Ecological Remediation Research Articles

Impact of Paenarthrobacter ureafaciens ZF1 on the soil enzyme activity and microbial community during the bioremediation of atrazine-contaminated soils

Bioremediation of atrazine-contaminated soil is considered a safe and effective approach in removing contaminates from the soil. However, the effects of adding foreign organisms to assist bioremediation on soil environmental quality and ecosystem are unclear. Here, the ecological remediation potential of strain Paenarthrobacter ureafaciens ZF1 on atrazine-contaminated soil was investigated through miniature experiments using variations in soil enzymes and bacterial communities as indicators. The results showed that strain ZF1 accelerated atrazine degradation, which could completely degrade atrazine at concentrations of 100 mg·L− 1 atrazine within 2 h in liquid medium and could remove up to 99.3% of atrazine (100 mg·kg− 1 in soil) within 6 days. During soil bioremediation, atrazine promoted the activities of urease and cellulase, and inhibited the activities of sucrase and catalase, while the strain ZF1 significantly promoted the activities of these four enzymes. High-throughput sequencing of 16S rRNA genes showed that ZF1 affected the relative abundance and bacterial community structure, and promoted bacterial diversity and evenness. Furthermore, redundancy analysis revealed a certain correlation among the strain ZF1, atrazine residue, soil enzyme activity, and soil bacterial community. The strain ZF1 in this work demonstrated remarkable potential for ecological restoration, and can be an effective and environmentally friendly alternative in remediating atrazine-contaminated soil.

Suspension Flame Spray Construction of Porous Polycaprolactone/Hydroxyapatite Coatings for Marine Ecological Remediation

Suspension Flame Spray Construction of Porous Polycaprolactone/Hydroxyapatite Coatings for Marine Ecological Remediation

Spatial accessibility between commercial and ecological spaces: A case study in Beijing, China

Abstract The accessibility evaluation between ecological and commercial spaces is important for “production-living-ecological” coordination. This article selects Tongzhou of Beijing as an example. Significance tests showed the commercial facilities in Tongzhou district followed an agglomerated distribution. Further exploration of the relationship between concentrated commercial and ecological spaces show the distribution of ecological space in Tongzhou district is unbalanced, which shows that the northern, western, and central regions of Tongzhou district cover a wide area, whereas the southeast region has a low level of accessibility. The coverage rate of ecological space of each street with 10 min walking is lower than 50% on average. The coverage rate of walking for 20 min varies greatly, and the sub-districts with high coverage rate are basically distributed along the north–south central axis and east–west central axis. Emerging commercial spaces have poor accessibility towards ecological space, which indicates that in the new commercial space, ecological space has not been considered in the planning. It also reflects that in the existing daily ecological management, managers tend to focus on the ecological remediation of the built area and ignore the ecological planning in the community construction stage of commercial space.

Dynamic Variations of Soil-Formation Indicators in Bauxite Residue Driven by the Integration of Waste Solids and Microorganisms.

Soil-formation process is critical to ecological rehabilitation on bauxite residue disposal areas. In this study, a soil column experiment was taken to assess the dynamic variations of soil-formation indicators in bauxite residue driven by the integration of waste solids and microorganisms. Results showed that the combination of waste solids and microorganisms significantly decreased the alkalinity, accumulated organic carbon content, and improved aggregate stability of bauxite residue. Compared with waste solids treatments, the addition of acid-producing microorganisms enhanced the changes of soil-formation indicators. The integration of waste solids and microorganisms increased the content of aliphatic carbon, presenting low thermal stability in the residues. The integration of waste solids and microorganisms provides a potentially effective method for soil formation and ecological remediation on bauxite residue disposal areas.

