[Determination of three new herbicide residues in soil, sediment and water by liquid chromatography-tandem mass spectrometry].

Herbicides play an important role in preventing and controlling weeds and harmful plants and are increasingly used in agriculture, forestry, landscaping, and other fields. However, the effective utilization rate of herbicides is only 20%-30%, and most herbicides enter the atmosphere, soil, sediment, and water environments through drift, leaching, and runoff after field application. Herbicide residues in the environment pose potential risks to ecological safety and human health. Therefore, establishing analytical methods to determine herbicide residues in environmental samples is of great importance. In this study, an analytical method based on liquid chromatography-tandem mass spectrometry (LC-MS/MS) in positive electrospray ionization mode (ESI+) was developed for the determination of isoxaflutole, metazachlor, and saflufenacil residues in soil, sediment, and water. The instrumental detection parameters, including electrospray ionization mode, mobile phase, and chromatographic column, were optimized. The mobile phases were methanol (A) and 0.1% formic acid aqueous solution (B). Gradient elution was performed as follows: 0-1.0 min, 60%A; 1.0-2.0 min, 60%A-90%A; 2.0-3.0 min, 90%A; 3.0-4.0 min, 90%A-60%A; 4.0-5.0 min, 60%A. The samples were salted after extraction with acetonitrile and cleaned using a C18 solid-phase extraction column. Different solid-phase extraction columns and leaching conditions were investigated during sample pretreatment. Working curves in the neat solvent and matrix were constructed by plotting the measured peak areas as a function of the concentrations of the analytes in the neat solvent and matrix. Good linearities were found for isoxaflutole, metazachlor, and saflufenacil in the solvent and matrix-matched standards in the range of 0.0005-0.02 mg/L, with r≥0.9961. The matrix effects of the three herbicides in soil, sediment, and water ranged from -10.1% to 16.5%. The limits of detection (LODs, S/N=3) for isoxaflutole, metazachlor, and saflufenacil were 0.05, 0.01, and 0.02 µg/kg, respectively. The limits of quantification (LOQs, S/N=10) for isoxaflutole, metazachlor, and saflufenacil were 0.2, 0.05, and 0.05 µg/kg, respectively. The herbicides were applied to soil, sediment, and water at spiked levels of 0.005, 0.1, and 2.0 mg/kg, respectively. The average recoveries for isoxaflutole, metazachlor, and saflufenacil in soil, sediment, and water were in the ranges of 77.2%-101.9%, 77.9%-105.1%, and 80.8%-107.1%, respectively. The RSDs for isoxaflutole, metazachlor, and saflufenacil were in the ranges of 1.4%-12.8%, 1.2%-7.7%, and 1.5%-11.5%, respectively. The established method was used to analyze actual samples collected from four different sites in Zhejiang Province (Xiaoshan, Taizhou, Dongyang, and Yuhang) and one site in Heilongjiang (Jiamusi). The proposed method is simple, rapid, accurate, stable, and highly practical. It can be used to detect isoxaflutole, metazachlor, and saflufenacil residues in soil, sediment, and water and provides a reference for monitoring the residual pollution and environmental behavior of herbicides.

Changes in soil fertility under partial organic substitution of chemical fertilizer: a 33-year trial.

BACKGROUND: This study examined the changes in soil fertility in a maize cropping area when chemical fertilizer was partially replaced with straw or livestock manure over a 33-year period. Four treatments were included: (i) CK (no fertilizer application); (ii) NPK (only chemical fertilizer application); (iii) NPKM (chemical fertilizer partly replaced with livestock manure); (iv) NPKS (chemical fertilizer partly replaced with straw). RESULTS: Soil organic carbon increased by 41.7% and 95.5% in the NPKS and NPKM treatments, respectively, over the 33-year trial compared with the initial concentration. However, soil organic carbon in NPK was significantly reduced by 9.8%. Soil total N, P and K increased in both NPKM and NPKS treatments compared to the original soil. Soil pH was significantly acidified from 7.6 to 5.97 in the NPK treatment during the experimental period. The NPKM and NPKS treatments buffered the acidification compared to NPK. Meta-analysis results showed that, compared with NPK, NPKM significantly raised soil bacteria and fungi populations by 38.7% and 58.6%; enhanced microbial biomass carbon and nitrogen by 66.3% and 63%, respectively; and increased sucrase, urease and catalase activities by 34.2%, 48.2% and 21.5%. NPKS significantly increased soil fungi and actinomycetes populations by 24.3% and 41.2%, respectively; enhanced microbial biomass carbon and nitrogen by 27.1% and 45%; and strengthened sucrase and urease activities by 36% and 20.3%, respectively. CONCLUSION: Long-term chemical fertilizer application led to the deterioration of soil fertility and environment. Partial replacement of chemical fertilizers with organic materials could significantly amend and buffer such negative effects. © 2023 Society of Chemical Industry.

Nitrogen inhibitors improve soil ecosystem multifunctionality by enhancing soil quality and alleviating microbial nitrogen limitation.

