Search

As a significant environmental issue, global warming will have a significant impact on soil microorganisms, especially soil bacteria. However, the effects of warming on the network structure of bacterial communities and the function of ecosystems remain unclear. Therefore, we examined the effects of three-year simulated field warming on the complexity of soil bacterial communities and predicted functions in a temperate steppe of Inner Mongolia. Warming significantly increased the α-diversity of bacteria in 2018 but did not affect it in 2019 and 2020. Warming increased network complexity and stability and keystone taxa, and these bacterial taxa also associated more closely with each other, indicating that the protection of interactions between bacterial taxa is very important for the conservation of biodiversity. Warming significantly increased aerobic chemoheterotrophy, ureolysis, and chemoheterotrophy, suggesting that warming increased the ability of bacteria to decompose organic matter and the emission of greenhouse gases, such as CO2 and CH4. Collectively, warming will alter soil bacterial community structure and its potential functions, further affecting key functions in grassland belowground ecosystems.

In order to prevent land degradation in areas before hosting big events such as the Winter Olympic Games (WOG), developing strategic vegetation restoration plans is key. To evaluate four experimental areas with different degrees of human impacts located in the Chongli District, northern Hebei Province, China, where the coming WOG 2022 will take considering: i) the feedback mechanisms between vegetation and soil in the process of future vegetation restoration; ii) the vegetation productivity of land in different land-use types; iii) the management mode considering the sustainable development as the primary goal. To achieve these goals, we applied a minimum soil data set (MDS) to screen the most relevant indicators (soil organic matter (SOM), total nitrogen (TN), total phosphorus (TP), available phosphorus (AP), available potassium (AK), available nitrogen (AN), soil bulk density (BD), soil porosity (SP), pH, clay, silt, sand and gravel), and the nonlinear scoring method to establish a soil quality index (SQI). For this purpose, 400 soil samples (0–20 cm depth), the total biomass of one natural grassland (NG) and abandoned farmland (AF), and the growing stock of natural secondary forest (NF) and a larch plantation (LP). The results showed that the SQI can be established based on TN, silt, TP and gravel. Under LP and AF land-use type, vegetation showing a poor effect on the improvement of soil quality (SQIs were significantly lower than the NF and NG). It was also observed that above 1700 m, the growing stock of artificial vegetation exceeds the range of vegetation productivity (about 165 m3·h−1) that the land can carry under the LP. We concluded that the main reason is the excessive depletion of N and P after human impacts. On the other hand, the SQI of NF and NG were higher, which is due to the significant improvement of soil quality by the conservation of the vegetation, so that no longer limited by the spatial distribution law, also showing higher vegetation productivity of land at different altitudes. This demonstrates that it is key to develop effective restoration plans considering the soil-vegetation relationship status of the NF and NG land-use types in this area in the territories used by the activities of the WOG 2022.

United Nations established 2021-2030 as the decade for ecosystem restoration and "prevent, halt and reverse the degradation of ecosystems worldwide". Ecosystem and land degradation are a global phenomenon. As a consequence of land degradation, in the late 1990s, the "Grain for Green Program" (GFGP) was established in Loess Plateau (China). It converted slope farmlands to forest or grassland over the, resulting in a visible "greening" trend. Other effects of GFGP on soil properties, land production, hydrological conditions, ecosystem services, and policy implications are the topics of this Special Issue. This Special Issue includes 17 contributions that cover recent research carried out in Loess Plateau in the mentioned topics at different spatial and temporal scales. The collection of papers presented in this Special Issue discusses critical issues in vegetation restoration and sustainable land management in the region. This Special Issue will contribute to United Nations strategy for ecosystems restoration.

