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مقایسه سمیت اکولوژیک نانوذرات اکسید مس و اکسید نیکل بر فعالیت‌های آنزیمی در دو خاک با بافت متفاوت | ||
| زیست شناسی خاک | ||
| دوره 14، شماره 1، شهریور 1405، صفحه 61-80 اصل مقاله (1.3 M) | ||
| نوع مقاله: مقاله پژوهشی | ||
| شناسه دیجیتال (DOI): 10.22092/sbj.2026.371895.293 | ||
| نویسندگان | ||
| شکوفه رضائی* 1؛ علی خانمیرزایی1؛ وحیده شریفی گلرو2 | ||
| 1گروه خاکشناسی، واحد کرج، دانشگاه آزاد اسلامی، کرج، ایران | ||
| 2دانش آموخته کارشناسی ارشد گروه خاکشناسی، واحد کرج، دانشگاه آزاد اسلامی، کرج، ایران | ||
| چکیده | ||
| گسترش روزافزون کاربرد نانوذرات مهندسی‌شده در صنایع و کشاورزی نگرانی‌هایی را در خصوص سلامت بستر خاک ایجاد کرده است. این پژوهش با هدف ارزیابی و مقایسه سمیت اکولوژیک نانوذرات اکسید مس و اکسید نیکل بر شاخص‌های بیوشیمیایی در دو نوع خاک با ویژگی‌های بافتی متفاوت انجام شد. آزمایش به‌صورت فاکتوریل در قالب طرح کاملاً تصادفی با سه فاکتور شامل نوع نانوذره (CuO و NiO)، غلظت نانوذره (۰، ۱۰۰، ۵۰۰ و ۱۰۰۰ میلی‌گرم بر کیلوگرم خاک خشک) و زمان انکوباسیون (7، 24 و ۷۲ روز) در دو خاک با بافت لوم شنی و رسی اجرا گردید. فعالیت آنزیم‌های اوره‌آز، فسفاتاز اسیدی و فسفاتاز قلیایی به‌عنوان شاخص‌های پاسخ زیستی اندازه‌گیری شد. نتایج نشان داد که نوع بافت خاک نقش تعیین‌کننده‌ای در شدت پاسخ آنزیمی ایفا می‌کند؛ به‌طوری‌که میانگین پایه فعالیت فسفاتاز اسیدی در خاک رسی (µg pNP g-1 h-1۶۵۸) حدود ۶۶ درصد بالاتر از خاک لوم شنی (µg pNP g-1 h-1۳۹۶) بود (0.01 >P). نانوذرات اکسید مس سمیت شدیدتری نسبت به نیکل اعمال کردند؛ به‌گونه‌ای که در غلظت ۱۰۰۰ میلی‌گرم بر کیلوگرم CuO، فعالیت آنزیم اوره‌آز در خاک لوم شنی در انتهای دوره (روز ۷۲) تا بیش از ۹۰ درصد نسبت به شاهد کاهش یافت. در مقابل، نانوذرات NiO در غلظت پایین (۱۰۰ میلی‌گرم بر کیلوگرم) در برخی موارد موجب افزایش فعالیت آنزیمی شدند. همچنین، اثر زمان بر فعالیت اوره‌آز در خاک رسی تفاوت معنی‌داری را نشان نداد (P > 0.05) که نشان‌دهنده پایداری آنزیمی در حضور 49/8 درصد رس است، در حالی‌که در خاک لوم شنی (با 19/8 درصد رس) فعالیت آنزیم‌ها نوسانات زمانی و کاهش معنی‌داری را تجربه کردند. به طور کلی، خاک‌های با بافت سبک حساسیت اکولوژیک بسیار بالاتری نسبت به آلودگی نانوذرات اکسید فلزی دارند و نانوذرات اکسید مس حتی در غلظت‌های پایین تهدیدی جدی‌تر نسبت به اکسید نیکل برای چرخه عناصر غذایی خاک محسوب می‌شوند. | ||
| کلیدواژه‌ها | ||
| آلودگی خاک؛ اوره‌آز؛ بافت خاک؛ فسفاتازها؛ نانوذرات اکسید فلزی | ||
| عنوان مقاله [English] | ||
| Comparison of Ecotoxicity of Copper Oxide and Nickel Oxide Nanoparticles on Soil Enzyme Activities in Two Different Soil Textures | ||
| نویسندگان [English] | ||
| shekoofeh rezaei1؛ Ali Khanmirzaei1؛ Vahideh Sharifi Golro2 | ||
| 1Department of Soil Science, Ka,C., Islamic Azad University, Karaj, Iran | ||
| 2Department of Soil Science, Ka,C., Islamic Azad University, Karaj, Iran | ||
| چکیده [English] | ||
| Background and Objectives: In recent decades, the rapid advancement of nanotechnology has revolutionized various sectors, including agriculture, medicine, and electronics. Consequently, the release of engineered nanoparticles (ENPs) into the environment has become increasingly unavoidable. Soil serves as a primary sink for these pollutants and accumulates nanoparticles through the application of nano-fertilizers, pesticides, wastewater sludge, and atmospheric deposition. Among various nanomaterials, metal oxide nanoparticles (MO-NPs), particularly copper oxide (CuO) and nickel oxide (NiO), are widely used due to their unique catalytic and antimicrobial properties. However, their accumulation in soil ecosystems raises serious concerns regarding their potential ecotoxicity to non-target organisms. Soil health and fertility are closely linked to the activity of soil microorganisms and their extracellular enzymes. Enzymes such as urease and phosphatases play pivotal roles in the biogeochemical cycling of nitrogen (N) and phosphorus (P), respectively. Any disruption in their functionality can lead to the deterioration of soil quality and nutrient availability. The toxicity of nanoparticles in soil is a complex phenomenon governed not only by the type and concentration of the contaminant but also by the physicochemical properties of the soil, such as texture and organic matter content. While studies have assessed the toxicity of individual nanoparticles, comparative research on the time-dependent effects of CuO and NiO nanoparticles in calcareous soils with distinct textures remains limited. Therefore, this study aimed to comparatively evaluate the ecological toxicity of CuO and NiO nanoparticles on key soil biochemical indicators (urease, acid phosphatase, and alkaline phosphatase) in two soils with contrasting textural properties (Sandy