Soil quality (SQI) is a comprehensive indicator reflecting the agricultural productivity of soil, and soil ecosystem multifunctionality (performing multiple functions simultaneously; EMF) can reflect complex biogeochemical processes. However, the effects of enhanced efficiency nitrogen fertilizers (EENFs; urease inhibitors (NBPT), nitrification inhibitors (DCD), and coated controlled-release urea (RCN)) application on the SQI and soil EMF and their relationships are still unclear. Therefore, we conducted a field experiment to study the effects of different EENFs on the SQI, enzyme stoichiometry and soil EMF in semiarid areas of Northwest China (Gansu, Ningxia, Shaanxi, Shanxi). Across the four study sites, DCD and NBPT increased SQI by 7.61-16.80 % and 2.61 %-23.20 % compared to mineral fertilizer, respectively. N fertilizer application (N200 and EENFs) alleviated microbial N limitation, and EENFs alleviated microbial N and C limitations to a greater extent in Gansu and Shanxi. Moreover, nitrogen inhibitors (Nis; DCD and NBPT) improved the soil EMF to a greater extent than N200 and RCN, DCD increased by 205.82-340.00 % and 145.00-215.47 % in Gansu and Shanxi, respectively; NBPT increased by 332.75-778.59 % and 364.44-929.62 % in Ningxia and Shanxi, respectively. A random forest model showed that the microbial biomass carbon (MBC), microbial biomass nitrogen (MBN) and soil water content (SWC) of the SQI factors were the main driving forces of soil EMF. Moreover, SQI improvement could alleviate microbial C and N limitations and promote the improvement of soil EMF. It is worth noting that soil EMF was mainly affected by microbial N limitation rather than C limitation. Overall, NIs application is an effective way to improve the SQI and soil EMF in the semiarid region of Northwest China.

[Effects of Vegetation Restoration on Soil Organic Carbon Sequestration and Aggregate Stability in Water-Eroded Environment: A Meta-analysis].

In order to clarify the differences in the effects of vegetation restoration strategies on soil carbon sequestration and aggregate stability under different water-eroded environments, we collected experimental data from 91 papers and evaluated the response of soil organic carbon (SOC) stock and aggregate stability to vegetation restoration based on Meta-analysis. The results showed the following:① compared with cropland or bare land, forestland/grassland restoration was beneficial to increase SOC stock and improve aggregate stability, but the dominant functions of the two were different. The effect of forestland restoration on carbon sequestration was stronger than that of grassland reforestation, and the effect of grassland restoration on aggregate stability was stronger than that of forestland restoration. ② Multi-factor Meta-analysis showed that the factors that significantly affected SOC were restoration year, soil clay content, vegetation coverage, mean annual precipitation (MAP), mean annual temperature (MAT), and soil depth. The positive effect of vegetation restoration on SOC stock increased with the increase in vegetation coverage rate. Grassland restoration had a more significant effect on SOC stock when soil clay content was 20%-32%, it was more likely to promote the carbon sequestration effect of grassland when MAP>800 mm or MAT<15℃, and there was no significant change in SOC stock under different restoration years. However, the effect of forestland restoration on SOC stock was more significant when soil clay content was>32%. Climate conditions had no limited effect on SOC stock in forestland, and there was a positive effect between SOC stock under forestland restoration and restoration years. ③ Vegetation restoration had stronger significant positive effects on mean weight diameter (MWD) and mean geometric diameter (GMD) when the clay content was 20%-32%, and MWD and GMD increased with the increase in vegetation coverage. ④SOC stock growth could explain 25% and 24% of the variation in the effect value of MWD and GMD, respectively. These results indicated that the formation of SOC was the result of multiple factors, and soil aggregate stability was limited only by vegetation coverage and soil clay content. The increase in SOC stock could promote the improvement of water stability MWD and GMD. These results can clarify the carbon sequestration effect of different vegetation restoration measures in water-eroded environments and provide theoretical reference for the restoration and reconstruction of degraded ecosystems.

Response of nitrate leaching to no-tillage is dependent on soil, climate, and management factors: A global meta-analysis.

No tillage (NT) has been proposed as a practice to reduce the adverse effects of tillage on contaminant (e.g., sediment and nutrient) losses to waterways. Nonetheless, previous reports on impacts of NT on nitrate ( NO 3 - ) leaching are inconsistent. A global meta-analysis was conducted to test the hypothesis that the response of NO 3 - leaching under NT, relative to tillage, is associated with tillage type (inversion vs non-inversion tillage), soil properties (e.g., soil organic carbon [SOC]), climate factors (i.e., water input), and management practices (e.g., NT duration and nitrogen fertilizer inputs). Overall, compared with all forms of tillage combined, NT had 4% and 14% greater area-scaled and yield-scaled NO 3 - leaching losses, respectively. The NO 3 - leaching under NT tended to be 7% greater than that of inversion tillage but comparable to non-inversion tillage. Greater NO 3 - leaching under NT, compared with inversion tillage, was most evident under short-duration NT (<5 years), where water inputs were low (<2 mm day-1 ), in medium texture and low SOC (<1%) soils, and at both higher (>200 kg ha-1 ) and lower (0-100 kg ha-1 ) rates of nitrogen addition. Of these, SOC was the most important factor affecting the risk of NO3 - leaching under NT compared with inversion tillage. Globally, on average, the greater amount of NO3 - leached under NT, compared with inversion tillage, was mainly attributed to corresponding increases in drainage. The percentage of global cropping land with lower risk of NO3 - leaching under NT, relative to inversion tillage, increased with NT duration from 3 years (31%) to 15 years (54%). This study highlighted that the benefits of NT adoption for mitigating NO 3 - leaching are most likely in long-term NT cropping systems on high-SOC soils.

