자료유형  

 학위논문

Control Number  

0016932531

International Standard Book Number  

9798379679026

Dewey Decimal Classification Number  

600

Main Entry-Personal Name  

Welikhe, Pauline.

Publication, Distribution, etc. (Imprint  

[S.l.] : Purdue University., 2020

Publication, Distribution, etc. (Imprint  

Ann Arbor : ProQuest Dissertations & Theses, 2020

Physical Description  

1 online resource(177 p.)

General Note  

Source: Dissertations Abstracts International, Volume: 84-12, Section: B.

General Note  

Advisor: Brouder, Sylvie.

Dissertation Note  

Thesis (Ph.D.)--Purdue University, 2020.

Restrictions on Access Note  

This item must not be sold to any third party vendors.

Summary, Etc.  

요약Eutrophication due to phosphorus (P) enrichment continues to be a primary water quality concern affecting freshwater and marine estuaries around the world. Excessive anthropogenic P inputs, driven by the need to meet the rising food and energy demands of a growing and increasingly urbanized population, have resulted in the buildup of P creating legacy (historical) P pools in agricultural landscapes. There is growing evidence that remobilization of accumulated legacy P can interfere with conservation efforts aimed at curbing eutrophication and improving water quality. Less is known about the magnitude and effects of these legacy P pools on dissolved reactive P (DRP) losses in tile-drained systems. This dissertation consists of three separate inquiries into how legacy P may affect DRP losses in tile drains. In the first inquiry, we examined the possibility of developing a suitable pedo-transfer function (pedoTF) for estimating P sorption capacity (PSC). Subsequent PSC-based indices (Phosphorus Saturation Ratio (PSR) and Soil Phosphorus Storage Capacity (SPSC)) were evaluated using daily water quality data from an infield laboratory. The pedoTF derived from soil aluminum and organic matter accurately predicted PSC (R2 = 0.60). Segmented-line models fit between PSR and soluble P (SP) concentrations in both desorption assays (R² = 0.69) and drainflows (R² = 0.66) revealed apparent PSR thresholds in close agreement at 0.21 and 0.24, respectively. Linear relationships were observed between negative SPSC values and increasing SP concentrations (R² = 0.52 and R2 =0.53 respectively), and positive SPSC values were associated with very low SP concentrations in both desorption assays and drainflows. Zero SPSC was suggested as a possible environmental threshold. Thus, PSC-based indices determined using a pedoTF could estimate the potential for SP loss in tile drains. Also, both index thresholds coincided with the critical soil test P level for agronomic P sufficiency (22 mg kg-1 Mehlich 3 P) suggesting that the agronomic threshold could serve as an environmental P threshold. In the second inquiry, PSC- based indices in addition to other site characteristics present in a P index (PI), were used as inputs in the development of a multi-layer feed-forward artificial neural network (MLF-ANN). The MLF-ANN was trained, tested, and validated to evaluate its performance in predicting SP loss in tile drains. Garson's algorithm was used to determine the weight of each site characteristic. To assess the performance of ANN-generated weights, empirical data from an in-field laboratory was used to evaluate the performance of an unweighted PI (PINO), a PI weighted using Lemunyon and Gilbert weights (PILG), and an ANN-weighted PI (PIANN) in estimating SP losses in tile effluent. The MLF-ANN provided reliable predictions of SP concentrations in tile effluent (R2 = 0.99; RMSE = 0.0024). Soil test P, inorganic fertilizer application rate (FPR), SPSC, PSR, and organic P fertilizer application rate (OPR), with weights of 0.279, 0.233, 0.231, 0.097, and 0.084, respectively, were identified as the top five site characteristics with the highest weights explaining SP loss in tile discharge. These results highlighted the great contribution of both contemporary and legacy P sources to SP concentrations in tile discharge.

Subject Added Entry-Topical Term  

Manures.

Subject Added Entry-Topical Term  

Eutrophication.

Subject Added Entry-Topical Term  

Water quality.

Subject Added Entry-Topical Term  

Phosphorus.

Subject Added Entry-Topical Term  

Back propagation.

Subject Added Entry-Topical Term  

Groundwater.

Subject Added Entry-Topical Term  

Soil testing.

Subject Added Entry-Topical Term  

Algae.

Subject Added Entry-Topical Term  

Soil erosion.

Subject Added Entry-Topical Term  

Watersheds.

Subject Added Entry-Topical Term  

Neural networks.

Subject Added Entry-Topical Term  

Drainage.

Subject Added Entry-Topical Term  

Corn.

Subject Added Entry-Topical Term  

Fertilizers.

Subject Added Entry-Topical Term  

Aluminum.

Subject Added Entry-Topical Term  

Sediments.

Subject Added Entry-Topical Term  

Testing laboratories.

Subject Added Entry-Topical Term  

Algorithms.

Subject Added Entry-Topical Term  

Effluents.

Subject Added Entry-Topical Term  

Performance evaluation.

Subject Added Entry-Topical Term  

Aquatic ecosystems.

Subject Added Entry-Topical Term  

Agriculture.

Subject Added Entry-Topical Term  

Agronomy.

Subject Added Entry-Topical Term  

Aquatic sciences.

Subject Added Entry-Topical Term  

Biogeochemistry.

Subject Added Entry-Topical Term  

Ecology.

Subject Added Entry-Topical Term  

Hydrologic sciences.

Subject Added Entry-Topical Term  

Microbiology.

Subject Added Entry-Topical Term  

Soil sciences.

Subject Added Entry-Topical Term  

Water resources management.

Added Entry-Corporate Name  

Purdue University.

Host Item Entry  

Dissertations Abstracts International. 84-12B.

Host Item Entry  

Dissertation Abstract International

Electronic Location and Access  

로그인을 한후 보실 수 있는 자료입니다.

Control Number  

joongbu:643151