典型林耕地转换模式下颗粒态磷流失的土壤主控因子光谱甄别

The modes of woodland and farmland transformation are diverse，which always lead to the occurrence of agricultural nonpoint source pollution, and resulted in Phosphorus in surface soil loss into water,to be the main component of nutrients in lakes. This phenomenon was particularly typical in Taihu Lake Basin. Therefore, to access the Phosphorus loss features has become the important foundation of Taihu Lake eutrophication governance. In existed studies, the modeling factors were numerous, data acquisition was difficult, and spatial variation characteristics were hardly to embodied effectively . And in this study, firstly, by means of soil physical and chemical analysis and GIS spatial evaluation, the primary factors of particulate phosphorus loss were selected preliminary. Afterwards, by using the character of hyper-spectral in detect soil component information rapidly, the laboratory spectra and field measured spectra were fitted and analyzed, the linkages between particulate phosphorus loss and soil properties variation were revealed, finally, the spectral identification for primary factors of particulate phosphorus loss in different woodland and farmland transformation modes were achieved, which can instead numerous modeling factors of primary factors, and then attain the goal of monitoring particulate phosphorus loss rapidly. For aboved, this study is helpful to Improve the research accuracy of particulate phosphorus loss, and also provide the basis for spatial differentiation governance of agricultural nonpoint source pollution.

林地开发以及耕地内部种植模式的调整是林耕地转换的主要模式。多样化的转换模式易引发农业面源污染,使土壤表层磷素主要以颗粒态的形式向水体流失，并成为湖泊营养盐的主要成分。这一现象在太湖流域较为典型，因此快速掌握农业面源磷流失特征已成为太湖水体富营养化治理的重要基础。针对现有研究模型因子繁多、数据获取难度大、空间分异特征难以有效体现的问题，本研究以颗粒态磷流失的特征分析为基础，初步遴选对其流失影响较大的土壤主控因子，再通过实验室与野外实测光谱的拟合以及对比分析，揭示颗粒态磷流失与土壤属性变化之间的定量联系，实现典型林耕地转换模式下土壤主控因子的光谱甄别，从而以关键指示性指标代替繁冗的建模因子，合理简化模型，达到快速监测颗粒态磷流失的目的。研究有助于提高土壤营养元素流失估算的时效性与准确性，也可为农业面源污染的差别化治理提供理论依据。

土地利用变化是造成流域面源磷流失的重要驱动因素，面源磷载荷研究模型因子繁多、数据获取难度大。因此利用光谱技术，快速甄别影响面源磷流失的关键土壤主控因子对面源污染的合理管控具有重要意义。本基金首先分析太湖流域土地利用变化特征，选取土地利用变化最为剧烈梅梁湾和竹山湾流域为研究区，结合文献调查和野外采样估算流域面源磷载荷。然后进行实验室光谱采集，确定土壤中磷的特征波段，估算不同土地利用类型下土壤磷含量。最后根据野外实测土壤光谱，结合面源磷流失强度，确定不同用地类型下面源磷流失的土壤主控因子及其光谱吸收特征，以达到快速监测面源磷流失的目的：.（1）确定了研究区面源磷载荷时空变化特征.利用SEDD模型可以准确估算研究区内面源颗粒态磷载荷，R2达到0.9以上，大部分地区面源颗粒态磷载荷呈现出较低的水平，高载荷区主要集中在中部地区，西部和东南部载荷较低，最低值为0 kg/km2，最高值为12.747 kg/km2；.（2）探讨了通过光谱直接估算土壤磷含量的可能性.直接用所有样本的光谱数据估算土壤磷含量时，建模集R2为0.6，而验证集R2仅为0.5，RMSE为1左右。将样本按照不同的用地类型分类后，茶园土壤磷的R2达到了0.82，RMSE为0.1，但是林地的结果并不理想，R2仅为0.21。土壤磷没有明显的光谱特征，通过光谱直接反演土壤磷含量精度还有待提高。.（3）明确了耕地、园地等典型用地类型下面源磷流失的关键主控因子.在耕地条件下，面源磷流失强度和光谱指数间的相关系数在650~670nm、1475nm、1680~1695nm处较高，最高达到0.74，确定耕地面源磷流失强度的土壤主控因子是有机质，二者之间呈正相关；在园地条件下，相关系数在685~690nm、710~720nm、1110~1115nm、1150~1155nm和2170nm处较高，确定主控因子是有机质、水分和Fe2+，面源磷流失强度和有机质及Fe2+呈负相关，和水分呈正相关。.通过本基金的实施，以第一作者/通讯作者身份在国内外权威学术期刊上累计发表论文8篇，全部被SCI收录，获得软件著作权一项，联合培养硕士研究生6名，超额完成基金立项时的考核指标。