Characterization of fungal melanins and soil humic acids by chemical analysis and infrared spectroscopy

Summary Humic acids from two Brazilian topsoils under savanna grassland and five soil fungal melanins were characterized by elemental, functional group and infrared analysis. C, N, total acidity, COOH, and phenolic OH contents were within the ranges reported for several other fungal melanins and soil humic acids. Compared with the soil humic acids, the infrared spectra of the fungal melanins showed greater detail, indicative of higher aliphaticity. They were similar to the type III infrared spectra of humic acids, which are characteristically high in proteinaceous material and polysaccharides. The infrared spectra of the humic acids from the two Brazilian soils studied were classified as type I, which includes most soil humic acids. Notwithstanding the greater detail, in some areas the fungal melanin spectra were similar to those reported for other fungal melanins and humic acids of different origins. The probable contribution of the melanic fungi to the formation of soil humic polymers is discussed.     

土样盒土表特征对近红外光谱测量土壤水分精度的影响

为了现场快速准确地检测土壤水肥状况,实现精细农业的目标。利用近红外光谱反射法测量土壤水分,了解土壤表面特征对测试结果的影响规律,是能否有效提高测量精度的关键,对快速测量大田的养分含量,实现精确定量管理也有重要的现实意义。该研究用近红外光谱技术测量了6个不同土样的土壤含水率,经回归分析发现：与直尺刮平相比,盒土表面筛控刮平处理的土样,其土壤含水率与光谱的相对吸收率之间有更好的相关性;不同类型的土样对光谱的相对吸收率是：中壤土＞重壤土＞轻壤土;在相同的表面处理条件下,粒径0.5≤d≤1 mm的土样,其含水率与光谱相对吸收率之间的相关性均较高。研究表明,土样表面均匀连续是测量精度提高的主要原因;而裂纹和划痕是影响测量精度的重要因素。     

基于近红外光谱技术的茶油原产地快速鉴别

为研究茶油原产地溯源问题,维护其市场秩序,促进公平竞争。该文利用近红外光谱技术采集湖南、江西、安徽和浙江4个不同产地茶油的光谱数据,并运用 Savitzky-Golay 平滑（savitzky-golay, SG）、多元散射校正（multiplicative scatter correction, MSC）、一阶导数（first derivation, FD）和矢量归一化（vector normalization, VN）等4种方法对其进行预处理。采用偏最小二乘法（partial least squares, PLS）提取最佳主成分,构建 PLS 回归模型;同时,采用主成分分析（principal component analysis, PCA）和 PLS 算法提取最佳主成分,作为 BP 人工神经网络（BP artificial neural network, BPANN）输入变量,构建 PCA-BPANN 和 PLS-BPANN 模型。以验证集相关系数 RP 和验证集均方根误差 RMSEP 为模型的评价指标,分别优选最佳 PLS 和 BPANN 模型。试验结果表明,SG-PLS-DA 和 SG-PLS-BPANN-DA 模型对未知样本的整体分类准确率均大于90%。其中,SG-PLS-BPANN-DA 的鉴别效果优于前者,其建模集相关系数 RC、均方根误差 RMSEC 分别为0.974、0.170,验证集相关系数 RP、均方根误差 RMSEP 分别为0.972、0.172,对上述两类样本集的总体分类准确率分别为98.15%、95.83%,该模型能较准确鉴别茶油原产地。研究结果可为快速辨别茶油原产地提供参考。     

In Situ Measurement of Soil Chemical Composition by Near-Infrared Spectroscopy: A Tool Toward Sustainable Vineyard Management

This study evaluated an in-field near-infrared (NIR) instrument to predict the contents of total nitrogen (TN), organic carbon (OC), potassium (K), sulfur (S), phosphorus (P), pH, and electric conductivity (EC) in soil vineyard samples (n = 70) sourced from three wine regions of Australia. Samples were analyzed using a portable NIR spectrophotometer (ASD FieldSpec III, 350–1800 nm). Partial least squares (PLS) regressions yield a coefficient of determination in calibration (R2) and a standard error in cross validation (SECV) of 0.74 (0.03) for TN, 0.92 (2.19) for S, 0.81 (0.42) for OC, 0.70 (109.2) for K, 0.84 (0.03) for EC, 0.83 (0.44) for pH, and 0.69 (24.6) for P, respectively. This study showed that it is possible to measure soil chemical properties in the vineyard, and the main advantages of this approach will be the speed, low cost, and ability to better manage and monitor soil fertility.     

Biological,Physicochemical, and Spectral Properties of Aerated Compost Extracts: Influence of Aeration Quantity

The goal of this experiment was to investigate the effect of aeration quantity (0, 11, 33, 55, and 77 L·min^?1) on the growth of aerated compost extracts from a pig manure–straw compost. When the aeration quantity was 11 L·min^?1, lettuce root growth enhancement of normalized compost extracts was at a maximum. As the aeration quantity increased, the total water-soluble organic carbon (TWSOC), total nitrogen (TN), total phosphorus (TP), humic carbon (humic C) content, and humification degree of compost extracts improved gradually. No differences in functional group structure were found among the aerated compost extracts. The positive root growth could be attributed to physicochemical and spectral characteristics, such as TN content, humic substances content, humification, aromaticity, and the low content of carboxyl groups. In conclusion, the aeration quantity of 11 L·min^?1 was suitable for the production of aerated compost extracts, which obtained much greater promotion growth.     

