Urbanization alters land use, increasing the rate of greenhouse gas (GHG) emissions and hence atmospheric compositions. Nitrous oxide (N₂O) is a major GHG that contributes substantially to global warming. N₂O emissions are sensitive to changes in substrate availabilities, such as litter and N input, as well as micro-environmental factors caused by land-use change upon urbanization. However, the potential impacts of changing litter and N on soil N₂O emissions along urban-rural gradients is not well understood. Here, we conducted an in situ study over 19 months in Cinnamomum camphora plantations along an urban-rural gradient, to examine the effects of the urban-rural gradient, N and litter input on N₂O emissions from C. camphora plantation soils and the underlying mechanisms via N, litter and microbial communities. The results showed that urban soil N₂O emissions were 105% and 196% higher than those from suburban and rural soil, respectively, and co-occurred with a higher abundance of AOA, nirS and nirK genes. Litter removal increased cumulative N₂O emissions by 59.7%, 50.9% and 43.3% from urban, suburban and rural soils, respectively. Compared with litter kept treatment, increases in AOA and nirK abundance were observed in urban soil, and higher rural nirS abundance occurred following litter removal. Additionally, the relatively higher soil temperature and available N content in the urban soil increased N₂O emissions compared with the suburban and rural soil. Therefore, in addition to changes in microbial communities and abiotic environmental factors, litter kept in C. camphora plantations along an urban-rural gradient is also important in mitigating N₂O emissions, providing a potential strategy for the mitigation of N₂O emissions.

Foliar δ³⁴S values of three soil-growing plant species (Platanus Orientalis L., Osmanthus fragrans L. and Cinnamomum camphora) have been analyzed to indicate atmospheric sulfur. The foliar δ³⁴S values of the three plant species averaged −3.11±1.94‰, similar to those of both soil sulfur (−3.73±1.04‰) and rainwater sulfate (−3.07±2.74‰). This may indicate that little isotopic fractionation had taken place in the process of sulfur uptake by root or leaves. The δ³⁴S values changed little in the transition from mature leaves to old/senescing leaves for both the plane tree and the osmanthus tree, suggestive of little isotope effect during sulfur redistribution in plant tissues. Significantly linear correlation between δ³⁴S values of leaves and rainwater sulfate for the plane and osmanthus trees allowed the tracing of temporal variations of atmospheric sulfur by means of foliar sulfur isotope, while foliage δ³⁴S values of the camphor is not an effective indicator of atmospheric sulfur.

Moss (as a reference material) and camphor (Cinnamomum Camphora) leaf, branch bark and bark samples were systematically collected across an urban-rural gradient in Guiyang (SW China) to determine the efficacy of using these bio-indicators to evaluate nitrogen (N) pollution. The tissue N concentrations (0.13%–2.70%) and δ¹⁵N values (−7.5‰ to +9.3‰) of all of these bio-indicators exhibited large spatial variations, as they recorded higher values in urban areas that quickly decreased with distance from the city center; moreover, both soil N concentrations and soil δ¹⁵N values were found no significant differences within each 6 km from the urban to the rural area. This not only suggests that the different N uptake strategies and variety of N responses of these bio-indicators can be reflected by their different susceptibilities to variations in N deposition but also reveals that they are able to indicate that urban N deposition is mostly from traffic and industry (NOₓ-N), whereas rural N deposition is mainly from agriculture (NHₓ-N). Compared to previously collected urban moss and camphor leaf samples, the significantly increased δ¹⁵N values in current urban moss and camphor leaf samples further indicate a greater contribution of NOₓ-N than NHₓ-N to urban N deposition. The feasibility of using the N concentrations and δ¹⁵N values of branch bark and bark as biomarkers of N deposition thus was further confirmed through the comparative use of these bio-indicators. It can be concluded that vascular plant leaves, branch bark and bark can be used as useful biomonitoring tools for evaluating atmospheric N pollution. For further study, quantitative criteria for the practical use of these bio-indicators in response to N deposition should be developed and the differences in the δ¹⁵N values of different plant parts should also be considered, particularly in urban environments that are severely disrupted by atmospheric pollution.

The transfer of pollutants from chemical fertilizers through food webs within cropland is well documented; however, its impacts on the wild animals that forage on croplands but roost in other locations remain poorly understood. The potential for this cross-ecosystem ‘spillover’ of pollutants is greatest for bats, some of which exploit urban settlements as roosting niches but must travel long distances to reach croplands as foraging niches. Here, we used hairs from a colony of insectivorous bats, Chinese Noctule (Nyctalus plancyi), from an urban area in Southwest China to assess whether exposure to heavy metals/metalloids by the bats varied from 1975 to 2016. Historical changes occurred in hair cadmium (Cd) concentrations in adult females, which was exclusively explained by the regional fertilizer application intensity (FAI), even considering the potential impacts of Cd emissions in urban areas, as indicated by camphor trees (Cinnamomum camphora) near the bats' roosting niche, and the potential impacts of Cd in industrial wastewater, as documented in authorized databases. Therefore, the data from this bat colony, as urban dwellers, indicates Cd accumulation and cross-ecosystem transfer from rural croplands to an urban area.

