Response of denitrification rate and denitrifiers to human disturbance intensity and physicochemical factors of overlying water in a subtropical stream, China

2021 ◽  
Author(s):  
Binjie Zhao ◽  
Qiuyang Chen ◽  
Siyue Li ◽  
Xiang Tan ◽  
Quanfa Zhang
Keyword(s):  
Human Disturbance ◽  
Denitrification Rate ◽  
Overlying Water ◽  
Disturbance Intensity ◽  
Physicochemical Factors ◽  
Subtropical Stream

scholarly journals Do biochar and polyacrylamide have synergistic effect on net denitrification and ammonia volatilization in saline soils?

2021 ◽  
Author(s):  
Yongchun Pan ◽  
Dongli She ◽  
Zhenqi Shi ◽  
Xinyi Chen ◽  
Yongqiu Xia
Keyword(s):  
Synergistic Effect ◽  
Physicochemical Properties ◽  
Ammonia Volatilization ◽  
Nitrate Nitrogen ◽  
Inorganic Nitrogen ◽  
Denitrification Rate ◽  
Saline Soils ◽  
Overlying Water ◽  
Application Rates ◽  
Salt Affected Soils

Abstract Salt-affected soils have poor structure and physicochemical properties, which affect soil nitrogen cycling process closely related to the environment, such as denitrification and ammonia volatilization. Biochar and polyacrylamide (PAM) have been widely used as soil amendments to improve soil physicochemical properties. However, how they affect denitrification and ammonia volatilization in saline soils is unclear. In this study, the denitrification and ammonia volatilization rates were measured in a saline soil field ameliorated with three biochar application rates (0%, 2% and 5%, w/w) and three PAM application rates (0‰, 0.4‰ and 1‰, w/w) over three years. The results showed that denitrification rates decreased by 23.63%-39.60% with biochar application, whereas ammonia volatilization rates increased by 9.82%-25.58%. The denitrification and ammonia volatilization rates decreased by 9.87%-29.08% and 11.39%-19.42% respectively, following PAM addition. However, there was no significant synergistic effect of biochar and PAM amendments on the denitrification and ammonia volatilization rates. The addition of biochar mainly reduced the denitrification rate by regulating the dissolved oxygen and electrical conductivity of overlying water and absorbing soil nitrate nitrogen. Meanwhile, biochar application increased pH and stimulated the transfer of NH4+-N from soil to overlying water, thus increasing NH3 volatilization rates. Hence, there was a tradeoff between denitrification and NH3 volatilization in the saline soils induced by biochar application. PAM reduced the denitrification rate by increasing the infiltration inorganic nitrogen and slowing the conversion of ammonium to nitrate. Moreover, PAM reduced the concentration of NH4+-N in the overlying water through absorbing soil ammonium and inhibiting urea hydrolysis, thereby decreasing NH3 volatilization rate.

scholarly journals Cumulative effects of infrastructure and human disturbance: a case study with reindeer

2021 ◽  
Author(s):  
Sindre Eftestøl ◽  
Diress Tsegaye ◽  
Kjetil Flydal ◽  
Jonathan E. Colman
Keyword(s):  
Habitat Use ◽  
Human Activity ◽  
Human Disturbance ◽  
Cumulative Effects ◽  
Gps Data ◽  
Negative Effects ◽  
Disturbance Intensity

