Science of the Total Environment最新文献

Among emerging pollutants, residuals of phenoxy herbicides, including 2-chloro-4-methylphenoxy acid (MCPA), are frequently detected in non-targeted areas. MCPA can be removed from environmental matrices using biological remediation methods including endophyte-assisted phytoremediation. The interactions between selected plants excreting to the rhizosphere plant secondary metabolites (PSMs) and plant-associated bacteria (incl. endophytes) can speed up the removal of organics and increase the plants resistance to pollutants such as MCPA. The role of plant-associated bacteria in endophyte-assisted phytoremediation has been partially described, however neither MCPA-tolerant endophytic bacteria has been isolated nor characterized. So far, promising results were obtained by simultaneous cultivation of Cucurbita pepo (zucchini) and amendment of soil with structurally related PSM syringic acid (SA), which can substantially enhance removal of MCPA from soil. Hence, the main aim of this research was to study the effect of PSM (SA) on the presence of functional MCPA-tolerant endophytic bacteria using a culture-dependent and -independent approach. Comparison between the molecular and microbiological analysis revealed differences between applied methods. However, irrespectively of the genera identification methods, presence of phenolic compounds (MCPA or SA) favorized presence of potential MCPA-degraders. On the basis of MCPA tolerance tests of isolated bacteria, two Pseudomonas endophytic isolates from zucchini roots and three isolates from zucchini leaves i.e. Pseudomonas sp., Paenarthrobacter sp. and Acinetobacter sp. were selected for further screening of plant growth promoting properties (PGPP). MCPA-tolerant endophytic bacteria showed multiple PGPP. Therefore, these isolates can potentially contribute to an improved fitness of plants used for the purpose of enhancing phytoremediation of environments polluted with phenoxy herbicides.

Mountain environments, as biodiversity hotspots, are subject to numerous anthropological pressures. In mountain areas, a common threat to stream biocenoses is the timber industry. Timber industry increases the fine sediment input into the mountain rivers; furthermore, timber transport requires the construction of low-water crossings across streams. Transversal barriers (weirs/fords/pipe culverts) may cause excessive erosion downstream and the accumulation of fine sediments upstream, thereby decreasing habitat heterogeneity. Moreover, mountain stream communities are sensitive to climate change; for e.g., climate change may result in increasing water temperature and decreasing flows. Boulder ramps are considered effective restoration measure for rivers; benthic macroinvertebrate community composition is an effective indicator of stream health. In this study, we selected two mountain streams catchment with forest management. The control was a stream without any objects in the streambed related to timber transport. The other stream contained weirs and pipe culverts. We considered an extensive study period that covered the stages before (2009) and after restoration (2014, 2017-2018, 2019). We present the hypothesis that boulder ramps can restore in-stream habitats, improve biodiversity, and increase the resilience of benthic macroinvertebrate communities to future environmental changes. Our study demonstrates the effectiveness of boulder ramps for mountain streams restoration. We indicated, that the habitat potential of the restored stream-reach for rheophilic and lithophilic invertebrates increased substantially. Moreover, the restored riffles allowed the streambed to be cleared of fine sediments, offering the microrefugia, which were beneficial for mountain stream invertebrates, thereby increasing the diversity and resilience of the benthic communities.

Application of herbicide-degrading bacteria is an effective strategy to remove herbicide in soil. However, the ability of bacteria to degrade a herbicide is often severely limited in the presence of other pesticide. In this study, the atrazine-degrading strain Klebsiella varicola FH-1 and acetochlor-degrading strain Bacillus Aryabhatti LY-4 were used as parent strains to construct the recombinant RH-92 strain through protoplast fusion technology. Compared with the parent strains, RH-92 exhibited enhanced ability to degrade herbicide mixture containing atrazine and acetochlor, exhibiting 63.16 % and 68.48 % higher degradation rates, respectively. RAPD analysis showed that gene rearrangement occurred during protoplast fusion, and the genetic similarity indexes of the fused strain RH-92 and the two parent strains were 0.5853 and 0.4240, respectively. HPLC-MS analysis confirmed that RH-92 shared similar degradation products and pathways with both parent strains but exhibited a novel metabolic pathway for the continuous degradation of CMEPA (degradation product of acetochlor) into MEA through amide bond hydrolysis. The activities of GSH, GST and SOD of RH-92 increased and the level of MDA decreased under the stress of compound herbicides. Strain RH-92 did not show a large number of bacterial apoptosis, and maintained good cell membrane integrity and permeability. The half-lives of atrazine and acetochlor were 4.9 d and 7.6 d when the parent strains FH-1 and LY-4 were applied in unsterilized soil containing herbicide mixture treatment,the application fusant RH-92 strain significantly reduced the half-life to 1.6 and 1.8 d, respectively. Furthermore, 16S rRNA sequencing indicated that RH-92 application effectively restored bacterial taxa with diminished relative abundances under herbicide mixture treatment, ameliorated phytotoxicity in soybean seedlings, and promoted enhanced vegetative growth in the roots and plant height. This study highlighted the application of fusant strains as a bioremediation strategy for combatting atrazine and acetochlor pollution in soil and provided theoretical insights.