Ecological remediation strategy for urban brownfield renewal in Sichuan Province, China: a health risk evaluation perspective

Urban brownfield sites are abandoned industrial land and their redevelopment may be affected by environmental pollution, as the latter may pose health risks for residents. In this study, six heavy metals (Pb, As, Cr, Zn, Ni, and Cu) were examined from 87 soil samples extracted from four land use types (industrial area, residential/commercial area, traffic area, and agricultural area) in the Mianyang thermal power plant area, Sichuan Province, China. The soil contamination and environmental risk were evaluated using the single factor index, geo-accumulation index and Human Health Risk Evaluation. ArcGIS was used to map out the spatial distribution of heavy metal concentrations and environmental risk. The results of these analyses have indicated that different land use types have significant effects on the heavy metal contamination of soil. There are 10 non-carcinogenic risk areas of heavy metals in industrial land, while in the other three types there are 9 non-carcinogenic risk areas of heavy metals. Under the brownfield renewal planning, the present study scheme provides an effective method of discernment for ecological remediation of soil heavy metals. In addition, it can aid brownfield in finding different remediation strategies with economic benefits for different risk levels of human health.

Evaluating the remediation potential of MgFe2O4-montmorillonite and its co-application with biochar on heavy metal-contaminated soils

In this work, a novel and efficient magnesium ferrite-modified montmorillonite (MgFe2O4-MMT) compound was prepared. MgFe2O4-MMT and biochar were mixed at 0:10, 1:9, 3:7, 4:6, and 10:0 w/w combinations and were used for heavy metal immobilization in soil polluted with multiple heavy metals. MgFe2O4-MMT can significantly increase soil alkalinity, and it exhibited the most optimal effect in immobilization of heavy metals in soil. The amounts of Cd, Pb, Cu, and Zn that were extracted by the toxicity characteristic leaching procedure (TCLP) decreased by 58.4%, 50.3%, 42.9%, and 24.7%, respectively. MgFe2O4-MMT can immobilize heavy metals through electrostatic interactions and cation exchange processes. Although, the immobilization of potentially toxic elements by MgFe2O4-MMT and biochar was inferior to that by MgFe2O4-MMT. The combined application of MgFe2O4-MMT and biochar dramatically increased the diversity and richness of the soil bacterial community. The Chao1 index for M3B7 treatment group was 1.7 and 1.2 times higher than that for the control and MgFe2O4-MMT treatment groups, respectively. The combination of biochar and MgFe2O4-MMT might be a cost-effective and ecological remediation approach for mild Pb and Cd contamination.

Leveraging doping and defect engineering to modulate exciton dissociation in graphitic carbon nitride for photocatalytic elimination of marine oil spill

Limited light absorption ability and rapid photogenerated electron-hole recombination severely impedes applications of g-C3N4. Herein, highly efficient point-defect engineering including dual dopants as well as vacancy was adopted to modulate the photo-induced exciton dissociation kinetics. Specifically, P, O dopants and carbon vacancy modified 3D honeycomb-like POCVN was fabricated through facile one-pot polymerization with (NH4)3PO4 as P, O precursors. The obtained POCVN catalyst exhibited superior photocatalytic degradation performance for n-tetradecane under visible light illumination (38.1 %), which was 4.6 and 1.8 times higher than that of bulk g-C3N4 (8.2 %) and tubular g-C3N4 (21.1 %), respectively. The suppressed recombination of electrons and holes contributed to the superior catalytic performance compared to pristine g-C3N4, single P and single O doping g-C3N4. Structural analysis demonstrated P atoms may replace C atoms of N-C = N, O atom located at P-O-C and carbon vacancies located at N = C-N2 position at heptazine framework. Based on experimental and theoretical analysis, it was found P, O and Cv defects prefer to accumulate together in 3-trizine ring, which is conductive to the formation of localized defect state in the band gap region. It resulted in high exciton dissociation efficiency, thus, more reactive radicals were generated. Based on this, degradation path, interference parameter, reactive radicals and toxicity evaluation were investigated deeply and systematically. This work shed light on non-metal green ecological remediation material for marine oil spill.

Adaptive Responses of Common and Hybrid Bermudagrasses to Shade Stress Associated With Changes in Morphology, Photosynthesis, and Secondary Metabolites.

