Delineating and identifying risk zones of soil heavy metal pollution in an industrialized region using machine learning.

The ability to control the risk of soil heavy metal pollution is limited by the inability to accurately depict their spatial distributions and to reasonably delineate the risk zones. To overcome this limitation and develop machine learning methods, a hybrid data-driven method supported by random forest (RF) and fuzzy c-means with the aid of inverse distance weighted interpolation was proposed to delineate and further identify risk zones of soil heavy metal pollution on the basis of 577 soil samples and 12 environmental covariates. The results indicated that, compared to multiple linear regression, RF had a better prediction performance for As, Cd, Cr, Cu, Hg, Ni, Pb, and Zn, with the corresponding R2 values of 0.86, 0.85, 0.78, 0.85, 0.84, 0.78, 0.79 and 0.76, respectively. The relative concentrations (predicted concentrations divided by risk screening values) of Cd (17.69), Cr (1.38), Hg (0.31), Pb (6.52), and Zn (8.24) were relatively high in the north central part of the study area. There were large differences in the key influencing factors and their contributions among the eight heavy metals. Overall, industrial enterprises (21.60% for As), soil pH (31.60% for Cd), and population (15.50% for Cr) were the key influencing factors for the heavy metals in soil. Four risk zones, including one high risk zone, one medium risk zone, and two low risk zones were delineated and identified based on the characteristics of the eight heavy metals and their influencing factors, and accordingly discriminated risk control strategies were developed. In the high risk zone, it will be necessary to strictly control the discharge of heavy metals from the various industrial enterprises and mines by the adoption of cleaner production practices, centralizedly treat the domestic wastes from residents, substantially reduce the irrigation of polluted river water, and positively remediate the Cd, Cr, and Ni-polluted soil.

Assessment of the Driving Pollution Factors of Soil Environmental Quality Based on China's Risk Control Standard: Multiple Bigdata-Based Approaches with Intensive Sampling.

Identifying the driving factors of soil environmental quality is critical in raising countermeasures for managing the soil environment efficiently and precisely. In 2018, China issued risk control standards to divide soil environmental quality into three classes to meet the demands of environment management. However, there is a lack of knowledge of this new standard. An intensive field-sampling research (2598 top-soil samples were analyzed) was conducted in the agricultural land of Hubei province, central China, to find the driving factors of pollutants based on this new standard. According to the standard, the proportion of classes 1, 2, and 3 in the overall quality grade was 57.3%, 41.7%, and 1%, respectively. The standardized index showed that the pollution levels of cadmium, arsenic, lead, and chromium were higher than that of mercury. The first component of the principal component analysis explained 56.4% of the total variance, and the loading of cadmium, arsenic and lead were -53.5%, -52.1%, and -51.2%, respectively. The general linear modeling found that cadmium and arsenic showed positive and significant effects (p < 0.001) on the grading results of soil environmental quality. Based on the random forest algorithm, cadmium showed the greatest importance on soil environmental quality (increase in mean squared error = 32.5%). Overall, this study revealed that cadmium, arsenic, and lead were driving pollutants affecting soil environment quality grade. The large data size increased the reliability and robustness of the study's conclusions, and it provided reference methods for future studies investigating China's new standard for assessing soil environmental quality.

Prediction Performance Comparison of Risk Management and Control Mode in Regional Sites Based on Decision Tree and Neural Network.

The traditional risk management and control mode (RMCM) in regional sites has the defects of low efficiency, high cost, and lack of systematism. Trying to resolve these defects and explore the application possibility of machine learning, a characteristic dataset for RMCM in regional sites was established. Three decision tree (DT) algorithms (CHAID, EXHAUSTIVE CHAID, and CART) and two artificial neural network (ANN) algorithms [back propagation (BP) and radial basis function (RBF)] were implemented to predict RMCM in regional sites. The results showed that in the aspects of accuracy (ACC), precision (PRE), recall ratio (REC), and F1 value, CART-DT was superior to CHAID-DT and EXHAUSTIVE CHAID-DT (E-CHAID-DT); and BP-ANN was superior to RBF-ANN. However, CART-DT was inferior to BP-ANN in ACC, PRE, REC, and F1 value. BP-ANN model is good at non-linear mapping, and it has a flexible network structure and a low risk of over-fitting. The case study of a typical county demonstration area confirmed the extensibility of the method, and the method has great potential in RMCM prediction in regional sites in the future.