The production of organic-mineral fertilizers from sewage sludge is one of the ecological options in their management. Though, pharmaceuticals and their derivatives, which accumulate in the sludge, could be a problem due to their impacts on the environment. This manuscript aimed at better understanding of risks posed by antimicrobial agents (AAs) in sludge-based fertilizers. Sewage sludge and sewage-based fertilizers (from two sewage treatment plants in two cities in Poland) were tested for 99 AAs. 26 AAs were detected in the sludge at concentrations reaching 112,000 μg/kg. Several AAs were successfully removed during the sludge treatment process (sulfasalazine, sulfapyridine, isoniazid, isonicotinic acid, erythromycin, clarithromycin, erythromycin N-desmethyl, clarithromycin N-desmethyl, azithromycin N-desmethyl, emtricitabine, ANP) with reduction ranging from 34 % to 96,5 %. It is worth noting that penicillin V and ofloxacin/levofloxacin were recorded at higher concentrations in the fertilizer than in the sludge, which indicates the process of concentration of these AAs as a result of drying the fertilizer. Penicillin V content increased by 153 % and 191 % in WWTP 1 and WWTP 2 samples, respectively. The level of ofloxacin/levofloxacin increased by 70 % in fertilizer from WWTP 1, and decreased by 40 % in fertilizer from WWTP 2. The AAs leaching test revealed that 7 AAs (isoniazid, sulfapyridine, ofloxacin/levofloxacin, clindamycin, azithromycin, isonicotinic acid, pyrazinoic acid 5-hydroxy-) have potential to leach into the receiving soil environment after sludge-based fertilizer application. The risk factor (RQ) for sulfapyridine, ofloxacin/levofloxacin, isonicotinic acid and linezolid was too low to estimate, below 0.1, so the risk has mild environmental impacts. An RQ value of isoniazid and clindamycin ranging from 0.1 to 1.0 indicates a low risk to soil. Azithromycin RQ >36 denoted a high environmental risk. This warrants further study to understand risks from AAs present in sludge-based products.

Neonicotinoid pesticide use has increased around the world despite accumulating evidence of their potential detrimental sub-lethal effects on the behaviour and physiology of bees, and its contribution to the global decline in bee health. Whilst flower colour is considered as one of the most important signals for foraging honey bees (Apis mellifera), the effects of pesticides on colour vision and memory retention in a natural setting remain unknown. We trained free flying honey bee foragers by presenting artificial yellow flower feeder, to an unscented artificial flower patch with 6 different flower colours to investigate if sub-lethal levels of imidacloprid would disrupt the acquired association made between the yellow flower colour from the feeder and food reward. We found that for doses higher than 4 % of LD₅₀ value, the foraging honey bees no longer preferentially visited the yellow flowers within the flower patch and instead, we suspect, reverted back to baseline foraging preferences, with a complete loss of the yellow preference. Our honey bee colour vision modelling indicates that discriminating the yellow colour from the rest should have been easy cognitive task. Pesticide exposure also resulted in a significant increase in Lop1, UVop, and Blop, and a decrease in CaMKII and CREB gene expression. Our results suggest that memory loss is the most plausible mechanism to explain the alteration of bee foraging colour preference. Across bees, colour vision is highly conserved and is essential for efficient pollination services. Therefore, our findings have important implications for ecosystem health and agricultural services world-wide.

The addition of exogenous organic carbon (C) to soil can either accelerate or retard the soil organic carbon (SOC) mineralization, i.e., the priming effect (PE), which plays a crucial role in SOC sequestration and thus is significant in the context of global warming. However, the influence of exogenous organic C quality on PE remains poorly understood, potentially limiting our understanding of SOC dynamics. Thus, we conducted a global meta-analysis to reveal the effect of exogenous organic C quality on PE through compiling a data set of 2031 experiment trials. Our results revealed that the addition of organic C significantly enhanced SOC decomposition by 46.23 % in agricultural soils. Labile C compounds induced a stronger PE than both intermediate and recalcitrant C compounds. Organic C materials rich in labile C compounds or with low lignin/N ratios exhibited a greater PE than the resistant substrates. Notably, a threshold C/N ratio of 25 was associated with a higher PE in substrates with C/N < 25. Given the pronounced PE observed with high-quality organic C addition (characterized by C/N <25, low lignin/N ratio, and easy decomposability), we proposed that "stoichiometric decomposition" might predominate the PE in agricultural soils. Collectively, the current study underscores the significant role of exogenous organic C quality in modulating the PE, emphasizing the need for further research to inform effective SOC management strategies.

