以浓缩10倍沼液和水稻甬优12种子为研究对象,探讨了浓缩沼液浸种对水稻甬优12种子萌发及幼苗质量的影响.结果表明:采用一定浓度范围内的浓缩沼液浸种,显著提升了水稻甬优12种子的发芽率,同时,水稻幼苗质量和活力显著增强,而浸种浓缩沼液若超出特定浓度范围,将显著抑制种子的发芽率及水稻幼苗质量和活力.浓缩沼液最佳浸种浓度为20％.在此最佳浓度下,对应的最佳浸种时间为24 h,超出此浸种时间,将显著抑制种子的发芽率.在浓缩沼液最佳浸种用量和最佳浸种时间下,催芽3 d,水稻甬优12种子的发芽率达到88.3％,幼苗芽长、 茎粗、 根数、 总根长及单苗生物量(干重)分别为4.6 cm、0.91 mm、6.2条、7.00 cm和1.53 mg,水稻幼苗呼吸速率达到33.6μmol·g-1·h-1(以鲜重计).

Quantum dots have unique physical and chemical properties and optical properties due to its special structure. In recent years, as a new type of fluorescent probe materials applied in chemical and biological analysis, medical diagnosis and other fields, quantum dots have become the focus of research. At present, some studies have been reported on the detection of heavy metal, veterinary drug and pesticide residues in food by using quantum dots as fluorescent probes. Related research reports showed that the use of quantum dots as a fluorescent probe to analyze the analyte with impact of food safety had advantages of high sensitivity, good selectivity, short response time, and less investment, which indicated the quantum dots as a fluorescent probe had wide application prospects in food safety inspection field. The malachite green had good antibacterial effect and low price, which was often illegally used in aquaculture as insecticides and fungicides. The malachite green had the potential carcinogenic effects, which was clearly listed in Chinese Food Animal Banned Veterinary Drugs and Compounds List in 2002, but in fact, malachite green residue has been detected in aquatic products breeding from time to time due to illegal addition. Malachite green residue detection method has been mainly reported, such as high performance liquid chromatography, surface enhanced Raman scattering spectroscopy, liquid chromatography-mass spectrometry (LC-MS), ultraviolet spectrometry,which were not easy to be applied and popularized at the basic unit, due to lower sensitivity, or longer single sample detection time, or expensive equipment, or complicated operation. Therefore, it was urgent to develop a detection method with high sensitivity, good selectivity, short response time and less input. Quantum dot fluorescent probe method in residue detection had the potential to meet the demand, but the current studies using the method of quantum dots to detect malachite green were rarely reported. In view of this, based on the application prospects of residue detection by quantum dot fluorescent probe method in the field of food safety, the feasibility of detecting malachite green residue with illegal addition in aquaculture was researched in the present study by a water-soluble quantum dot fluorescent probe method, and the purpose was to establish a method to detect trace residues of malachite green in actual water and fish products. In this study, water- soluble CdTe/ZnS quantum dot fluorescent probe was synthesized under mild conditions with 3-mercaptopropionic acid as a stabilizer. The main influence factors of water-soluble CdTe/ZnS quantum dot fluorescent probe to detect malachite green in the detection system were investigated, including buffer system type, buffer pH, buffer concentration, concentration of quantum dots, reaction time, concentration of malachite green, coexisting ions, etc. The best condition was obtained for the water-soluble CdTe/ZnS quantum dot probe method to detect malachite green on the basis of above investigation. Under the optimal detection condition, water-soluble CdTe/ZnS quantum dot fluorescent probe for quantitative detection of trace residues of malachite green was carried out in water and fish products. At the same time, the mechanism of water-soluble CdTe/ZnS quantum dot fluorescent probe method being used for the detection of trace residues of malachite green was studied by using ultraviolet-visible (UV-Vis) absorption spectroscopy and resonance light scattering technique. As a result, a simple, rapid and sensitive approach to quantitative determination of illegally added malachite green residues in aquaculture was developed based on the fluorescence quenching of water-soluble CdTe/ZnS quantum dots by malachite green. Under the optimized conditions, i.e., pH=8.0, 0.065 mol/L Tris-HCl and 1.60×10-4 mol/L CdTe/ZnS in the detection system, the linear range of water-soluble CdTe/ZnS quantum dot fluorescent quenching intensity versus the concentration of malachite green from 0.0193 mg/L to 1.28 mg/L, with a correlation coefficient of r=0.999 and a limit of detection of 0.00543 mg/L. The proposed method had been applied to quantitative determination of malachite green in muscle tissue of fish and water for freshwater and marine aquaculture successfully, with the recovery percentage of 90.4%- 100.3% and relative standard deviations of 0.37%-1.01% for added malachite green. The detection results of aquatic products and aquaculture water were consistent with the results of LC-MS method, while the results of false positive rate and false negative rate test were the same with real samples, which indicated that the water-soluble quantum dot fluorescent probe method of malachite green residue detection was more specific. The fluorescence quenching mechanism was further investigated by using UV-Vis absorption spectra and resonance light scattering. The results indicated that the fluorescence quenching of water-soluble CdTe/ZnS quantum dots by malachite green was due to fluorescence resonance energy transfer system being constructed between CdTe/ZnS quantum dots (donor) and malachite green (acceptor).

