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# 所有论文

41. 题目: How does uncertainty of soil organic carbon stock affect the calculation of carbon budgets and soil carbon credits for croplands in the U.S. Midwest?

Cropland carbon budget depicts the amount of carbon flowing in and out of agroecosystems and the changes in carbon stocks of soil and living biomass during the same period. Soil carbon credit is the additional change in soil carbon stock under certain farming practices compared with the business-as-usual practices. Accurately calculating cropland carbon budget and soil carbon credit is critical to assessing climate change mitigation potential in agroecosystems. The calculation of cropland carbon budget and soil carbon credit is sensitive to local soil and climatic conditions, especially initial soil organic carbon (SOC) stock, which is determined by both SOC concentration (SOC%) and bulk density (Bulk_Density). SOC stock data are either from soil sampling or gridded public survey data. In agroecosystem models, SOC stock data are a key model input for quantifying cropland carbon budget and soil carbon credit. However, various types and degrees of uncertainties exist in SOC stock datasets, which propagate to the quantification of SOC stock change. In particular, a large discrepancy is found in two widely used SOC stock datasets — Rapid Carbon Assessment dataset (RaCA) and Gridded Soil Survey Geographic Database (gSSURGO) — in the U.S. Midwest, with a relative difference (quantified using Normalized Root Mean Square Error, NRMSE) of 48.0% for 0–30 cm SOC stock between the two datasets. It remains largely unclear how uncertainty in SOC stocks affects the calculation of cropland carbon budget and soil carbon credit. To address this question, we used a well-validated process-based agroecosystem model, ecosys, to assess the impacts of SOC stock uncertainty on carbon budget and soil carbon credit calculation in the U.S. Midwestern corn-soybean rotation systems. Our results reveal the following findings: (1) A sizable discrepancy exists in simulated cropland carbon budget between using gSSURGO and using RaCA for their SOC% and Bulk_Density as model inputs, with a Pearson correlation coefficient (r) of only 0.4 for simulated change of SOC stock (ΔSOC) using these two different soil datasets. (2) Simulated cropland carbon budget components were more sensitive to initial SOC% than to Bulk_Density. For example, the upper and lower quartiles of multi-year averaged ΔSOC were −29.8 and 4.8 gC/m2/year for the selected counties respectively, with an uncertainty of 13.7 and 0.7 gC/m2/year induced by uncertainties in initial SOC% and Bulk_Density, respectively. (3) Both simulated ΔSOC and its uncertainty were negatively correlated with initial SOC%, whereas ΔSOC was negatively correlated with air temperature, and ΔSOC uncertainty was positively correlated with air temperature. (4) The uncertainty of calculated soil carbon credits was much smaller compared with the uncertainty of calculated absolute carbon budgets assuming the same SOC stock uncertainty level in the inputs. Specifically, in our assessment comparing planting cover crops vs no cover crop, the uncertainty of calculated soil carbon credits induced by initial SOC% uncertainty was less than 4% (relative to the quantified value of the soil carbon credits) for 90% of the cases. Our analysis highlights that high accuracy measurement of SOC% as inputs is needed for the calculation of cropland carbon budgets; however, soil carbon credit quantification is much less sensitive to the initial SOC% inputs, and the current publicly available soil datasets (e.g., gSSURGO) are largely suitable for the calculation of soil carbon credits.

42. 题目: Sources, characteristics, and in situ degradation of dissolved organic matters: A case study of a drinking water reservoir located in a cold-temperate forest

Dissolved organic matter (DOM) plays a pivotal role in the biogeochemical cycles of elements and the regulation of forest ecosystem functions. However, studies on the regional and seasonal characteristics of DOM in cold-temperate montane forests are still not comprehensive. In this study, samples of water, soil, and sediment from different sites in the forest drainage basin were collected, and their DOM was characterized by an excitation-emission matrix and parallel factor analysis (EEM-PARAFAC). The results showed that terrestrial-sourced humic-like substances were the dominant DOM in the studied reservoir and inflowing rivers. The quality and quantity of DOM exhibited spatiotemporal variations with the influence of terrain and monsoonal precipitation. The average concentration of dissolved organic carbon (DOC) in the wet season was 11.62 mg/L, which was higher than that in the dry season (8.18 mg/L). Higher humification index (HIX) values were observed in the wet season and upstream water than in the dry season and reservoir water. Fourier transform ion cyclotron resonance mass spectrometry (FTICR-MS) was used to further develop a molecular-level understanding of the in situ degradation process of DOM. The results indicated that photodegradation rather than biodegradation may play a dominant role in the in situ degradation of terrestrial-sourced humic-like substances under natural conditions. The biodegradability of DOM was enhanced after the in situ degradation process. Additionally, a significant decrease in the precursors of disinfectant byproducts in DOM was observed after in situ degradation. To our knowledge, this is the first study of the sources, characteristics, and in situ degradation of DOM in a reservoir in a cold-temperate forest. These findings help better understand the quality, quantity, and biogeochemical process of DOM in the studied reservoir and may contribute to the selection of drinking water treatment technologies for water supply.

