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Agricultural non-point source pollution refers that substance such as nitrogen and phosphorus cause water environment pollution through surface runoff and underground leakage in agricultural production activities. Water environment pollution related to agricultural non-point source pollution in the Huaihe River Basin is becoming more and more prominent. Therefore, it is necessary to analyze the characteristic of soil nutrient in cultivated land and explore the spatial variation and influencing factors of soil nutrients at the watershed scale. A total of 239 topsoil samples were collected from the Guo river basin, and the related factors of soil organic matter (SOM), total carbon (TC), total nitrogen (TN), total phosphorous (TP), total potassium (TK) and potential of hydrogen (PH) were studied by using descriptive statistics and geostatistical methods. The results showed that TK and PH were weak variation, while SOM, TC, TN and TP were medium variation. Soil pH, TP, TK, TC and SOM had moderate spatial variability, which was caused by both random factors and structural factors such as soil texture, soil type, fertilization and local ecological restoration management. Soil TN showed a strong spatial correlation, mainly due to soil texture and soil type. If the recommended fertilization amount is still given based on the average value of soil nutrients ignoring the spatial heterogeneity, it will not only affect crop production efficiency and fertilizer utilization, but may also cause greater environmental pollution. This study can provide a theoretical basis for the management of agro-ecological environments throughout the basin area.

Heavy metals contaminate the soil that alters the properties of soil and negatively affect plants growth. Using microorganism and plant can remove these pollutants from soil. The present investigation was designed to evaluate the induced effect of Bacillus pumilus on maize plant in Cadmium (Cd) contaminated soil. Three different concentrations of Cd (i.e. 0.25, 0.50 and 0.75 mg kg −1 ) were applied in soil under which maize plants were grown. The germination percentage, shoot length, leaf length, number of leaves, root length, fresh weight and nutrient uptake by maize plant were determined. The experiment was conducted by using complete randomized design (CRD) with three replicates. The result indicated that germination percentage, Shoot length, leaf length, root length, number of leaves, and plant fresh weight were reduced by 37, 39, 39, 32 and 59% respectively at 0.75 mg kg −1 of CdSO 4 concentration but when maize seeds inoculated with Bacillus pumilus significantly increased the germination percentage, shoot length, leaf length, number of leaves, plant fresh weight at different concentrations of CdSO 4 . Moreover, the plant protein were significantly increased by 60% in T6 (0.25 mg kg −1 of CdSO 4  + inoculated seed) and Peroxidase dismutase (POD) was also significantly higher by 346% in T6 (0.25 mg kg −1 of CdSO 4  + inoculated seed), however, the Superoxide dismutase (SOD) was significantly higher in T5 (0.75 mg kg −1 of CdSO 4  + uninoculated seed) and was 769% higher as compared to control. The Cd contents in Bacillus pumilus inoculated maize roots and shoots were decreased. The present investigations indicated that the inoculation of maize plant with Bacillus pumilus can help maize plants to withstand Cd stress but higher concentration of Cd can harm the plant. The Bacillus pumilus has good potential to remediate Cd from soil, and also have potential to reduce the phyto availability and toxicity of Cd.

With the rapid rate of urbanization, green infrastructure land is increasingly being converted to urban construction land, and the fragmentation of regional green infrastructure (GI) networks is intensifying. The connectivity of a GI network is of paramount importance for maintaining both regional biodiversity and regional ecosystem service capacity, among others. In this paper, an innovative approach to planning a GI network is presented. The proposed approach is based on the Morphological Spatial Pattern Analysis (MSPA) method, minimum path method, and circuit theory. Using the Zhengzhou–Kaifeng metropolitan area in China as a case study, we argue that the combination of the MSPA method and circuit theory can more fully and comprehensively identify the components of a GI network and its key areas. The methodology consists of three steps: (i) Identifying the cores and bridges of the GI by the MSPA method based on land use data, followed by determining the hubs of the GI network by assessing the connectivity of the core area; (ii) establishing potential connecting corridors between hubs by the minimum path method; (iii) identifying the “pinch point” area of the potential connecting corridors based on current density by applying circuit theory. This approach not only makes identification of the “hubs” and “links” in the green infrastructure network more scientific and comprehensive, but it also further identifies “pinch point” areas of the connecting corridors that require priority protection or recovery. The research results can be used as a practical reference for urban planners when planning urban land use.

