Advances in Watersheds Water Pollution and Ecological Restoration

Table of Contents

1. Frontmatter

2. Water Environment Modeling and Pollution Traceability in Watersheds

   1. Frontmatter

   2. Chapter 1. Three-Dimensional Electrolysis Coupled with Fenton Treatment of Fermented Pharmaceutical Wastewater Factor Effects and Kinetic Research

      Hongbo Liu, Changxin Luo, Xiaona Ji, Sen Li, Hongyan Li, Xi Tian

      Abstract

      To address the issue of secondary effluent from fermentation pharmaceutical wastewater exceeding discharge standards, a test was conducted using three-dimensional electrolysis coupled with Fenton treatment to oxidize the wastewater, considering its difficult biodegradability. Through a one-factor test, the effect of different operating conditions on the COD removal rate of wastewater was explored, using kinetic equations to examine the system's reaction rate and the relationship between reactant concentration and change. The results showed that the COD removal rate reached 72.6% when the reaction time was 120 min, the current intensity was 1.50 A, the activated carbon dosage was 20.00 g/L, the H₂O₂ concentration was 8.00 mmol/L, the initial pH was 3.00, the Fe²⁺ concentration was 2.00 mmol/L, and the spacing between the plates was 5 cm. It complies with the discharge requirements of the Emission Standards for Water Pollutants in the Fermentation Pharmaceutical Industry and exceeds the Class A standard of the Emission Standards for Pollutants from Urban Wastewater Treatment Plants. The three-dimensional electrolysis coupled Fenton process effectively treats fermented pharmaceutical wastewater secondary effluent in accordance with the three-level kinetic law and attenuation model.

   3. Chapter 2. The Trend and Correlation Between Temperature Information Entropy and Extreme Precipitation

      Xu Zang, Chunlei Shi

      Abstract

      In the background of global warming, many observations have indicated an increasing trend of extreme precipitation. In this paper, we use global temperature and precipitation data from 1979 to 2021 to analyse the trends of temperature, information entropy and extreme precipitation in the global, northern and southern hemisphere, and discuss the correlation between information entropy and extreme precipitation. The results show that there is a significant warming trend in the global, northern and southern hemisphere. There is a decreasing trend in information entropy in global, northern and southern hemispheres. The most significant decreasing trend is −2.5 × 10^–3/yr in the Northern Hemisphere. Extreme precipitation shows an increasing trend, with the northern hemisphere showing the most significant increase at 0.73 mm/yr. There is a significant negative correlation between information entropy and interannual changes in extreme precipitation in the global, northern and southern hemispheres. The correlation in the northern hemisphere is the most significant with −0.63, indicating that the decrease in information entropy could indicate the increase in extreme precipitation.

   4. Chapter 3. Characteristics of Bacterial Community in Xuanwu Lake and Its Inflow/Outflow Channels, and Their Relationship with Environmental Factors in Nanjing, China

      Qifan Yuan

      Abstract

      Bacteria play a very important role in the material circulation and energy flow of lake ecosystem. In this study, high-throughput sequencing technology and multivariate statistical analysis were used to investigate the bacterial community in Nanjing Xuanwu Lake and its inflow/outflow channels, and the main environmental factors affecting the bacterial community composition were analyzed. The results showed that there were different α diversity of bacteria community in Xuanwu Lake and the inflow/outflow channels. At the phyla level, the bacterial communities in Xuanwu Lake and its inflow/outflow channels were mainly composed of Cyanobacteria, Actinobactria, Firmicutes, Proteobacteria, Patescibacteria, Verrucomicrobia, and Planctomycetes. Cyanobacteria, Firmicutes and Proteobacteria were the most abundant phyla in the lake, outflow channels and inflow channels, respectively. At the generic level, it consisted mainly of Cyanobium PCC-6307, hgcI clade, Terrimicrobium, CL500-29 marine group, Defluviitalea, and Ruminiclostridium. Cyanobium PCC-6307, Defluviitalea and Ruminiclostridium were the most abundant genus in the lake, outflow channels and inflow channels, respectively. Typical correspondence analysis showed that TN, TDN, NO₃⁻–N and pH were the most significant environmental factors affecting the bacterial community in Xuanwu Lake and its channels. The research results could provide theoretical evidences for the aquatic ecosystem security and environmental management of Nanjing Xuanwu Lake.