43. 题目: Delimiting conditions under which natural organic matter can control Fe speciation and size in freshwaters

Pollutant and nutrient mobility in natural waters is typically controlled by sorption onto the high surface area of colloidal particles, most of which may form by precipitation of Fe(III)(hydr)oxides. Therefore, prediction of the speciation and size of Fe is critical to managing water quality. Prediction from pH and dissolved oxygen (D.O.) saturation can fail because of Fe binding to natural organic matter (N.O.M.) in natural waters.

We test the influence of environmental variables –temperature, illumination and mixing order of Fe and N.O.M. with D.O.– on the impact of N.O.M. Differences in mixing order simulate Fe(II) mixing with N.O.M. in groundwater prior to emerging, in comparison to Fe(II) emerging into oxic surface waters containing N.O.M.

Fe speciation and size were measured in waters containing N.O.M. with and without D.O., but also a water to which N.O.M. and then D.O. were added sequentially. Without D.O. free Fe(II) bound to N.O.M. and became a filterable particle. Binding increased with pH and at 7.5 was sufficient for Fe speciation in oxic waters to become influenced by whether mixing had been sequential or simultaneous. Therefore, at high pH Fe speciation in oxic surface waters requires knowledge of N.O.M. content of this water and upstream groundwaters.

Cold (10 °C) decreased anoxic binding of Fe(II) to N.O.M. and both cold and darkness also decreased Fe binding to N.O.M. under oxic conditions, because in both cases Fe(III)(hydr)oxide surfaces out-compete N.O.M. for binding Fe. Cold and darkness therefore overwhelm the effect of mixing order on oxic Fe speciation, and cold even makes the presence or absence of N.O.M. irrelevant. In the cold or dark, prediction of Fe speciation and size in surface waters may not require knowledge of N.O.M. content of upstream groundwaters. Furthermore, when cold, prediction may not even require knowledge of N.O.M. content of the surface waters.

44. 题目: Improving electrochemical characteristics of plant roots by biochar is an efficient mechanism in increasing cations uptake by plants

Electrochemical properties of roots such as zeta potential and cation exchange capacity are important factors that play a critical role in the absorption of nutrients by plants. Adding biochar to the soil may improve the electrochemical properties of the roots and thereby increase absorption of nutrients by plants. Thus, this research was laid out under greenhouse condition to evaluate the possible effects of biochar addition to soil (25 g biochar kg−1 soil) on changing electrochemical properties of roots, nutrients absorption, and growth parameters of safflower (with a deep root system) and mint (with a shallow root system) plants. Biochar noticeably increased pH and cation exchange capacity of soil, safflower and mint growth, calcium, magnesium and iron contents in roots and maximum sorption capacity of these nutrients by plant roots. Electrochemical measurements reveled that biochar application increases negative charges on root surface area (by about 30% and 36% in safflower and mint roots, respectively), cation exchange capacity of roots and root activity in both plants. On the other hand, biochar reduced zeta potential in plant roots (more negative potential). Reduction of zeta potential by biochar application were about 31% and 42% in safflower and mint roots, respectively. The cation-exchange groups (hydroxycinnamic acid + carboxyl groups) were increased due to biochar treatment by about 30% in safflower and 32% in mint roots. As an annual plant with deep roots, safflower roots had more functional groups, cation exchange capacity and root activity than mint plant in both biochar and control conditions. Results of this research showed that biochar not only adjusts physicochemical properties of rhizosphere, but also improves electrochemical specification of plant roots via increasing number of functional groups on root cell walls, which enhances maximum sorption capability of plant roots.