Alteration of ploidy in one particular plant species often influences their environmental adaptation. Warm-season bermudagrass is widely used as forage, turfgrass, and ground-cover plant for ecological remediation, but exhibits low shade tolerance. Adaptive responses to shade stress between triploid hybrid bermudagrass cultivars [“Tifdwarf” (TD), “Tifsport” (TS), and “Tifway” (TW)] and tetraploid common bermudagrass cultivar “Chuanxi” (CX) were studied based on changes in phenotype, photosynthesis, and secondary metabolites in leaves and stems. Shade stress (250 luminance, 30 days) significantly decreased stem diameter and stem internode length, but did not affect the leaf width of four cultivars. Leaf length of CX, TD, or TW showed no change in response to shade stress, whereas shade stress significantly elongated the leaf length of TS. The CX and the TS exhibited significantly higher total chlorophyll (Chl), Chl a, carotenoid contents, photosynthetic parameters [PSII photochemical efficiency (Fv/Fm), transpiration rate, and stomatal conductance] in leaves than the TW and the TD under shade stress. The CX also showed a significantly higher performance index on absorption basis (PIABS) in leaf and net photosynthetic rate (Pn) in leaf and stem than the other three cultivars under shade stress. In addition, the TS maintained higher proantho cyanidims content than the TW and the TD after 30 days of shade stress. Current results showed that tetraploid CX exhibited significantly higher shade tolerance than triploid TD, TS, and TW mainly by maintaining higher effective photosynthetic leaf area, photosynthetic performance of PSI and PSII (Pn and Fv/Fm), and photosynthetic pigments as well as lower Chl a/b ratio for absorption, transformation, and efficient use of light energy under shade stress. For differential responses to shade stress among three triploid cultivars, an increase in leaf length and maintenance of higher Fv/Fm, gas exchange, water use efficiency, carotenoid, and proanthocyanidin contents in leaves could be better morphological and physiological adaptations of TS to shade than other hybrid cultivars (TD and TW).

An eco‐evolutionary perspective on the humpty‐dumpty effect and community restoration

In recent decades, anthropogenic and natural disturbances have increased in rate and intensity around the world, leaving few ecosystems unaffected. As a result of the interactions among these multiple disturbances, many biological communities now occur in a degraded state as collections of fragmented ecological pieces. Restoration strategies are traditionally driven by assumptions that a community or ecosystem can be restored back to a pre‐disturbance state through ecological remediation. Yet despite our best efforts, attempts to restore fragmented communities are often unsuccessful. One explanation, the humpty‐dumpty effect, suggests that once a community is disassembled, it is difficult to reassemble it even in the presence of all the original pieces. This hypothesis, while potentially useful, often fails to incorporate the multitude of other critical mechanisms that affect our abilities to put fragmented communities back together. Here, we extend the original humpty‐dumpty analogy to incorporate eco‐evolutionary changes that can hinder successful restoration. A systematic literature review uncovered few studies that have explicitly considered how the original humpty‐dumpty effect has affected restoration success in the 30 years since its inception. Using case studies, we demonstrate how the application of our extended eco‐evolutionary humpty‐dumpty framework may determine the success of restoration actions via ecological and evolutionary changes in fragments of communities. Lastly, given continued anthropogenic disturbances and projected climatic changes, we make five recommendations to facilitate more successful restoration efforts given our revised eco‐evolutionary humpty‐dumpty effects framework. These guidelines, combined with clearly defined management goals are aimed at both keeping ecological communities as intact as possible while ensuring that future ecosystem restorations might more successfully put the ecological community pieces back together.