Loam vs. Clay) to understand the interaction between soil matrix and nanoparticle toxicity kinetics. Materials and Methods: To investigate the role of soil texture in modulating nanoparticle toxicity, two surface soil samples (0–30 cm) were collected from agricultural lands with distinct physicochemical characteristics. The first soil was characterized as Sandy Loam (Sand: 58.2%, Clay: 19.8%, Organic Carbon: 0.70%), while the second soil was classified as Clay (Sand: 18.2%, Clay: 49.8%, Organic Carbon: 1.37%). The study was conducted as a factorial experiment based on a Completely Randomized Design (CRD) with three replications under controlled laboratory conditions at 25°C. The experimental factors included Nanoparticle Type (Copper oxide ~40 nm and Nickel oxide 10–20 nm, both with 99% purity), Concentration (four levels: 0, 100, 500, and 1000 mg kg⁻¹ dry soil), and Incubation Time (three intervals: 7, 24, and 72 days) to assess toxicity kinetics. To simulate realistic exposure conditions and avoid any solvent-related interference, nanoparticles were added to the soil as dry powder (uncoated) and thoroughly mixed. Soil moisture was maintained at 60% of field capacity (FC) throughout the incubation. At each sampling time, enzyme activities were assayed using standard spectrophotometric methods: Urease activity was quantified by measuring the ammonium released during urea hydrolysis, while Acid and Alkaline Phosphatase activities were quantified by the release of p-nitrophenol (pNP) using p-nitrophenyl phosphate as the substrate. Statistical analyses, including Independent Samples t-test for baseline comparison and ANOVA followed by Duncan’s multiple range test for treatment effects, were performed to interpret the data. Results: Independent t-test results revealed a significant inherent difference in the biological potential of the two soils. The baseline activity of acid phosphatase in the Clay soil (658 µg pNP g⁻¹ h⁻¹) was approximately 66% higher than that of the Sandy Loam soil (396 µg pNP g⁻¹ h⁻¹) (P < 0.01), emphasizing the role of clay and organic matter in supporting enzymatic pools. Analysis of variance revealed significant main effects and interactions (Time × Type × Concentration). CuO nanoparticles exerted consistently higher and more persistent toxicity than NiO across both soil types. In the Sandy Loam soil, the impact was severe due to low buffering capacity. At the highest concentration (1000 mg kg⁻¹) of CuO, urease activity plummeted by over 90% relative to the control by the end of the incubation period (day 72). This inhibition is primarily attributed to the relatively high solubility of CuO and the interaction of Cu²⁺ ions with thiol (-SH) groups in enzyme active sites. Conversely, NiO nanoparticles exhibited a time-lag toxicity pattern, where significant inhibition in Sandy Loam soil was delayed until day 72. In contrast, the inhibitory effects were notably ameliorated in the Clay soil. A key finding was the non-significant main effect of incubation time on urease activity (P > 0.05) in the clay soil. This suggests that the high clay content (49.8%) facilitated the formation of stable enzyme-clay-humus complexes, which protected urease enzyme from denaturation and proteolytic degradation over time. Interestingly, NiO nanoparticles at lower concentrations (100 mg kg⁻¹) occasionally demonstrated a hormetic effect (stimulation of activity), particularly for alkaline phosphatase in the early stages, contrasting with CuO which generally followed a strict dose-dependent inhibition pattern. Conclusion: This study provides robust evidence that soil texture is a key determinant in the ecological risk assessment of engineered nanoparticles. Light-textured (Sandy Loam) soils exhibit significantly higher ecological sensitivity to metal oxide contamination compared to heavy-textured (Clay) soils, which possess a "protective effect" due to higher colloidal content. Among the tested pollutants, CuO nanoparticles pose a more severe and immediate threat to soil nutrient cycling than NiO due to their higher chemical reactivity. The findings suggest that environmental risk assessments for nanomaterials must account for site-specific soil properties and the dynamic nature of toxicity (aging effect) over time. Future research should focus on molecular‑level mechanisms and long-term field monitoring to further validate these interactions. | ||
| کلیدواژه‌ها [English] | ||
| Metal oxide nanoparticles, Phosphatases, Soil pollution, Soil texture, Urease | ||
| مراجع | ||
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