Simulation of land use landscape pattern evolution from a multi-scenario simulation: a case study of Nansi Lake Basin in China.

Reasonable regulation of the total amount and layout of land resources is the significant cornerstone for releasing the potential of land resources. This study explored the spatial layout and evolution characteristics of the Nansi Lake Basin from the perspective of land use and simulated the spatial distribution pattern under multiple scenarios in 2035 with the Future Land Use Simulation model which more effectively reflected the process of land use change in the actual situation, revealing the land use change of the Nansi Lake Basin under the influence of different human activities. Analysis indicated that the simulation results obtained using the Future Land Use Simulation model strongly agree with reality. By 2035, the magnitude and spatial distribution of land use landscapes will change significantly under three scenarios. The findings provide a reference for the adjustment of land use planning in the Nansi Lake Basin.

Land-use changes and ecosystem services under different scenarios in Nansi Lake Basin, China.

Ecosystem services (ESs) have been affected drastically by rapid urban sprawl and significant land-use changes (LUC) in Nansi Lake Basin (NLB) in China. Based on land-use data with a 30-m resolution from 1990 to 2015, we analyzed the process of LUC by atlas analysis and explored the impacts of LUC on ecological service value (ESV) under urban sprawl. The results showed that water area and buildup land increased significantly from 1990 to 2015. The area of cultivated land, forests, grassland, and unutilized land decreased. Land transfer mainly occurred between cultivated land, water area, and grassland. The total amount of land transfer was 4830.64 km2, and the average transfer rate is 185.79 km2/year in 26 years. The most obvious transfer occurred in period IV. The increased buildup land was mainly transferred from cultivated land. The total urban sprawl in the NLB was 1623.37 km2 in the past 26 years, with an average expansion rate of 62.44 km2/year, with the fastest sprawl in period IV. Tengzhou city was the most prominent area of expansion. Its ESV increased by 5.73 × 107 US$ with an increased rate of 2.21 × 106 US$/year. The annual total value of regulating and supporting services in the first-level ESs in the NLB accounted for 54.8 and 25.2% of the total ESV in all years, which were the primary types of ESs. Water area, forests, and cultivated land were the principal contributors to ESV changes. In conclusion, urban sprawl had a significant negative effect on ESV changes. Urban sprawl, water area, forests, and cultivated land were all sensitive factors for ESV changes.

Effect of chemical aging of Alternanthera philoxeroides-derived biochar on the adsorption of Pb(II).

In this study, biochar was prepared from Alternanthera philoxeroides (AP) under O2-limited condition at 350 °C (LB) and 650 °C (HB) and treated with aging by HNO3/H2SO4 oxidation. Structural changes of the biochar after aging treatment and the treatment's effect on Pb(II) absorption were explored. The results showed that oxygen-containing functional groups, aromatic structure and surface area of the biochar increased after the aging treatment. However, the integrity of the tubular structure was broken into fragments. The adsorption process of Pb(II) was in accordance with the pseudo-second-order kinetic model and fitted by the Langmuir model. With the increase of pH, the adsorption capacities of Pb(II) increased gradually, and the adsorption effect was best at pH 5. The aged HB presented a decrease of the carboxyl group, which caused less adsorption capacity of Pb(II) than that of aged LB. The maximum adsorption capacities of Pb(II) on fresh biochar at 350 °C and 650 °C were 279.85 and 286.07 mg·g-1 and on aged biochar were 242.57 and 159.82 mg·g-1, respectively. The adsorption capacity of HB for Pb(II) was higher than that of LB, and the adsorption capacity of aged biochar for Pb(II) decreased obviously, which might be attributable to changes in physicochemical properties of biochar after the aging treatment.

Ecological function zoning of Nansi Lake Basin in China based on ecosystem service bundles.

Ecological function zoning is an essential means of scientific management of ecosystems. According to the characteristics of ecological function zoning, implementing zoning control is conducive to the governance and protection of the ecological environment and the maintenance of ecological sustainability. This study was conducted with the Nansi Lake Basin as the cross-section for 2018. The Integrated Valuation of Ecosystem Services and Trade-offs model was adopted to assess and measure five ecosystem services, including water yield, crop production, soil conservation, carbon storage and carbon sequestration, and habitat quality. The Self-Organizing Feature Maps neural network was applied to obtain the ecosystem service bundles, and then, the ecological function zones were divided. The results indicated that the overall spatial pattern of ecosystem services in the study zone showed a decreasing schema from east to west; There was a trade-off between supply services and support services and a synergy between supply services and regulatory services; according to the bundling results, the Nansi Lake Basin was divided into four ecological functional zones: the eastern ecological surplus zone, the central crop supply zone, the western ecological balance zone, and the lake habitat protection zone. The results showed that (1) the spatial distribution of various ecosystem services in the Nansi Lake Basin showed spatial heterogeneity and specific regional laws, showing a decreasing pattern from the east to the west as a whole, especially in soil conservation, carbon sequestration, and habitat quality. (2) According to the supply and spatial distribution of each ecosystem service, the Nansi Lake Basin was divided into four ecological functional zones: the eastern ecological surplus zone, the central crop supply zone, the western ecological balance zone, and the lake habitat protection zone. (3) For zone I, provisioning services and regulation services were in synergy. For zone II and zone III, the provisioning service had a trade-off relationship with the regulation service and the supporting service. For zone IV, supporting services were trade-offs not only with provisioning services but also with regulating services. In general, the trade-offs between ecosystem service in the Nansi Lake Basin were stronger than the synergies, and the overall benefits of ecosystem services were smaller. Relying on the perspective of the ecosystem service bundles, at the county level, this study provided an analysis of the trade-offs and synergies among ecosystem services in the Nansi Lake Basin, which helped formulate the management plan for the corresponding region and provided the appropriate recommendations for regional habitat conservation and restoration.

