As a commonly used chelator, ethylenediaminetetraacetic acid (EDTA) enters soil environment inevitably and has the potential to cause negative effects on soil organisms. The objective of the current ...study was to investigate the effects of EDTA on earthworm growth, survival and activities of antioxidant enzymes. The assessment for EDTA toxicity toward earthworms (Eisenia fetida) was conducted on day 14 and 35 after exposure to four concentrations (0, 5, 10, 15 mmol kg−1) of EDTA under turfgrass growing conditions. Exposure to EDTA resulted in a significant decrease of earthworm growth and survival. The toxicity of EDTA increased with the increase in concentration and exposure duration. The activities of antioxidant enzymes increased at low concentration and decreased at high concentration, which indicates that oxidative stress was induced by EDTA addition. These results suggest EDTA is highly toxic and ecologically dangerous to earthworms.
●EDTA exhibited high toxicity to earthworms.●Earthworm growth and survival decreased with increasing EDTA concentration and exposure duration.●Oxidative stress was observed in earthworms exposed to EDTA at two duration times.●EDTA is potentially harmful to earthworms and deserves special concern.
•SCB and NCB exhibited a certain degree of toxicity to earthworms.•SCB and NCB significantly decreased the biomass and survival of E. fetida after 35- and 60-d exposures.•The induction of oxidative ...stress was observed in earthworms exposed to three modified nano-CBs.•Five percent modified nano-CB is potentially harmful to earthworms and deserves special concern.
Modified nano-carbon adsorbents have been employed in the immobilization of heavy metals in soil due to their good adsorption capabilities regarding metal ions. However, an assessment of their risks has not been extensively performed with soil organisms. To assess the toxic effects of three types of modified nano-carbon black (CB) on soil organisms, a laboratory test was conducted to expose the earthworm Eisenia fetida to artificial soil supplemented with 5% H2SO4-, HNO3- and KMnO4-modified nano-CB (SCB, NCB and KCB, respectively) under turfgrass growing conditions. The tested earthworms were systematically investigated for survival, biomass and the activities of antioxidant enzymes, including superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT). SCB and NCB were found to be more toxic and ecologically dangerous to E. fetida because significant decreases in biomass and survival were observed after 35- and 60-d exposures and the survival rate showed a tendency to decrease with exposure duration. The activities of SOD, CAT and POD were inhibited in all treatments with modified nano-CBs at 35- and 60-d, which indicated that oxidative stress was induced by modified nano-CBs. The results suggest that there is potential harm to earthworms in soil with 5% modified nano-CB and that it deserves special attention.
Municipal solid waste compost can be used to cropland as soil amendment to supply nutrients and improve soil physical properties. But long-term application of municipal solid waste (MSW) compost may ...result in accumulation of toxic metals in amended soil. Phytoremediation, especially phytoextraction, is a novel, cost-effective, and environmentally friendly approach that uses metal-accumulating plants to concentrate and remove metals from contaminated soils. Ethylenediaminetetraacetate (EDTA) was applied to metal-contaminated soil to increase the mobility and phytoavailability of metals in soil, thereby increasing the amount of toxic metals accumulated in the upper parts of phytoextracting plants. The objectives of this study were (1) to investigate the accumulation and spatial distribution of toxic metals (Cd, Cr, and Pb) in mulberry from MSW compost with the application of EDTA and (NH
4
)
2
SO
4
, (2) to examine the effectiveness of EDTA and (NH
4
)
2
SO
4
applied together on toxic metals (Cd, Cr, and Pb) removal by mulberry under field conditions, and (3) to evaluate the potential of mulberry for phytoextraction of toxic metals from MSW compost. The tested plant—mulberry had been grown in MSW compost field for 4 years. EDTA solution at five rates (0, 50, 100, 50 mmol L
−1
+ 1 g L
−1
(NH
4
)
2
SO
4
, and 100 mmol L
−1
+ 1 g L
−1
(NH
4
)
2
SO
4
) was added into mulberry root medium in September 2009. Twenty days later, the plants were harvested and separated into six parts according to plant height. Cd, Cr, and Pb contents in plant samples and MSW compost were analyzed using an atomic absorption spectrophotometer. In the same treatment, Cd, Cr, and Pb concentrations in mulberry shoot were all higher than those in root, and Cd and Pb concentrations in shoot increased from lower to upper parts, reaching the highest in leaves. Significant increases were found in toxic metal concentration in different parts of mulberry with increasing EDTA concentration, especially when combined with (NH
4
)
2
SO
4
. Mulberry exhibited high ability to accumulate Cd with bioconcentration factors (BCFs) higher than 1. EDTA application also significantly increased Cd BCFs. More than 30 % of metal uptake was concentrated in mulberry branches (stem of above 100 cm height) and leaves. Results presented here show that mulberry is a woody plant that has the potential of Cd phytoextraction from MSW compost by removing leaves and cutting branches. The application of EDTA combined with (NH
4
)
2
SO
4
significantly enhanced the efficiency of mulberry in removing Cd from the compost medium. Adding (NH
4
)
2
SO
4
into the compost will lower the risk of the exposure of environment to excessive non-biodegradable EDTA in a large-scale EDTA-assisted phytoextraction by reducing the dosage of EDTA. In China, the need for sod is increasing day by day. Sod is often produced on arable soil and sold together with soils. This would lead to the soil being infertile and the soil layer thin. After several times’ production, the soil can no longer be used for cultivating crops and be destroyed. In order to fully utilize MSW compost resources and save valuable soil resources, MSW compost can be used to replace arable soil to produce sod after extraction of toxic metals in it.
