Biodegradable microplastics (BMPs), which form as biodegradable plastics degrade in agricultural settings, may influence plant growth and soil health. This study investigates the effects of BMPs on tomato growth and the microbial mechanisms involved. A greenhouse experiment applied BMPs—polyhydroxyalkanoate (PHA), polylactic acid (PLA), poly(butylene succinate-co-butylene adipate) (PBSA), and poly(butylene-adipate-co-terephthalate) (PBAT)—to tomato plants. The study analyzed their effects on plant growth, soil properties, and rhizosphere microbial communities. BMP treatments significantly reduced tomato biomass, height, and chlorophyll content compared to the control. PLA0.1 decreased the chlorophyll a/b ratio, while PLA1 increased it. Elemental analysis showed PLA1 increased phosphorus, calcium, and potassium in leaves, whereas all BMPs reduced nitrogen levels. BMPs also altered soil nitrogen and DOC levels, significantly shifting rhizosphere microbial communities, with a notable increase in Betaproteobacteria abundance. Ecological network analysis revealed that BMPs disrupted key microbial modules linked to plant growth. Beneficial modules positively associated with biomass and nutrient uptake were reduced under BMP treatments, whereas harmful microbial taxa in module 3, associated to poor plant health, were promoted. These shifts suggest that BMPs disrupt microbial ecological relationships critical for optimal plant growth. The findings highlight the potential negative impacts of BMPs on tomato growth through changes in microbial dynamics and soil properties.

High-risk antibiotic resistance genes (ARGs) in reclaimed water-irrigated soil pose a potential threat to ecosystem and human health. Inorganic fertilization – including with nitrogen, a key ingredient in agricultural production – may affect the ARG profile in soil. However, little is known about nitrogen fertilization's influence on ARGs profiles in the soil–plant system. This study investigated the effects of different nitrogen fertilizer types (CO(NH2)2, NO3–-N (NaNO3) and NH4+-N (NH4HCO3)) and different nitrogen fertilizer application rates (low, medium, high) on the distribution of high-risk ARGs in reclaimed water-irrigated soil and plants using quantitative PCR, high-throughput sequencing and metagenomic sequencing. Soil microcosms results revealed that nitrogen fertilization significantly affected the pattern of high-risk ARGs in soil, and also affected high-risk ARGs abundance and transfer capacity in plants. Compared with nitrogen fertilizer application rate, nitrogen fertilizer types significantly contributed to enhancing the soil resistome, with the order of CO(NH2)2 > NO3–-N ≈ NH4+-N. The medium application of NO3–-N and NH4+-N significantly reduced high-risk ARGs abundance in the leaf endophyte. Bacterial community mainly drove the variation of ARGs in nitrogen-fertilized soil–plant system, and class I integron and metal resistance genes (MRGs) also had direct effects on these high-risk ARGs. A similar high-risk ARGs pattern was also found in field plot experiments, and several dangerous pathogens were observed as the main high-risk ARGs potential hosts in nitrogen-fertilized soil. Based on an economic assessment, application of NH4+-N (NH4HCO3) could reduce costs by $1,312.83 ha−1 compared with NO3–-N (NaNO3). These results showed that the more important role of nitrogen type might be an effective and economical way to control high-risk ARGs spread in soil–plant system under reclaimed water irrigation.

High frequent detection of sulfamethoxazole (SMX) in wastewater cannot be effectively removed by constructed wetlands (CWs) with a traditional river sand substrate. The role of emerging substrate of hematite in promoting SMX removal and the effect of influent SMX loads remain unclear. The removal efficiency of SMX in hematite CWs was significantly higher than that in river sand CWs by 12.7-13.8% by improving substrate adsorption capacity, plant uptake and microbial degradation. With increasing influent SMX load, the removal efficiency of SMX in hematite CWs slightly increased, and the removal pathways varied significantly. The contribution of plant uptake was relatively small (< 0.1%) under different influent SMX loads. Substrate adsorption (37.8%) primarily contributed to SMX removal in hematite CWs treated with low-influent SMX. Higher influent SMX loads decreased the contribution of substrate adsorption, and microbial degradation (67.0%) became the main removal pathway. Metagenomic analyses revealed that the rising influent load increased the abundance of SMXdegrading relative bacteria and the activity of key enzymes. Moreover, the abundance of high-risk ARGs and sulfonamide resistance genes in hematite CWs did not increase with the increasing influent load. This study elucidates the potential improvements in CWs with hematite introduction under different influent SMX loads.