   5. Chapter 4. Effects of Environmental Variables on Zooplankton Communities in the Xincun Lagoon, Hainan, China

      Dongrong Zhang, Jian Qian, Lihong Chen, Jieqing Yang, Weihua Feng, Haifeng Zhang, Baoxing Huang

      Abstract

      Due to its natural environmental advantages, the lagoon has become a significant fish farming area, with zooplankton playing a crucial role as bait for fish. The population dynamics of zooplankton are closely correlated with environmental variables in the lagoon. Therefore, it is necessary to analyze the population characteristics of zooplankton in different areas within the lagoon to understand the impact of environmental variables on their population structure. Through an analysis and study of fixed-point sampling in the Xincun Lagoon, it was observed that copepods dominated the species composition of zooplankton, accounting for 37.00% of the total number of species. Additionally, there were high numbers of planktonic larvae, primarily reflected in the composition of dominant species. On the other hand, the abundance of jellyfish was linked to anthropogenic pollution in the lagoon water environment. The analysis of environmental variables revealed that the Xincun Lagoon had severe DIN and DIP pollution. DIP and salinity also emerged as important factors influencing the distribution of zooplankton populations in the lagoon. Notably, the biomass, abundance, and diversity indices of zooplankton in the fish farming area were significantly lower than those in the lagoon mouth waters. This result suggests that the eutrophication in the Xincun Lagoon has exceeded its self-purification capacity and is deteriorating. The findings of this study highlighted the importance of long-term monitoring of zooplankton and environmental variables in the Xincun Lagoon, as well as active intervention measures, to promote the sustainable development of aquaculture in the lagoon.

   6. Chapter 5. The Characteristics of Microbial Community Structure in Tunnel Type Underground Reservoir in Island Areas

      Jie Li, Qiannan Jin, Yuan Gao, Xinyi Cao, Lijun Liu

      Abstract

      To reveal characteristics of microbial community structure in tunnel type underground reservoir in island areas. By comparing the microbial communities in fully enclosed reservoirs, semi-closed reservoirs, and raw water using high-throughput sequencing of bacterial 16S rRNA and microeukaryotic 18S rRNA genes, we found that the alpha diversity of bacterial communities followed the order: fully enclosed reservoir water > raw water > semi-closed reservoir water. In contrast, the alpha diversity of microeukaryotic communities followed the order: raw water > semi-closed reservoir water > fully enclosed reservoir water. Additionally, the absolute dominant species varied among these water sources. Combined with the correlation analysis between environmental factors and microorganisms, the bacterial community and microeukaryotes community are significantly affected by environmental factors as a whole, and bacterial community is more affected by environmental factors than microeukaryotes community. The composition of microbial community structure in the water body is different under different conditions, whether it is bacteria or microeukaryotes, and bacterial community is more sensitive to environmental factors than microeukaryotes community. Leading to a comprehensive understanding of the characteristics of microbial community under different conditions of tunnel type underground reservoir at the perspective of microbial communities.

   7. Chapter 6. In-Situ Test Study on Lake Evaporation on the Ordos Plateau

      Xiaoyong Wang, Honglin Ma, Zebing Dai, Xueqin Zhang

      Abstract

      There are a large number of lakes on the Ordos Plateau. Lake evaporation, as the main discharge mode of surface water, is one of the key equilibrium items for the accurate evaluation of water resources. Studying lake evaporation has important practical significance and scientific value for the understanding about regional water cycle, the evaluation of water resources, and the ecological and environmental protection of lakes. However, the measured data of lake evaporation in this region are limited, and most of them are calculated with conversion method and formula method. In this study, an in-situ test was carried out on Mukainao, a typical lake on the Ordos Plateau. An evaporator was installed in the middle of the lake to measure the water surface evaporation and analyze the correlation between evaporation and meteorological factors, and the in-situ lake evaporation was compared with the pan evaporation of lakeside land surface and the theoretical value of Penman Formula. It is shown by the study that lake evaporation is greatly affected by humidity and air temperature; the conversion coefficient between the water surface evaporation of lake and the small pan evaporation on lakeside land surface is about 0.85, larger than previous studies; the lake evaporation is little affected by the salinity of lake water and can be ignored; the correlation analysis result is relatively high compared with the calculated results of Penman Formula, so Penman Formula can be used to estimate lake evaporation in the absence of measured data.

