Agricultural plastic greenhouse (PG) production can extend the growing season of crops to satisfy domestic consumption in countries such as China. Workers in PGs have potential higher phthalate exposure risks than the general population as phthalate accumulation has been observed in greenhouse soil, air, and crops. To date, biomonitoring tests of phthalates for the working population have not been carried out. To address this shortage, we conducted a pilot study in Shaanxi Province, China, among 35 healthy PG workers by follow-up recording their seasonal dietary habits and work activities and urine sample collection and measurement between 2018 and 2019. The objectives were to uncover the association between phthalate metabolites and the population characteristics, seasonal and diurnal variations and causes, and to estimate exposure risks and contributions of exposure pathways from PG production systems. A total of 13 phthalate metabolite concentrations (Σ₁₃ phthalate metabolites) ranged from 102 to 781 (5th-95th) ng/mL (median: 300 ng/mL). Mono-n-butyl phthalate (MNBP) made up 51.3% of Σ₁₃ phthalate metabolites, followed by the sum of four di-2-ethylhexyl phthalate (DEHP) metabolites (24.2%), mono-2-isobutyl phthalate (MIBP) (13.4%), and mono-ethyl phthalate (MEP) (9.8%). The concentrations of MNBP and MIBP in summer were significantly higher than the levels in winter (p < 0.0001). A total of 62.3% of the PG worker population was shown to have exposure risks, and the proportion was as high as 79.4% in summer. Phthalate exposure of the workers from PG production systems constituted over 20% of the total creatinine-based daily intake, and consuming vegetables and fruit planted in PGs and inhalation in PGs were the two largest exposure pathways. Our findings demonstrate that it is important to protect workers in PGs from phthalate exposure risks, and phasing out the use of plastic materials containing phthalates in PGs is imperative, to guarantee food safety in PGs.

Long-term substantial application of fungicides in greenhouse cultivation led to residual pollution in soils and then altered soil microbial community. However, it is unclear whether residual fungicides could affect the diversity and abundance of antibiotic resistance genes (ARGs) in greenhouse soils. Here, the dissipation of fungicides and its impact on the abundance of ARGs were determined using shotgun metagenomic sequencing in the greenhouse and mountain soils under laboratory conditions. Our results showed the greenhouse soils harbored more diverse and abundant ARGs than the mountain soils. The application of carbendazim, azoxystrobin, and chlorothalonil could increase the abundance of total ARGs in the greenhouse soils, especially for those dominant ARG subtypes including sul2, sul1, aadA, tet(L), tetA(G), and tetX2. The abundant ARGs were significantly correlated with mobile genetic elements (MGEs, e.g. intI1and R485) in the greenhouse soils but no significant relationship in the mountain soils. Meanwhile, the co-occurrence patterns of ARGs and MGEs, e.g., sul2 and R485, sul1 and transposase, were further verified via the genetic arrangement of genes on the metagenome-assembled contigs in the greenhouse soils. Additionally, host tracking analysis indicated that ARGs were mainly carried by enterobacteria in the greenhouse soils but actinomyces in the mountain soils. These findings confirmed that some fungicides might serve as the co-selectors of ARGs and elevated their abundance via MGEs-mediated horizontal gene transfer in the greenhouse soils.

In an attempt to evaluate the behavior of Dechlorane plus (DP) in soil-vegetable systems, this work investigated the uptake and translocation of DP by vegetables and the dissipation of DP in soil under greenhouse and conventional conditions. To address human dietary exposure to DP, estimated dietary intake via vegetable consumption was calculated. The uptake potential indexes of DP from soil into root for tomato and cucumber cultivated under different conditions ranged from 0.089 to 0.71. The ranges of uptake potential indexes of DP from resuspended soil particles into stem, leaf and fruit were 0.68–0.78, 0.27–0.42 and 0.39–0.75, respectively. The uptake potential indexes in greenhouse vegetables were generally higher than those in conventional vegetables when the vegetables had been planted in contaminated soil, indicating that greenhouse enhanced the uptake of DP with a high soil concentration by vegetables. The translocation factor (TF) values of DP in vegetables were in the range of 0.022–0.17, indicating that DP can be transported from root to fruit even though it has a high octanol water partition coefficient (KOW). The half-lives of DP dissipation in soil ranged from 70 to 102 days. The dissipation of DP in greenhouse soil was slightly slower than that in conventional soil. Higher estimated dietary intake (EDI) values of DP via greenhouse vegetables were observed due to the higher concentration of DP in greenhouse vegetables than conventional vegetables. These results suggested that greenhouses should not be adopted for vegetable production in contaminated regions.