The scarcity of freshwater resources has increased the use of nonconventional water resources such as brackish water, reclaimed water, etc., especially in water-scarce areas. Whether an irrigation cycle using reclaimed water and brackish water (RBCI) poses a risk of secondary soil salinization to crop yields needs to be studied. Aiming to find an appropriate use for different nonconventional water resources, pot experiments were conducted to study the effects of RBCI on soil microenvironments, growth, physiological characteristics and antioxidation properties of crops. The results showed the following: (1) compared to FBCI, the soil moisture content was slightly higher, without a significant difference, while the soil EC, sodium and chloride ions contents increased significantly under the RBCI treatment. With an increase in the reclaimed water irrigation frequency (Tri), the contents of EC, Na+ and Cl− in the soil decreased gradually, and the difference was significant; the soil moisture content also decreased gradually. (2) There were different effects of the RBCI regime on the soil’s enzyme activities. With an increase in the Tri, the soil urease activity indicated a significant upward trend as a whole. (3) RBCI can alleviate the risk of soil salinization to some extent. The soil pH values were all below 8.5, and were without a risk of secondary soil alkalization. The ESP did not exceed 15 percent, and there was no possible risk of soil alkalization except that the ESP in soil irrigated by brackish water irrigation went beyond the limit of 15 percent. (4) Compared with FBCI, no obvious changes appeared to the aboveground and underground biomasses under the RBCI treatment. The RBCI treatment was conducive to increasing the aboveground biomass compared with pure brackish water irrigation. Therefore, short-term RBCI helps to reduce the risk of soil salinization without significantly affecting crop yield, and the irrigation cycle using reclaimed-reclaimed-brackish water at 3 g·L−1 was recommended, according to the experimental results.

Due to the widespread use of tetracyclines antibiotics (TCs) in livestock breeding, TCs has always caused soil pollution. TCs cannot only enter soil and water bodies through multiple channels but also accumulate in them over a long period. It is more abundant in soils, agricultural land. Primarily, should explore efficient methods for removing or degrading TCs. This review provides an overview of the birth, development and problem of soil contamination of TCs. Then focuses on the toxicity and effects of TCs on microorganisms, animals, and plants. Furthermore, in the following chapters, microbial -, plant -, animal - biodegradation methods are introduced to summarize the species and plants applied in soil TCs removal at this stage. Meanwhile, the principle mechanism of advanced oxidation processes is analyzed deeply to fill the gap. In addition, a case of microbial fuel cells based on sustainable bioenergetics with promising prospects for soil TCs removal is presented. Due to the interaction between carbonaceous materials and soil, the characteristics of adsorption method under soil environment are deeply analyzed.

【Objective】 Constructed wetland is a biotechnological technique to treat wastewater; its function depends on a multitude of biotic and abiotic factors. This paper compares the performance of eight wetlands constructed by different materials. 【Method】 The eight wetlands we studied were constructed by fine sand only (CK), fine sand + corn straw powder (JW), fine sand + industry glucose (PW), sand + corn-straw biochar (SW), fine sand + eisenia fetida (KQ), fine sand + corn straw powder + eisenia fetida (JQ), fine sand + industrial glucose + eisenia fetida (PQ), fine sand + corn stover biochar + eisenia fetida (SQ), respectively. 【Result】 Adding corn-straw biochar, industrial glucose and corn-straw power increased the COD removal rate by 81.80%, 88.58% and 85.77%, respectively, compared to CK. Adding industrial glucose combined with corn straw powder improved purification efficiency of total N (TN) and total P (TP) by 7.0% and 2.8%, respectively. Wetland with industrial glucose and corn straw powder had the best TN removal rate, reaching 98% and 98.2%, respectively. Adding corn-straw power along with eisenia fetida was most effective to remove cooper, compared with other treatments. On average, introducing eisenia fetida to the wetlands increased the removal rates of COD, Cu and Zn by 1.8%, 6.3% and 2.6%, respectively, while adding corn-stover biochar significantly increased the removal rate of NH4+-N. Compared with corn straw powder and corn straw biochar, industrial glucose was more efficient for removing COD, total N and N, and Cu. 【Conclusion】 Adding eisenia fetida and organic carbon to the wetland can improve its efficacy to remove COD, nitrogen and heavy metals, especially corn-stover powder combined with eisenia fetida. For removing Cu, corn straw powder combined with eisenia fetida works the best.

