Ecological Engineering最新文献

Sediment dredging is an important countermeasure for remediating eutrophic shallow lakes, which may significantly alter benthic fauna via changing sediment characteristics and bottom dissolved oxygen (DO) conditions. However, current understanding on the effects of sediment dredging on bivalves remains unclear. Here, Corbicula fluminea, a native species in Asia undergoing substantial population declines in shallow lakes in the Yangtze River Basin (China) due to eutrophication, was taken as an example to examine the response of freshwater bivalves to dredging. We hypothesized that (1) in hypoxia conditions, sediment dredging benefits the survival of C. fluminea via coarsening the sediment, which would improve DO conditions at sediment-water interface (SWI); and (2) in habitats with sufficient DO, a mixture of coarse sand and fine sediment simulating sediment conditions after dredging, would increase C. fluminea growth since this species is both filter and deposit feeder. To test the above hypotheses, we conducted an outdoor mesocosm experiment that simulated the living conditions of C. fluminea under different dissolved oxygen and sediment type conditions. In addition, we used a 15-year monitoring program of C. fluminea in Lake Taihu that have been experiencing dredging several times to assess possible changes in population dynamics. We found that coarse sediment benefited C. fluminea via improving DO conditions at SWI, indicating that dredging benefits the survival of C. fluminea, which is consistent with our first hypothesis. In sufficient DO conditions, coarse sediment improved growth of C. fluminea, consistent with our second hypothesis. However, in natural ecosystems the effectiveness of sediment dredging is time-limited. Therefore, our results also suggested that sediment dredging should be taken together with other measures, such as pollution reduction and ecological restoration, to recover C. fluminea populations.

Extensive green roofs (EGRs) play a crucial role in urban environments, offering numerous environmental, economic, and social benefits. However, their performance largely depends on plant selection and adaptation to local climatic conditions. This study investigates the suitability of six perennial Euro-Mediterranean species for EGRs in Mediterranean and semi-arid regions, under different water regimes. A two-year experimental analysis was conducted in Rome (Italy) assessing flowering and mortality rates. Results revealed species-specific responses to irrigation levels, with notable performances observed in Thymus serpyllum, Saponaria ocymoides, and Teucrium chamaedrys, showcasing resilience to water stress. Conversely, Lavandula stoechas and Cerastium tomentosum exhibited sensitivity to water availability, emphasizing the importance of species selection for EGRs. No species completely adhered to the expected flowering period, but showed a general tendency of anticipation, and sometimes an extended flowering period, with some differences between the species. The study underscores the complexity of plant-environment interactions and highlights the need for diversified species composition to enhance EGR functionality and resilience.

Sustainable long-term use of land rehabilitated following mining is required to be resilient to fire and other disturbances. We analysed the vegetation responses to three fires in grassland pasture and open woodland on rehabilitated open-cut coal mine sites in Queensland, Australia. Two fires in central Queensland were controlled burns to manage fuel loads and test the vegetation and landform response, while the third fire, in southeastern Queensland, was an unintended wildfire. We monitored several ecological variables at the study sites for up to five years following the fires and found that vegetation cover, biomass and species richness recovered to pre-fire or unburnt control values within two years. However, one study site experienced lower than average rainfall during the three to five-year post-fire period, resulting in a significant reduction in vegetation cover of between 14 and 31 %, and biomass between 45 and 57 % compared to pre-fire values. Tree and shrub densities changed significantly at two of the sites, reflected in a 635 % increase in stem density of Acacia stenophylla (A.Cunn. ex Benth.) and 82 % mortality of Atriplex nummularia Lindl. subsp. nummularia individuals <2 m in height and 100 % mortality in the 2-5 m height class. The results suggest that rehabilitated pasture systems in central and southern Queensland are resilient to fire in the short-term but are vulnerable to long-term shifts in climate, particularly if a fire precedes a long period of drought. Further resilience work is needed to i) compare rehabilitation recovery with unmined vegetation communities to determine residual risk of future fire impacts, ii) account for seasonality in resilience assessments and iii) understand recovery traits of seed mix combinations sourced from disparate regions.