Understanding the competition and coexistence of flagship carnivores is key to creating strategies for their conservation in the face of global carnivore declines. Although studies exploring the ...dynamics and competition between tigers (Panthera tigris) and leopards (P. pardus) span decades, there is a lack of understanding regarding the factors that influence their coexistence mechanisms on a broad scale, as well as the drivers determining their exploitative and interference competition. We gathered a comprehensive list of research papers among which 36 papers explored the interspecific interactions between tigers and leopards and tested the influence of biotic and abiotic factors on the coexistence mechanisms along three dimensions using multiple response variables regression models; we also tested the influence of ecological drivers determining the exploitative or interference competition between tigers and leopards. Elevation and ungulate density were the most important predictors in regulating the coexistence mechanisms. Tigers and leopards exhibited more positive relations/higher overlaps as elevation increased in the spatial niche. In addition, they showed a higher dietary overlap in the prey-rich regions. We determined that interference competition between tigers and leopards was less frequently observed in habitats with dense tree cover and homogeneous vegetation structures. Meanwhile, studies with multiple metrics would promote the detection of interference competition. Our study provides new insight into the competitive interactions and coexistence mechanisms of tigers and leopards on a broad scale. Policy-makers and managers should pay more attention to the factors of elevation, prey abundance, and habitat structures for the conservation of tigers and leopards.
Abstract
Environmental filtering is deemed to play a predominant role in regulating the abundance and distribution of animals during the urbanization process. However, the current knowledge about the ...effects of urbanization on the population densities of terrestrial mammals is limited. In this study, we compared two invasive mammals (dogs
Canis lupus familiaris
and cats
Felis silvestris
) and three indigenous mammals (Siberian weasels
Mustela sibirica
, Amur hedgehogs
Erinaceus amurensis
, and Tolai hares
Lepus tolai
) in response to urbanization using camera trap distance sampling (CTDS) in the rural–urban landscape of Tianjin, China. We used generalized additive mixed models (GAMMs) to test the specific responses of their densities to levels of urbanization. Invasive dogs (2.63 individuals/km
2
, 95% CI: 0.91–7.62) exhibited similar density estimations to cats (2.15 individuals/km
2
, 95% CI: 1.31–3.50). Amur hedgehogs were the most abundant species (6.73 individuals/km
2
, 95% CI: 3.15–14.38), followed by Tolai hares (2.22 individuals/km
2
, 95% CI: 0.87–5.68) and Siberian weasels (2.15 individuals/km
2
, 95% CI: 1.06–4.36). The densities of cats, Siberian weasels, and Amur hedgehogs increased with the level of urbanization. The population densities of dogs and cats were only influenced by urban‐related variables, while the densities of Siberian weasels and Amur hedgehogs were influenced by both urban‐related variables and nature‐related variables. Our findings highlight that the CTDS is a suitable and promising method for wildlife surveys in rural–urban landscapes, and urban wildlife management needs to consider the integrated repercussions of urban‐ and nature‐related factors, especially the critical impacts of green space habitats at finer scales.
At present, nanoscale materials have been produced with unprecedented speed due to their widespread use and may inevitably be released into the environment. As an effective adsorbent for heavy ...metals, nanoscale carbon black (CB) can be used to immobilize metals in contaminated soil, but no information is available regarding its effect on soil nematodes. In the present study, laboratory bioassays were performed to investigate the impact of three rates (1%, 3%, and 5% mass ratios) of HNO3 or H2SO4 modified nanoscale carbon black (NCB or SCB) on the abundance and composition of nematode communities during 120 d of turfgrass growth. The results showed that 5% NCB and SCB treatments significantly increased plant shoot biomass of two crops. The total number of nematode genera in the control was greater than in nano-CB treatments. Plant parasites dominated across all treatments, with dominant genus Helicotylenchus. The abundance of total nematodes and each of the four trophic groups responded negatively to nano-CB addition. Three percent and 5% NCB addition significantly decreased the abundance of total nematodes, plant parasitic and bacterivorous nematodes, compared to the control. The species diversity, richness, community evenness and maturity index of soil nematodes were significantly decreased by 3% and 5% nano-CB compared to the control. This study revealed that modified nano-CB, as an amendment with a rate of 3% or higher, could cause significant disturbance to the soil food web and thus affect soil nematodes in the short-term.
•Modified nano-CBs negatively affected the abundance of total nematodes and each of the four trophic groups.•The diversity, evenness, richness and maturity indices of soil nematodes were decreased by 3% and 5% nano-CBs.•1% modified nano-CB did not affect soil nematode abundance and diversity significantly.•Modified nano-CBs with a rate of >3% could cause significant disturbance to soil nematodes in the short-term.
Application of sewage sludge (SS) in agriculture is an alternative technique of disposing this waste. But unreasonable application of SS leads to excessive accumulation of heavy metals in soils. A ...column experiment was conducted to test the availability of heavy metals to Lolium perenne grown in SS-treated soils following diethylene triamine penta acetic acid (DTPA) application at rates of 0, 10 and 20 mmol kg⁻¹soil. In order to prevent metal leaching in DTPA-assisted phytoextraction process, a horizontal permeable barrier was placed below the treated soil, and its effectiveness was also assessed. Results showed that DTPA addition significantly increased metal uptake by L. perenne shoots and metal leaching. Permeable barriers increased metal concentrations in plant shoots and effectively decreased metal leaching from the treated soil. Heavy metals in SS-treated soils could be gradually removed by harvesting L. perenne many times in 1 year and adding low dosage of DTPA days before each harvest.
PDF