Abstract Context Within Rangifer ranges, many studies focus on expanding infrastructure and human activity negatively influencing habitat use. Little documentation exists on how disturbances act in synergy (i.e. cumulative effects), nor methods to test such effects. Objectives (1) Investigate how cumulative disturbance at different distances affects reindeer habitat use and (2) at what disturbance levels and distances loss of habitat functionality occurs. Methods Disturbance intensity levels for trails and infrastructure were based on expected amount of human activity, on a scale from 1 to 6. To test cumulative disturbance, we adapted the multi-grain method and summed-up disturbance intensity levels within “disturbance distance intervals” (0–0.25, 0.25–1, 1–2 km, etc. instead of 0–0.25, 0–1, 0–2 km, etc.), and tested reindeers’ avoidance using GPS data for 2011–2018. Results We found decreased habitat use within 0.25 km with increasing cumulative disturbance for snow free and winter seasons. For spring, a similar effect occurred up to 1 km. Reductions in use in areas with highest cumulative disturbance within these zones were between 92 and 98%. Strongest avoidance during spring supports previous studies. Comparatively, the multi-grain approach showed negative effects up to 3 km. Conclusions Our approach provides novel results and precisely estimates where cumulative effects actually occur. Reindeer in our study tolerate low intensities of human disturbance, while further increase in disturbance intensity reduces habitat functionality. We suggest clustering future human developments within areas of high disturbance, i.e. where functional habitat use is already lost or highly reduced. Our method can be used for other areas and species.

scholarly journals Landscape Pattern Evolution and Its Response to Human Disturbance in a Newly Metropolitan Area: A Case Study in Jin-Yi Metropolitan Area

Land ◽  
2021 ◽  
Vol 10 (8) ◽  
pp. 767
Author(s):  
Tao Wu ◽  
Peipei Zha ◽  
Mengjie Yu ◽  
Guojun Jiang ◽  
Jianzhen Zhang ◽  
...  
Keyword(s):  
Metropolitan Area ◽  
Landscape Pattern ◽  
Human Disturbance ◽  
Human Activities ◽  
Patch Type ◽  
Human Interference ◽  
Disturbance Intensity ◽  
Landscape Types ◽  
The Impact ◽  
Pattern Index

The impact of human interference on the ecological environment has attracted a significant amount of attention. In this study, hemeroby index (HI) was constructed to quantify the degree of human disturbance, and the relationship between HI and landscape pattern index was explored in a newly metropolitan area. The main objectives of this study were to analyze the temporal and spatial characteristics of landscape pattern and human disturbance in the process of urbanization of county-level cities in China, and to explore the relationship between the landscape pattern index and human disturbance under different disturbance intensity. The conclusions showed that: (1) the degree of human interference in the new area is on the rise, with a slow increase from 1980 to 2010, but since 2010, human interference has increased significantly. The diffusion of human disturbance intensity has obvious spatial directivity, spreading from east to west. (2) The impact of human activities on landscape pattern is shown as increasing fragmentation and increasing number of landscape types. With the enhancement of human activities, the heterogeneity and fragmentation of landscape types in the region reach their highest points. With the continuous increase of human activities, on a certain scale, the landscape types will gradually tend to be the same, and the same type of landscape patches will become one piece and tend to be integrated. This phenomenon is particularly obvious at the patch type level. (3) There is an inflection point value between human disturbance and landscape pattern index in landscape or patch type. On both sides of the inflection point value, the landscape pattern parameters and human disturbance have obvious opposite trends. (4) In the low interference range (1 ≤ HI < 4), with the increase of human interference, more heterogeneous structures (shown in the increase of SHDI) are brought to the landscape, there is more landscape fragmentation (shown in the decrease of LPI, CONTRACT, and AI), and the patch shape and landscape structure tend to be complex (shown in the increase of LSI, SQP, ED, and other indexes); in the high interference range (4 ≤ HI ≤ 7), due to human intervention, the increase of LPI, contract, and AI indicates that intense human activities turn the landscape into a broken and scattered structure and tend to be consistent and homogeneous. LSI, SQP, and ED were negatively correlated with HI at this stage, indicating that with the enhancement of human activities, the complexity of landscape shape decreased.