A hybrid data-driven framework for diagnosing contributing factors for soil heavy metal contaminations using machine learning and spatial clustering analysis.

The efficacy of source apportionment is often limited by a lack of information on natural and anthropogenic contributing factors influencing soil heavy metal (HM) contaminations. To overcome this limitation and develop the data mining methods, a novel hybrid data-driven framework was proposed to diagnose the contributing factors in an industrialized region in Guangdong Province, China, mainly using a combination of naive Bayes (NB), random forest (RF), and bivariate local Moran's I (BLMI) on the basis of the multi-source big data. The medium industry types of enterprises from the freely available Baidu point of interest data were successfully classified, and then the 250 contaminating enterprises as a contributing factor were identified by the optimized NB classifier. The quantitative contributions of the nine contributing factors for the As, Cd, and Hg concentrations were determined by the optimized RF. The twelve spatial clustering maps between the three HM concentrations and the four key contributing factors were generated by BLMI, explicitly revealing their mutual interactions and internal effects and also intuitively showing the "high-high" areas and their distributions. This framework can obtain rich information on contributing factors such as medium industry types, contribution rates, spatial clusters, and spatial distributions.

Effectiveness of protection areas in safeguarding biodiversity and ecosystem services in Tibet Autonomous Region.

The Tibet Autonomous Region of China constitutes a unique and fragile ecosystem that is increasingly influenced by development and global climate change. To protect biodiversity and ecosystem services in Tibet, the Chinese government established a system of nature reserves at a significant cost; however, the effectiveness of nature reserves at protecting both-biodiversity and ecosystem service functions in Tibet is not clear. To determine the success of existing nature reserves, we determined importance areas for the conservation of mammal, plant, bird, amphibian, and reptile species, and for the protection of ecosystem service functions. The results indicated that important conservation areas for endangered plants were mainly distributed in the southern part of Nyingchi City, and for endangered animals, in the southern part of Nyingchi and Shannan Cities. Extremely important conservation areas for ecosystem service functions of carbon sequestration, water and soil protection, and flood regulation were mainly distributed in the southern part of Nyingchi and Shannan Cities, northern and southeastern parts of Nagqu City, and southern part of Ngari area. Based on an analysis of spatial overlap in protection areas, we conclude that existing natural reserves need to be expanded, and new ones need to be established to better protect biodiversity in Tibet Autonomous Region.

Investigation and Systematic Risk Assessment in a Typical Contaminated Site of Hazardous Waste Treatment and Disposal.

A total of 214 sampling sites of a hazardous waste disposal center were surveyed in a two-stage pollution investigation, including soil boreholes and groundwater monitoring wells. Results showed that chemical oxygen demand (COD) (4.00-2930.00 mg/L), fluoride (0.07-9.08 mg/L), chromium (0.12-1.20 µg/L), nickel (0.15-459.00 µg/L), lead (0.10-10.20 µg/L), cadmium (Cd) (0.05-16.40 µg/L), and beryllium (0.06-3.48 µg/L) were detected in groundwater samples. For soils, Cd in soil (78.7 mg/kg) exceeded the risk screening value (65 mg/kg) for soil contamination of the second type of development land (GB36600-2018), and there remained the risk of leakage in the landfill detection investigation. Then, a health risk assessment was carried out. Based on the definitions of the groundwater exposure pathway (HJ 25.3-2019) and the pollution investigation of groundwater, the carcinogenic and non-carcinogenic risks of groundwater were generally considered to be negligible. The carcinogenic risk and non-carcinogenic risk of the concerned pollutant in soil for risk assessment (Cd) under the condition of reutilization exceeded the corresponding acceptable levels (1E-06 and 1). The (non-)carcinogenic risk of Cd mainly came from oral intake of soil and inhalation of soil particles under two conditions of reutilization and non-utilization, so on-site workers and surrounding residents should be properly protected from the mouth and nose to minimize the intake of pollutants from the soil and soil particles. The area of soil contaminated by Cd was about 630.58 m2, and the amount of pollution was about 1261.16 m3. The heavy metal pollution was only distributed in the depth range of 0-2 m, and the suggested risk control value of soil pollutants under the condition of reutilization for Cd was 56 mg/kg. Based on different pollution characteristics of soil, groundwater, and the landfill, targeted control measures were proposed.

Land use changes in Zhangjiakou from 2005 to 2025 and the importance of ecosystem services.