45. 题目: Extracellular Polymeric Substances Enhance Dissolution and Microbial Methylation of Mercury Sulfide Minerals

46. 题目: Effect of Rice Straw- and Bamboo-Derived Biochar on Pollution Controlling and Health Risks of Heavy Metals in a Rice-Rape-Corn Rotation Area of Eastern China

Potential human health risk with agricultural food consumption grown in heavy metal–contaminated soil has rarely been investigated. A field experiment was conducted to investigate the effect of rice straw biochar and bamboo biochar on Cd/Cu phytoavailability, stabilization, and human health risk with crop consumption grown in contaminated soil. In this study, rice straw biochar and bamboo biochar were applied to contaminated soil (at the rate of 1.125 × 104 and 2.25 × 104 kg·ha−1) to suppress Cd/Cu bioavailability and thereby mitigating their accumulation in rice, rape, and corn. The results showed that biochar application had significantly reduced DTPA extractable Cd/Cu content in contaminated soil, especially the high dosage addition. Biochar application considerably influenced chemical fraction of Cd/Cu, which was notably increased in residual fraction and decreased in exchangeable fraction of Cd/Cu in biochar-amended soil. Compared to the control treatment, biochar application had significantly reduced Cd/Cu concentration in rice, corn, and rape seed, respectively. Hazard quotients (HQ) associated with rice, corn, and rape consumption were significantly reduced in biochar-amended soil. Consequentially, human cancer risk (HCR) value for Cd associated with rice consumption was significantly reduced by 27.70% with bamboo biochar (at the rate of 2.25 × 104 kg·ha−1) treatment. The possible mechanisms in reducing HQ and HCR were due to biochar efficiency to decrease bioavailable Cd, promote the Cd immobilization, and suppress the crop uptake. In conclusion, these results highlighted the potential for biochar to mitigate the phytoavailability and accumulation of heavy metals and thereby reducing heavy metals exposure associated with rice consumption. Thus, biochar is a promising eco-friendly material to be used to diminish HQ and HCR in soil crop system.

47. 题目: Deglacial release of petrogenic and permafrost carbon from the Canadian Arctic impacting the carbon cycle

The changes in atmospheric pCO2 provide evidence for the release of large amounts of ancient carbon during the last deglaciation. However, the sources and mechanisms that contributed to this process remain unresolved. Here, we present evidence for substantial ancient terrestrial carbon remobilization in the Canadian Arctic following the Laurentide Ice Sheet retreat. Glacial-retreat-induced physical erosion of bedrock has mobilized petrogenic carbon, as revealed by sedimentary records of radiocarbon dates and thermal maturity of organic carbon from the Canadian Beaufort Sea. Additionally, coastal erosion during the meltwater pulses 1a and 1b has remobilized pre-aged carbon from permafrost. Assuming extensive petrogenic organic carbon oxidation during the glacial retreat, a model-based assessment suggests that the combined processes have contributed 12 ppm to the deglacial CO2 rise. Our findings suggest potentially positive climate feedback of ice-sheet retreat by accelerating terrestrial organic carbon remobilization and subsequent oxidation during the glacial-interglacial transition.

48. 题目: Interactions between soil organic matter chemical structure and microbial communities determine the spatial variation of soil basal respiration in boreal forests

Interactions between soil organic matter (SOM) composition and microbial communities determine soil basal respiration (BR, SOM-derived CO2). However, few studies have investigated the relative importance of SOM chemical structure, microbial community composition, and soil environmental factors to the spatial variability of soil BR on a large scale. Here, organic and mineral layer soils were collected along a 650-km boreal forest transect in Northeast China. Combining 13C-nuclear magnetic resonance spectroscopy and high-throughput sequencing techniques, SOM chemical structure, microbial community composition, and soil physicochemical properties were determined to investigate the biotic and abiotic drivers of soil BR. Soil BR, microbial communities, and soil physicochemical properties exhibited significant spatial heterogeneity across sites, but the variations were independent of latitude regardless of soil layer. Soil BR rates were significantly higher in the organic layer than in the mineral layer (0.82 vs. 0.31 CO2-C kg−1soil−1 h−1, P < 0.001). Multi-model averaging and partial regression showed that SOM chemical structure exhibited the strongest control on the spatial variation of soil BR (contributing 23.0 %), followed by the organic layer soil C/N ratio (contributing 17 %). However, only soil C/N ratio was the most important predictor of soil BR variation in the mineral layer. Copiotrophic bacteria had a higher impact on soil BR than oligotrophic bacteria. In addition, soil physicochemical properties (i.e. pH, mechanical composition) indirectly affected soil BR through regulating soil microbial composition, especially bacteria. Overall, these results highlighted that SOM chemical structure directly or indirectly affected the microbial decomposition of SOM, and contributed more relative to SOM quality. These findings should be incorporated into ecosystem process models to better predict the response of boreal forest soil C emissions to climate change.