Dust deposition can supply nutrients that affect marine phytoplankton, but changing trophic statuses of the surface ocean increase the complexity of interpreting the process. In this study, four onboard incubation experiments amended with various nutrients and dust were performed in the Kuroshio Extension (KE) and Kuroshio–Oyashio transition (TR) of the northwest Pacific (NWP), which are characterised by lower and higher trophic statuses, respectively. According to the nutrient-addition experiments, phytoplankton were limited by nitrogen (N) in the KE, and limited by iron (Fe) or co-limited by Fe and phosphorus (P) in the TR. Dust additions supplied a considerable amount of N and Fe but negligible amount of P to stimulate phytoplankton growth, as indicated by chlorophyll a (Chl a) concentration. In the KE incubations, dust additions enhanced the shift of phytoplankton size structure towards larger cells from dominantly pico-sized (0.2–2 μm) Chl a to comparable contributions from each size class (i.e. pico-, nano-: 2–20 μm, micro-: >20 μm). On the basis of the large shift of size structure towards nano- or micro-phytoplankton in the unamended control treatments in the TR, dust additions furtherly promoted the shift towards micro-phytoplankton becoming the dominant contributor to the total Chl a. The collective analysis of the data from experiments in both regions revealed that, the extent of phytoplankton growth stimulation and the shift towards larger cells were enhanced gradually with increasing amounts of nutrient uptake (including N, P, and silicon). The nutrient uptake ratios of phytoplankton converged towards the Redfield ratio in comparison to the wider range of nutrient ratios in the dust-amended seawater. This study suggested consistencies in the dynamic of phytoplankton growth, shift of size structure, and nutrient uptake following dust additions in the KE and TR, although the trophic status and limiting nutrient varied between these two regions.

The incidence of asthma and its related allergic diseases has increased dramatically over the last decade. Asthma is a complex disease caused by genetic and environmental factors. Nonylphenol (NP), a typical endocrine disrupting chemical (EDC), is a major current focus in asthma research. Pregnant Sprague-Dawley rats (n = 8–10 per group) were given a consecutive daily dose of NP (25, 50, or 100 mg/kg/day) or an equivalent volume of vehicle by gavage from gestational day 7 until postnatal day (PND) 21. Exposure to 100 mg/kg NP increased the body mass of the offspring on PND 43. Perinatal exposure to NP in maternal rats led to a dose-dependent increase of NP level in the lung tissue of the offspring. The numbers of lymphocytes and neutrophils in bronchoalveolar lavage fluid were significantly higher in the 100 mg/kg NP group than those in the control. Histopathological examination of the lung showed that exposure to high dose NP resulted in a slightly thickened bronchiolar smooth muscles with inflammatory cell infiltration. In the cytoplasm of type II epithelial cells, osmiophilic lamellar bodies were observed, with emptied lamellar bodies. NP significantly increased the expressions of high mobility group box 1 protein (HMGB1) mRNA and nuclear factor κB (NF-κB) mRNA in the lung tissue of the offspring in a dose dependent manner. Similarly, the expressions of HMGB1, NF-κBp65 and estrogen receptor-β (ER-β) proteins increased with an increase of NP dose. NP content was positively correlated with the expressions of HMGB1 and NF-κB mRNA as well as HMGB1, NF-κBp65, and ER-β proteins in the lung tissue of offspring. Perinatal exposure to NP from the maternal rats might induce airway inflammation in the offspring, which may be due to NP-induced infiltration of inflammatory cells into the airway, and pathological alterations in airway structure as well as abnormal expression patterns of inflammation-related genes, proteins (including HMGB1 and NF-κB) and estrogen receptor β.

Land use change alters the hydrological process, which in turn affects the migration of heavy metals. However, analyses of the watershed-scale distribution of heavy metals from slope to dam fields have seldom been studied. In this study, three land-use types on the slope (cropland, shrubland, grassland) and dam land in the channel on the Loess Plateau were selected to analyze the relationship between the change of slope erosion rate and the migration process of Manganese (Mn), Chromium (Cr), Zinc (Zn), Vanadium (V), Nickel (Ni), Copper (Cu), Arsenic (As) and Cobalt (Co) in soil. Moreover, the sources of heavy metals in sediments and their historical deposition process were revealed. It was found that the concentrations of Cr and As were higher in cropland than that in grassland and shrubland. The soil erosion of cropland was the most serious, and the maximum annual erosion rate was as high as 10,853.56 t km−2. The distribution of heavy metals was related to erosion rate in the cropland. With soil erosion, Cr, V, As, Co and Zn in cropland were prone to runoff migration. Cr and As in dam sediments mainly originated from the agricultural activities in cropland. Cu, Co, Mn, Ni, V and Zn in the dam land were largely affected by soil parent material. Land use and soil erosion were important factors influencing the redistribution of heavy metals. By optimizing land use patterns and reducing soil erosion, it is possible to control the migration and accumulation of heavy metals in the watershed. The findings of this study can serve as important reference for reducing non-point source pollution.