Changes in local land use affect regional ecological services, development planning, and optimal use of space. We analyzed the effects of changes in land use from 2000 to 2025 on the spatial distribution of ecosystem services using CLUS-S modeling to evaluate ecosystem functions in Zhangjiakou, China. We found that the urban ecosystem area in Zhangjiakou increased and farmland decreased between 2000-2025. Water conservation was relatively high and was concentrated in the nature reserves of southern Zhangjiakou. Soil conservation was mainly distributed in eastern and southern counties. The results of the CLUE-S model showed that the relative operating characteristics of the six land use types were > 0.70, and the logistic regression equation was able to successfully explain the distribution pattern of the different types of land use.

Dextran sulfate-modified pH-sensitive layered double hydroxide nanocomposites for treatment of rheumatoid arthritis.

To reduce the side effects of methotrexate and increase its anti-inflammatory effect, we developed a drug delivery system, dextran sulfate-modified methotrexate-loaded layered double hydroxide nanocomposites (LDH-MTX-DS), with both targeting and pH-sensitivity for the treatment of rheumatoid arthritis. The nanocomposites had a mean particle size of 303.1 ± 8.07 nm, zeta potential of - 12.4 ± 0.7 mV, encapsulation efficiency of 49.64%, and loading efficiency of 16.81%. In vitro release experiments demonstrated that the drug was released faster in PBS at pH 5.5 than at pH 7.4, which reflected the pH-sensitivity of this system. Cellular uptake assays displayed higher cellular uptake rate of the dextran sulfate-modified targeting carrier compared with that of a non-targeting carrier (P < 0.01), which indicated that the LDH-MTX-DS could actively target scavenger receptors on the surface of activated RAW 264.7 cells. In vivo pharmacodynamic experiments showed that, after the second (P < 0.001) and third (P < 0.05) administrations, the preparation group exhibited significantly improved therapeutic efficacy in adjuvant-induced arthritis (AIA) rats when compared with free MTX alone. These results indicated that this drug delivery system was promising in the treatment of rheumatoid arthritis. Graphical abstract.

Polyvinyl alcohol microlens array obtained by solvent evaporation from a confined droplet array.

In this study, polyvinyl alcohol (PVA) microlens arrays (MLAs) were prepared, and the dynamics of contact lines and contact angles during confined PVA solution droplet evaporation were investigated by in situ optical microscopy. First, hydrophobic layers patterned with hydrophilic microholes array modified substrates were prepared by photolithography and coating methods. The flowing of PVA solution on the substrates formed droplets in each microhole self-assembly. The substrate was then heated to allow evaporation of the solvent. The results showed the contact line of confined droplets pinned at the junction between the hydrophilic and hydrophobic areas during the whole evaporation process. The apparent contact angle decreased nonlinearly during evaporation. The evaporation of PVA solution droplet in each microhole followed a constant contact radius mode, meaning constant contact area and declined contact angle during evaporation. After complete solvent evaporation, PVA formed a convex shape with convergent lens character in each microhole. In sum, the obtained PVA convex arrays with uniform sizes and good focusing properties would have potential applications in wavefront sensing, infrared focal plane detection or CCD array light accumulation, laser array scanning, laser display, optical fiber coupling, and many other optical systems.

Analysis of the spatial characteristics and driving forces determining ecosystem quality of the Beijing-Tianjin-Hebei region.

Water shortage is one of the main hinder drivers of sustainable development in the Beijing-Tianjin-Hebei region, and ecological restoration is one of the main means to effectively curb ecological degradation. Addressing ecological degradation in the Beijing-Tianjin-Hebei region has been a major concern of the Chinese government, and this has led to a focus on intensified ecological restoration efforts in this area. However, the effect of these restoration actions is not clear. To understand how ecological restoration is impacting ecological quality in the Beijing-Tianjin-Hebei region, we used geographical information system technology, such as the vegetation index-biomass method and cumulative net primary production (NPP) method, to assess the change in ecosystem quality. We carried out the pixel binary model and Pearson's correlation coefficient analyses to understand the driving forces behind the change. Results showed that from 2000 to 2010, the quality of the Beijing-Tianjin-Hebei ecosystem has been improving, that natural vegetation is slowly re-establishing, and that there has been a slow increase toward climax communities. The change in ecosystem quality is positively correlated with the Sanbei shelterbelt and Beijing-Tianjin Sandstorm control project and negatively correlated with socioeconomic and agricultural factors.