A national scale survey was conducted to determine an array of inorganic and organic contaminants in agricultural soils from two cultivation modes (greenhouse vs. open field) in 20 provinces across China. The investigated contaminants include organochlorine pesticides (OCPs), phthalate esters (PAEs), polycyclic aromatic hydrocarbons (PAHs), lead (Pb), zinc (Zn), copper (Cu) and cadmium (Cd). The large amounts of agrochemicals used and special cultivation mode in greenhouse caused substantial soil pollution and deterioration of soil quality. Mean concentrations of both OCPs and PAEs in greenhouse soil were approximately 100% higher than those in open field. The pH values were 6.85 ± 1.04 and 7.34 ± 0.84 for greenhouse and open field, respectively (p > 0.05). The soil microbial community was predicted to be affected by pollution in greenhouse through the PICRUSt analysis of 16s rRNA sequences. The 12 variables including various chemicals and soil properties together explained 15% of the observed variation in the community composition. In the studied variables, PAEs and lead were the primary factors affecting microbial diversity in greenhouse soils, while pH had the greatest impact on the microbial community in open field soils. These findings enhanced our understanding of the environmental impact and contamination management of greenhouses worldwide.

As a result of metal mining activities in Pakistan, toxic heavy metals (HMs) such as chromium (Cr) and lead (Pb) often enter the soil ecosystem, accumulate in food crops and cause serious human health and environmental issues. Therefore, this study examined the efficacy of biochar for contaminated soil remediation. Poplar wood biochar (PWB) and sugarcane bagasse biochar (SCBB) were amended to mine-contaminated agricultural soil at 3% and 7% (wt/wt) application rates. Lactuca sativa (Lettuce) was cultivated in these soils in a greenhouse, and uptake of HMs (Cr and Pb) as well as biomass produced were measured. Subsequently, health risks were estimated from uptake data. When amended at 7%, both biochars significantly (P<0.01) reduced plant uptake of Cr and Pb in amended soil with significant (P<0.01) increase in biomass of lettuce as compared to the control. Risk assessment results showed that both biochars decreased the daily intake of metals (DIM) and associated health risk due to consumption of lettuce as compared to the control. The Pb human health risk index (HRI) for adults and children significantly (P<0.01) decreased with sugarcane bagasse biochar applied at 7% rate relative to other treatments (including the control). Relative to controls, the SCBB and PWB reduced Cr and Pb uptake in lettuce by 69%, 73.7%, respectively, and Pb by 57% and 47.4%, respectively. For both amendments, HRI values for Cr were within safe limits for adults and children. HRI values for Pb were not within safe limits except for the sugarcane bagasse biochar applied at 7%. Results of the study indicated that application of SCBB at 7% rate to mine impacted agricultural soil effectively increased plant biomass and reduced bioaccumulation, DIM and associated HRI of Cr and Pb as compared to other treatments and the control.