The exploitation of groundwater resources is of great importance and has become crucial in the last few decades, especially in arid regions, where surface water resources are scarce and unreliable. The Hexi Corridor (HC) is one of the most agriculturally rich and densely populated areas of arid northwestern China. Increasing demand for water, due to rapid population growth, oasis expansion and urbanization, has increased groundwater use, resulting in wide-scale depletion in this region. Sustainable management of aquifers in the HC requires accurate estimates of the current situation of groundwater resource sustainability. In this work, groundwater storage anomaly (∆GWS) were estimated using the Gravity Recovery and Climate Experiment (GRACE) satellite data, the Global Land Data Assimilation System (GLDAS) data and the water-table fluctuation (WTF) method based on in-situ groundwater level data. Combined with the groundwater sustainability index (SIGWS), groundwater sustainability in the HC was then evaluated. Potential factors that could affect regional groundwater sustainability were analyzed by including and testing climate and socio-economic variables during the period of 1981 to 2016. We found that (1) groundwater in the HC has experienced a general deterioration (except for a sudden and sharp increase observed around 2002) in both storage and sustainability, from ∆GWS = 16.79 cm/year and SIGWS = 0.46 (1985–1990) to ∆GWS = −28.96 cm/year and SIGWS = 0.008 (2007–2016); (2) the lowest value of groundwater sustainability in the HC appeared in the central and eastern regions (SIGWS = 0); (3) human activity was confirmed to be the dominant factor driving the processes of deterioration in groundwater sustainability in the HC, and during the research period, it is striking that relatively limited “positive” effects of the water management project were detected on the regional groundwater resource; this result indicates that damaged groundwater sustainability cannot be easily reversed unless a long-term management policy is implemented. This study also proves that GRACE gravity satellite data has great application potential in groundwater sustainability evaluation in arid regions, especially in developing countries where in-situ data are scarce, and highlights the importance of joint management of surface water and groundwater, in groundwater sustainability management.

Calcium nitrate (Ca(NO3)2) addition can be used to control the release of phosphorus from sediments, however it can also cause an increase in the concentration of nitrate‑nitrogen (NO3−-N) in the water column. The risk of NO3−-N release from the Ca(NO3)2-injected sediments may be reduced by the placement of the anion exchange resin (AER) capping layer. In this study, the effectiveness of the combined use of Ca(NO3)2 addition and AER capping to prevent the liberation of phosphorus from sediments was investigated, and the reduction of the risk of NO3−-N released from the Ca(NO3)2-injected sediment by the AER capping was also evaluated. The combined application of Ca(NO3)2 addition and AER capping could tremendously reduce the amount of soluble reactive phosphorus (SR-P) in the overlying water, with SR-P reduction rates of 75.9–98.7%. Furthermore, it could cut down the contents of high-resolution diffusive gradients in thin films (DGT)-labile phosphorus in the sediments, resulting in the formation of phosphorus static layer in the upper sediments. The combined treatment using Ca(NO3)2 and AER had a relatively small effect on the contents of mobile phosphorus in the sediments, but it could greatly increase the amount of residual phosphorus in the top 30 mm sediments (increased by 27.7–42.9%). The amount of NO3−-N in the overlying water under the action of the combined treatment method using Ca(NO3)2 and AER was much lower than that under the action of the single Ca(NO3)2 treatment during the early stage of sediment remediation. In conclusion, the combined use of Ca(NO3)2 addition and AER capping is a more promising strategy for the control of sedimentary phosphorus release than the single use of Ca(NO3)2 addition from the point of view of both the control efficiency of P release from sediments and the releasing risk of the added nitrate.

