter the soil solution and be absorbed by crops, and is the HM with the highest pollution risk in the study area. The PERI shows that the proportions of low ecological risk, moderate risk, and high risk soil samples are 44.23%, 54.40%, and 1.37% of the total number of samples, respectively. Hg and Cd were the major sources of risk because of their high toxicity coefficient. The PMF analysis indicates that there are four major sources of HMs in the study area human activity, natural sources, coal mining and traffic emissions, and agricultural sources with the risk contribution ratios of 9.29%, 53.67%, 11.23%, and 25.81%, respectively. The PMF analysis effectively quantified the ecological risk from these sources, providing a reference for further pollution control and prevention measures.
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