49. 题目: Mineralization of autochthonous particulate organic carbon is a fast channel of organic matter turnover in Germany's largest drinking water reservoir

50. 题目: Development of a quantitative structure-activity relationship model for predicting quantum yield of hydroxyl radical generation from organic compounds

51. 题目: Soil organic matter gain by reduced tillage intensity: Storage, pools, and chemical composition

Soil organic matter (SOM) loss due to intensive cultivation is the focus of studies on climate change and food security. Dropping tillage intensity has been widely reported as a potential tool for SOM increase; however, the chemical composition, storage mechanisms, and vertical distribution of SOM gain are not fully understood, especially in calcareous soils. This study aimed to analyze the increased SOM conditions among pools and depths in an eighteen-year-long field experiment comparing SOM under conventional moldboard plowing (PT), deep cultivation (DC), and no tillage (NT) systems on a base-saturated Endocalcic Chernozem (Loamic). Soil samples were collected from the 0–10 cm and 30–40 cm soil layers and divided into mineral phase-associated organic matter (<63 µm, stable pool; MPAOM) and aggregate related organic matter (>63 µm, labile pool). The aggregate related organic matter was further divided into particulate organic matter (POM, <1.0 g cm-3) and aggregates-associated organic matter (AAOM, >1.0 g cm-3). Results indicated an overall increase in soil organic carbon (SOC) concentration in the topsoil in the order of PT<DC<NT. The surplus did not manifest as POM but as either MPAOM or AAOM fractions. This increase likely resulted from the surplus above-ground plant residue input, as the SOC content in the 30–40 cm layer did not change. The additional SOM, stabilized in the soil, did not affect SOM composition between depths and fractions, suggesting preferential SOM binding by the fine fraction and aggregates. This suggests preferential binding of the more aromatic and less complex SOM to the fine fraction, even for the surplus SOM in recent years. This fractionation maintains or even increases the difference between organic carbon pools (soil fractions) in terms of SOM composition. In addition, vertical differentiation as a result of tillage intensity mitigation was established by an increase in the stratification of aromaticity. These results suggest the key role of dissolved SOM movement in the profile as a potential driving force for the differentiation of aromaticity with depth. The results also emphasize the role of local conditions on OM composition changes, establishing the complexity of the process and difficulties of holistic model construction.

52. 题目: Organic carbon and silt determining subcritical water repellency and field capacity of soils in arid and semi-arid region

Soil water repellency (SWR) is frequently observed in different types of land use and climates. Since SWR potentially enhances the difficulty of water infiltration in soil, the phenomenon can severely impact the water use of plants in arid regions. Therefore, understanding the origin of SWR is crucial in arid and semi-arid regions. This study investigated the fundamental and hydrological properties of soils in three arid ecosystems (desert, farmland, and forest). Analysis was done to determine any potential links between these properties, vegetation cover, and the severity of SWR. It was found that SWR was positively correlated with soil organic carbon (SOC), silt content, and field capacity of soil, where the SWR was in subcritical SWR range. The linear correlation and hierarchical clustering analysis confirmed that the SOC and silt content was the critical factor affecting the occurrence and persistence of SWR. The major source of organic carbon and nutrients to the soil was vegetation, which also had an impact on the distribution of soil carbon. The most striking observation was that the silt content was strongly correlated with both field capacity (r = 0.817, p = 0.001) and SWR (r = 0.710, p = 0.010), which can be attributed to the SOC on silt. In arid and semi-arid regions, the specific surface area of silt was relatively larger than that of sand. Meanwhile, compared to the clay in soil, the proportion of silt was much higher. The results imply that silt could significantly affect the soil hydrological properties and that silt content could serve as a new proxy for predicting water repellency in arid and semi-arid regions.