Efficient removal of zwitterionic tetracycline (TC) from water is a critical environmental challenge which is not fully addressed by conventional treatment technologies. A magnetic N-doped sludge biochar (MNSBC) was the first time synthesized by simple one-pot hydrothermal method. pH, ionic species/strength and humic acid concentration were the critical factors affecting TC adsorption. Elovich and Freundlich models better describing the experimental data illustrated that TC adsorption onto MNSBC was a multi-layer physicochemical adsorption process. Lewis acid-base, π-π conjugation, electrostatic interactions and pore filling were the main adsorption mechanism. MNSBC also exhibited excellent performance for TC adsorption in various environmental waters, which achieved removal rates of up to 91.6%, 89.0%, 82.0% and 80.8% in mineral, tap, lake and Yangtze River waters, respectively. The magnetic susceptibility of MNSBC allowed it to be easily collected after adsorption. Regeneration using NaOH could maintain its sustainable adsorption performance. Furthermore, MNSBC showed a very low release levels of iron and total nitrogen at all pH ranges (from 3 to 11), which suggested its suitability for water treatment applications. This study developed a simple technology for synthesis of effective TC adsorbent for different environmental waters and identified a circular economy pathway to reuse of water industry wastes.

The transfer of antibiotic resistance genes (ARGs) in soil under reclaimed water irrigation poses a potential environmental risk. Regulation of NPK fertilizer could influence the behavior of bacterial communities, mobile genetic elements (MGEs), and soil properties, which determine the fate of ARGs. To identify the key element in NPK fertilizer and realize efficient regulation, we explored the effect of individual N, P, K fertilization on ARG variation in tomato rhizosphere and bulk soils. Compared with an unfertilized treatment, N fertilization resulted in greater decreases in the abundance of ARGs (decreases of 24.06%-73.09%) than did either P fertilization (increases of up to 35.84%, decreases of up to 58.80%) or K fertilization (decreases of 13.47%-72.47%). The influence of different forms of N (CO(NH2)2, NaNO3, and NH4HCO3), P (Ca(H2PO4)2 and CaMgO4P+), and K (KCl and K2(SO4)) fertilizers was also investigated in this study, and showed the influence of NaNO3, CaMgO4P+, and K2(SO4) on reducing ARGs abundance was greater in different types of N, P, K fertilizers. Bacterial communities showed the strongest response to N fertilization. The reduced bacterial diversity and abundance of ARG-host and non-host organisms explained the decline of total ARG abundance in soil. In soils fertilized with either P or K, the effect of soil properties, especially total nitrogen and pH, on ARG variation was greater than that of bacterial community and MGEs. These results suggest that N regulation of in NPK fertilizer may be an effective way to reduce the risks of ARGs in soil associated with reclaimed water irrigation.

为揭示外源物质生物炭、硝化抑制剂、脲酶抑制剂复配对温室气体排放的影响,采用室内培养试验,比较外源物质不同组合[对照(CK)、生物炭(BC)、硝化抑制剂(NP)、脲酶抑制剂(NB)、生物炭+硝化抑制剂(BCNP)、生物炭+脲酶抑制剂(BCNB)、硝化抑制剂+脲酶抑制剂(NPB)、生物炭+硝化抑制剂+脲酶抑制剂(BCNPB)]对温室气体排放的影响,同时监测土壤pH、NH+4-N、NO-3-N等影响因子的变化规律.结果表明:与CK相比,各处理均抑制了土壤N2O排放,其中NPB处理抑制效果最显著;所有处理均促进了土壤CO2排放;除BC处理为负效应外,土壤CH4排放效应与CO2结果类似;除BCNB处理外,其他处理对全球增温潜势有一定的抑制作用,其中NPB处理的抑制效果最佳.培养结束时,与CK相比,除NP处理提高了土壤pH外,其他6个处理均降低了土壤pH;在无机氮含量方面,与CK相比,各处理均增加了土壤NH+4-N含量,BCNPB、NP、NPB处理减少了NO-3-N含量,NB、BC、BCNP、BCNB处理增加了NO-3-N含量.综合考虑全球增温趋势和土壤性质,本试验条件下硝化抑制剂+脲酶抑制剂处理为抑制温室气体排放的最优外源物质处理.

