Treated livestock wastewater reuse for irrigation and straw return in arid regions have become common practices worldwide. However, many uncertainties still exist regarding the effects of the returning straw sizes on heavy metal accumulation in soil and plants under treated livestock wastewater irrigation. In a pot experiment growing maize and soybean, large (5–10 cm), medium (1–5 cm), and small (<1 cm) sizes of wheat straw were amended to assess the changes in Cu and Zn distribution in the rhizosphere, bulk soils, and plants. Groundwater and swine wastewater were used as irrigation water resources. The results showed that irrigation with swine wastewater significantly reduced soil pH and increased the concentration of soil-available potassium. Concentrations of Cu in soil were more sensitive to swine wastewater and straw application than those of Zn in soil. Swine wastewater irrigation increased the accumulation of Cu and Zn in plants with higher concentrations of Zn, while straw return tended to inhibit this increase, especially when a small size of straw was employed. In addition to providing a reference for revealing the interaction mechanism between swine wastewater irrigation and straw return, this study proposes feasible solutions to improve the efficiency of agricultural waste recycling and realize sustainable agricultural development.

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.

Environmental hazards and remediation of pharmaceuticals and personal care products（PPCPs）have recently received growing attentions. Thus, investigating the purification effect of azolla on domestic sewage containing PPCPs is important. Representative PPCPs gemfibrozil, carbamazepine, and azolla were used as test materials, and indoor simulation culture tests were conducted to investigate the growth of azolla in domestic wastewater at both different incubation times（1, 2, 4, and 8 d）and different initial concentrations of PPCPs(0,1, 10, 100, and 1 000 μg·L -1 ), as well as the removal rates of conventional pollutants（ammonia nitrogen, NH3-N; nitrate nitrogen, NO 3 --N;total phosphorus, TP; chemical oxygen demand, COD）and PPCPs. With an increase of the initial concentration of PPCPs in domestic wastewater, the relative growth rate and tolerance index of azolla showed a trend of first increasing and then decreasing, and the growth of azolla was inhibited under the treatment of 100 and 1 000 μg · L -1 PPCPs. Compared with the control, the removal effect of azolla on nitrogen and phosphorus was significantly enhanced under 1 and 10 μg·L -1 PPCPs treatment（P＜0.05）, but was significantly weakened under100 and 1 000 μg·L -1 PPCPs treatment（P＜0.05）. When treating with different initial concentrations of PPCPs, the effect of azolla on COD removal was significant, and the COD removal rate increased with the increase of the initial concentration of PPCPs. The removal effect of azolla on gemfibrozil and carbamazepine was enhanced with increasing incubation time. The removal rate of gemfibrozil increased with increasing initial concentration of PPCPs(except for 1 000 μg·L -1 PPCPs treatment), whereas the removal rate of carbamazepine decreased with increasing initial concentration of PPCPs. Azolla has a good removal effect on both PPCPs and conventional pollutants other than ammonia nitrogen in domestic wastewater and can be used as a remediation treatment plan for domestic wastewater containing typical PPCPs.

随着药品和个人护理品(Pharmaceuticals and Personal Care Products,PPCPs)生产和使用量的增加,PPCPs及其代谢产物在再生水中的检出种类、检出量不断增多,再生水灌溉可影响PPCPs在土壤-作物(蔬菜)系统中的分布及累积,但其规律及驱动机制尚不明确.为探明再生水滴灌条件下滴头布置方式对PPCPs在土壤-作物(蔬菜)系统累积的影响,该研究采用盆栽试验比较2种滴头布置方式(在番茄根部、在两番茄中间)对土壤剖面及番茄各器官中PPCPs累积量的影响,并进一步分析PPCPs在土壤-作物(蔬菜)系统累积的驱动机制.结果表明,再生水灌溉条件下不同滴头布置方式造成了PPCPs在土壤、作物(蔬菜)中累积规律的差异性,滴头布置在两番茄中间处理较其他处理而言增加了0～5 cm土层吉非罗齐累积量(P<0.05),降低了番茄叶部卡马西平和根部吉非罗齐的累积量(P<0.05),较滴头布置在番茄根部处理降低了番茄叶部吉非罗齐和根部三氯生的累积量(P<0.05);不同再生水灌溉方式通过影响土壤微环境指标导致了土壤中PPCPs分布规律的差异性,滴头布置在植株中间处理较其他处理增加了0～5 cm土层pH值,导致该土层下吉非罗齐的累积量高于其他处理(P<0.05).研究可为基于新兴污染物PPCPs防控的再生水农业安全利用提供理论依据.

随着药品和个人护理品(PPCPs)生产和使用量的增加,PPCPs及其代谢产物在水体、土壤环境中的检出量、检出种类与日俱增.本文基于国内外已有的相关文献,总结了典型PPCPs通过不同途径进入土壤-作物系统的环境风险,并从PPCPs在土壤-作物系统中的降解行为特征和迁移累积规律等方面对PPCPs环境行为及归趋的最新研究进展进行了综述,指出目前研究存在的PPCPs种类、浓度、输入方式以及环境背景的单一性等突出问题,并对该领域未来研究趋势进行了展望,如不同类别PPCPs的环境行为特征、与土壤微环境的互作机制、降解或螯合产物及其环境行为与风险等方面的研究,对于探明PPCPs对生态环境的影响规律及对人类健康的潜在危害具有重要意义.

【Background and objective】 Rhizosphere is the interface of soil and plant housing a unique microbial community which not only mediates carbon and nutrient cycles but is also the underlying drivers of soil structure genesis. Soil microorganisms self-restructure following environmental change, which has a consequence for all biogeochemical processes. The purpose of this study is to investigate if and how dripping rate affects the microbial community of the rhizosphere of tomato drip-irrigated using reclaimed water. 【Method】 Pot experiment was conducted in an intelligent artificial climate chamber. It compared three dripping rates: 2, 4 and 8 L/h, with traditional flood irrigation taken as the control. After harvesting the plants, microbial community in the different root zone soil layers (0~5, 5~10, and 10~15 cm) of each treatment was analyzed using the 16S rDNA microbial diversity sequencing method. 【Result】 Microbial diversity index under drip irrigation was higher than that under the control, regardless of the dripping rate, and their difference was most significant in the 5~10 cm soil layer (P<0.05). Dripping rate did not show a significant impact on dominant flora at phylum and genus level, but the relative abundance of microbial community changed with edaphic factors such as pH, EC, total phosphorus. Dripping at the rate of 2 L/h increased the total phosphorus content in the 10~15 cm soil compared with other treatments, and it also significantly increased the relative abundance of Bacteroidetes. Compared with the control, the drip irrigations increased pH and reduced the relative abundance of Sphingomonas in the 10~15 cm soil. When the dripping rate was 2 L/h, the abundance of each functional microbial pathway was the highest in the top 0~5 cm soil. 【Conclusion】 Dripping rate in using reclaimed water to irrigate tomato altered the physical and chemical properties of soil, thereby shifting microbial community and microbial distribution in the rhizosphere. It also reshaped the distribution of the abundance of some functional flora in soil profile. Our finding implicates that selecting an appropriate drip irrigation rate could have a significant consequence for carbon and nutrient cycles in drip-irrigated crops using reclaimed water due to its impact on microbial community and the associated functions.