To assess ozone sensitivity of subtropical broadleaved tree species and explore possible underlying mechanisms, six evergreen and two deciduous native species were exposed to either charcoal-filtered air or elevated O₃ (E-O₃, ∼150ppb) for one growing season. Initial visible symptoms in deciduous species appeared much earlier than those in evergreen species. The species which first showed visible symptoms also had the largest reductions in biomass. E-O₃ induced significant decreases in photosynthesis rate, chlorophyll content and antioxidant capacity but a significant increase in malondialdehyde content in two deciduous species and two evergreen species (Cinnamomum camphora and Cyclobalanopsis glauca). Except C. glauca, however, E-O₃ had no significant effects on stomatal conductance (gₛ), total phenols and ascorbate contents. Difference in O₃ sensitivity among all species was strongly attributed to specific leaf mass rather than gₛ. It suggests that some subtropical tree species will be threatened by rising O₃ concentrations in the near future.

Camphor wood is welcomed by museums due to its insect-repelling effect but the smell indicates a potential risk to the collections. In order to judge the suitability of camphor wood as a museum storage material, typical camphor wood (Cinnamomum camphora) samples aged for different years were evaluated by conducting the Oddy test. Gas chromatography–mass spectrometry (GC-MS), X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDS), and time of flight–secondary ion mass spectrometry (ToF-SIMS) were applied to identifying the volatile organic compounds (VOCs) emitted by the materials and the corrosion products, respectively. The results showed that the camphor wood samples led to visible corrosion on copper and lead coupons. GC-MS indicated that the major VOCs emitted were terpenes and their derivatives, while XRD, EDS, and ToF-SIMS provided various clues to the corrosion mechanisms. Pb₁₀(CO₃)₆(OH)₆O and CuO were regarded as the major corrosion products of lead and copper coupons, respectively. The study provides the museum curators and the conservators with abundant information to reassess the application of camphor wood to museums as well as a different way to understand the mechanism of metallic corrosion caused by camphor wood.

Copper (Cu) and cadmium (Cd) are ordinary heavy metals. Unreasonable development and utilization of these heavy metals will cause severe pollution to the soils and consequently bring damage to human health. Therefore, recovering soils polluted by heavy metals is crucial. An indoor pot experiment was carried out involving seven treatments, namely, low-concentration Cu stress (Cu1), high-concentration Cu stress (Cu2), low-concentration Cd stress (Cd1), high-concentration Cd stress (Cd2), low-concentration Cu–Cd combined stress (Cu1Cd1), and high-concentration Cu–Cd combined stress (Cu2Cd2), and an uncontaminated soil as a control. Results demonstrated that the net photosynthetic rate and chlorophyll content are approximately 8.36–72.51% and 7.22–36.50%, respectively, lower under the Cu, Cd, and Cu–Cd combined stresses than under the control. The net photosynthetic rates are higher under Cu2 and Cd2 than under Cu1 and Cd1; by contrast, the net photosynthetic rate of leaves is lower under Cu2Cd2 than under Cu1Cd1. The net photosynthesis rate of Cinnamomum camphora is significantly positively correlated with superoxide dismutase activity but is significantly negatively correlated with the total chlorophyll, malondialdehyde, soluble sugar, and proline contents. Young Cinnamomum camphora grows well under Cu, Cd, and Cu–Cd combined stresses and is applicable in ecologically restoring heavy metal–contaminated soils.

The formation of a common mycorrhizal network (CMN) between roots of different plant species enables nutrient transfers from one plant to another and their coexistence. However, almost all studies on nutrient transfers between CMN-connected plants have separately, but not simultaneously, been demonstrated under the same experimentation. Both conspecific and heterospecific seedlings of Cinnamomum camphora, Bidens pilosa, and Broussonetia papyrifera native to a karst habitat in southwest China were concurrently grown in a growth microcosm that had seven hollowed compartments (six around one in the center) being covered by 35.0-μm and/or 0.45-μm nylon mesh. The Ci. camphora in the central compartment was supplied with or without Glomus etunicatum and ¹⁵N to track N transfers between CMN-connected conspecific and heterospecific seedlings. The results showed as follows: significant greater nitrogen accumulations, biomass productions, ¹⁵N content, % Nₜᵣₐₙₛfₑᵣ, and the Nₜᵣₐₙₛfₑᵣ amount between receiver plant species ranked as Br. papyrifera≈Bi. pilosa > Ci. camphora under both M⁺ and M⁻, and as under M⁺ than under M⁻ for Ci. camphora but not for both Bi. Pilosa and Br. papyrifera; the CMN transferred more nitrogen (¹⁵N content, % Nₜᵣₐₙₛfₑᵣ, and Nₜᵣₐₙₛfₑᵣ amount) from the donor Ci. camphora to the heterospecific Br. papyrifera and Bi. pilosa, with a lower percentage of nitrogen derived from transfer (%NDFT). These findings suggest that the CMN may potentially regulate the nitrogen transfer from a donor plant to individual heterospecific receiver plants, where the ratio of nitrogen derived from transfer depends on the biomass strength of the individual plants.

Natural adsorbent (Cinnamomum camphora sawdust) modified by organic acid (oxalic acid, citric acid, and tartaric acid) was investigated as a potential adsorbent for the removal of hazardous malachite green (MG) dye in aqueous media in a batch process. The extent of MG adsorption onto modified sawdust increased with increasing organic acid concentrations, pH, contact time, and temperature but decreased with increasing adsorbent dosage and ionic strength. Kinetic study indicated that the pseudo-second-order kinetic model could best describe the adsorption kinetics of MG. Equilibrium data were found to fit well with the Langmuir model, and the maximum adsorption capacity of the three kinds of organic acid-modified sawdust was 280.3, 222.8, and 157.5 mg/g, respectively. Thermodynamic parameters suggested that the sorption of MG was an endothermic process. The adsorption mechanism, the application of adsorbents in practical wastewater, the prediction of single-stage batch adsorption system, and the disposal of depleted adsorbents were also discussed.