Engineering-Geological Studies Of The Territory, Soils Of Foundation And Foundations Of The Architectural Monument Of The "Melnikov’s House" In Moscow

2019 ◽  
pp. 41-51
Keyword(s):  
Working Condition ◽  
Overlying Water ◽  
North East ◽  
The North ◽  
Geological Processes ◽  
Architectural Monument ◽  
Geological Conditions ◽  
Zone Of Influence ◽  
Complex Engineering ◽  
Building Engineering

On the basis of engineering and design surveys of the building, engineering-geological and geophysical studies of the soils of the territory conducted by the article authors, as well as with due regard for the results of studies conducted on this territory by other authors, the features of the foundations, soils of their foundation and engineering-geological conditions of the territory of the Melnikov House are established. It is shown that the Melnikov house is located under complex engineering-geological conditions on the territory of high geological risk, in the zone of influence of tectonic disturbance. To the North of the area there is a zone of intersection of the observed disturbance with a larger disturbance that can have an impact on geological processes. To the North-East of the site of the Melnikov House, a sharp immersion of the roof of carbon deposits was revealed. It promotes groundwater seepage into limestone of the carbonate strata from overlying water-bearing sands and activation of processes of suffusion removal and sinkhole phenomena of the soil. The surveyed area is assessed as potentially karst-hazardous and adjacent to it from the North-East territory as karst-dangerous. In this regard any construction on the adjacent territory can provoke activation of sinkhole phenomena on the surface. The foundations of the building are basically in working condition. Existing defects can be eliminated during repair. The foundation soils mainly have sufficient bearing capacity. Areas of the base with bulk soil can be reinforced. However, when developing a project for the reconstruction of the building and its territory, it should be taken into account that the design of the Melnikov House does not provide for its operation on the loads at the formation of sinkholes.

Evaluation of the Power Transformer Magnetizing Inrush Currents

2020 ◽  
Vol 10 (10) ◽  
pp. 20-32
Author(s):  
Aleksey A. KUVSHINOV ◽  
◽  
Vera V. VAKHNINA ◽  
Aleksey N. CHERNENKO ◽  
◽  
...  
Keyword(s):  
Power Transformer ◽  
Geomagnetic Disturbance ◽  
Inrush Current ◽  
Geomagnetic Disturbances ◽  
Disturbance Intensity ◽  
Magnetizing Inrush Current ◽  
Inrush Currents ◽  
Instantaneous Values ◽  
The Mathematical Model ◽  
Analytical Expressions

The mathematical model of a shell-core power transformer’s magnetization branch is substantiated. By using the model, analytical expressions for the magnetizing current instantaneous values under the conditions of geomagnetic disturbances can be obtained. Quantitative assessments of the magnetizing inrush current amplitudes and durations versus the geomagnetic disturbance intensity are obtained. The dynamics of the power transformer magnetic system saturation transient and changes in the magnetization inrush current amplitudes and durations after a sudden occurrence of geomagnetic disturbances are shown. The error of estimating the magnetizing inrush current amplitudes under geomagnetic disturbances is determined based on comparison with experimental data.

Effects of human disturbance on understory woody species composition and diversity in fengshui forests

2009 ◽  
Vol 17 (5) ◽  
pp. 458 ◽  
Author(s):  
Lü Hao-rong ◽  
Liu Song-song ◽  
Zhu Jian-yun ◽  
Ye Yong-chang ◽  
Chen Hong-yue ◽  
...  
Keyword(s):  
Species Composition ◽  
Human Disturbance ◽  
Woody Species

Factors Affecting Bioconcentration of Trace Organic Contamination in Waters

1989 ◽  
Vol 21 (2) ◽  
pp. 147-150 ◽  
Author(s):  
D. W. Hawker ◽  
D. W. Connell
Keyword(s):  
Molecular Weight ◽  
Bioconcentration Factor ◽  
Aqueous Solubility ◽  
Organic Chemicals ◽  
Organic Contamination ◽  
Hydrophobic Organic Chemicals ◽  
Factors Affecting ◽  
Water Partition Coefficient ◽  
Physicochemical Factors ◽  
Trace Organic

The influence of some important biological and physicochemical factors on the bioconcentration of hydrophobic organic chemicals is outlined. For non-ionizable, persistent compounds the bioconcentration factor can be related to a compound's octanol/water partition coefficient, aqueous solubility and molecular weight, while the lipid content of an organism also affects the bioconcentration potential of these compounds. The effect of ionization and biodegradation of organic chemicals on bioconcentration is also discussed.

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