Seed mass, dormancy and germinability variation among maternal plants of four Arabian halophytes

AbstractCoastal desert vegetation of the Arabian Peninsula is almost entirely dominated by halophytes. Natural populations provide a genetic resource for ecological remediation and may also have direct economic value. High intrapopulation variation of seed traits is presumed to increase population persistence in the unpredictable climatic conditions of this hyper-arid desert. We investigated whether intrapopulation variation of seed mass, dormancy and germinability of four species was attributable to maternal individuals. Arthrocnemum macrostachyum, Halothamnus iraquensis, Haloxylon salicornicum and Seidlitzia rosmarinus are commonly distributed Arabian halophytes with differing seed weight variation. All species exhibited a higher germination when exposed daily to 12 h light, compared to seeds in darkness. A higher germination was correlated with a shorter germination time. For H. iraquensis and S. rosmarinus, a shorter germination time was negatively correlated with germination synchrony. H. salicornicum showed the highest intrapopulation variation of seed traits, followed by A. macrostachyum, S. rosmarinus and H. iraqensis. We found that individuals within populations of all the studied species showed variability in germination but the extent of variation was species-specific. The variation in seed mass and germination among the individuals of the studied species may facilitate a temporal distribution of germination, which may reduce the risk of seed bank exhaustion. The results of this study could assist conservation and management by improving the efficiency of seed collection from wild populations of these species.

Green Conversion of Coal Fly Ash into Soil Conditioner: Technological Principle and Process Development

White mud is residue discharged during the acid method in the aluminum extraction process from coal fly ash, and this material is harmful to the environment. The implementation of an environmentally friendly and valuable way to use white mud is a key factor restricting the commercial application of the acid method in the fly ash alumina extraction technology. An analysis of white mud revealed the following: (1) it was highly enriched in SiO2 (70–80%) while concentrations of acid-soluble elements, such as Na, Al, and Fe, and some hazardous heavy metals, including Pb and Cr, were significantly lower than raw fly ash; (2) approximately 80% of SiO2 had relatively high reaction activity because of the foregoing Al-extraction treatment. Through an ingenious green chemical process, the complete conversion of white mud into silicon–calcium fertilizer (SCF) was achieved under very mild reaction conditions (approximately 100 °C and atmospheric pressure). Waste liquor was totally recycled, and no secondary solid waste was generated. The SCF had an available silicon content (ASC) of 35%, significantly higher than the commercial standard (20%). Converting them into soil conditioners or ecological remediation materials with the lowest possible energy consumption and secondary pollution may be the most promising approach for the future disposal of aluminosilicate industrial solid wastes.

Effects of heavy metals on bacterial community surrounding Bijiashan mining area located in northwest China.

Heavy metal (HM) pollution is a severe and common environmental problem in mining area soil. It is imperative to understand the micro ecological characteristics of mining area soil for HM contaminated soil remediation. This study described the effects of HM pollution level and soil physical and chemical parameters on microbial diversity. In this study, high-throughput sequencing technology was used to study the effects of HM pollution on the diversity and composition of the soil microbial community. The soil groups were barren, exhibiting alkaline pH, low total nitrogen (TN), and total potassium (TK) according to soil fertility standard. Compared with the control group, there was severe multiple HM pollution in the other five groups, including lead (Pb), cadmium (Cd), zinc (Zn), and copper (Cu). The dominant phyla accounting for more than 1% of the overall community in all soil groups were Proteobacteria (34.432 ± 7.478%), Actinobacteria (22.947 ± 4.297%), Acidobacteria (10.47 ± 2.439%), Chloroflexi (7.89 ± 2.980%), Planctomycetota (5.993 ± 1.558%), Bacteroidota (4.275 ± 1.980%), Cyanobacteria (3.478 ± 2.196%), Myxococcus (2.888 ± 0.822%), Gemmatimonadota (2.448 ± 0.447%), Firmicutes (1.193 ± 0.634%), Patescibacteria (0.435 ± 0.813%), and Nitrospirota (0.612 ± 0.468%). Proteobacteria and Actinobacteria were predominant at the phylum level, which showed a certain tolerance to HMs. In addition, redundancy analysis (RDA) results showed that Pb, Cu, Zn, and Cd were strongly correlated with each other (P < 0.01). Other nutrient elements (except for TK) were significantly positively correlated with each other. Cu and nutrient element TK had an important impact on bacterial community structure. Therefore, bacteria with the function of HM tolerance and bioremediation in extreme environments should be researched, which provides a foundation for future ecological remediation of contaminated soil by using microbial remediation technology.