Background Zinc (Zn) and nickel (Ni) are nutrients that are crucial for plant growth; however, when they are present at higher concentrations, they can cause toxicity in plants. The present study aimed to isolate plant growth promoting endophytic bacteria from Viburnum grandiflorum and assess its plant and defense promoting potential alone and in combination with R P in zinc (Zn) and nickel (Ni) toxic soil. The isolated endophytic bacteria were identified using 16s rRNA gene sequencing. For the experiment, twelve different treatments were applied using Zn, Ni, isolated endophytic Bacillus mycoides (Accession # MW979613), and rock phosphate (RP). The Ni, Zn and R P were used at the rate of (100 mg/kg) and (0.2 g/kg) respectively. A pot experiment with three replicates of each treatment was conducted using a complete randomized design (CRD). Results The results indicated that Ni (T5 = seed + 100 mg/kg Ni and T9 = seed + 100 mg/kg Zn) and Zn concentrations inhibited plant growth, but the intensity of growth inhibition was higher in Ni-contaminated soil. Bacillus mycoides and R P at 100 mg/Kg Zn (T12 = inoculated seed + 100 mg/kg Zn + R P 0.2 g/kg.) increased the shoot length, leaf width, protein and sugar content by 57%, 13%, 20% and 34%, respectively, compared to the control. The antioxidant enzymes superoxide dismutases (SOD), peroxidase (POD) were decreased in contaminated soil. Furthermore, Ni and Zn accumulation was inhibited in T11 (seed + 100 mg/kg Zn + R P 0.2 g/Kg) and T12 (inoculated seed + 100 mg/kg Zn + R P 0.2 g/Kg) by 62 and 63% respectively. The Cu, Ca, and K, contents increased by 128, 219 and 85, Mn, Na, and K by 326, 449, and 84% in (T3 = inoculated seed) and (T4 = inoculated seed + R P 0.2 g/Kg) respectively. Conclusions Ni was more toxic to plants than Zn, but endophytic bacteria isolated from Viburnum grandiflorum , helped wheat ( Triticum aestivum ) plants and reduced the toxic effects of Ni and Zn. The effect of Bacillus mycoides was more prominent in combination with R P which promoted and suppressed heavy-metal toxicity. The reported combination of Bacillus mycoides and R P may be useful for improving plant growth and overcoming metal stress.

Soil erosion has a severe impact on habitat and productivity. It is considered to be a major environmental threat prevalent in ecosystems. However, few researchers have studied the spatial distribution of soil erosion intensity among different geographic environmental factors. The Qin River Basin is a geographical unit consisting of mountains, hills, and plains with significant regional characteristics, and it has a basin area of 14,810.91 km 2 . This study uses the Geographical Information Systems, Revised Universal Soil Loss Equation model to analyze the spatiotemporal changes in the soil-erosion intensity in the Qin River Basin from 1990 to 2018. Different environmental factors of land use, slope and altitude on erosion intensities of 19 secondary land types were analyzed. It can better reflect the soil erosion under different environmental factors and different land use types. Results show that the soil erosion modulus of Qin River Basin were 10.25 t hm −2 a −1 , and it belong to slight erosion from 1990 to 2018. Soil erosion intensity is greater in grassland and woodland than in cropland. The strongest soil erosion occurred in the sparse forestland, and the lowest was in beach land. Soil erosion was the highest for a slope of 15~25° and an altitude of 1200~1500 m. Rainfall and slope are important factors lead to soil erosion, indicating weak water and soil conservation implemented in these areas. Therefore, priority should be given to these geomorphic units to formulate and implement soil-erosion control and ecological restoration policies in the Qin River Basin. This study provides a good reference for preventing and controlling soil erosion in river basins.

Urbanization is causing profound changes in ecosystem functions at local and regional scales. The net primary productivity (NPP) is an important indicator of global change, rapid urbanization and climate change will have a significant impact on NPP, and urban expansion and climate change in different regions have different impacts on NPP, especially in densely populated areas. However, to date, efforts to quantify urban expansion and climate change have been limited, and the impact of long-term continuous changes in NPP has not been well understood. Based on land use data, night light data, NPP data, climate data, and a series of social and economic data, we performed a comprehensive analysis of land use change in terms of type and intensity and explored the pattern of urban expansion and its relationship with NPP and climate change for the period of 2000–2015, taking Zhengzhou, China, as an example. The results show that the major form of land use change was cropland to built-up land during the 2000–2015 period, with a total area of 367.51 km2 converted. The NPP exhibited a generally increasing trend in the study area except for built-up land and water area. The average correlation coefficients between temperature and NPP and precipitation and NPP were 0.267 and 0.020, respectively, indicating that an increase in temperature and precipitation can promote NPP despite significant spatial differences. During the examined period, most expansion areas exhibited an increasing NPP trend, indicating that the influence of urban expansion on NPP is mainly characterized by an evident influence of the expansion area. The study can provide a reference for Zhengzhou and even the world's practical research to improve land use efficiency, increase agricultural productivity and natural carbon sinks, and maintain low-carbon development.