[Construction and Application of Early Warning System for Soil Environmental Quality].

Early warning of soil environmental quality is an important basis for implementing classified and graded soil risk management measures. To quickly understand the regional soil environmental quality and take effective measures in time to prevent continuous soil pollution before deterioration of soil environmental quality, a simple, effective, and quantifiable early warning system for soil environmental quality of agricultural land and development land was respectively established based on environmental capacity and pollutant input-output flux theory. Furthermore, corresponding method and mechanism for early warning were defined based on soil environmental quality standards, food safety standards, and carcinogenic risk coefficients. The agricultural land in Youxian county and the development area within the fifth-ring in Beijing were chosen to assess the soil environmental quality and predict risks of heavy metals exceeding standards in different scenarios. The results show that the soil environmental quality of the agricultural land in Wangling and Taoshui Town both can be classified to the fifth early warning level. Compared with other remediation measures, the Cd contents of soil can be lowered to risk screening levels in the short term by the scenario of "paddy straw not returned to the field". The soil quality in the development area within the fifth-ring in Beijing belongs to the first early warning level under both the "no intervention" and the "decreased input" scenarios, which means that Cd, Cu, Pb, and Zn all need more than 50 years to reach their threshold values to pose potential health risks.

[Construction and Application of an Evaluation System for Soil Environmental Carrying Capacity].

To understand the effect of soil environmental carrying capacity on pollutants and human activities, as well as to effectively prevent the aggravation of soil pollution and control soil environmental risks, a comprehensive indicator system for soil environmental carrying capacity is developed by analyzing the input-output flux and risk characteristics of soil pollutants. Furthermore, an evaluation method for soil environmental carrying capacity is proposed by defining safety coefficients related to evaluation indicators. Based on evaluation of soil environmental quality, the system reflects soil properties, pollution evolution trends, and risk characteristics, focusing on the soil buffering function. Further, a quantitative evaluation is carried out to assess the regional soil environmental carrying capacity of heavy metals on development land in Beijing. The results show that the soil environmental carrying capacity of Cu, Zn, Pb, and Cd in Beijing varies widely. The soil environmental carrying capacity of Cd is much lower than that of other elements. Four policy recommendations are proposed as significant for effective soil pollution prevention and control:clarifying concepts for soil environmental carrying capacity, improving the evaluation framework, constructing an information database, and implementing demonstration pilots.

Environmental function zoning for spatially differentiated environmental policies in China.

Different regions in China face greatly dissimilar ecological and environmental problems due to large variations in natural conditions and socioeconomic development levels. Such spatial variability calls for regionalized environmental management and protection policies. Environmental function zoning is an effective tool for the design and implementation of differentiated environmental policies. To contain the ecological degradation in different regions of China, we first created a comprehensive environmental function evaluation index system that included 25 socioeconomic and environmental indicators for the three key elements of natural ecological security protection, healthy human living environment maintenance, and regional environment carrying capacity. To clarify the division of Chinese environmental function zoning in the new period, we use GIS and remote sensing technology. We generated 1-km resolution grid data for the 25 indicators and implemented this index system to evaluate the environmental function of the 2414 counties in China. Differentiated environmental management objectives and strategies were designed and implemented for different zones to avoid the phenomenon of one size fits all. This work lays a scientific foundation and provides a quantitative tool for the design and implementation of differentiated management. By considering not only the natural system but also the social and economic systems and their interactions, this evaluation of environmental function provides a more comprehensive view and thus offers new insights on balancing environmental protection and socioeconomic development.

Saccharides in straw hydrolysate decrease cell membrane damage by phenolics by inducing the formation of extracellular matrix in yeast.

The bioconversion of rice straw into ethanol can alleviate the energy crisis and solve problems related to waste treatment. In this study, the effect of soluble polysaccharides (SPs) produced during rice straw saccharification on the formation of extracellular matrices (EMs) by the yeast Saccharomyces cerevisiae was investigated. SPs were characterized by high-performance liquid chromatography (HPLC) and fourier transform infrared spectroscopy (FT-IR). SPs reduced the inhibition of alcohol dehydrogenase activity by phenolic acids (PAs) and regulated the intracellular redox state, resulting in higher ethanol production. The results of flow cytometry, confocal laser scanning microscopy, and atomic force microscopy indicated that PAs changed microbial morphology and caused damage in microbial cell membranes. The protective effect of SPs against cell membrane damage could be attributed to the synthesis of polysaccharide-dependent extracellular matrix, which maintained cellular integrity even under phenolic acid stress. These findings provide new strategies to improve pretreatment and saccharification processes.