Satellite Remote Sensing of Water Quality Variation in a Semi-Enclosed Bay (Yueqing Bay) under Strong Anthropogenic Impact

The semi-enclosed bays impacted by heavy anthropogenic activities have weak water exchange and purification capacities. Most of the sea bays have suffered severe eutrophication, water quality deterioration, ecosystem degradation and other problems. Although many countries and local governments have carried out corresponding environmental protection actions, the evaluation of their effectiveness still requires monitoring technology and data support for long-term water environment change. In this study, we take Yueqing Bay, the fourth largest bay in China, as a case to study the satellite-based water quality monitoring and variation analysis. We established a nutrient retrieval model for Yueqing Bay to produce a long-term series of nutrient concentration products in Yueqing Bay from 2013 to 2020, based on Landsat remote sensing images and long-term observation data, combined with support vector machine learning and water temperature and satellite spectra as input parameters, and then we analyzed its spatiotemporal variations and driving factors. In general, nutrient concentrations in the western part of the bay were higher than those in the eastern part. Levels of dissolved inorganic nitrogen (DIN) were lower in summer than in spring and winter, and reactive phosphate (PO4-P) levels were lower in summer and higher in autumn. In terms of natural factors, physical effects (e.g., seasonal variations in flow field) and biological effects (e.g., seasonal differences in the intensity of plankton photosynthesis) were the main causes of seasonal differences in nutrient concentration in Yueqing Bay. Nutrient concentration generally increased from 2013 to 2015 but decreased slightly after 2015. Over the past decade, the economy and industry of Yueqing Bay basin have developed rapidly. Wastewater resulting from anthropogenic production and consumption was transported via streams into Yueqing Bay, leading to the continuous increase in nutrient concentrations (the variation rates: aDIN&gt;0, aPO4−P&gt;0), which directly or indirectly caused high nutrient concentrations in some areas of the bay (e.g., Southwest Shoal at the mouth of Yueqing Bay). After 2015, the various ecological remediation policies adopted by cities around Yueqing Bay have mitigated, to some extent, the increasing nutrient concentration trends (the variation rates: aDIN&lt;0, aPO4−P&lt;0), but not significantly (P &gt; 0.1). The environmental restoration of Yueqing Bay also requires continuous and long-term ecological protection and restoration work to be effective. This research can provide a reference for ecological environment monitoring and remote sensing data application for similar semi-enclosed bays, and support the sustainable development of the bay.

Chromium Distribution, Leachability and Speciation in a Chrome Plating Site

Hexavalent chromium (Cr(VI)) waste produced by chrome plating activities pollutes the surrounding environment and harms human health. However, information about the chromium (Cr) pollution characteristics of actual electroplating sites is still lacking. In this study, the concentration, leachability and speciation of Cr in soils from a typical chrome plating site were analyzed. Our results showed that this site was severely contaminated by Cr (7.2 to 7735.2 mg/kg) and Cr(VI) reached the mean concentration of 138.7 mg/kg. The spatial distribution of Cr(VI) was related to the plating processes. Chrome plating and sewage treatment areas could be considered as the hot spots of contaminated sites. The vertical distribution of Cr(VI) was mainly affected by soil properties, where the loam layer retained and reduced a large amount of Cr(VI) due to its high content of iron minerals and finer particle fractions. Additionally, the chemical extraction results showed that Cr was mainly in non-residual fractions and the existence of Cr(VI) led to a high leaching toxicity based on the toxicity characteristic leaching procedure (TCLP) results. Moreover, X-ray photoelectron spectroscopy (XPS) results revealed the speciation of Cr in the long-term contaminated soils. A large amount of Cr(VI) was reduced into Cr(III) and mainly existed as Cr(OH)3 and Cr2O3. Furthermore, Cr(VI) tended to precipitate as CaCrO4 and persisted in soils. Therefore, it is necessary to find appropriate strategies to remediate these contaminated soils. Overall, these findings strengthen our understanding of Cr(VI) behaviors and lay a foundation for the future pollution investigation, ecological remediation and risk assessment of sites contaminated by electroplating.