Climate variation and land use changes have been widely recognized as two major factors that impact hydrological processes. However, it is difficult to distinguish their contributions to changes in streamflow. Quantifying their contributions to alteration of streamflow is especially important for the sustainable management of water resources. In this study, the changes in streamflow for the period of 1960–2008 at two stations (Dongwan and Luhun) were analyzed in the Yihe watershed in China based on hydrological data series and climate parameters. Using a non-parametric Mann–Kendall (MK) and Pettitt’s test, as well as Budyko analysis, we first examined the trends of hydroclimatic variables and the breakpoint of annual streamflow over the past 50 years. Subsequently, we evaluated the contributions of annual precipitation (P), potential evapotranspiration (PET), and land use condition (represented by w), respectively, to streamflow variation. We observed a decreasing trend for P, as well as increasing trends for PET and w. Annual streamflow showed a significant downward trend with an abrupt change occurring in 1985 during the period of 1960–2008. Accordingly, we divided the studied period into two sub-periods: period I (1960–1985) and period II (1986–2008). The sensitivity of the streamflow to the different environmental factors concerned in this study differed. Streamflow was more sensitive to P than to PET and w. The decrease in P was the greatest contributor to the decline in streamflow, which accounted for 50.01% for Dongwan and 55.36% for Luhun, followed by PET, which accounted for 24.25% for Dongwan and 24.45% for Luhun, and land use change was responsible for 25.25% for Dongwan and 20.19% for Luhun. Although land use change plays a smaller role in streamflow reduction, land use optimization and adjustment still have great significance for future water resource management, since climate variation is difficult to control; however, the pattern optimization of land use can be achieved subjectively.

With the acceleration of urbanization, the heat island effect, as a prominent feature of urban climate, has attracted more attention. Differences in urban landscape patterns have an essential impact on the urban thermal environment. The objective of the study is to examine the impact of urban landscape types and patterns on surface temperature. Taking Zhengzhou City, China, as an example, using Google Earth remote sensing images, an urban landscape type map was created, and landscape indices were calculated. The land surface temperature (LST) of the study area was retrieved by the Landsat-8 thermal infrared band. Correlation analysis indicated that the relationships between urban landscape patterns and the thermal environment were as follows: (i) The scale indices (percentage of landscape (PLAND), largest patch index (LPI), edge density (ED), patch density (PD)) of urban landscape types with cooling effect (water body, riverfront area, park, high-rise building) were significantly negative correlated with mean LST of each partition. (ii) Conversely, there were significant positive correlations between the PLAND and LPI of landscape types with warming effect (block, development land, railway land) and the LST of the partition. (iii) The DIVISION index of the four kinds of landscapes with cooling effect was highly positively correlated with LST, and the DIVISION and SPLIT indices of the three kinds of landscapes with warming effect displayed a remarkable negative relationship with LST. Therefore, under the condition of scale control, integrated distribution of landscape with cooling effect, scattered distribution of landscape with warming effect, and reduced connectivity of landscape with warming effect will contribute to effectively alleviating the formation of urban heat islands.

Optimizing the layout of green infrastructure (GI) is an effective way to alleviate the fragmentation of urban landscapes, coordinate the relationship between urban development and urban ecosystem services, and ensure the sustainable development of cities. This study provides a new technical framework for optimizing GI networks based on a case study of Kaifeng, an exemplar of many ancient cities along the Yellow River in China. To do this, we used a morphological spatial pattern analysis (MSPA) methodology and combined it with Procedure for mAthematical aNalysis of lanDscape evOlution and equilibRium scenarios Assessment (PANDORA) model to determine the hubs of the GI network. Then we employed a least-cost path approach to simulate potential corridors linking the hubs. We further identify the key ‘pinch points’ of the GI network that need priority protection based on circuit theory. Altogether, this framework takes patches that have a high level of ecosystem services and are more important in maintaining overall connectivity as hubs, thereby improving the accuracy of hub identification. Moreover, it establishes a direct connection between GI construction and ecosystem services, and improves biodiversity conservation by optimizing the network structure of GI. The results of the case study show that this framework is suitable for GI planning and construction, and can provide effective technical support for the formulation of urban sustainable development strategies.

Oily sludge contains a wide range of carcinogenic and toxic organic and inorganic compounds that enter into the terrestrial environment and may be toxic to plants. Plants grown over oily sludge–contaminated soil may undergo changes in physiology and in the antioxidant enzymes system due to the presence of toxic hydrocarbons. Information is scarce regarding the inoculation of oily sludge on the changes in the physiology of plants. The present study evaluated the effect of a constructed bacterial consortium and fertilizers on maize (Zea mays L.) growth and survival and on its antioxidant system under the stress environment of 30% and 60% oily sludge. Maize grown over 30% and 60% oily sludge was inoculated with a consortium of plant growth–promoting rhizobacteria strains (Bacillus cereus [Acc KF859972], Bacillus altitudinis [Acc KF859970], comamonadaceae (Delftia) [Acc KF859971], and Stenotrophomonas maltophilia [Acc KF859973]). The bioavailability of some phytotoxic trace elements was also evaluated. Germination was inhibited when plants were grown without inoculation; however, no inhibition to the germination of maize was observed when bacterial consortium was added to oily sludge. A significant difference in the bioavailability of Cu and Zn was observed under maize rhizosphere oily sludge inoculated with consortium. Germination rate, protein, superoxide dismutase, and peroxidase in bacterial consortium–inoculated maize was higher in plants grown in oily sludge compared with plants grown in untreated sludge. The bacterial consortium suppressed the oxidative stress of plants grown in oily sludge and enhanced maize tolerance to oily sludge. The bacterial consortium can be used for enhancing plant nutrient uptake and to increase biochemical and plant enzymes and can be used by oil refineries to remediate soils contaminated with oily sludge.