   8. Chapter 7. Pilot Study on Odor Compounds Treatment in Raw Water by High-Speed Sedimentation and Biological Filtration

      Shuo Zhang, Jiajiong Xu, Min Rui

      Abstract

      The odor compounds removal under low temperature is one of the difficulties in drinking water treatment. In a pilot, the enhanced coagulation sedimentation process and biological filtration was studied, and the effects of permanganate, powdered activated carbon, aeration, filter aid and filter rate reduction were analyzed. The results showed that high concentration of enanthal was the main odor compound in raw water. The 2-methylisoborneol and dimethyltrisulfide were also detected and geosmin was not detected. Permanganate pre-oxidation, powdered activated carbon, coagulation sedimentation and biological filtration could remove odor compounds, among which the removal amount of coagulation sedimentation was the largest and the aeration effect was limited. When the concentration of odor compounds was high, the enanthal was higher than the olfactory threshold. Ozone activated carbon process should be required to further remove enanthal to meet the national standard.

   9. Chapter 8. Adsorption of Cd (II) from Wastewater by Cuttlebone and Its Derived Materials

      Hongqi Xie, Jun Liu, Xiao Sun, Xiaoao Bai, Zhaohui He

      Abstract

      In this study, materials CB-Y, CB-Z₁ and CB-Z₃ with different degrees of deacetylation were prepared from cuttlebone, a fishery waste, for the removal of Cd(II) from wastewater. The effects of key factors such as contact time, Cd(II) concentration and pH were explored for different working conditions.. Adsorption kinetics were fitted using Pseudo-first-order, Pseudo-second-order, Elovich and Intraparticle diffusion models, and adsorption isotherms were fitted using Langmuir, Freundlich, and Temkin models. The experiments showed that the adsorption of Cd(II) by the three materials increased gradually with the increase of pH, and the maximum adsorption amount could reach 765.84, 783.22, and 809.07 mg/g, respectively. The adsorption kinetics showed that the adsorption equilibrium time was 120 h, and the adsorption all conformed to the proposed two-stage kinetic model and the Elovich model. The adsorption isotherms showed that the adsorption amount increased with the Cd(II) concentration increased, and the adsorption all conformed to Langmuir model and Temkin model. The capability of Cd(II) adsorption is in the order of CB-Z₃ > CB-Z₁ > CB-Y, which indicated that the deacetylation operation improved the adsorption performance of the materials. Therefore, cuttlebone and its derived materials are biosorbents with good adsorption performance and have a promising application in the treatment of Cd(II)-containing wastewater.

   10. Chapter 9. Study on the Treatment of Ammonium Nitrogen in Micro-Polluted Water by Modified Zeolite and Chemical Regeneration

       Hui Yang, Yuzheng Liu, Meiling Dong

       Abstract

       In surface water bodies, ammonium nitrogen is a widespread and essential substance for living organisms, and it is also a common substance in polluted source water, and excessive ammonium nitrogen will lead to eutrophication of water bodies. This paper summarizes and analyzes the modification and regeneration methods of zeolite in current water treatment and the current research status of modified zeolite for removing ammonium nitrogen in water, and tests a variety of modifiers for zeolite modification by immersion, and the test found that CTAB (cetyltrimethylammonium bromide) as a modifier has a counteracting effect on the adsorption of ammonium nitrogen by zeolite, and SDBS (sodium dodecylbenzenesulphonate) as a modifier modifying zeolite has a very good Under the condition of pH 7, the removal rate of zeolite modified by 20 g/L SDBS solution for 50 mL of a 5.0 mg/L ammonium solution could reach 72%, and the regeneration of adsorption-saturated zeolite with 1 mol/L NaOH + NaCl solution still reached 86.3% regeneration rate after three times of desorption and regeneration.