The aim of the present study was to identify measures to better protect the water quality of the Hexi Resevoir, China, via an im-proved understanding of the movement of nitrogen from land to water caused by nitrogen runoff due to soil erosion. Nitrogen losses caused by rain and the resulting soil erosion were assessed in field experiments on dry land, cultivated land, woodland, fallow land, and nursery land. Under natural rainfall conditions, the amounts and concentrations of nitrogen losses differed between the five types of land use.The annual losses of total nitrogen in runoff followed the following order:cultivated land(156.92 kg·hm-2)>dry land(114.24 kg·hm-2)>nursery land (35.61 kg·hm-2)>fallow land(3.99 kg·hm-2)>woodland(1.59 kg·hm-2). The nitrogen runoff losses from fallow land and woodland were less than those from cultivated land and dry land, which are both influenced by cultivation. Therefore, to improve the water quality of the Hexi Resevoir, it will be necessary to manage the surrounding land more appropriately. This will effectively reduce the nitrogen runoff losses and their potential impact on the water quality of the Hexi Reservoir. Our results also showed that nitrogen runoff loss is primarily in the form of particulate nitrogen, followed by nitrate nitrogen and ammonium nitrogen under different land uses. The annual runoff losses of particulate nitrogen from upland, cultivated land, woodland, fallow land, and nursery land accounted for about 61.67%, 61.42%, 75.56%, 65.09%, and 69.11%, respectively, of the total annual nitrogen losses. In contrast, the annual runoff losses of nitrate nitrogen accounted for about 26.21%, 28.56%, 16.35%, 21.30%, and 23.20%, respectively, of the total nitrogen losses. The annual runoff loss of ammonium nitrogen accounted for about 8.90%, 7.87%, 6.92%, 11.78%, and 4.83%, respectively, of the total nitrogen losses. Thus, the key to reducing both nitrogen loss-es and their negative effects on the water quality of the Hexi Reservoir is to decrease surface soil erosion and eliminate the losses of particu-late nitrogen. The appropriate modulation of land-use types is recommended to control the source of non-point-source pollution of the Hexi Reservoir.

In order to research the coordination relation between sepiolite application and the contents of available lead(Pb) and cadmium(Cd) in soil or rice absorption and redistribution of Pb and Cd, a pot experiment was conducted by selecting the soil sampled from a area polluted by Pb and Cd combination in Shaoxing City of Zhejiang Province and atypical late Japonica Rice Varieties in Zhejiang Province(Jia 33) with lower accumulation for Pb, Cd. The results showed that:the contents of available Pb and Cd in soil were significantly negatively correlated with the concentration of sepiolite added, the correlation coefficients of contents of available Pb and Cd with the concentration of sepiolite added were -0.940 respectively and -0.952, which reached the significant level(P<0.01).The contents of Pb and Cd in rice roots, stems, leaves and polished rice had different reducing rates with the increase of the concentration of sepiolite. In addition, with the increase of the concentration of sepiolite added, the enrichment coefficients of Pb and Cd in rice roots, stems, leaves and polished rice decreased dramatically. At the same time, Pb and Cd absorbed by roots transferred to the stems decreasingly, Pb and Cd absorbed by stems transferred to the polished rice decreasingly. When the addition of Sepiolite was 9.00 g·kg-1 soil, the contents of Pb and Cd in polished rice of Jia 33 were(0.14±0.02) mg·kg-1 and(0.03±0.01) mg·kg-1 respectively, which were all lower than the national limit index(GB 2762-2012). Compared with the control group, the enrichment coefficients of Pb in roots, stems and leaves and polished rice decreased by 8.83%, 29.96%, 49.20%, 79.41% respectively, and the enrichment coefficients of Cd decreased by 23.08%, 63.22%, 44.00%, 82.35% respectively. In addition, the transportation coefficients of Pb and Cd absorbed by roots transfer to the stems were decreased by 23.18% and 52.19% respectively and the transportation coefficients of stem rice translocation of Pb and Cd absorbed by stems transfer to the polished rice were decreased by 70.83%, 52.00%, respectively. This result means the sepiolite had a good resistance control in the migration and redistribution of Pb and Cd in soil rice system on the soil polluted by lead and cadmium, indicating the combination of rational application of sepiolite and rice varieties with lower accumulation for heavy metals can achieve safe agricultural utilization of the soil with combined contamination by a relatively higher concentration of Pb and Cd.