53. 题目: One-step preparation of lignin-based magnetic biochar as bifunctional material for the efficient removal of Cr(VI) and Congo red: Performance and practical application

The lignin-based magnetic biochar (LMB) was fabricated with a facile one-step solvothermal method. The spherical Fe3O4 was successfully loaded on the lignin-based biochar. LMB could efficiently remove Cr(VI) and Congo red (CR) synergistically with the adsorption of biochar and the catalytic/reduction of Fe3O4. LMB showed a removal efficiency of 100% for Cr(VI) (100 mg/L) at 30 min. The LMB could be a catalyst to activate persulfate (PS) to degrade CR. The LMB+PS system showed a removal efficiency of 94.3% for CR at 60 min. Moreover, LMB could simultaneously remove 41.5% of Cr(VI) and 91.5% of CR in the mixed Cr(VI) and CR solution. The simulated wastewater studies showed that LMB exhibited superior high Cr(VI) (100%) and CR (82%) removal efficiencies with the coexistent of anions, cations, and organic matter. LMB can be effectively applied to remove Cr(VI) and CR and purify different contaminated water bodies.

54. 题目: Electro-activating persulfate via biochar catalytic cathode for sulfamethazine degradation: performance and mechanism insight

This work prepared biochar particle electrodes (BCPE) from excess sludge and biochar catalytic cathodes (BCCC) synthesized by modifying nickel foam electrodes with BCPE. Then, both of them were constructed as electrocatalytic systems for activating persulfate (PS) to degrade sulfamethazine (SMZ). BCPE demonstrated remarkable electrocatalytic PS performance, in which oxygen-containing functional groups and Fe3O4 are the main active sites. The quenching experiment and electron paramagnetic resonance (EPR) results indicate that free hydroxyl radicals, sulfate radicals and superoxide radicals are generated in solution of the particle electrode system. On the contrary, most of the above radicals generated by BCCC exist on the electrode surface, and the direct electron transfer from the power source to BCCC effectively improves the mass transfer rate and catalytic performance, thus leading to the complete degradation of 50 mg/L SMZ within 60 min. Fe2+/Fe3+ released by BCCC was below the ambient concentration, which constituted a stable cycle in the electrocatalytic system and efficiently activated PS. The calculation results of density functional theory and oxygen reduction reactions verified the mechanism of activation. Electrostatic surface potential distribution calculation showed that Fe and C were the main active site. In silico toxicity assessment by ADMETlab2.0 found a significant decrease in overall toxicity of SMZ degradation products.

55. 题目: The effects of short-term, long-term, and reapplication of biochar on the remediation of heavy metal-contaminated soil

Biochar, a cost-effective amendment, has been reported to play pivotal roles in improving soil fertility and immobilizing soil pollutants due to its well-developed porous structure and tunable functionality. However, the properties of biochar and soils can vary inconsistently after field application. This may affect the remediation of biochar on heavy metal (HM)-contaminated soil being altered. Therefore, we selected lettuce as a model crop to determine the effects of short-term, long-term, and reapplication of biochar on soil physicochemical properties, microbial community, HM bioavailability, and plant toxicity. Our investigation revealed that the long-term application of biochar remarkably improved soil fertility, increased the relative abundance of the phylum Proteobacteria which was highly resistant to HMs, and reduced the abundance of phylum Acidobacteria. These changes in soil properties decreased the accumulation of Cd and Pb in lettuce tissues. The short- and long-term applications of biochar had no substantial effects on biomass, quality, and photosynthesis of lettuce. Moreover, the short-term and reapplication of biochar had no significant effects on soil bacterial communities but decreased the accumulation of Cd and Pb in lettuce tissues. It showed that the changes in the physical, chemical, and biological properties of soil after long-term application of biochar promoted the remediation of HM-contaminated soil. Furthermore, microbial community compositions varied with metal stress and biochar application, while the relative abundance of the phylum Actinobacteria in HM-contaminated soil with long-term biochar application was markedly higher than in HM-contaminated soil without biochar application.