   11. Chapter 10. Pollutant Discharge Behavior and Impacts of Wastewater Treatment Plants in a Time Perspective

       Yang Jiang, Peng Zhang, Cong Li, Gui-Liang Zhong, Xiang-Dong Qiu, Ying-Qi Xiang, Xue-Jun Xu, Yong-Jun Ou

       Abstract

       In the context of the big data era, wastewater treatment plants (WWTPs) have accumulated a huge amount of time-series data, which are particularly important for the study of the water quality change law of WWTPs, so given the trending, comprehensive, and mineable nature of WWTPs effluent quality time series data, the flowing behavior of a Wastewater Treatment Plant (WWTP) in the southwest region was analyzed. The overall effluent water quality situation of this WWTP in 2022 is lower than that in 2021, with exceedance rates of chemical oxygen demand, total phosphorus, total nitrogen ammonia, nitrogen, and pH all within two-thousandths of a percent, and the plant is in stable operating condition. According to the main problems existing in the operation of the WWTP, the proposed distribution fitting significance level test and self-organized neural network clustering method will classify the operating conditions of WWTPs, which will help to diagnose the abnormality of WWTPs, assess the status, and optimize the guidance.

   12. Chapter 11. Analysis of Vertical Structure Characteristics of Atmospheric Pollution During Rain to Snow Processes in Shenyang

       Dian Li, Jinglin Cui, Xiaoou Li, Wanting Hou, Xiaoling Chai

       Abstract

       In order to study the vertical structure characteristics of atmospheric pollution under different weather processes, the perspective of the weather system, horizontal wind field, vertical velocity and echo intensity were analyzed comparatively form two rain to snow processes in Shenyang by using the conventional and unconventional meteorological data and atmospheric pollutant monitoring data. The results show that it had stronger intensity, concentrated region of pseudo-equivalent potential temperature was stiff under 850 hPa, lower frontal slope was sharp with a short frontogenesis time, increasing pollutant concentration was fast, strong temperature advection led to the obvious pollutant transport, features of reflectivity was changing very rapidly during rain to snow in the process I. It had weaker intensity, magnitude of inclination of pseudo-equivalent potential temperature was small, lower frontal slope was gentle with a long frontogenesis time, increasing pollutant concentration was slow, there was a large vertical velocity and development of clouds was favorable, influence of wet deposition was clear in the process II. The concentration of pollutants reached the maximum during the period of rain to snow.

   13. Chapter 12. Analysis of Rainfall Characteristics and Impacts in the Earlier Stage of Geological Disasters in Wuhan Based on Machine Learning

       Li Ming, Linyi Li

       Abstract

       Based on the data of geological hazards and rainfall in Wuhan from 2016 to 2021, the characteristics of rainfall before geological hazards in Wuhan were classified by using machine learning methods, and the impact of rainfall on different types of geological hazards was analyzed. The results show that the geological hazards in Wuhan can be basically divided into two types: slope type and ground collapse. There were 253 geological hazards from 2016 to 2021, mainly small-scale hazards. 52.9% of 134 geological disasters had heavy rainfall within 15 days. And 57 Geological hazards occurred after the 65 rainstorm days. The method of calculating effective rainfall has sound effects on the meteorological risk analysis of slope geological hazards. Four heavy rainfall models inducing geological disasters are established. Machine learning method is used to extract features respectively, and their influence is analyzed.