Use of Near Infrared Reflectance Spectroscopy (NIRS) for Predicting Soil Fertility and Historical Management

This study tests the potential of near infrared reflectance spectroscopy (NIRS) for predicting soil fertility and management history from topsoil (0–10 cm deep) spectra. Soil fertility was assessed by measuring the growth of a test plant, and soil management history was determined through inquiries with farmers. Moreover, NIRS predictive value was compared with that of a group of topsoil parameters: total carbon and nitrogen, nitrate, potential respiration and denitrification, and microbial biomass. Modelling used partial and modified partial least square regressions to ensure comparisons between predictions by NIRS versus by soil parameters. Soil fertility and management history were well predicted by NIRS (Q² = 0.78 and R² = 0.89 both; Q² and R² are cross-validation and calibration coefficients of determination, respectively), as were the soil parameters (Q² = 0.79–0.92 and R² = 0.86–0.98). Soil fertility and management history were more accurately predicted by NIRS than by the set of soil parameters.     

Fate of humic acids isolated from natural humic substances

Composition of humic acids (HA) is a function of plant-derived inputs, degradation processes regulated by microorganisms, organo-mineral interactions and age. Characterization of different origin humic substances is important for evaluation of their contribution to stabile and labile carbon pool in the environment. The relative abundance of chemical components in HA isolated from soils, compost, commercial lignohumates, alginite, acadiane and lignite was studied with aim to quantify content of important biomarkers such as amino acid, lipids and polyphenols. HA were considered as a heterogeneous complex and high concentration of peptides, polyphenols and lipids was determined in acadian-HA to compare with soil-HA. Compost-HA contained much more amino acids to compare with soil-HA samples. Alginite-HA and lignite-HA were similar in biomarkers content to soil-HA. Fourier transform infrared spectroscopy confirmed that chemical composition and functional groups content differs with the origin, humification degree and the age of studied samples. Soil-HA are typically composed of a variety of ?OH, COOH?, C–O, C–H₂, (aliphatic and aromatic) groups, quinines, lignin fragments, polysaccharide, monosaccharide and proteins fragments, which are linked together by ?O?, ?NH?, ?H=, >C=O, metal ions and –S? groups. ¹³C NMR spectroscopy showed that aromatic carbon content was the highest in lignite-HA and soil-HA.     

鱼腥草素同系物对红细胞膜蛋白上酪氨酸残基荧光特性的影响

研究了鱼腥草素同系物（HOU-Cn,n=8,10,12）对红细胞膜蛋白酪氨酸（Tyr）残基荧光特性的影响.结果表明：不同浓度的HOU-Cn均能降低Tyr的荧光强度,随着HOU-Cn碳链的延长,Tyr的荧光强度下降幅度减小.动力学参数的结果表明焓变ΔHand熵变ΔS均为正值,而自由能ΔG为负值,说明HOU-Cn与细胞膜蛋白的结合主要是由HOU-Cn与膜蛋白质疏水相互作用引起的熵驱动自发过程.     

唐山地区玉米秸秆中铁、铜含量及其与成熟度的相关性

[目的]为确定唐山各地区添加剂的用量和平衡饲料中微量元素的含量提供理论基础。[方法]采用高温灰化法对玉米秸秆进行前处理,并采用火焰原子吸收光谱法测定唐山地区玉米秸秆中铁、铜的含量,分析其与秸秆成熟度的相关性。[结果]唐山6个地区玉米秸秆中铁、铜含量不同,部分地区之间存在显著差异。乐亭地区玉米秸秆中铁含量最高,而遵化地区铁含量最低。滦县玉米秸秆中铜含量最高,而丰南地区铜含量最低。在遵化地区3种成熟度的玉米秸秆中,遵化(青)和遵化(黄)的铁、铜含量均明显高于遵化(冬)。[结论]唐山各地区玉米秸秆中铁、铜的含量不仅存在地区差异,而且受其成熟度的影响。     

茶叶渣对水溶液中Cu2+的吸附研究

为研究茶叶渣对水溶液中Cu2+的吸附及其机理,利用台湾高山茶叶渣对水溶液中Cu2+进行了吸附实验,考察pH、吸附时间、反应温度、Cu2+初始浓度等因素对吸附效能之影响。实验结果表明：台湾高山茶叶渣对Cu2+有很好吸附效果,吸附平衡时间约为60 min;随着反应温度增加,对Cu2+的吸附效能逐渐提高。在固定初始Cu2+浓度、吸附时间、震荡转速及反应温度下,pH会影响茶叶渣对Cu2+的吸附效能,pH 4时吸附效果最佳。对Cu2+的吸附效能均可使用Langmuir与Freundlich等温吸附方程式进行推估,但比较相关系数,前者较后者有更佳的推估能力;分别计算30、40和50℃下的吸附热力学参数,对应的吉布斯自由能(ΔG0)均为负,表明该反应自发进行;焓变(ΔH0)＞0,证实该反应为吸热反应;熵变(ΔS0)＞0,说明该吸附反应是熵增的过程;茶叶渣吸附前后的红外谱图分析,表明物理吸附为茶叶渣吸附Cu2+的主要机制。