This paper aims to test several modeling approaches for predicting toxicity of binary mixtures with potential synergy and antagonism. The approach based on the construction of isoboles was first tested and criticized. In contrast to conventional approaches, and in order to be mathematically consistent with the additivity assumptions, non-linear isoboles have been constructed. This approach was compared with that proposed by Minto et al. (2000), which measures deviations from additivity by considering standardized variables and which considers the entire Hill concentration-response curves. The selected models were tested on a case study related to chlorine-based disinfectant by-products (DBPs), using experimental data describing the effect of five DBPs (monochloroacetic acid, dichloroacetic acid, trichloroacetic acid, bromochloroacetic acid and 1,1-dichloropropan-2-one) on a unicellular green algae Raphidocelis subcapitata. The approach based on the construction of isoboles has shown its limitations. Indeed, in cases where the individual substances involved have different slopes in terms of their Hill concentration-effect relationships, the so-called zone of indetermination can be large. Furthermore, conclusions drawn from isoboles based on EC₅₀s or EC₂₀s may not be consistent. Minto's approach makes it possible to construct interaction indicators that consider the entire Hill concentration-response curve. Response surfaces can be constructed to visualize the areas of concentration of the two substances involved that maximize the interaction effects.

Understanding the solubility dynamics of elements during wet deposition is crucial for assessing their environmental impacts. In this study, we investigated the solubility behaviour of various elements originating from natural and anthropogenic sources using a dataset of 106 samples describing the sequential collections of 8 rainfall events. Our results reveal distinct solubility patterns depending on the type of event, with mineral-dust events exhibiting lower solubility and anthropogenic events displaying higher solubility, in relation with dust content and pH. The study of intra-event solubility reveals variations over short periods during a rain event, which evolve differently according to the chemical elements and depend mainly on the origin of the aerosols scavenged by the rain. In the case where the aerosol origin is the same during a rain event, the precipitation characteristics and in-cloud scavenging mechanisms play a role on the elemental solubility as the rainfall progresses.

Research about patterns of aboveground carbon stock (AGC) across different tropical forest types is central to climate change mitigation efforts. However, the aboveground carbon stock (AGC) quantification for Brazilian cloud forest ecosystems along the altitudinal gradient is still scarce. We aimed to evaluate the effects of abiotic and biotic on AGC and the AGC distribution between species and families of tree communities along an altitudinal Brazilian Atlantic cloud forest gradient of the Mantiqueira Mountain Range, Southeastern Brazil. We analyzed the relationships between AGC and biotic (taxonomic and functional diversity based on structural attributes) and abiotic factors (altitude and soil properties) across seventy plots (10 × 20 m) distributed in seven cloud forest sites at different elevations (from 1.100 to 2.330 m a.s.l.) using linear mixed models and machine learning approaches. We found significant variations in AGC stock along the altitudinal gradient, which was explained mainly by altitude and large-sized trees. We observed that approximately 5 % of the total sampled individuals were responsible for >50 % of the AGC stock of the tree community in the different sites. This result demonstrates how carbon-dominant tree species' have a higher relative contribution to the AGC at community level than species richness and abundance. The Myrtaceae was the most species-rich and carbon-dominant family, which holds four of the total hyperdominant species in the study region. This study reveals new and important ecological patterns of AGC stock in Southeastern Brazil's cloud forest tree communities, where large-sized trees and altitude are the main biotic and abiotic factors, respectively. These insights enhance our understanding of AGC stock in these unique forest ecosystems and emphasize the need for targeted conservation strategies that protect dominant species and their habitats.

Air-source heat pumps are popular in buildings to provide cooling and heating. However, how the air discharged by air-source heat pump outdoor units affects the dispersion of air pollutants in urban street canyons remains poorly understood. This study used coupled simulations to examine the effects that air-source heat pump outdoor units had on vehicle-induced indoor and outdoor air pollution in an urban street canyon and how these effects varied based on the arrangement of outdoor units or the presence of building envelope components (e.g. overhangs and balconies). Data from wind-tunnel experiments and field measurements were used to validate simulation models. The air pollution exposure in indoor environments and air pollutant dispersion in pedestrian spaces were quantified using the personal intake fraction (P_IF) and net escape velocity (NEV), respectively. Results indicate that when being installed on both north and south sides of each building, outdoor units could reduce the average P_IF by up to 62 %. In the presence of overhangs or balconies, occupants could have greater exposure due to outdoor units, with an increase in the average P_IF of up to 12 %. Outdoor units also facilitated the removal of vehicle-emitted air pollutants from pedestrian spaces, increasing the average NEV by up to 57 %. This positive effect, however, could almost be eliminated by the presence of balconies. The results lead to a better understanding of the role of outdoor units on the dispersion of air pollutants in urban street canyons and provide insights into the potential health benefits gained from outdoor units.