Nutrients Distribution and Contamination Assessment in Seawater and Surface Sediment of the Coastal Wetlands,Northern Beibu Gulf
Bibliographic record
Abstract
Coastal wetlands have important ecological service functions in reducing nutrients into the sea and diminishing eutrophication of the estuaries.But the input of nitrogen and phosphorous to the costal wetlands in China has increased significantly with the economic development of coastal areas in these years.The induced seawater eutrophication and sediment contamination have caused negative impacts on fishery resources,human health and seawater utilization.The content,distributions and contamination status of nutrients in seawater and surface sediment of the coastal wetlands,northern Beibu Gulf(with water depth less than 6 m) are analyzed and assessed based on the investigation data obtained in April and May,2009.The results indicated that the surface sediment in the eastern study area,bounded by Dafeng River estuary,is sandy deposit;while salty and clayey sediment dominated in the western part.The mean contents of dissolved inorganic nitrogen(DIN,including NO 3 —N,NO 2 —N,NH 4 + —N),PO 4 3—P and COD Mn in the seawater were(211.84 ± 37.44) mg/L,(11.01±12.11) mg/L and(0.92±0.32) mg/L.The mean contents of total nitrogen(TN),total phosphorus(TP) and total organic carbon(TOC) in the surface sediments were(373±355) mg/g,(232.28±157.34) mg/g and(0.45±0.46)%,respectively.Medium to strong positive correlations exsit among the nutrients in the seawater or surface sediment,suggesting these nutrient elements originate from similar sources.High contents of DIN and PO 4 3—P distributes in the sea area of Maowei sea and eastern part of Lianzhou bay.It is speculated to be caused by the large scale aquacuture developed in these areas.However,chemical oxygen demand(COD) content showed decreasing seaward.Seawater eutrophication in the area of Maowei sea and eastern part of Lianzhou bay was evaluated serious employing the method of eutrophication index.The contents of TN,TP and TOC in the surface sediments were controled clearly by particle size,which was evidenced by the strong positive correlations between the sediment median diameter and the contents of nutrients.The high contents of nutrients were found in fine-grained sediments because of their higher absorption ability and lower porosity to prevent degradation of organic matters.Sediment TOC/TN ratios demonstrated that the organic matter is predominantly terrigenous in the surface sediment of Qin River estuary,Qinzhou harbour,Fangcheng habour,Qisha harbour and the northeasten part of Pearl bay.According to the'guidelines for the protection and management of aquatic sediment quality in Ontario',the contents of TOC,TN and TP in the surface sediments lied in their lowest effect levels of 1%,550 μg/g and 600 μg/g for most part of the study area,meaning the sediment was clean-marginally polluted and had potential to affect fish or sediment-dwelling organisms except the tops of Qingzhou bay and Tiehangang bay along with the middle estuary of Dafeng River,where the content was slightly greater than the lowest effect levels,implying the sediment is marginally-significantly polluted and could affect sediment use by some benthic organisms.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.002 | 0.001 |
| Science and technology studies | 0.001 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.001 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".