Cladoceran community succession and identification of anthropogenic signals since 1950s in Lake Tianchi in Yunlong County, northwest Yunnan

从1950s开始, 云南地区部分湖泊受到了水文调控(如筑坝)和鱼类引入等流域开发活动的直接影响, 湖泊水环境与生态系统结构已出现明显改变. 开展浮游动物群落的长期生态响应评价有助于认识气候波动和人为胁迫的影响模式. 本文选取云龙天池进行了沉积物记录分析, 在重建过去100年环境变化历史的基础上开展了枝角类群落的多指标分析(物种组成、个体大小、生物量等), 进一步结合多变量分析识别了枝角类群落构建的关键驱动因子. 结果显示, 云龙天池在过去100年间经历了明显的水位波动, 约1962年以前水位较低, 1950s起的水文调控(筑坝)导致湖泊水位波动上升, 2006年以来略有下降. 枝角类群落随水位波动呈现由底栖种向浮游种占优转变的模式, 并在2006年以来底栖种略有增加. 总体上, 低水位时期底栖枝角类占优, 高水位时期浮游枝角类占优. 水体营养水平也对枝角类群落产生了较为显著的影响. 在沉积物总氮和有机质通量上升时, 长额象鼻溞(Bosmina longirostris)相对丰度和枝角类浓度都明显上升. 枝角类象鼻溞个体大小表明, 1969年鱼类引入后象鼻溞的壳长、壳刺长度、触角长度显著减小, 反映了鱼类捕食压力上升的影响. 本研究进一步揭示了水文调控和鱼类引入对湖泊环境和生物群落结构的驱动影响. 其中, 1960s以前云龙天池处于自然波动的状态, 湖泊环境和枝角类群落变化主要受气候(如降水、气温)的影响; 1960s以来人类活动的影响强度已经掩盖了气候变化的信号, 成为影响湖泊生态演化轨迹的主要因素. 为了开展有效的湖泊保护与生态治理, 有必要综合评估水文调控、鱼类引入等人类活动对湖泊生态健康的长期影响.;Since the 1950s, many lakes in Yunnan have been directly impacted by watershed development activities such as hydrological regulation (such as damming) and fish introduction, and thus lake environment and ecosystem structure have changed significantly. Investigation on the long-term response of zooplankton communities to limnological changes is vital for understanding the effects of climate change and anthropogenic stresses on lakes. In this study, Lake Tianchi from Yunlong County, northwest Yunnan, was selected for reconstructing environmental change history over the past 100 years, with a focus on the succession of the cladoceran community and the identification of its environmental drivers. The results showed that Lake Tianchi has experienced significant fluctuations in water level over the past 100 years, which was relatively low before about 1962, gradually rose during 1962-2006 due to hydrological regulation (damming), and slightly declined from about 2006 onward. The dominant taxa of cladoceran community shifted from littoral species to planktonic ones while benthic taxa slightly increased after 2006. In brief, benthic cladocerans were generally dominant during the low water-level period, while planktonic taxa predominated when water level rose. The percentage of Bosmina longirostris and the cladoceran concentration were both increased when the sedimentary TN and LOI₅₅₀ increased since the 1960s, suggesting that the influence of nutrients on the compositional change and production of cladocerans. After planktivorous fish was introduced in 1969, the carapace, carapace mucro and antennule lengths of Bosmina were all significantly decreased, suggesting the influence of increasing predation pressure by zooplanktivorous fish. This study highlights the long-term impacts of hydrological regulation and fish introduction on the lake environment and biological community structure. Before the 1960s, the lake was generally in natural conditions, lake environment and cladoceran communities were mainly affected by climate (precipitation, temperature), while, after the 1960s, the influence of human activities has overridden the role of climate change and become the main factor in affecting the ecological structure of Lake Tianchi. For lake protection and ecological remediation, it is necessary to comprehensively assess the impact of multiple human activities (i.e. hydrological regulation and fish introduction) on lake ecosystem health for generating appropriate restoration strategies.

