The combined application of organic and synthetic nitrogen (N) fertilizers is being widely recommended in China’s vegetable systems to reduce reliance on synthetic N fertilizer. However, the effect of substituting synthetic fertilizer with organic fertilizer on vegetable productivity (yield, N uptake and nitrogen use efficiency) and reactive nitrogen (Nr) losses (N₂O emission, N leaching and NH₃ volatilization) remains unclear. A meta-analysis was performed using peer-reviewed papers published from 2000 to 2019 to comprehensively assess the effects of combined application of organic and synthetic N fertilizers. The results indicate that overall, the vegetable yield, N₂O emission and NH₃ volatilization were not significantly changed, whereas N leaching was reduced by 44.6% and soil organic carbon (SOC) concentration increased by 12.5% compared to synthetic N fertilizer alone. Specifically, when synthetic N substitution rates (SRs) were ≤70%, vegetable yields and SOC concentration were increased by 5.5%–5.6% and 13.1–18.0%, and N leaching was reduced by 41.6%–48.1%. At the high substitution rate (SR>70%), vegetable yield was reduced by 13.6%, N₂O emission was reduced by 14.3%, and SOC concentration increased by 16.4%. Mixed animal-plant sources of organic N preferentially increased vegetable yield and SOC concentration, and reduced N₂O emission and N leaching compared with single sources of organic-N. Greenhouse gas (GHG) emission was decreased by 28.4%–34.9% by combined applications of organic and synthetic N sources, relative to synthetic N fertilizer alone. We conclude that appropriate rates (SR ≤ 70%) of combined applications of organic and synthetic N fertilizers could improve vegetable yields, decrease Nr and GHG emission, and facilitate sustainable development of coupled vegetable-livestock systems.

Microbial biofilms can rapidly colonize plastic debris in aquatic environments and subsequently, accumulate chemical pollutants from the surrounding water. Here, we studied the microbial colonization of different plastics, including polyethylene terephthalate (PET), polypropylene (PP), polyvinyl chloride (PVC), and polyethylene (PE) exposed in three freshwater systems (the Qinhuai River, the Niushoushan River, and Donghu Lake) for 44 days. We also assessed the biofilm mass and associated metals attached to plastics. The plastics debris characteristics, such as contact angle and surface roughness, greatly affected the increased biofilm biomass. All types of metal accumulation onto the plastic substrate abundances significantly higher than the concentrations of heavy metal in the water column, such as Ba (267.75 μg/g vs. 42.12 μg/L, Donhu Lake), Zn (254 μg/g vs. 0.023 μg/L the Qinhuai River), and Cr (93.75 μg/g vs. 0.039 μg/L, the Niushoushan River). Compared with other metals, the heavy metal Ba, Cr and Zn accumulated easily on the plastic debris (PET, PP, PVC, and PE) at all incubation sites. Aquatic environmental factors (total nitrogen, total phosphorus, and suspended solids concentrations) largely shaped metal accumulation onto plastic debris compared with plastic debris properties.

Antibiotics can stimulate the growth of model cyanobacterial species under pure culture conditions, but their influence on cyanobacterial blooms in natural aquatic ecosystems remains unclear. In this study, three commonly detected antibiotics (sulfamethoxazole, tetracycline, and ciprofloxacin) and their ternary mixture were proved to selectively stimulate (p < 0.05) the growth and photosynthetic activity of cyanobacteria in an aquatic microcosm at an environmentally relevant exposure dose of 300 ng/L under both oligotrophic and eutrophic conditions. Under the eutrophic condition, cyanobacteria reached a bloom density of 1.61 × 10⁶ cells/mL in 15 days without antibiotics, while the cyanobacteria exposed to tetracycline, sulfamethoxazole, ciprofloxacin, and their ternary mixture exceeded this bloom density within only 10, 8, 7, and 6 days, respectively. Principal coordinate analysis indicated that the antibiotic contaminants accelerated the prokaryotic community succession towards the formation of a cyanobacterial bloom by promoting the dominance of Microcystis, Synechococcus, and Oscillatoria under the eutrophic condition. After 15 days of culture, the antibiotic exposure increased the density of cyanobacteria by 1.38–2.31-fold and 2.28–3.94-fold under eutrophic and oligotrophic conditions, respectively. Antibiotic exposure generated higher stimulatory effects on cyanobacterial growth under the oligotrophic condition, but the antibiotic(s)-treated cyanobacteria did not form a bloom due to nutrient limitation. Redundancy analysis indicated that the three target antibiotics and their ternary mixture affected the prokaryotic community structure in a similar manner, while tetracycline showed some differences compared to sulfamethoxazole, ciprofloxacin, and the ternary antibiotic mixture with regard to the regulation of the eukaryotic community structure. This study demonstrates that antibiotic contaminants accelerate the formation of cyanobacterial blooms in eutrophic lake water and provides insights into the ecological effects of antibiotics on aquatic microbial communities.