为了探讨淡水资源不足地区微咸水的合理利用方式.通过盆栽试验,以清水灌溉为对照,研究不同比例微咸水与再生水混合灌溉对水盐、水溶性离子、滴水穿透时间WDPT、有机质以及酶活性的影响,并利用第二代生物综合响应指数法(IBRv2)对微咸水与再生水混灌效应进行评价.结果 表明:(1)与再生水灌溉(T1)相比,随着混合溶液中微咸水比重的升高,土壤含水率和含盐量逐渐升高且差异显著(P＜0.05).(2)与T1处理相比,随着混合溶液中微咸水比重的升高,土壤K+、Ca2+含量呈降低趋势,Na+、C1-含量显著升高,SO42-含量显著降低,Mg2+含量无明显变化规律.(3)与CK2(清水灌溉)相比,T1处理土壤WDPT和有机质含量差异不显著;与T1处理相比,随着混合液中微咸水比重的进一步提高,土壤WDPT和有机质含量总体上呈升高趋势.(4)不同比例微咸水-再生水混合灌溉对土壤酶活性的影响不同.土壤蔗糖酶活性以T2处理(微咸水-再生水1∶2灌溉)最高,土壤脲酶以T3处理(微咸水-再生水1∶1灌溉)最高但和其他处理差异不显著.(5)基于IBRv2指数法,T2处理IBRv2最小,为6.89.因此,综合考虑土壤环境质量指标,在淡水资源匮乏地区利用微咸水(5 g/L)灌溉时,可以考虑用再生替代清水与微咸水配合使用,微咸水-再生水混灌比例以1∶2为宜.

Brackish water has to be used to irrigate crops for harvest due to the scarcity of freshwater resources. However, brackish water irrigation may cause secondary soil salinization. Whether the combined utilization of different non-conventional water resources could relieve the risk of secondary soil salinization has not been reported. In order to explore the safe and rational utilization of brackish water in areas where freshwater resources are scarce, a pot experiment was conducted to study the risk of secondary soil mixed irrigation and rotational irrigation using brackish water and reclaimed water or freshwater. The results indicated that: (1) Short-term irrigation using reclaimed water did not cause secondary soil salinization, although increasing soil pH value, ESP, and SAR. The indices did not exceed the threshold of soil salinization. (2) Compared with mixed irrigation using brackish–freshwater, the contents of soil exchangeable Ca2+, K+, and Mg2+ increased, and the content of soil exchangeable Na+ decreased under rotational irrigation using brackish-reclaimed water. In addition, the contents of soil exchangeable Na+ and Mg2+ under mixed irrigation or rotational irrigation were significantly lower, and the exchangeable K+ content of the soil was higher compared with brackish water irrigation. The exchangeable Ca2+ content under rotational irrigation was higher than that of brackish water irrigation, while the reverse was seen under mixed irrigation. (3) For different combined utilization modes of brackish water and reclaimed water, the ESP and SAR were the lowest under rotational irrigation, followed by mixed irrigation and brackish water irrigation. The ESP under brackish water treatment exceeded 15%, indicating a certain risk of salinization, while ESPs under other treatments were below 15%. Under mixed irrigation or rational irrigation using reclaimed-brackish water, the higher the proportion or rotational times of reclaimed water, the lower the risk of secondary soil salinization. Therefore, short-term combined irrigation using brackish water and reclaimed water will not cause the risk of secondary soil salinization, but further experiments need to verify or cooperate with other agronomic measures in long-term utilization.