Biodegradable polymers green synthesis of nanoparticle – An overview

Green nanotechnology disclosures can change over a wide scope of existing cycles and objects to work on ecological quality, work on the climate, and save the normal and non-renewable assets. Metal nanoparticles and nanocomposites are utilized in an assortment of synergist applications, hardware, science and clinical applications, material science, physical science, ecological remediation, and interdisciplinary fields, and their harmfulness is to a great extent dictated by underlying elements like size, shape, creation, and surface chemistry. Furthermore, it is basic to pick harmless to the ecosystem, nontoxic, and straightforward settling specialists and Functionalization pathways to expand the existence of metal nanoparticles and keep away from unfortunate impacts like accumulation in fluid arrangements and natural solvents, just as to stay away from ecological defilement and to reuse nanoparticles. Metal nanoparticles adjustment and surface Functionalization have become 'greener' lately, with biocompatible settling specialists, for instance, Biodegradable polymers and compounds, for instance, have been presented. These specialists had the option to make a wide scope of the especially stable circular, bar, and bloom molded metal nanoparticles, opening up additional opportunities for their application and large-scale manufacturing. The present status of the workmanship in the usage of biocompatible and biodegradable homo-and copolymers, just as compounds, to deliver stable, biologically harmless, particular, and dynamic metal nanoparticles for wanted applications is summed up in this review paper.

Interactions among Rhizosphere Microorganisms, Mechanisms and Potential Application in Phytoremediation

Numerous bacteria, archaea, algae and fungi, accumulated in the root systems of plants, constitute complex plant rhizosphere microbial communities. They have been proved to emerge striking importance in the communication between plant and environment, and shows promising in environmental governance. In this background, this paper briefly introduces the basic interaction mechanisms of rhizosphere microbial community, and further discusses the applications and prospects of this kind of community interaction in environmental bioremediation. On this basis, an idea of constructing a microbe-loading platform based on synthetic biology and its applications in comprehensive ecological remediation is advanced.

Facilitation of Morus alba L. intercropped with Sedum alfredii H. and Arundo donax L. on soil contaminated with potentially toxic metals

Tree-herb intercropping is a prospective approach for the ecological remediation of soil contaminated with potentially toxic metals (PTMs). In this study, the facilitation and microbial community response of woody plant Morus alba L. intercropped with Cd/Zn hyperaccumulator Sedum alfredii H. and pioneer plant Arundo donax L. were carried out in the PTM-contaminated soil. The results indicated that the intercropping system can improve M. alba L. growth, as well as increase its PTMs uptake. The dried biomass of M. alba L. in the intercropping system was increased observably (p < 0.05) by 55.1%. Meanwhile, the contents of chlorophyll in M. alba L. leaves, PTMs contents in M. alba L. roots, and the relative abundance of Rhizobiaceae, Singulisphaera, Isosphaeraceae, and Arthrobacter in the M. alba L. rhizosphere were also notably (p < 0.05) enhanced. Meanwhile, the interactions of microorganisms in the intercropped plants rhizosphere might contribute to improving the biological quality of the contaminated soil. Soil sucrase and acid phosphatase activities in the intercropping system were significantly (p < 0.05) increased by 97.03% and 34.91% relative to the control. Furthermore, in the intercropping system, 93.61%, 61.30%, and 79.18% of Cd, Pb, and Zn were extracted by S. alfredii H., 72.16% of Cu was extracted by A. donax L., and 46.38% of Mn was extracted by M. alba L., which indicated that the extraction amounts of PTMs among the intercropped plants were relatively compensated. The results suggested that the tree-herb intercropping might increase the coexistence of plants and facilitate the adaptability for ecological remediation of PTM-contaminated soils.