Reservoirs are lentic man-made waterbodies resulting from river damming processes. Pollutants coming from adjacent areas can accumulate in the water and sediment of these modified freshwater environments. Fish are often found in reservoirs occupying several trophic niches. Biochemical biomarkers are early warning signals of environmental disturbance to an organism. It is essential to understand how pollutants, abiotic variables and biochemical biomarker responses behave throughout the seasons to implement biomonitoring programs. Loricariichthys anus and Geophagus brasiliensis were collected, and abiotic variables were seasonally measured for one year, at six sampling sites in Passo Real reservoir, in a subtropical region of Southern Brazil. Biochemical biomarkers were analyzed in four tissues of both fish species, as well as metal and pesticide concentrations in the reservoir’s water and sediment. Redundancy analysis (RDA) was carried out to find the temporal relationship between biomarkers and environmental variables. RDA has clearly shown the separation of seasons for both species. Azoxystrobin, simazine and propoxur were the pesticides mostly contributing to the variation, whereas metals had lesser contribution to it. Seasonality appears to be the main factor explaining biomarkers’ variability. PERMANOVA has confirmed the effect of temperature and dissolved oxygen on biomarkers of both fish species. Thus, it is hard to differentiate if the fluctuation in biomarkers’ responses only reflects the normal state of organisms or it is a biological consequence from negative effects of fish exposure to several types of pollution (sewage, pesticides, and fertilizers) entering this aquatic system. In this study, to circumvent the seasonality issue on biomonitoring, the analysis of biomarkers on these fish should not be carried out in organs directly affected by temperature (such as liver and gills), or during reproduction periods (mainly in Spring).

Southwestern China contains the largest and most well-developed karst region in the world, and the potentially toxic elements (PTEs) content in the soils of the region is remarkably high. To explore the internal and external control factors and sources of soil PTEs enrichment in this area and to provide a basis for the treatment of PTE pollution, 113 soil samples were collected from Hengxian County, a karst region in Guangxi Province, southwestern China. The importance of eighteen influencing factors including parent material, weathering, physicochemical properties, topography and human activities were quantitatively analyzed by (partial) redundancy analysis. The sources of PTEs were identified using the Pb isotope ratio and absolute principal component score/multiple linear regression (APCS-MLR) model. The contents of all soil PTEs were higher than the corresponding background values of Guangxi soils. The contents in Cu, Zn, Cd, Hg and Pb were the highest in the soil from carbonate rock. The factor group of geological background and weathering explained 26.5% for the accumulation and distribution of soil PTEs and the influence of physicochemical properties was less than 2% but increased to 25.6% through interaction with weathering. Fe (47.1%), Al (42.1%), Mn (22%), chemical index of alteration (12.8%) and clay (11.9%) were the key factors affecting the soil PTEs, while the influence of human activities was weak. Pb isotope ratio and APCS-MLR classified 62.8–74% of soil PTEs as derived from natural sources, whereas 18.23% and 18.95% were derived from industrial activities and agricultural practice/traffic emissions, respectively. The Pb isotope ratio showed that the natural sources account for up to 90% of the Pb in the soil from carbonate rock, the highest contribution among the studied soils. The results of the study can provide background information on the soil PTEs contamination in the karst areas of China and other areas worldwide.

In this study, the influencing factors and sources of historical changes in polycyclic aromatic hydrocarbons (PAHs) in the sediment core of Fuxian Lake were analyzed. Before 1970, the Σ₁₆PAH concentration fluctuated widely, with one or more maximum values. During 1971–2004, the Σ₁₆PAH concentration showed a slow growth trend, while during 2005–2017, the concentration increased sharply, reaching a peak value of 821 ng g⁻¹. dw in 2017. The results of a positive matrix factorization (PMF) model demonstrated that before 1970, PAHs were mainly derived from biomass burning in the Fuxian Lake sediment core, with an overall contribution of 40 %. During 1971–2004, the source of PAHs was mainly coal combustion, with an overall contribution of 34 %. During 2005–2017, PAHs primarily originated from traffic, with an overall contribution of 33 %. Population, coal, GDP, motor, and petroleum had a significant influence on low molecular weight (LMW) PAHs in 1980–2004 and 2005–2017. Motor, coal, population, and GDP had a greater impact on high molecular weight (HMW) PAHs. Before 1970 and in 1971–2004, meteorological factors had little effect on PAHs in the sediment core in Fuxian Lake. During 2005–2017, day and rainfall were significantly negatively correlated with HMW PAHs, while temperature and wind were not correlated with PAH concentrations. During 2005–2017, total organic carbon (TOC) and total nitrogen (TN) had greater adsorption effects on HMW PAHs than on LMW PAHs. Before 1970 and in 1971–2004, the adsorption effects of TOC and TN on 3–4-ring PAHs were greater than those of 2-ring and 5–6-ring PAHs. Total phosphorus (TP) had no adsorption effect on PAHs in the entire sedimentary column.

Heavy metal pollution was the main risk during livestock manures composting, in which microorganisms played a vital role. However, response strategies of microbial community to heavy metals stress (HMS) remained largely unclear. Therefore, the objective of this study was to reveal the ecological adaptation and counter-effect of bacterial community under HMS during chicken manures composting, and evaluating environmental implications of HMS on composting. The degradation of organic matters (more than 6.4%) and carbohydrate (more than 19.8%) were enhanced under intense HMS, suggesting that microorganisms could quickly adapt to the HMS to ensure smooth composting. Meanwhile, HMS increased keystone nodes and strengthened significant positive correlation relationships between genera (p < 0.05), indicating that bacteria resisted HMS through cooperating during composting. In addition, different bacterial groups performed various functions to cope with HMS. Specific bacterial groups responded to HMS, and certain groups regulated bacterial networks. Therefore, bacterial community had the extraordinary potential to deal with HMS and guarantee chicken manures composting even in the presence of high concentrations of heavy metals.