Due to reclaimed water, irrigation can cause human health and environmental risks. Soil amendments are applied to reveal the abundance of pathogens and antibiotic resistance genes in rhizosphere soil irrigated by reclaimed water and to better understand the effects of environmental factors on the rhizosphere soil bacterial composition, which has guiding significance for the reasonable use of soil amendments. In this study, the effects of biochar, bioorganic fertilizer, humic acid, loosening soil essence, and corn vinasse on bacterial community diversity and certain gene abundances in rhizosphere soil under drip irrigation with reclaimed water were studied using high-throughput assays and quantitative PCR. The results showed that biochar significantly increased pH, organic matter, and total nitrogen contents in the rhizosphere soil. The corn vinasse significantly decreased soil pH and increased the contents of total nitrogen and total phosphorus but significantly increased the soil EC value (P<0.05). The effects of the five soil amendments on the α-diversity of rhizosphere bacteria were not significantly different. The bacterial community structure and diversity of rhizosphere bacteria were similar at different taxonomic levels, but their relative abundance was different. α-Proteobacteria, γ-Proteobacteria, Bacteroidia, Actinobacteria, Acidimicrobiia, and Anaerolineae were the dominant bacteria in all treatments. The dominant genera consisted of Pseudomonas, Sphingobium, Sphingomonas, Cellvibrio, Allorhizobium-Neorhizobium-Pararhizobium-Rhizobium, Flavobacterium, and Algoriphagus (relative abundance>1%). Correlation analysis of environmental factors showed that the composition of the rhizosphere bacterial community was strongly correlated with pH, EC, total nitrogen, and total phosphorus content. The abundances of pathogenic bacteria and antibiotic resistance genes were 103-107 copies·g-1 and 104-108 copies·g-1, respectively. There were significant differences in the detection levels of pathogens and antibiotic resistance genes. Bioorganic fertilizer, loosening soil essence, and corn vinasse significantly increased the abundances of some antibiotic resistance genes, whereas humic acid and corn vinasse significantly decreased the abundances of Pseudomonas syringae, Ralstonia solanacearum, and total coliforms (P<0.05). A significant correlation was found between pathogens (Arcobacter, Bacillus cereus, Pantoea agglomerans, and Fecal bacteroidetes) and antibiotic resistance genes (tetA, tetB, tetO, tetQ, sul1, ermB, and ermC). In conclusion, while monitoring pathogens and antibiotic resistance genes in the agricultural environment under reclaimed water irrigation, attention should be paid to the rational application of soil amendments to avoid exacerbating the spread of biological contamination.

To explore the effects of mixed irrigation on soil and crops, a pot experiment was conducted in two salinity levels of brackish water, four levels of mixed brackish-reclaimed water and freshwater irrigation as the control. The soil Na-Cl to Ca-SO4 contents changed, and activities of soil alkaline phosphatase and polyphenol oxidase changed, exhibiting a 'V'-shaped curve with increasing the proportion of reclaimed water in the mixture. At the same brackish-reclaimed water level, there were no significant differences in alkaline phosphatase and polyphenol oxidase activities except for soil alkaline phosphatase activity decreasing significantly with the increase in salinity under brackish water irrigation. Mixed irrigation obviously improved superoxide dismutase activity but no significant influences on aboveground dry weight, underground biomass or crop physiological indexes (chlorophyll, soluble protein, malondialdehyde, peroxidase, catalase). Based on the integrated biological response index version 2 (IBRv2), the deviation of reclaimed water irrigation was the smallest, followed by 1:1 and 1:2 (3, 5 g/L brackish water salinities, respectively), with IBRv2 values of 7.94, 12.55 and 16.04. Therefore, considering the soil-crop characteristics, limited daily water amount and inadequate pipeline facilities for reclaimed water, the brackish-reclaimed water ratio should be 1:1 and 1:2 at 3, 5 g/L of brackish water, respectively.

The extensive use of imidacloprid (IMI) has led to its being frequently detected in natural water, also caused the potential damage to the ecosystem. Development of efficient, green and sustainable technique is demanded to eliminate this problem. A novel biochar (KMCBC) derived from agriculture waste of corn cob was first time co modified by potassium hydroxide (KOH), ferric chloride (FeCl3) and zinc chloride (ZnCl2), which showed the greater adsorption amount (410 mg g-1 at 298 K) for imidacloprid (IMI). Pseudo-second-order kinetic and Langmuir isotherm models fitted well with the experimental data, together with the physicochemical characterization analysis, demonstrating that the adsorption process of IMI by KMCBC might be mainly controlled by micropore filling, 7C -7C electron donor-acceptor and functional groups interactions (H-bonding and complexation). Additionally, the thermodynamics parameters suggested that IMI adsorption in this study was a spontaneous, endothermic and randomly increasing process. Besides, KMCBC owned the easy separation performance and promising environmental safety, also exhibited a high selective adsorption capacity regardless of solution pH (its optimum adsorption performance for IMI was obtained at pH = 5), inorganic ions strength and humic acid (HA) concentrations. The regenerated KMCBC (synergistic ultrasound/ethanol) could sustainably and efficiently adsorb IMI in the reuse cycles. Therefore, this study provided an efficient, green and sustainable adsorbent of KMCBC for IMI removal.