The construction of less damaging (here called fish-friendly) pumping stations has taken place in recent years, but it is unknown if they provide efficient and timely passage to migratory fish, such as European eel (Anguilla anguilla (L.)). The pump is often the only downstream passage route and operation, i.e., fish passage opportunity, is temporally variable depending on precipitation and prevailing river levels. Once the pumps are operating, eels must also consider the pumping station an attractive downstream passage route. Here, the movement of seaward migrating silver European eel (n = 59) upstream of a fish-friendly shrouded Archimedean Screw Pump (ASP) was assessed during three migrations (December–March in 2018/19, 2019/20 and 2020/21) with highly contrasting hydrology using acoustic telemetry. The overall passage rate was low (36.8 %) and minimum passage time was 65.2 days during a year with very little pump operation (2018/19), with seven eels tagged with long-life transmitters passing the pumping station the following year (2019/20). Furthermore, the median number of approaches to the pumping station was seven, with 36.8 % (n = 7) approaching more than 10 times. By contrast, passage rate was high (95.0 %), maximum passage time was 2.7 and 34.0 days (minimum = 3 min in both years) and all but one eel passed during the first approach during the two wettest years (2019/20 and 2020/21). Eels were almost exclusively nocturnal, regardless of pump operation, with 96.1 % of total approaches occurring between sunset and sunrise and no eels passed downstream during the day. Ultimately, limited eel passage opportunity during dry periods and a reluctance to pass when operational curtailed the effectiveness of these pumps to provide efficient and timely passage. Thus, measures are required to align pump operation with the timing of eel migration, especially in dry years, and reasons for retreat from the pumping station during operation must be identified and alleviated.

This study evaluated the performance of four types (zeolite, gravel, complete woodchip, and vertical shaft) of pilot-scale partially saturated vertical flow wetlands for treating domestic wastewater. The zeolite-woodchip PSVF design achieved a mean total nitrogen removal of 80 % and also performed best in terms of ammonium-N removal (99 %). The complete woodchip design also achieved a similar mean reduction in TN but by having better nitrate removal. The corresponding changes in alkalinity and nitrogen species measured above and below the unsaturated zones of the PSVF suggest that classical nitrification and denitrification are the main mechanisms involved in nitrogen removal. All four systems achieved >95 % removal for biochemical oxygen demand and total suspended solids. Phosphorus removal was 55 % for zeolite, gravel and vertical shaft, and 37 % for the complete woodchip system. The elimination of E. coli ranged between 1.7 and 2.8 log₁₀ in all four systems, with the complete woodchip PSVF delivering the highest reduction. PSVF wetlands can provide effluent quality equivalent to multistage hybrid systems while occupying a significantly lower footprint without additional power requirements.

The Northeast black soil region in China is an important grain-producing area where various pesticides are extensively used to increase grain yields. However, this practice poses serious risks to the ecological health of soil and water systems, necessitating effective measures. Vegetative filter strips (VFS) are commonly used to mitigate agricultural diffuse pollutants, but their efficiency varies across different regions, requiring assessment. This study employed flume experiments, the VFSMOD-W model, and redundancy analysis (RDA) to evaluate the efficacy of VFS in runoff, sediment, and pesticide removal, as well as influencing factors. The results showed that VFS reduced outflow rate of runoff by 8 %–64 % and sediment by approximately 90 %, achieving load removal rates of 61 % and 95 % respectively. Pesticide load removal efficiency ranged from 37 % to 94 %, with higher efficiency for adsorbed pesticides like chlorpyrifos compared to water-soluble ones like atrazine. Interflow and vertical seepage were significant pathways for pesticide transport in VFS, with chlorpyrifos concentrations at 4 %–26 % and atrazine at 20 %–37 % of inflow concentrations. The VFSMOD-W model accurately predicted VFS efficiency (NSE > 0.90), and RDA results indicated that environmental factors could explain 86.7 % of the variation in VFS performance, with soil vertical saturated hydraulic conductivity (VKS) being the most influential factor, followed by rainfall intensity (T), saturated soil water content (OS), initial soil water content (OI), and filter slope for each segment (SOA). Optimizing soil moisture characteristic factors and increasing infiltration are crucial for VFS performance. Applying VFSMOD-W for precise VFS design can help reduce construction costs. In the future, long-term field monitoring and evaluation of VFS efficiency after implementation should be conducted in the black soil region of Northeast China to provide data supporting the improvement of VFSMOD-W simulation accuracy. This will also offer recommendations for the government in formulating VFS configuration schemes.

Sustainable urban development faces challenges in efficiently using spaces, reducing pollutants, and greening cities. We examined how cadmium accumulation in soils from polluted irrigation water affects marigold (Calendula officinalis L.) safe and healthy products and how plant growth-promoting rhizobacteria (PGPRs) can remediate cadmium on marigold for multifunctional urban vertical system development. The study was a factorial arrangement with a randomized complete block design. The first factor was cadmium (0, 1, 2 and, 3 mg/kg soil through irrigation with Cadmium-polluted water), and the second factor was PGPR treatments (P.flu, P.putida, T.SP, Mix1 (P.flu + A.lipo), Mix2 (T.SP+ A.choro), Mix 3 (P.flu + A.lipo + T.SP+ A.choro)), and the control. In all the PGPR treatments, total chlorophyll, flowers' fresh and dry weight and antioxidant enzymes' activity significantly increased (p ≤ 0.05). There was no obvious risk to human health for oral and dermal use of marigold products in bacterial inoculated treatments (1 > Health Risk Index). Using flower of the plants treated with Thiobacillus thioparus strain 300, Mix1 (P.flu + A.lipo), Mix2 (T.SP+ A.choro), Mix3 (P.flu + A.lipo + T.SP + A.choro), if irrigated with up to 2 mg/kg soil Cd were safe and healthy ($\text{Estimated Daily Intake}<0.001$, Carcinogenetic Risk <1E-6, Target Hazard Quotient <1). Therefore, this research, for the first time, showed that using nature-based combined soil bacteria strains, we can create vertical green systems with double functionality: pollution remediation and healthy marigold flower production in cadmium-contaminated soils of up to 2 mg/kg.