[Isolation and identification of a heterotrophic nitrifying and aerobic denitrifying Acinetobacter sp. YF14 and its denitrification activity].

OBJECTIVE: We separated, screened and identified a heterotrophic nitrifying and aerobic denitrifying bacterium from the surface sediment of a culture pool. Furthermore, we studied the role it plays in denitrification. METHODS: We separated the bacterium through enrichment culture, identified it by observing its morphological characteristics, studying its physiological and biochemical properties and making phylogenetic analysis of its 16S rDNA sequences. Then we studied the growth curve by regularly measuring the OD600 value, studied the influencing factors and optimum conditions of denitrification through orthogonal experiment, and examined its denitrification activity through interaction with the activated sludge of sewage treatment plant. RESULTS: The strain was identified as Acinetobacter and named A. sp. YF14, which is the first known Acinetobacter that carries out heterotrophic nitrification and aerobic denitrification. It reached the logarithmic growth phase after 12 hours, the stationary phase after 22 hours, and the decline phase after 45 hours. Using strain YF14 in a reactor under heterotrophic conditions, the NH+-N and total nitrogen removal rates reached 92% and 91% respectively within 3 days. In addition, nitrate and nitrite nitrogen were not observed during the incubation. Under aerobic incubation conditions, almost all of the nitrogen was removed through denitrification in the nitrate or nitrite culture medium inoculated with strain YF14. The orthogonal experiment results indicated that the denitrification effect was optimal when the rotate speed, carbon source, inoculation percentages, carbon nitrogen ratio and pH were 160 r/min, glucose, 1% , 8: 1 and 6. 5, respectively. Sorting Order of the factors on the denitrification effect was rotate speed > inoculation percentages > carbon source > carbon nitrogen ratio > pH. The strain YF14 could improve the denitrification rate by about 30% when interacting with active sludge. CONCLUSION: The strain YF14 coupling of heterotrophic nitrification and aerobic denitrification is feasible and is of practical value in water treatment.

Role of soil rhizobacteria in phytoremediation of heavy metal contaminated soils.

Heavy metal pollution of soil is a significant environmental problem and has its negative impact on human health and agriculture. Rhizosphere, as an important interface of soil and plant, plays a significant role in phytoremediation of contaminated soil by heavy metals, in which, microbial populations are known to affect heavy metal mobility and availability to the plant through release of chelating agents, acidification, phosphate solubilization and redox changes, and therefore, have potential to enhance phytoremediation processes. Phytoremediation strategies with appropriate heavy metal-adapted rhizobacteria have received more and more attention. This article paper reviews some recent advances in effect and significance of rhizobacteria in phytoremediation of heavy metal contaminated soils. There is also a need to improve our understanding of the mechanisms involved in the transfer and mobilization of heavy metals by rhizobacteria and to conduct research on the selection of microbial isolates from rhizosphere of plants growing on heavy metal contaminated soils for specific restoration programmes.

[Effects of Hg contamination on paddy soil microbial and enzymatic activities].

With pot experiment, the microbial and enzymatic activities in two paddy soils were investigated at different Hg2+ loadings. The results showed that after harvest, all measured microbiological and enzymological indices including microbial biomass carbon, respiration rate, and activities of urease, acid phosphatase, and dehydrogenase in test soils were increased under low Hg treatments ( <2 mg Hg x kg(-1)) while decreased under high Hg treatments ( > or =2 mg Hg x kg(-1)), except the basal respiration and metabolic quotient were partly increased with increasing Hg level. Among the test indices, soil microbial quotient was a microbiological index more sensitive to Hg contamination. The enzymatic activity in test yellowish red soil was higher than that in test silty loam soil. ED50 analysis indicated that Hg had a stronger ecological toxicity on soil urease in test silty loam soil and on acid phosphatase in test yellowish red soil.