Antibiotics and corresponding antibiotic resistance genes (ARGs) are emerging pollutants in wastewater that pose a significant threat to the environment and human health. Constructed wetlands (CWs) are a cost-effective technology for eliminating these pollutants through substrates, plants, and microorganisms. Detailed reviews of the roles of CW substrates on antibiotic and ARG removal and recent progress in the field are lacking. This paper reviews the mechanisms influencing antibiotic and ARG (intracellular and extracellular) removal in CWs, and natural, biomass, chemical, modified, industrial, novel, and combined substrates on their removal efficiencies. Generally, substrates remove antibiotics and ARGs mainly through adsorption, biodegradation, chemical oxidation, and filtration. Other mechanisms, such as photolysis, may also contribute to removal. Natural substrates (e.g., gravel, zeolite) are more frequently employed than other types of substrates. The removal performance of antibiotics and intracellular ARGs by zeolite was better than that of gravel through enhanced substrate adsorption, filtration, and biodegradation processes. Moreover, Mn ore showed promising high capability to remove high concentration of antibiotics through various removal pathways. In addition, combined substrates of soil/sand/gravel and other substrates further facilitate antibiotic removal. Future research is suggested to explore the mechanisms of competitive adsorption and redox-controlled biodegradation, investigate the effect of Fe/Mn oxides on the removal of antibiotics and ARGs via chemical oxidation, evaluate the removal of extracellular ARGs by CWs with different substrates, and investigate the effect of substrates on removal of antibiotics and ARGs in full-scale CWs.

Fluoroquinolones are one of most commonly used antibiotics for preventing and treating bacterial infections and their unsatisfactory removal by conventional wastewater treatment technology have aroused widespread attention. A novel adsorbent of KMSBC was the first time synthesized and tested to adsorb three typical fluoroquinolone antibiotics of CIP, NOR and OFL from water. The characterization analysis showed that KMSBC possessed the superior porous structure, abundant functional groups and greater graphitic degree. Together with kinetics, isotherms, thermodynamics and critical factors (e.g., biochar dose, reaction time/temperature, fluoroquinolone antibiotics concentration, pH, co-existing ionic strength and HA concentration) analysis suggested that pore filling, π-π conjugation, H-bonding and electrostatic interaction were the key mechanisms for fluoroquinolone antibiotics adsorption by KMSBC. KMSBC exhibited the optimum adsorption performance at pH = 5 despite the adsorbates. The maximum adsorption capacity of KMSBC for CIP, NOR and OFL were 49.9, 55.7 and 47.4 mg/g at 25 °C, respectively. Also, KMSBC exhibited the good magnetic sensitivity and stability with the leaching concentrations of Fe were far below than environmental limit (GB5749-2006) at various pH (from 3 to 12), ionic strength and HA concentrations. Additionally, KMSBC performed a stable sustainable adsorption performance in recycles by NaOH regeneration. Thus, KMSBC had the potential to be a promising adsorbent for fluoroquinolone antibiotics removal with favorable adsorption capacity, environmental security and easy regeneration performance.

The abuse of antibiotics poses a threat to the ecological environment and biological health, and how to effectively reduce the residue of tetracycline (TC) in the environment has attracted much attention. In this study, three types of pristine biochar (BCs: PBC300, PBC500, and PBC700) were prepared using agricultural waste shiitake mushroom bran at different pyrolysis temperatures to remove TC from water. The structure and surface chemistry of the adsorbents were characterized using different analytical techniques such as scanning electron microscopy, Fourier transform infrared spectroscopy, X-ray diffraction, and thermogravimetric analysis. These changes in physicochemical properties improve the adsorption capacity of BC. The PBC300 and PBC500 conform to the Langmuir isothermal adsorption model, while the PBC700 is more compatible with the Freundlich model. According to the fitting results of the Langmuir isotherm model, the maximum saturated adsorption capacities of PBC300, PBC500 and PBC700 for TC were 7.568 mg/g, 14.994 mg/g and 17.684 mg/g, respectively. The correlation coefficients of the pseudo-second-order kinetic models were 0.9882, 0.9882 and 0.9996, respectively, which could well fit the adsorption process of TC by the three BCs, indicating that chemical adsorption was dominant. With the help of machine learning, the relationship between the physicochemical properties of BC and the adsorption capacity of TC was effectively explored. The random forest model was able to fit the adsorption process of BC on TC better. It is expected that this study will guide the rational application of BC in the treatment of TC wastewater.

