污水灌溉对土壤水力电导率的影响: 耦合场取样与饱和水力电导率的实验室测定
Summary
在这里, 我们提出了一个方法, 匹配的土壤样本大小和水力电导率测量装置, 以防止所谓的墙上流动沿土壤容器内被错误地包括在水流测量。它的使用表明, 从污水灌溉网站收集的样本。
Abstract
自二十世纪六十年代代初以来, 宾夕法尼亚州立大学进行了一项替代性废水排放实践研究, 并对其影响进行了监测。污水被用于由大学管理的森林和耕地, 而不是将处理过的废水排放到溪流中, 从而直接影响水流质量。在考虑废水回用时, 与土壤水力电导率降低有关的问题。本手稿中描述的方法是, 将土壤样本大小与实验室的水力电导率测量仪的大小相匹配, 提供了相对快速的样品收集和控制的好处。实验室边界条件。结果表明, 污水回用对土壤在 depressional 地区深层输送水的能力有一定的影响。大部分的土壤水力电导率的下降似乎与收集样品的深度有关, 并通过推断, 与土壤结构和质地的差异有关。
Introduction
几十年来, 把处理过的废水从市镇排放到溪流是一种标准做法。这类废水主要用于减少由于废水排出而导致接收水域微生物的生物耗氧量的可能性。微生物的耗氧量会降低废水中的有机物, 从而减少水体排出的氧气量, 从而危害水生生物, 包括鱼类。
近几十年来, 人们对无机营养素、某些金属和废水中的其他化学物质产生了危害。由于 Kolpin 发表的一项研究 。1, 对以前未考虑过的一系列化学品的更大关注已经演变。这项由美国地质学会出版的研究, 提高了人们对在美国由于污水处理设施排出的河流和溪流中各种个人护理产品和其他化学品的认识。
自二十世纪六十年代代初以来, 宾州州立大学的研究人员研究并开发了一种在潮湿地区具有独特性的替代污水排放实践。污水被用于由大学管理的森林和被裁剪的土地, 而不是将处理过的废水排放到溪流中, 从而直接影响水流质量。这个应用领域, 绰号 “生活过滤器”, 当前接受所有从校园产生的废水并且一些从自治市。这减少了过量营养素进入切萨皮克湾的溪流的可能性, 保护当地冷水渔业免受对鱼类有害的温水废水的排放, 并防止其他化学品的运送。包含在直接接触水生生态系统的废水中。
然而, 行为变化的后果总是存在的, 而这种替代性使用设施对此并不免疫。关于废水的应用是否对土壤允许水渗入土壤表面23、4、5以及造成更大的径流的能力产生了负面影响, 出现了一些问题,是否有可能污染当地的水井与化学品 (营养素, 抗生素或其他药物化合物, 个人护理产品) 所含的废水, 以及这些化学品是否正在创造负环境影响, 例如通过将化学物质吸收到植物中生长的6植株上, 或在现场7土壤生物中抗生素耐药性的发展。
由于其中的一些问题, 本研究旨在确定污水灌溉对土壤水力传导饱和度的影响。所采用的方法涉及从灌溉区内外的选定地点收集土壤, 并将土壤样品容器大小与实验室设置相匹配。土壤样品容器要适应实验室仪器和水的作用, 通过样品中的土壤基质从土壤和土壤样品容器中向下移动的水中分离出来。该协议描述了如何构造实验室设备以确保发生这种情况。
土壤样品收集使用一个液压核心取样器连接到拖拉机。土壤核心从起伏的景观中的选定区域收集, 并保留在安装在土芯取样器中的塑料套筒中。这些核心是收集从一个黑格斯敦淤泥沃土, 位于山顶景观位置或在 depressional 地区。六个代表首脑会议和六个 depressional 地点从灌溉区取样 (总共12个灌区取样地点)。此外, 还从毗邻的非灌溉区 (总共六个非灌溉场址) 取样了三个首脑会议和三个 depressional 场址。在每个地点收集最多六个核心的最大深度约为1200毫米, 每芯样品约150毫米长 (样品的100毫米被包含在塑料套筒和50毫米被包含在金属取样器的切削头中。).从金属取样器中取出后, 含有所收集的土芯的塑料套管装有端盖, 直立输送到实验室, 并存放在直立, 直到用于确定饱和水力电导率。同时, 在每个深度收集土壤样品, 以确定土壤和土壤溶液浓度的钙 (钙), 镁 (镁) 和钠 (Na) 使用 Mehlich 3 萃取估计土壤浓度8和去离子水1:2 土壤质量比的萃取物: 水质量。采用电感耦合等离子体原子发射光谱法 (AES) 对水提物进行了化学分析, 计算了钠吸附比 (SAR)。
对饱和水力电导率的测定主要采用恒定水头法9。一种含有钙和钠盐的溶液来模拟出水电导率 (EC) 和 SAR 的出水, 这样土壤就会暴露在水质变量中, 类似于在田间应用的废水。在这种情况下, 欧共体是 1.3 dS/米和 sar 是 3, 反映了欧共体和 sar 最近几年在样品期间之前。[技术上说, SAR 的单位是 (milliequivalents/公升)½并且通常不被辨认在文学。
对克鲁特和埃弗里特·德克森9恒水头法的改造, 是通过沃克8的流动分离器的开发, 防止在土基质外发生的柱流被列入土液的估算中。电导 率。该流量分离器是使用聚氯乙烯 (PVC) 管材选择和加工, 以配合土壤样品大小。屏幕支持土壤样品, 并允许通过土壤基质的水流出样品的底部。第二个插座发出的水流出的塑料套管内, 从而消除所谓的 “壁流” 不正确地包括在估计的水量, 通过土壤基质。
Protocol
Representative Results
Discussion
收集现场、未受干扰的土壤样品和获得其水力电导值的能力在获得现场数据代表方面具有重要意义。为了最好地代表田间条件, 重要的是使用土壤样本保持在物理状态代表他们的环境在田间。例如, 从现场收集的土壤样品, 然后由抽样或处理诱发压实, 将会遇到影响饱和水力传导性的结构变化。
在受控实验室设置中测量土壤水力电导率也很重要。然而, 使用实验室方法来计算饱?…
Disclosures
The authors have nothing to disclose.