Few studies have been carried out so far for measuring concentrations of NH3, NO2 and O3 in plastic greenhouses. In this study, NH3, NO2 and O3 concentrations were measured with passive sampler technology in a plastic greenhouse located in the Changsha suburb in southern China over a one and a half month period (November 30, 2008 to January 11, 2009). Soil in the greenhouse was subjected to four treatment (T) types (no N fertilizer T1, common urea T2, coated urea T3 and common urea with nitrification inhibitor dicyandiamide (DCD) T4. The average concentrations (μg/m3) of NH3, NO2 and O3 in descending order was: T4 (31.66) > T2 (25.93) > T3 (23.52) > T1 (7.96), T2 (10.99) > T3 (8.16) > T4 (7.48) > T1 (5.20), T2 (75.05) > T3 (64.20) > T4 (63.85) > T1 (49.02), respectively. This implied that photochemical reactions took place and that harmful gases accumulated after application of N fertilizer in the plastic greenhouse. DCD inhibited the conversion of ammonium to nitrate, increased NH3 volatilization and decreased NO2 level. The coated urea decreased the emissions of NH3 and increased nitrogen use efficiency. We found significant positive correlations (p < 0.01) between temperature and both NH3 and NO2 levels. Correlations between soil pH and both NH3 and NO2 concentrations were also significant (p < 0.01). The O3 average concentration from March 31, 2009 to April 10, 2009 in the higher latitude of the Yinchuan suburb in northern China was two times greater than that in the Changsha suburb in southern China. The O3 daily concentrations in the Yinchuan suburb exceeded 160 μg/m3 (i.e., China's Grade I standard), and the maximal value 214.83 μg/m3 exceeded 200 μg/m3 (i.e., China's Grade III standard).

Due to the increasing concerns of heavy metal contamination in greenhouse soil, the safe production of vegetables, especially leafy vegetables, is largely limited. In this study, the cadmium (Cd) concentration and major nutritional qualities of 23 main celery cultivars from China were compared in a greenhouse experiment. Large genotypic differences in biomass, cadmium accumulation and nutrition traits were observed. The biomass of cultivars Hongqin (HQ), Jialifuniyadiwangxiqin (JZ), Jinhuangqincai (JH) and Shanqincai (SQ) was significantly higher than that of the others. The Cd concentration in the edible part ranged from 0.53 to 2.56 mg·kg⁻¹ DW, of which SQ exhibited the lowest Cd concentration. In addition, SQ had the lowest Cd transport factor (TF) and bioconcentration factor (BCF), followed by Liangfengyuqin (LF). Simultaneously, both genotypes had a relatively higher chlorophyll content and vitamin C concentration and lower cellulose content. Therefore, the two genotypes SQ and LF were selected as promising candidates for growth in a moderately Cd-contaminated greenhouse to achieve safe production. Further correlation analysis and redundancy analysis showed that the Cd concentration in the edible part was positively correlated with the cellulose content but negatively correlated with the vitamin C concentration. The results of celery variety screening provide a safe production strategy for moderately polluted greenhouse vegetable soils.

To deal with the problems of increasing the heavy metal (HM) bioavailability and declining the soil biological properties resulting from a direct application of solid digestate (SD). A low-temperature fruit biochar and pig-SD (BSD-0, BSD-1, BSD-2, BSD-4, BSD-8) co-application experiment was performed to evaluate enzyme activities and HM bioavailability in Cd-polluted greenhouse soil. The advantage of BSD co-applications compared to SD application was maintained the stable of pH and electrical conductivity (EC) in soil and was more effective to improve soil organic matter (OM). BSD-8 treatment significantly promoted the uptake of available nitrogen, available phosphorus, and available potassium by plants. The immobilization effect of BSD co-applications on Cu, Zn, and Cd was better than SD application. BSD-8 treatment has the best immobilization effect on Cd and the contents of bioavailable Cd was 0.167 mg kg⁻¹. The optimal enzyme activities of invertase, urease, and alkaline phosphatase were shown in BSD-8 treatment, which were 0.027 mg glucose g⁻¹ soil h⁻¹, 88.654 mg NH₃-N g⁻¹ soil h⁻¹, and 15.766 μmol PNP g⁻¹ soil h⁻¹, respectively. The activities of enzymes also were influenced by soil physicochemical properties and HM bioavailability. BSD-8 treatment was suggested as an appropriate mixing proportion to alleviate soil acidification and salinization, decreasing HM bioavailability and stimulating enzyme activities in Cd-polluted soil. Statement of Novelty Solid digestate (SD) is commonly used for agricultural crops as organic fertilizer because of its abundant nutrients and long-term soil fertility maintenance. However, excessive application of SD may cause heavy metal bioavailability to increase and soil biological properties to decline, while the effects of biochar and SD (BSD) co-applications on greenhouse soil enzyme activities and heavy metal bioavailability are often neglected. To deal with these problems, a greenhouse experiment was established comparing the effects of co-applications of different SD application rates with low-temperature fruit biochar on HM bioavailability and biological properties. Our research uses the weight of SD per square meter as the fertilization basis for the rational utilization of SD and gives evidence for the safety and effectivity of BSD co-applications in agriculture.