In order to enhance the ecological security of the coastal ecosystem, the Chinese government has initiated a comprehensive program for the removal of Spartina alterniflora. Upon completion of the removal project, the area underwent a notable transformation, transitioning from its original vegetated state to a predominantly bare salt marsh landscape. This transformation has the potential to give rise to new ecological security issues and facilitate the re-invasion of Spartina alterniflora. At the time of writing, restoration work is underway in the restoration area, with the aim of reinstating native vegetation, specifically Suaeda salsa. Nevertheless, the survival strategies that the target species, Suaeda salsa, may employ to adapt to the challenging wave environment remain unknown, potentially introducing unforeseen challenges to the revegetation efforts. To address this issue, we conducted a study to examine the impact of water-imposed drag forces on the physiological and biomechanical properties of Suaeda salsa, with the aim of defining its survival strategies in wave environments. Our research findings indicate that Suaeda salsa exhibits limited sensitivity to wave disturbance. Suaeda salsa is relatively rigid and thus finds it difficult to adjust its shape flexibly in order to withstand the mechanical force caused by wave motion. As the intensity of the wave increases, Suaeda salsa exhibits a tolerance strategy. In the optimal wave environment (before the failure of plant tissue under extreme wave drag force), enhanced waves can stimulate the growth of Suaeda salsa, thus potentially contributing positively to the restoration efforts of the Yellow River Delta.

Local wetlands such as APW provide ecosystem service benefits to local residents, and as a nature-based carbon sink, they play a key role in improving local resilience and adapting to climate change. This study was conducted to evaluate function of local wetlands that are ecologically important, but are damaged in blind spots of management, and to reveal differences by ecological area and function through functional evaluation. Functional scores for each of the eight evaluation items were compared by dividing them into 3 catchments according to the watershed system and topography using modified ‘RAM’. As a result of the evaluation, the overall average function of 399 priority wetlands was 1.96/3.0, which was medium-level, and among the eight evaluation items, AESREC, Habitat, and AQHAB function were high. In detail it was confirmed in order of AESREC, Habitat, AQHAB, WQUAL, RUNOFF, SHPRO, GWATER and FSTOR. The average function for each catchment were in order of 02GG, 01SAM, 03WS.

Although riparian vegetation is widely acknowledged for its positive impact on soil and water quality and its role in regulating terrestrial greenhouse gas emissions in agricultural landscapes, there remains a gap in understanding how different types of riparian vegetation affect aquatic greenhouse gas production. Thus, the objective of this study was to investigate whether the type of vegetation within riparian zones influenced aquatic environmental factors, subsequently impacting aquatic greenhouse gas emissions. To address this, we measured greenhouse gases in the aquatic environment bordered by riparian zones with herbaceous vegetation (GRS) compared to undisturbed natural riparian forests dominated by deciduous (UNF-D) or coniferous (UNF-C) vegetation or a rehabilitated riparian forest (RH). Our findings indicate that aquatic CO₂ concentrations were not influenced (p < 0.05) by vegetation type ranging from 9 g L⁻¹ to 11 g L⁻¹. In contrast, aquatic CH₄ concentrations were significantly lower (p < 0.05) in treed riparian zones, ranging from 14 μg L⁻¹ to 24 μg L⁻¹, compared to a riparian zone with herbaceous vegetation (34 μg L⁻¹). However, we observed significantly higher (p < 0.05) aquatic N₂O concentrations in treed riparian zones (9.5 μg L⁻¹ to 10.3 μg L⁻¹), particularly those dominated by coniferous vegetation (23.0 μg L⁻¹), compared to the riparian zone with herbaceous vegetation (7.7 μg L⁻¹). The total CO₂-C equivalent (i.e., CO₂ + CH₄ + N₂O) was highest in the riparian zone with coniferous trees (UNF-C: 10,717 mg CO₂-Ceq L⁻¹), followed by the GRS (9494 mg CO₂-Ceq L⁻¹), RH (9423 mg CO₂-Ceq L⁻¹) and UNF-D (9,183 mg CO₂-Ceq L⁻¹) riparian zone. Moreover, riparian vegetation was influenced by various environmental factors that likely controlled physicochemical and biological processes related to the production of greenhouse gases within the aquatic environment.