为保护主要饮用水源合溪水库水质，长兴县将合溪水库集雨区农业种植结构向苗木种植方式调整，但缺乏优化施肥管理模式。针对该问题，选取集雨区典型苗木种植地进行径流小区定位试验，设置了撒施（对照）、地膜覆盖、秸秆覆盖、区外设置植草缓冲带、条施、穴施6个处理，研究不同施肥管理模式下苗木地径流磷素流失特征，筛选最优施肥管理模式，实现最大化的削减农田磷素流失。结果表明：不同施肥管理模式下，苗木地地表径流年总磷素径流流失通量大小顺序为：撒施（对照） > 地膜覆盖 > 条施 > 穴施 > 区外植草缓冲带 > 秸秆覆盖，撒施（对照）、地膜覆盖、条施、穴施、区外设置植草缓冲带和秸秆覆盖六种施肥管理模式下的年总磷素径流流失通量分别为：9.60、9.14、5.49、4.44、2.48、1.37 kg hm-2 a-1，说明穴施、区外设置植草缓冲带和秸秆覆盖是较佳的施肥管理模式，若将其优化组合将显著消减合溪水库集雨区苗木地径流磷素流失及其对合溪水库水质的潜在影响。此外，不同施肥管理模式下，苗木地径流水样磷素流失的首要形态均为颗粒态磷，其次为溶解态磷，其中，撒施（对照）、地膜覆盖、秸秆覆盖、区外植草缓冲带、条施和穴施小区径流年均流失的颗粒态磷占流失总磷的比例分别是66.09%、70.69%、67.97%、71.63%、68.11%和67.87%。

In order to assess production potential of two low Cd accumulating varieties ( Oryza sativa L. Jia?33 and Xiush?ui?128) of rice in Cd contaminated paddy fields in Xiangyin of Hunan, a field experiment was conducted to explore rela?tionship of Cd content in rice with soil Cd concentration, threshold of soil Cd concentration for safety production of polished rice, and impacts of soil pH and soil organic matter content on Cd concentration in polished rice. Results show that Cd concentrations in polished rice of both cultivars ( Jia?33 and Xiushui?128) were significantly and positively related to con?centration of soil available Cd in the paddy field with correlation coefficient being 0. 982 and 0. 978, respectively. Accord?ing to the criteria in the National Standard for Grains and Food Safety ( GB 2715-2012) , the threshold of soil available Cd for safety production of Jia?33 and Xiushui?128 was 0. 307 and 0. 293 mg·kg-1 , respectively. Increased soil pH and con?tent of soil organic matter by liming and application of organic manure reduced the content of soil available Cd in the paddy field, and hence uptake, transport and accumulation of Cd in rice. Pearson analysis reveals that Cd accumulation in pol?ished rice was significantly and negatively related to soil pH and content of organic matter, which indicates that the two are important factors regulating cadmium accumulation in polished rice.

采用田间径流小区定位研究方法,以合溪水库集雨区苗木种植地为研究对象,设置了撒施(对照)、地膜覆盖、秸秆覆盖、区外设置植草缓冲带、条施、穴施6种施肥管理处理小区,探究不同施肥管理模式对合溪水库集雨区苗木地径流氮素流失的影响,筛选最佳施肥管理模式.结果表明:不同施肥管理模式下,苗木地地表径流年总氮素径流流失通量大小顺序为:撒施(对照)＞覆膜＞条施＞穴施＞区外植草缓冲带＞秸秆覆盖,撒施(对照)、地膜覆盖、条施、穴施、区外设置植草缓冲带和秸秆覆盖6种施肥管理模式下的年总氮素径流流失通量分别为35.61,18.30,15.86,12.94,8.18,3.44 kg/(hm2·a),说明穴施、区外设置植草缓冲带和秸秆覆盖是较佳的施肥管理模式,将其优化组合后会显著消减水库集雨区苗木地径流氮素流失及其对水库水质的潜在影响.此外,不同施肥管理模式下,苗木地径流水样氮素流失的主要形态为颗粒态氮,其次为硝态氮,其中,撒施(对照)、地膜覆盖、秸秆覆盖、区外植草缓冲带、条施和穴施年均流失的颗粒态氮占流失总氮的比例分别为69.11％,68.87％,68.04％,61.89％,61.17％和65.09％;年均流失的硝态氮占流失总氮的比例分别为23.18％,23.36％,20.21％,27.20％,32.02％和28.71％.