Soil mineral nitrogen regulation by a novel porous material in structurally degraded soils.

BACKGROUND: The availability of soil nitrogen (N) decreases as the structure of agricultural soils degrades. Traditional methods focus on organic amendments that indirectly affect the porosity and N content of soil. Due to the low efficiency of such amendments, new materials, particularly highly porous materials, are needed to improve the quality of soil, which has opened new directions. RESULTS: The addition of 2 to 7 mm of porous clay ceramic (PLC) significantly increased the fresh weight of Brassica chinensis. The soil aeration porosity (>50 µm) increased by 0.69% on average in response to 1% PLC application. Soil NO3 - -N, NH4 + -N and mineral N increased by 3.3, 1.3 and 4.6 mg kg-1 on average, respectively, following a 1% PLC application rate. The initial N content of the high PLC treatments was the lowest in the incubation experiment. The parameters of soil N mineralization, i.e. potentially mineralizable N (N0 ), the first-order rate constant (k) and the mineralization composite index (N0  × k), increased obviously as the amount of PLC increased. Porosities larger than 1000 µm were significantly more positively correlated with the parameters of soil N mineralization than those <500 µm. The Pearson correlation coefficients suggested that high porosity, mineral N and N0 values had significant positive relationships with the fresh weights in double seasons. CONCLUSION: The application of PLC increased soil aeration and enhanced the availability of soil N, which yielded large vegetable harvests in clayey soils in the short term. © 2022 Society of Chemical Industry.

Surgical Compliance and Outcomes in Gastric Cancer: a population-based cohort study.

Background: Surgical resection is one of curative treatment for gastric cancer (GC), however, a set of patients show poor surgical compliance in the USA. We aimed to identify the risk factors associated with surgical compliance and investigate the difference in survival. Methods: GC patients diagnosed between 1973 and 2014 were identified from the Surveillance Epidemiology and End Results (SEER) databases. Based on different surgical compliance and treatment regimen, patients were classified into three subgroups: surgical compliance group, surgical noncompliance group, and non-surgical group. Multivariable Logistic regression analysis was adopted to identify the factors related to surgical compliance; Multivariable Cox regression was used to investigate the prognostic factors. Overall survival (OS) and cancer-specific survival (CSS) were analyzed using the Kaplan-Meier estimator method. Results: Of 79374 GC patients who were recommended for surgical therapy, 15201(19.2%) cases did not perform surgery. Poor compliance of surgery was related to old age, American Indian/Alaska Native race, poor grading/late staging, single/widowed status, lower socioeconomic status and earlier time of diagnosis. As expected, GC patients of surgical compliance group showed significantly more favorable survival than the other two groups (P<0.0001); notably, the outcome of surgical noncompliance group came close to that of non-surgical group. Conclusion: GC patients of poor surgical compliance demonstrated adverse survival, which was comparable to that of non-surgical patients. The poor surgical compliance was associated with older age, American Indian/Alaska Native race, poor tissue differentiation/advanced stage of tumor, single/widowed status, lower socioeconomic status and earlier time of diagnosis.

[Animal gene pyramiding in cross populations].

Gene pyramiding aims at producing individuals with one superior economic trait according to the optimal breeding scheme involving selection of favorable target alleles or linked markers after crossing basal populations and pyramiding them into a single individual. In consideration of animal traditional cross program along with the features of animal segregating population, four types of cross programs and two types of selection strategies for gene pyramiding are performed from practice perspective of view, two population cross for pyramiding two genes (denoted II), three populations cascading cross for pyramiding three genes (denoted III), four population symmetrical (denoted IV-S) and cascading cross for pyramiding four genes (denoted IV-C), and various schemes (denoted cross program-A-E) were designed for each cross program with different levels of initial favorable allele frequencies, basal population sizes, and trait heritabilities. The process of gene pyramiding for various schemes were simulated and compared based on the population hamming distance, average superior genotype frequencies, and average phenotypic values. By simulation, the results showed that larger base population size and higher initial favorite allele frequency resulted in higher efficiency of gene pyramiding. The order of parent crossing was shown to be the most important factor in cascading cross, but had no significant influence on the symmetric cross. The results also showed that genotypic selection strategy was superior to phenotypic selection in accelerating gene pyramiding. The method and corresponding software would be used to compare different cross schemes and selection strategies. Moreover, our study would help to build the optimal gene pyramiding simulation platform.