Acknowledgements
作者想感谢宾夕法尼亚州立大学物理工厂办公室提供部分资金支持这个项目。农业部-区域研究项目 W-3170 也提供了部分资金。我们要感谢以法莲 Govere 协助进行分析工作。我们最深切的谢意是查尔斯沃克, 他的工程设计和施工技巧使我们有可能进行这项工作。
Materials
| Sampling equipment: | |||
| Soil Sampler Drill Rig | Giddings Machine Co. Inc | #25-TS / Model HDGSRTS | * NOTE: This model is comparable to the model we utilized but which is no longer produced |
| Kelly Bar | Giddings Machine Co. Inc | #KB-208 8 Ft. Kelly Bar | |
| Soil Sample Collection Tube | Giddings Machine Co. Inc | #ZC-180 4-3/4” X 7-1/4” | |
| Soil Collection Tube Bit | Giddings Machine Co. Inc | #ZC-190 4-3/4” Standard Relief | |
| Plastic Liner for Soil Sample | Giddings Machine Co. Inc | #ZC-208 3-5/8” x 6” | Enough for the number of samples being collected |
| Black end caps a for bottom of sample liners | Giddings Machine Co. Inc | To retain samples in liners | |
| Red end caps a for top of sample liners | Giddings Machine Co. Inc | To retain samples in liners | |
| Cooler Chest | Store & maintain samples upright in sample liners during transport from field to lab | ||
| Protective gear: | |||
| Hardhats, googles, and gloves | other items as needed for personal protection | ||
| Saw | |||
| Drill and bits | |||
| PVC Cement | |||
| 6 to 8 – 19 mm x 184 mm x 2438 mm boards | |||
| 2 – barbed fittings; 13 mm HB x MGHT | to connect plastic tubing to supply gutter and to drainage gutter | ||
| 6 – barbed fitting | to connect plastic tubing to outer PVC cylinder to allow for water drainage | ||
| 3000 mm long – 19 mm OD / 13 mm ID plastic tubing | |||
| 6 – 85 mm diameter circular mesh pieces | Can be cut from (e.g.) a 600 mm long, 6 mm x 18 gauge wire mesh (e.g. galvanized steel gutter guard) | ||
| Schedule 40 PVC pipe – 96 mm ID / 114 mm OD | |||
| Schedule 40 PVC pipe – 73 mm ID / 89 mm OD | |||
| Schedule 40 PVC pipe – 63 mm ID / 73 mm OD, OR 6 – 73 mm plastic shower drains | |||
| Schedule 40 PVC pipe – 25 mm ID | |||
| 6 – 6 mm thick x 155 mm square sheets of PVC | Can purchase 2 – 6 mm x 300 mm (appx) sheets for about $20 each from: https://www.interstateplastics.com/Pvc-Gray-Sheet-PVCGE~~SH.php?vid=20180212222911-7p | ||
| 6 – 140 mm by 19 mm plastic funnels | To direct water flowing from soil sample into collection beaker | ||
| Adhesive caulk | |||
| 1 – length of 150 mm x 1200 mm wire mesh cloth | 4 Mesh works well | ||
| 2 – 120 mm x 1219 mm plastic gutter with end caps | |||
| 4 – gutter hangers | |||
| 1 – additional gutter end cap | To be cut as described in procedures to create a constant head in the supply gutter | ||
| 1 – large plastic tub | Appx 65 L in volume, for example, to serve as water source for the hydraulic conductivity procedure | ||
| 1 – large plastic tub | To serve for wetting up soil samples | ||
| 1 – Submersible pump | e.g. Beckett M400 AUL or M400 AS | ||
| Plastic tubing | Various sized drainage tubes, water supply tube, and drain from drainage gutter | ||
| Container of Cheese Cloth | To place at bottom of soil sample help retain soil in plastic sample container during hydraulic conductivity and wetting up | ||
| Rubber bands | Large enough to fit around plastic sample liners tightly | ||
| Scale which measures to at least 0.1 gram | |||
| Beaker or other container to collect water from each sample | |||
| Sodium Chloride | For creating a water quality similar to that which is typically applied to the soil | ||
| Calcium Chloride | For creating a water quality similar to that which is typically applied to the soil |
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