Extraction of Flavonoids from the Saccharification of Rice Straw Is an Integrated Process for Straw Utilization.

To date, bioethanol is not economically competitive. One strategy to overcome this limitation is co-producing ethanol and high value-added products as an integrated process. The results of this study demonstrated that flavonoids could be extracted from rice straw, and the flavonoids apigenin and kaempferol were detected by HPLC. Compared with untreated straw, ball-milling slightly increased the total amount of flavonoids and antioxidant activity measured by ABTS, DPPH, and FRAP assays. The saccharification step in the bioconversion of straw strongly affected the extraction of flavonoids from straw. The residue obtained after saccharification of ball-milled straw for glucose production was more suitable for flavonoid extraction than untreated and ball-milled straw. The yield of flavonoids from the residue was 1.51-fold higher than that from untreated straw. The antioxidant activity of flavonoids derived from the residue was similar to that of flavonoid-rich biomasses such as rice bran and wheat bran. More importantly, saccharification may significantly affect the conditions of flavonoid extraction. In this respect, treatment with cellulase may reduce the extraction time from 2.0 to 0.5 h and the extraction temperature from 80 to 30 °C. Therefore, saccharification in the bioconversion of straw may be considered as an enzyme pretreatment step for the efficient extraction of flavonoids from straw, serving as a sustainable process for straw utilization.

Synthesis and evaluation of cationic polymeric micelles as carriers of lumbrokinase for targeted thrombolysis.

To achieve targeted thrombolysis, a targeted delivery system of lumbrokinase (LK) was constructed using RGDfk-conjugated hybrid micelles. Based on the specific affinity of RGDfk to glycoprotein complex of GPⅡb/Ⅲa expressed on the surface of membrane of activated platelet, LK loaded targeted micelles (LKTM) can be delivered to thrombus. The hybrid micelles were composed of polycaprolactone-block-poly (2-(dimethylamino) ethyl methacrylate) (PCL-PDMAEMA), methoxy polyethylene glycol-block- polycaprolactone (mPEG-PCL) and RGDfk conjugated polycaprolactone-block- polyethylene glycol (PCL-PEG-RGDfk). PCL-PDMAEMA was synthesized via ring open polymerization (ROP) and atom transfer radical polymerization (ATRP). PCL-PEG-RGDfk was synthesized via ROP and carbodiimide chemistry. The prepared LKTM was characterized by dynamic light scattering (DLS) and transmission electron microscope (TEM). Colloidal stability assay showed the prepared LKTM was stable. Biocompatibility assay was performed to determine the safe concentration range of polymer. The assay of fluorescent distribution in vivo demonstrated that LKTM can be efficiently delivered to thrombi in vivo. Thrombolysis in vivo indicated the thrombolytic potency of LKTM was optimal in all groups. Notably, the laboratory mice treated with LKTM exhibited a significantly shorter tail bleeding time compared to those treated with LK or LK-loaded micelles without RGDfk, which suggested that the targeted delivery of LK using RGDfk-conjugated hybrid micelles effectively reduced the bleeding risk.

Utilization of the saccharification residue of rice straw in the preparation of biochar is a novel strategy for reducing CO2 emissions.

Once rice straw has been bioconverted into biofuels, it is difficult to further biodegrade or decompose the saccharification residue (mainly lignin). Taking into account the pyrolysis characteristics of lignin, in this study the saccharification residue was used as a raw material for the preparation of biochar (biochar-SR), a potential soil amendment. Biochar was prepared directly from rice straw (biochar-O) with a yield of 32.45 g/100 g rice straw, whereas 30.14 g biochar-SR and 30.46 g monosaccharides (including 20.46 g glucose, 9.11 g xylose, and 0.89 g arabinose) were obtained from 100 g of rice straw. When added to liquid soil extracts as a soil amendment, almost nothing was released from biochar-SR, whereas numerous dissolved solids (about 70 mg/L) were released from biochar-O. Adding a mixture of biochar-SR and autotrophic bacteria improved soil total organic carbon 1.8-fold and increased the transcription levels of cbbL and cbbM, which were 4.76 × 103 and 3.76 × 105 times those of the initial blank, respectively. By analyzing the soil microbial community, it was clear that the above mixture favored the growth of CO2-fixing bacteria such as Ochrobactrum. Compared with burning rice straw or preparing biochar-O, the preparation of biochar-SR reduced CO2 emissions by 67.53% or 37.13%, respectively. These results demonstrate that biochar-SR has potential applications in reducing the cost of sustainable energy and addressing environmental issues.

pH-sensitive release of insulin-loaded mesoporous silica particles and its coordination mechanism.

