Soil samples from 0–1050 cm depth were collected from a 20-year field experiment with two N fertilization treatments: 0 (N0) and 600 kg N ha −1 year −1 (N600). Amplicon sequencing and quantitative PCR analyses were performed to profile the vertical distribution of soil microbial communities and denitrification genes.The soil microbial community structure and diversity were strongly influenced by soil depth and N fertilization. The 250 cm depth was identified as a threshold depth, as dramatically different microbial communities were found below and above this depth.Quantitative PCR results showed that the absolute abundance of denitrification genes decreased with increasing soil depth.This study elucidated the profound effects of long-term N input on the composition and diversity of the microbial communities and the abundance of denitrifiers in the deep vadose zone. Our results provide basic information for use in mitigating nitrate leaching by enhancing microbial denitrification in deep vadose zones in intensive agricultural areas.
Irrigation with saline water is increasingly popular for reclaiming saline-alkali soil and for increasing crop productivity in some countries and regions. The purpose of this study was to investigate the alteration of salt ions distribution within different soil aggregate fractions after irrigation with freezing saline water. The experimental site is located on the coastal plain in Haixing County, Hebei Province, China. In a field experiment after irrigation with freezing saline water for 6 years, soil samples (0-10, 10-20 and 20-30 cm depths) were collected from three treatments: freezing saline water irrigation with plastic film mulching (IM); freezing saline irrigation without plastic film mulching (IO); and no saline irrigation and no mulching (CK). The bulk soils were separated into five size classes (i.e., 5-8, 2-5, 1-2, 0.25-1 and <0.25 mm) by the dry-sieving method. Then, the salinity and ion (i.e., Ca2+, Mg2+, K+, Na+, HCO3-, SO42- and Cl-) concentrations within each aggregate size class were determined following the methods of Lao (1988). The total salt content was calculated as the sum of the cations and anions. 咸水灌溉可以作为一种改良盐碱地和提高作物生产力的技术越来越受重视。本研究旨在研究多年冰冻咸水灌溉后不同土壤团聚体组分中盐离子分布的变化。咸水结冰灌溉试验位于河北省沧州市中科院海兴盐碱地资源高效利用研究基地，研究开始于2008年，试验设对照CK（无灌溉无覆膜CK）、灌溉无覆膜（IO）、灌溉和覆膜（IM）三个处理，三次重复；小区面积40m2。冰冻咸水灌水量为180mm，灌水时气温-10.3℃；覆盖地膜于3月土壤表面冰层融化且入渗完成后。土样采集工作于2014年4月，每个小区分层取原状土壤，层次：0-10cm，10-20cm，20-30cm；在实验室分别测定土壤团聚体和含盐量。每个小区两个重复。土壤干团聚体的测定：采用干筛分法。土壤分级为5.0, 2.0, 1.0和 0.25 mm系列样品筛，每一粒级的土壤收集称重计算百分数。土壤含盐量的测定：采用土/水比1:5进行浸提，浸提液用化学滴定法测定，其中HCO3-含量用双指示剂滴定，Cl-含量用AgNO3滴定，SO42+含量用EDTA间接络合滴定，Ca2+和Mg2+含量用EDTA滴定，K+和Na+含量用阴阳离子平衡法求得，再以各阴阳离子的浓度之和求得总含盐量。
There are many environments on Earth that are so remote that they are inhospitable to humans and conventional sensing equipment. Yet, these environments can hold information of ecological and cultural significance that cannot be gathered anywhere else. Current methods of gathering information in these environments give an important window, but utilizing modern sensors to capture 3D information can allow us to interpret existing data and understand the environments in new and unique ways. This thesis will demonstrate how 3D capture can improve data collection and interpretation in three separate remote environments. First, I will show how Synthetic Aperture Sonar on autonomous underwater vehicles paired with optimized feature detectors can improve target detection and seafloor recognition. Next, I will show how RGBD cameras, photogrammetry, and LIDAR can be used in isolated Guatemalan archaeological excavations to visualize and contextualize ancient sites in relation to each other and to our broader understanding of Mayan history. Finally, I will demonstrate the effectiveness and potential of RGBD cameras for fish stock assessment through detection and length and biomass measurement in open waters and in aquaculture.
Eastern Mediterranean archaeological sites record intensified marine resource use among coastal hunter-gatherer groups in the Upper Mesolithic (~10.5-8.5 ka (1)) and into the Early Neolithic, followed by a decline in fishing effort as the widespread use of agriculture and pastoralism was established in the Neolithic (~8.5-4 ka (2)). We used a fish microfossil record of teeth, bones, scales, and otoliths deposited in an Aegean deep-sea sediment core to show that pelagic fish availability may have played a role in shaping this dietary evolution. We found elevated deposition of pelagic fish remains during what broadly corresponds to the Mesolithic and Early Neolithic periods, with fish fossil abundance increasing 12-fold starting around ~10 ka. The abundance of fish remains then declines in the open ocean during the Middle-Late Neolithic, with fish fossils decreasing 6-fold after ~6 ka. Our findings reveal that fish were abundant when Mesolithic and Early Neolithic coastal hunter-gatherer groups were exploiting them more heavily, and diminished as human fish use declined and widespread agriculture was established in the Neolithic. We infer that environmental changes in fish availability altered the costs and benefits of the different subsistence strategies, with fishing being a productive strategy during the Upper Mesolithic, and reliance on domesticated resources becoming increasingly advantageous as fish availability declined into the Neolithic. We argue that Early Holocene environmental changes influenced not only the uppermost marine trophic levels, but also the choices and economies of early humans, ultimately favoring the development of agriculture in the Neolithic.
These folders store the results of the automated extraction of individual potsherd fragments in the soil surface provided by two different approaches. They both used the same orthophotomsaic. The original images were acquired by a DJI Phantom 4 Pro V2.0 flying at a height of around 3m above ground. These were acquired as part of the survey of the city of Abdera and its environments. These images correspond to plot 591. These are preliminary results of work in progress. Future research will provide more developed algorithms and processes. This is only intended to document the provisional results as they were in early summer 2020.
Research guide and teaching tool for the analysis of digital archives and digital resources in the humanities. Developed from the author's doctoral research and for the postgraduate classes 'Digital resources in the humanities' (Digital Humanities) and 'Concepts and Contexts' (Archives and Records Management) at UCL.