56. 题目: Nitrogen immobilization caused by chemical formation of black- and amide-N in soil

Nitrogen (N) immobilization controls the N availability in soil, however, mechanisms involved in the chemical N fixation into soil organic N (SON) through reactions of reactive N compounds with soil organic matter (SOM) is not clear. Knowledge about the composition and stability of chemically produced SON is limited, which impedes understanding of the interplay of N and carbon (C) cycles at both the local and global scale. Here, we studied the chemical N immobilization of nitrite in soils from grassland, cropland, and forest with 15N labelling technique. And solid state 15N- and 13C NMR spectroscopies were applied to further explore the structure of chemically immobilized SON. We found that the chemical retention rate of nitrite did not differ significantly between land-uses, while the fulvic acid fraction was the SOM component most reactive to nitrite. In contrast to the common assumption that amides are mainly of biological origin and that black N compounds are formed from organic N compounds at high temperature during fires, our study revealed that amides and black N in the form of pyrroles were the main products of chemical reactions of nitrite with SOM. These findings indicate that chemical processes play a key role in biogeochemical N cycling, and provide new insight into the mechanisms of CN interactions in soil.

57. 题目: Passivation mechanism of Cu and Zn with the introduction of composite passivators during anaerobic digestion of pig manure

Heavy metals in livestock manure pose a threat to the environment after biogas fertilizer being utilized, while its bioavailability is reduced substantially by passivator during the anaerobic digestion. In this study, an optimal composite passivator of humic acid, fly ash and biochar with proportion of 7.5%:7.5%:7.5% and 5.0%:7.5%:7.5% is obtained and the passivation mechanism on Cu and Zn during anaerobic digestion of pig manure is explored. The content of humic acid (HA) in biogas residue increased by 15.66-27.82%, which promoted the transformation from FA-Cu/Zn to HA-Cu/Zn and was beneficial to the passivation of Cu and Zn. The bioavailability of Cu and Zn was reduced by the adsorption and complexation at the early and middle stages of anaerobic digestion. Humic substances play a major role in the passivation of heavy metals at the late stage. The composite passivator can improve the humification degree of biogas residue and reduce heavy metal biotoxicity.

58. 题目: Self-activation of potassium/iron citrate-assisted production of porous carbon/porous biochar composites from macroalgae for high-performance sorption of sulfamethoxazole

Excellent biochar properties are crucial for sorption performance, and a developed pore structure is especially important. Herein, novel porous carbon/porous biochar (PC/PB) composites, in which the porous biochar and porous carbon were prepared at the same time, were synthesized via a green method from algal biomass with the help of the self-activation of citrate for the first time, and the composites were evaluated for the sorption of sulfamethoxazole (SMX). Many micro/meso/macropores were introduced into the PC/PB composites, which showed high specific surface areas (up to 1415 m2 g−1) and pore volumes (up to 1.08 cm3 g−1). The PC/PB composites displayed excellent SMX sorption capacities, which reached 844 mg g−1. Pore filling played a crucial role in determining the sorption capacity, and hydrogen bonding, electrostatic interactions and π-π stacking controlled the sorption rate. This study provides an improved method for preparation of porous biochar.

59. 题目: Simultaneous Organic Matter and Nitrogen Removal from Piggery Slaughterhouse Wastewater Using Bioaugmented Gaslift Membrane Bioreactor

60. 题目: Organic matter governs weathering rates and microstructure evolution during early pedogenesis

Soil aggregation and the translocation of clay and organic matter are significant pedogenic processes that manifest in diagnostic horizons in mature soil. Yet, their onset might date to much earlier stages of soil development where host rock weathering is dominant and litter from pioneer vegetation is the only input of organic matter. We present a time-lapse experimental-pedogenesis study on early host rock weathering that shows the formation of aggregates and clay translocation in response to irrigation with and without organic matter released from a litter layer. The presence of organic matter increases total carbonate dissolution capacity and results in a characteristic surface morphology, while simultaneously slowing down the dissolution rate. With the dissolution of carbonates, clay minerals of the host rock and iron from pyrite are released. Controlled by the presence of organic matter, both are either transported with the seepage water or form crusts and aggregates from clay minerals and freshly precipitated secondary iron oxides. Our study shows that the interplay of dissolution, neoformation of secondary minerals, translocation, and aggregation of organic matter and clay-sized minerals shape soil structure evolution during early pedogenesis in carbonate host rocks.

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