Soil pollution by heavy metals (HMs) has rapidly become a major threat to vegetable security. Nearly all cultivated soils are at risk of metal accumulation, and greenhouse soils are among the most heavily impacted soils. In this study, a rapid assessment of HMs at trace concentrations was conducted via portable X-ray fluorescence (PXRF) spectroscopy in Shouguang, China. Measurements were made via PXRF under in situ, ex situ and sieved conditions and by inductively coupled plasma mass spectrometry (ICP-MS) after acid digestion. The performance of each PXRF measure relative to the ICP-MS method was assessed by linear regression. Redundancy analysis was performed to quantify the proportion of explained variability between the PXRF and ICP-MS data. Evaluation of the possible sources of HMs and their potential risks was then conducted by multivariate analysis. The results showed that the PXRF data were closely correlated with ICP-MS quantification for Cu, Mn and Zn, whereas no significant correlations were found for As, Ni and Pb. The uncertainties of PXRF measurement derived from soil heterogeneity accounted for 20.02% of total variability and those from moisture and particle size accounted for 20.15%. The geo-accumulation index (Igₑₒ) indicated that the greenhouse soils were potentially contaminated by Cu and Zn (Igₑₒ > 0), which can be attributed to anthropogenic activities. Overall, PXRF spectroscopy is promising as a rapid and nondestructive in situ technique for assessing the potential risks of HMs at trace concentrations in greenhouse soils.

Natural estrogens in greenhouse soils with long-term manure application are becoming a potential threat to adjacent aquatic environment. Porous stalk biochar as a cost-effective adsorbent of estrogen has a strong potential to reduce their transportation from soil to waters. But the dominant adsorption mechanism of estrogen to stalk biochars and retention of estrogen by greenhouse soils amended with biochar are less well known. Element, function groups, total surface area (SAₜₒₜₐₗ), nano-pores of stalk biochars, and chemical structure of 17β-estradiol (E2, length 1.20 nm, width 0.56 nm, thickness 0.48 nm) are integrated in research on E2 sorption behavior in three stalk-derived biochars produced from wheat straw (WS), rice straw (RS), and corn straw (CS), and greenhouse soils amended with optimal biochar. The three biochars had comparable H/C and (O + N)/C, while their aromatic carbon contents and total surface areas (SAₜₒₜₐₗ) both varied as CS > WS > RS. However, WS had the highest sorption capacity (logK ₒc), sorption affinity (K f), and strongest nonlinearity (n). Additionally, the variation of Langmuir maximum adsorption capacity (Q ⁰) was consistent with the trend for SA₁.₂₋₂₀ (WS > RS > CS) but contrary to the trend for SAₜₒₜₐₗ and SA<₁.₂ (CS > WS > RS). These results indicate that pore-filling dominates the sorption of E2 by biochars and exhibits “sieving effect” and length-directionality-specific via H-bonding between –OH groups on the both ends of E2 in the length direction and polar groups on the inner surface of pores. After the addition of wheat straw biochar, the extent of increase in the sorption affinity for E2 in the soil with low OC content was higher than those in the soil with high OC content. Therefore, the effectiveness for the wheat straw biochar mitigating the risk of E2 in greenhouse soil depended on the compositions of soil, especially organic matter.