【Objective】 Reducing greenhouse gas (GHG) emissions from soils play an important role in controlling the temperature rise not exceeding 1.5 ℃ by the end of the century. GHG emission is complicated, affected by various physical and biogeochemical processes. In this paper, we studied the impact of irrigation water sources on emissions of CO2, N2O, and CH4 from soils. 【Method】 Incubation experiment was conducted indoors in microcosms. The microcosms were irrigated using reclaimed wastewater, livestock wastewater respectively, with irrigation with fresh groundwater taken as the control. During the experiment, we measured, concurrently, the emissions of CO2, N2O and CH4, the changes in soil pH, water-filled porosity (WFPS), NH4+-N and NO3--N, as well as other edaphic factors. 【Result】 Reclaimed water and livestock wastewater irrigations both significantly increased the emission of CO2, N2O and CH4, compared to irrigation with groundwater (P<0.05). In particular, it was found that reclaimed water irrigation increased N2O emission most, while livestock wastewater irrigation respired more CO2 and CH4 compared to other treatments. In terms of global warming potential (GWP), there was no significant difference in GWP between the reclaimed water irrigation and the livestock wastewater irrigation; however, compared to groundwater irrigation, they both significantly increased GWP (P<0.05). Compared to the control, the livestock wastewater irrigation reduced soil pH, while the reclaimed water irrigation increased soil pH, both at significant levels. Nitrogen in soil irrigated with groundwater was lower than that irrigated by the reclaimed and livestock wastewaters. 【Conclusion】 In terms of GWP and change in soil properties, reclaimed wastewater and livestock wastewater irrigation increased GHG emissions and enhanced mineral nitrogen in soil.

【Objective】 Using treated wastewater as a supplementary water resource for irrigation is one solution to helping relieve the pressure resulting from water shortage in many regions around the world. Since reclaimed wastewater is rich in nutrients and elements that are beneficial and harmful to crops and soil microbial communities, the impact of reclaimed water irrigation on microbial activity and physicochemical properties of soil is likely to vary with other agronomic practices, which remains poorly understood. The purpose of this paper is to address these issues. 【Method】 The experiments were conducted in pots repacked with soil. The irrigation amount was the same in all pots, and every pot was irrigated four times after emergence and each time irrigated 1 L water, with nitrogen fertilization varying only(0, 120, 150, 180 mg/L). Clean water irrigation was taken as the control. During the experiment, we measured the change in nitrogen distribution and urease activity in each pot. 【Result】 Compared with the control, reclaimed water irrigation did not show significant effect on soil organic mass (SOM), total nitrogen (TN), ammonium, but reduced soil pH, electrical conductivity (EC) and water-soluble Na+ content. It also increased soil nitrate, water-soluble K+ and urease activity in the 0~10 cm soil layer, all at significant level. Soil physicochemical properties and urease activity in the 0~5 cm soil were negatively correlated with TN and water-soluble Na+, while positively correlated with water-soluble K+, all at significant level. 【Conclusion】 For all treatments we compared, reclaimed water irrigation coupled with 120 mg/kg of nitrogen fertilization was most beneficial to increasing soil nutrients and urea activity in the soil.

【Objective】 Nitrogen exists in different forms which have different effects on soil biogeochemical processes and plant growth and nutrients acquisition. The purpose of this paper is to investigate the impact of combinations of different nitrogen forms on the growth and physiological traits of ryegrass in hydroponic culture under Cd stress. 【Method】 We used treated wastewater as the hydroponic culture and grew the ryegrass by contaminating the culture with Cd concentration set at 0.01 and 0.1 mg/L, respectively. The nitrogen was nitrate and ammonium with the nitrate : ammonium ratio being set at 100∶0, 75∶25, 50∶50, 25∶75 and 0∶100. In each treatment, we measured the physiological traits of the plant 【Result】 When the Cd concentration was 0.01 mg/L, increasing nitrate application promoted the growth of both roots and shoots, as well as absorption of Cd by the ryegrass when the nitrate : ammonium ratio increased from 25% to 100%. When Cd concentration increased to 10 mg/L Cd, the MDA content in the ryegrass was lower than that at 0.01 mg/L concentration, regardless of the nitrate : ammonium ratio. The content of MDA in the ryegrass under Cd stress was the lowest when nitrate : ammonium was 100∶0. We also found that Cd stress boosted the activities of CAT and POD in the ryegrass when the amount of ammonium increased from 50% to 100%. 【Conclusion】 Increasing ammonium in the nutrient solution benefited Cd2+ absorption by the ryegrass, thereby reducing its detrimental impact on ryegrass growth and development.