This study aimed to evaluate internal biomarkers and external estimation of exposure to polycyclic aromatic hydrocarbons (PAH) in a high cancer mortality area in southeast China and identify which of these showed a stronger association of PAH with cancer mortality. A retrospective death survey was conducted to determine the mortality rate of cancer. Cumulative and aggregate external exposures to PAHs of local residents were estimated by field sampling. Three regions in southwest China with gradient PAH exposure levels from high to low (H, M, and L) were selected in this study. Research participants were selected from these three regions using a statistical sampling method. To determine the internal exposure, urinary OH-PAHs were measured using the first morning urine samples. From the retrospective death survey, the highest age-standardized lung cancer mortality rate occurred in Region H (78 per 100,000 person-years), followed by that in Regions M (33 per 100,000 person-years) and L (15 per 100,000 person-years), and the rate was nearly four times China's national mortality rate (20 per 100,000 person-years). Residents estimated daily aggregate exposure doses per unit body weight to carcinogenic benzo(a)pyrene equivalent concentration were 159 ± 14 ng-kg−1-day−1, 7.41 ± 2.76 ng-kg−1-day−1, and 6.13 ± 2.89 ng-kg−1-day−1 in Region H, M, and L, respectively. The participants in Region M had the greatest urinary OH-PAH concentration (9.10 ± 4.92 μg-g−1 crt), followed by Region H (8.01 ± 4.22 μg-g−1 crt) and L (7.12 ± 3.10 μg-g−1 crt). The spatial difference in the total OH-PAHs was not statistically significant. Aggregate and cumulative exposure to 16 PAHs from external routes were found, and external exposure had a stringer relationship with lung cancer mortality than internal exposure.

Dust deposition can bring nutrients and trace elements to the upper ocean and affect phytoplankton growth and community structure. We conducted a comparative study using on-board microcosm experiments amended with varying amounts of dust (0.2, 1, and 2 mg L−1) in the East China Sea (eutrophic zone), the subtropical gyre (low-nutrient and low-chlorophyll zone, LNLC), and the Kuroshio-Oyashio transition region (high-nutrient and low-chlorophyll zone, HNLC) of the Northwest Pacific Ocean. The additions of dust supplied a considerable amount of nitrogen (N) and negligible phosphorus (P) relative to the seawater collected for incubation experiments (baseline), contributing to increases in Chlorophyll a with increasing dust additions. Significant linear correlations were observed between the net growth rates of larger cells (i.e., micro-size: >20 μm and nano-size: 2–20 μm) and available N (sum of baseline and added N) at each zone, demonstrating that phytoplankton size structure shifts towards larger cells with the increasing dust additions. In the experiments conducted in LNLC and HNLC zones, micro-sized phytoplankton (primarily consisting of diatoms) benefited most from dust additions. In the experiments conducted in eutrophic zone, however, the primary beneficiary was the nano-sized phytoplankton (primarily consisting of dinoflagellates). When a time lag of one day in relative abundance of diatoms (RAD, the abundance of diatoms divided by the sum of diatoms and dinoflagellates) relative to the N:P ratio was considered, we found the RAD increased substantially with increases in the N:P ratio until the ratio approached the Redfield ratio (N:P = 16:1), and then the RAD decreased gradually as the N:P ratio increased. This was ascribed to the lower sensitivity of dinoflagellates to nutrient shortage, relative to diatoms. Overall, our results suggested that the overwhelming input of N relative to P by dust deposition might cause significant ecological impacts by altering the N:P ratio of varying trophic seawaters.

Understanding the relative effect sizes of climate-related environmental variables and nutrients on the high annual variation in the phytoplankton biomass in eutrophic lakes is important for lake management efforts. In this study, we used a data set of phytoplankton dynamics in eutrophic Lake Taihu that cover more than two decades (1993–2015) to show the variation in and the drivers of phytoplankton biomass under complex, fluctuating environmental conditions. Our results showed that the phytoplankton biomass increased slowly over the studied period despite the recent decrease in nutrient levels. The distribution of the phytoplankton biomass expanded spatially towards the central lake region, and seasonally towards the autumn and winter. Nutrients were still the primary predictors of the long-term phytoplankton biomass trend. The effect size of climate-related variables was also high and close to the effect size of nutrients. Among the climate-related variables, wind speed and underwater available light were more important predictors than temperature. The biomass of the phytoplankton taxonomic groups showed different responses to the environmental variables based on their niches. However, the compensatory dynamics affecting biomass were weak at phylum level, and synchronous dynamics drove the variation in total biomass. Our findings highlight the effect of climate-related variables on the phytoplankton biomass in Lake Taihu, which has experienced high nutrient loadings and concentrations for more than two decades. Therefore, changes in climate-related variables, such as wind speed and underwater available light, should be considered when evaluating the amount that nutrients should be reduced in Lake Taihu for future lake management.