   14. Chapter 13. Characteristics of Drought Periodicity Based on Morlet Wavelet Analysis: A Case Study of Guanzhong Region

       Shuhan Yang, Hui Qian

       Abstract

       Many geological data show that the arid environment is not always dry, but there are periodic dry and wet changes. Therefore, it is very important to study the dry and wet change law and mechanism of arid environment to understand the future evolution of arid environment. Morlet wavelet analysis is an analysis method with time, frequency domain and multi-layer resolution, which can obtain the periodic characteristics of hydrometeorological data (year, season, month) on a certain time scale, so as to evaluate its future development trend. Based on 60 years of monthly rainfall data from 1959 to 2019 in Guanzhong region, this paper takes SPI-12 as the drought index, and uses the real part time–frequency distribution map of wavelet coefficients to obtain the time and frequency variation characteristics of SPI-12 time series at six hydrographic stations in Fengxiang, Changwu, Pucheng, Huashan, Taibai and Wugong in Guanzhong region. It reflects the periodic variation characteristics of drought degree in Guanzhong region on a certain time scale, it provides a research basis for the early warning of drought events in Guanzhong region in the future and an effective technical reference for the study of the change regularity of drought events in arid and semi-arid regions in the future.

   15. Chapter 14. Environmental Risks of the Agricultural Application of Emulsified Asphalt on Soil and Groundwater

       Jiawei Zhao, Jicai Wang, Jiali Xu, Chunhui Luo, Jie Hong, Bin Zheng

       Abstract

       Emulsified asphalt is of valuable significance when applied to agricultural soil improvement for it can improve soil structure and thus enhance its water retention capacity. However, due to the complex chemical composition of emulsified asphalt as a petrochemical material, its utilization will inevitably have a certain impact on the agricultural soil and the underlying groundwater environment. Thus, reasonable use of emulsified asphalt relies on exploring the environmental risks of emulsified asphalt to agricultural soil and groundwater. In this study, three different types of emulsified asphalt are selected and separately added to dry soil and saturated soil respectively to simulate the state of emulsified asphalt in the vadose zone and saturated zone. The potential environmental risks of emulsified asphalt on soil and groundwater are analyzed through laboratory testing (pH meter, Atomic Absorption Spectrophotometer, Atomic Fluorescence Spectrophotometer, Gas Chromatograph, Gas Chromatography and Mass Spectroscopy, High Performance Liquid Chromatography) of heavy metal and organic compounds content in soil and water. The results show that when adding emulsified asphalt to dry soil and ensuring thorough mixing, subsequent sampling and testing reveal no significant change in the concentration of heavy metals within the soil. The concentration of TPHs (C10-C40) increases with the increase of emulsified asphalt, but it is still within the standard range After emulsified asphalt is sprayed into the saturated soil, the soil shows a water-soil-milk mixed form. After the filtering and sampling test, it is found that the cadmium, lead, TPHs (C10-C40), Benzo [a] pyrene and benzene of the water body exceed the groundwater quality standards of China. The experimental results show that the application of emulsified asphalt in farmland has a relatively small impact on the soil but poses a certain influence on the groundwater. Consequently, we need to consider the type and intended purpose of emulsified asphalt, as well as the manner in which it is utilized, to prevent contamination of groundwater resources.

   16. Chapter 15. Characteristics and Potential Ecological Effects of Heavy Metal Pollution in Sediment of a Reservoir

       Lu Zhang, Yao Du

       Abstract

       The Tongshanyuan Reservoir, located in southwest Zhejiang Province, serves as a crucial water supply and irrigation source but is currently facing significant heavy metal pollution. To develop effective pollution prevention and control measures and ensure the well-being of the population within the water resource radiation area, seven sampling points were designated within the reservoir. The contents of Cd, Cr, Cu, Ni, Pb, Zn, Hg, U and other heavy metals were determined using an inductively coupled plasma mass spectrometer. Principal component analysis was employed to analyze the distribution characteristics of pollution while potential ecological risk assessment methods were used to evaluate its impact on the ecosystem. The results revealed varying degrees and ranges of heavy metal contamination in the sediment of the reservoir with severity ranking as follows: S7 > S3 > S4 > S6 > S2 > S5 > S1. Pollution primarily concentrated in densely populated areas with frequent human activities along Right Branch Stream and Duze Town. Notably severe contamination was observed for mercury (Hg) and cadmium (Cd) in sediment samples which posed high potential ecological risks originating mainly from agricultural pollution upstream of Left Branch Stream and industrial pollution upstream of Right Branch Stream. Appropriate control measures can be implemented to mitigate heavy metal pollution levels in order to safeguard both aquatic ecosystems and human health.