In this work, we investigated the feasibility of employing metal ion that coordinated with amino group grafted mesoporous silica as a pH-sensitive release carrier of insulin. Mesoporous silica particles were firstly grafted with amino groups. After coordination of metal ions onto the surface of mesoporous pore, insulin was loaded onto mesoporous silica particles through coordination bonds with metal ions. Insulin-loaded mesoporous silica particle with an acid sensitivity between the pH range of physiological environment (pH 7.4) and diabetic acidosis (pH 7.0) and with an insulin encapsulation rate of 74.50% was identified by investigating the influence factors of pH response value. The morphology of particles was confirmed by different analytical methods, indicating that insulin-loaded mesoporous silica particles maintained the rod-like and orderly hexagonal phase mesoporous structure. The coordination mechanism results showed that half of the amino groups on the carrier were coordinated with Cu2+, and insulin was successfully coordinated with Cu2+ without any damage on the secondary structure. The amount of insulin coordination with Cu2+ was positively correlated with the pH of the reaction solution. The cytotoxicity result shows that SBA15-NH2-Cu2+-Ins was biocompatible with cells in the concentration ranging from 25 to 100 µg·mL-1. In vivo study preformed on rats showed that the insulin-loaded particles elicited a period hypoglycemic response. Furthermore, fluorescence and UV methods revealed that insulin-loaded mesoporous silica particles had no significant effect on the secondary structure of serum albumin.

Tapping the Bioactivity Potential of Residual Stream from Its Pretreatments May Be a Green Strategy for Low-Cost Bioconversion of Rice Straw.

In this study, it was found that the residual stream from pretreatments of rice straw exhibited high antioxidant activity. Assays based on the Folin-Ciocalteu colorimetric method confirmed that the residual stream contained large amounts of phenolic compounds. Three antioxidant assays were employed to evaluate the bioactivity of the residual stream. Strong linear correlations existed among the release of phenolic compounds, saccharification efficiency, and antioxidant activity. The alkaline pretreatment provided a much greater release of phenolic compounds, especially phenolic acids, compared to the acid pretreatment, and consequently, it had stronger linear correlations than the acid pretreatment. Antibacterial experiments demonstrated the ability of the phenolic compounds in the residual stream to inhibit the growth of microorganisms, indicating the potential of these compounds as antimicrobial agents. To discuss the possibility of the co-production of antimicrobial agents and biofuels/biochemicals, both acid and alkaline pretreatments were optimized using response surface methodology. Under the optimal conditions, 285.7 g glucose could be produced from 1 kg rice straw with the co-production of 3.84 g FA and 6.98 g p-CA after alkaline pretreatment. These results show that the recovery of phenolic compounds from the residual stream could be a green strategy for the low-cost bioconversion of rice straw.

Influence of rice straw-derived dissolved organic matter on lactic acid fermentation by Rhizopus oryzae.

Rice straw can be used as carbon sources for lactic acid fermentation. However, only a small amount of lactic acid is produced even though Rhizopus oryzae can consume glucose in rice straw-derived hydrolysates. This study correlated the inhibitory effect of rice straw with rice straw-derived dissolved organic matter (DOM). Lactic acid fermentations with and without DOM were conducted to investigate the effect of DOM on lactic acid fermentation by R. oryzae. Fermentation using control medium with DOM showed a similar trend to fermentation with rice straw-derived hydrolysates, showing that DOM contained the major inhibitor of rice straw. DOM assay indicated that it mainly consisted of polyphenols and polysaccharides. The addition of polyphenols and polysaccharides derived from rice straw confirmed that lactic acid fermentation was promoted by polysaccharides and significantly inhibited by polyphenols. The removal of polyphenols also improved lactic acid production. However, the loss of polysaccharides during the removal of polyphenols resulted in low glucose consumption. This study is the first to investigate the effects of rice straw-derived DOM on lactic acid fermentation by R. oryzae. The results may provide a theoretical basis for identifying inhibitors and promoters associated with lactic acid fermentation and for establishing suitable pretreatment methods.