In this study, heterogeneous Fenton-like degradation of ofloxacin (OFX) was investigated by sludge derived carbon (SC). The effects of SC catalyst, temperature and pH on the efficiency of ofloxacin degradation were investigated. SC treated with sulfuric acid (SC-H2SO4) performed high catalytic activity, indicating that sulfate group produced low pH of the surface and was beneficial for heterogeneous Fenton-like degradation. The removal of ofloxacin and TOC was 91.5% and 62.3%, respectively, after 180 min adsorption and 540 min oxidation, at pH 6 and a dosage of 138 mg L−1 H2O2. It was found that OFX conversion increased with the decrease of pH and OFX was degraded under the wide range of pH (3–6) by SC-H2SO4. These promising results clearly demonstrate the potential of the heterogeneous Fenton-like process for the effective degradation of ofloxacin by SC-H2SO4. Based on intermediated products identified by gas chromatography–mass spectrometry, a possible OFX oxidation pathway in Fenton-like reaction was proposed.

Our previous study showed that endosulfan increases the risk of cardiovascular disease. To identify toxic mechanism of endosulfan, we conducted an animal study for which 32 male Wistar rats were randomly and equally divided into four groups: Control group (corn oil only) and three treatment groups (1, 5 and 10mgkg-1·d-1). The results showed that exposure to endosulfan resulted in injury of cardiac tissue with impaired mitochondria integrity and elevated 8-OHdG expression in myocardial cells. Moreover, endosulfan increased the expressions of Fas, FasL, Caspase-8, Cleaved Caspase-8, Caspase-3 and Cleaved Caspase-3 in cardiac tissue. In vitro, human umbilical vein endothelial cells (HUVECs) were treated with different concentrations of endosulfan (1, 6 and 12μgmL-1) for 24h. An inhibitor for Ataxia Telangiectasia Mutated Protein (ATM) (Ku-55933, 10μM) was added in 12μgmL-1 group for 2h before exposure to endosulfan. Results showed that endosulfan induced DNA damage and activated DNA damage response signaling pathway (ATM/Chk2 and ATR/Chk1) and consequent cell cycle checkpoint. Furthermore, endosulfan promoted the cell apoptosis through death receptor pathway resulting from oxidative stress. The results provide a new insight for mechanism of endosulfan-induced cardiovascular toxicity which will be helpful in future prevention of cardiovascular diseases induced by endosulfan.

A significant amount of polycyclic aromatic hydrocarbons (PAHs) adsorbed in street dust ends up in runoff. Accordingly, evaluating the content, possible wash-off load and constituent risks associated with street dust is critical for urban runoff usage. Based on the PAH concentrations examined in this study, different risk assessment methods were applied and the differences among results were analyzed. An improved PAH wash-off calculation method was established and the annual PAH wash-off load was obtained. In addition, emission sources were diagnosed based on isomer ratios and PMF methods. The overall mean ΣPAHs (sum of 16 individual PAHs) concentration in the street dust was 3.70 μg/g, with the highest mean concentrations found for main roads (5.18 μg/g). Adjacent anthropogenic activities had a greater effect on pollution characteristics of street dust than land use types. The toxic risk order was park (0.64 μg/g) > main road (0.57 μg/g) > residence (0.32 μg/g) > street (0.29 μg/g) > commerce (0.23 μg/g), while that of the ecological risk index was main road (1278) > street (920) > residence (904) > commerce (713) > park (195). Although the park sites had a high level of toxic risk, they showed low ecological risk because they had less dust mass per unit area, indicating a great difference in the risk evaluation results and the difference methods. Using different values for different magnitudes of the antecedent dry days, rainfall event amounts, and dust mass fraction of different size ranges, the average wash-off load of ΣPAHs from street dust was calculated to be 23 kg per year in Beijing from 2000 to 2014 with an improved wash-off load calculation method. The main sources of PAHs in the street dust of Beijing's center were identified as gasoline emissions, diesel emissions, coal combustion and unburned petroleum.