Long-term and high-bioavailable potentially toxic elements (PTEs) strongly influence the microbiota in electroplating sites

Multiple potentially toxic elements (PTEs) wastes are produced in the process of electroplating, which pollute the surrounding soils. However, the priority pollutants and critical risk factors in electroplating sites are still unclear. Hence, a typical demolished electroplating site (operation for 31 years) in the Yangtze River Delta was investigated. Results showed that the soil was severely polluted by Cr(VI) (1711.3 mg kg−1), Ni (6754.0 mg kg−1) and Pb (2784.4 mg kg−1). The spatial distribution of soil PTEs performed by ArcGIS illustrated that the soil pollution varied with plating workshops. Hard Cr electroplating workshops (HCE), decorative Cr electroplating workshops (DCE) and sludge storage station (SS) were the hot spots in the site. Besides, the toxicity characteristic leaching procedure (TCLP) - extractable Cr and Ni contents in different workshops were significantly related (P < 0.05) to their bioavailable fractions (exchangeable fraction (F1) + bound to carbonate fraction (F2)), which pose potential risk to humans. Although the soil total Pb concentration was high, its mobility was very low (<0.007%). Moreover, the soil microbial community dynamics under the stress of long term and high contents of PTEs were further revealed. The soil microbiota was significantly disturbed by long term and high concentration of PTEs. A bit of bacteria (Caulobacter) and fungi (Cladosporium and Monocillium) showed tolerance potential to multiple metals. Furthermore, the canonical correspondence analysis (CCA) showed that the bioavailable fractions (F1 + F2) of Cr and Ni were the most critical environmental variables affecting microbiota. Therefore, remediation strategies are required urgently to reduce the bioavailability of soil Cr and Ni. The results of this study provide an overview of the pollution distribution and microbial dynamics of a typical plating site, laying a foundation for ecological remediation of electroplating sites in Yangtze River Delta of China.

Adaptability to High Temperature and Stay-Green Genotypes Associated With Variations in Antioxidant, Chlorophyll Metabolism, and γ-Aminobutyric Acid Accumulation in Creeping Bentgrass Species.

High temperature limits the cultivation and utilization of cool-season plants in many regions worldwide. Recently, extreme hot waves swept across the globe in summer, leading to enormous economic loss. The evaluation and identification of genotypic variation in thermotolerance within species are critical to breeding for environmental adaptation and also provide potential materials to explore thermo-resistant mechanism in plants. Forty-two accessions of creeping bentgrass (Agrostis stolonifera), which is a cool-season perennial grass for turf and ecological remediation, were collected from 15 different countries. Physiological traits, namely, chlorophyll (Chl) content, electrolyte leakage, photochemical efficiency, performance index on absorption basis, leaf relative water content, and osmotic potential were used to evaluate the heat tolerance of these materials in controlled growth chambers and field during summer. Stay-green and early-aging genotypes were selected to further reveal the potential mechanism of tolerance to senescence and heat damage associated with alterations in Chl metabolism, antioxidant and photosynthetic capacity, and endogenous γ-aminobutyric acid (GABA). Findings showed that there were significant genetic variations in physiological traits among 41 materials in response to high temperature stress. The 13M, PROVIDENCE, and LOFTS L-93 were the top three accessions with superior tolerance to heat and summer stress than other materials in terms of laboratory and field tests. In response to heat stress, the stay-green genotype PROVIDENCE exhibited significantly higher photochemical efficiency, net photosynthetic rate, transpiration rate, and water use efficiency than the heat-susceptible W6 6570. Delayed leaf senescence in relation to less Chl loss was detected in the PROVIDENCE associated with maintenance of significantly higher expression levels of Chl-anabolic genes (AsCHLH, AsPBGD, and AsPOR) and lower Chl-catabolic gene AsPPH under heat stress. Genetic attributes, such as better capacity to scavenge reactive oxygen species and higher endogenous GABA content could play positive roles in alleviating heat-induced senescence, oxidative damage, and metabolic disturbance in the PROVIDENCE.