Multidimensional water level and water quality response to severe drought in Xingyun Lake.

Drought stress has a significant impact on the quality and quantity of lake water. Understanding this impact is crucial for preventing water security risks and pollution recovery. However, there is a lack of systemic understanding of how drought affects water quality and quantity, and how they change in multiple dimensions. This manuscript established a synthesized methodology with the principles to judge the applicability and three steps of application to detect the change in water quality and water level under severe drought in Xingyun Lake, China. Results show that (1) The water level and water quality of Xingyun Lake have a synchronous and evident response to drought during 2009-2014. The rainfall during 2008-2015 declined by 22.9 % to normal, and the inundated area and lake water depth in 2012 decreased by 10.50 % from 2002 to 1.38 m to the average depth, respectively. The pollution index climbed above 1.21 after 2008, fluctuating around 1.42. (2) Under drought, the water quality indicators significantly changed in the terms of the overall feature, trend, eigenvalue, and morphological characteristics. The water quality indicators of Set2008-2015 are significantly different from set2000-2007 and not in the groups of set1994-2000. The morphological characteristics of water quality indicators in set2008-2015 differs significantly from that in set2000-2007 shown by the minimum, maximum, median, quartiles, and extreme values. (3) Although NH3-N showed no significant change, the water quality deteriorated in the physical, chemical, and biological aspects. The TP, IMN, and BOD5 changed more evidently than DO and NH3-N. (4) Water quality grade and indicator concentration deteriorated significantly and sharply under severe drought and are threatened deeply by TP and TN. The synthesized methodology is scientifically constructed and canbe employed in the characteristics cognition of water quality and water level to severe drought in and out of this research. And the intervention time and various regulating measures for pollution degradation and water quality recovery canbe constructed based on the multi-dimensional analysis of water quality change under drought evolution.

Dynamics of algal blooms in typical low-latitude plateau lakes: Spatiotemporal patterns and driving factors.

The alpine lakes distributed on the plateau are crucial for the hydrological, and biogeochemical cycle, and also serve as a guarantee for regional economic development and human survival. However, under the influence of human interference and climate fluctuations, lakes are facing problems of eutrophication and subsequent algal blooms (ABs) with acceleration, and the development and driving factors of this phenomenon need to be considered as a whole. In this study, ten lakes located on the Yunnan-Guizhou Plateau were selected as the study area to analyze the spatiotemporal distribution of ABs and possible controlling forces. The FAI (Floating Algae Index) derived from multiple MODIS products and water quality data under high-frequency monitoring were selected as the data sources for characterizing ABs. Three nutrient parameters and five meteorological variables were used to explore the driving factors affecting ABs. Various methods of trend detection and correlation analysis have been applied. The main results are as follows: (1) Dianchi Lake (in lake area) and Xingyun Lake (in area proportion) are the two lakes with the most serious ABs in the historical period; (2) ABs are mainly distributed on the shoreline and northern edge of lakes, and tend to stay away from the lake center during high-temperature periods of the day; (3) Six lakes show a decreasing trend in ABs, especially after 2018, while other lakes (including Fuxian, Chenghai, Yangzong, and Erhai) are increasing, not only in peak value but also in duration; (4) Lakes with severe ABs are all P-restricted lakes, the minimum temperature is the most sensitive meteorological factor, while the impact of precipitation against ABs has a time lag; (5) Establishing a warning system of temperature and nutrient concentration is critical in ABs adaptive strategy. This study is expected to provide scientific references for regional water management and the restoration of the eutrophic aquatic ecosystem.

Articular Cartilage Fragmentation Improves Chondrocyte Migration by Upregulating Membrane Type 1 Matrix Metalloprotease.

OBJECTIVE: This study was undertaken to elucidate the mechanism of improved chondrocyte migration after juvenile articular cartilage fragmentation. DESIGN: In vitro organ culture with rabbit cartilage fragments and cell culture with rabbit chondrocytes were performed. In part A, minced juvenile cartilage fragments (~0.5 × 0.5 × 0.5 mm) from rabbits, planted in gelatin sponge and fibrin glue, were cultured for 2, 4, or 6 weeks in vitro and compared with the cartilage chunks (~4 × 4 × 1 mm) and membrane type 1 matrix metalloprotease (MT1-MMP) inhibitor groups. Chondrocyte outgrowth was evaluated on histology and confocal laser scanning microscopy. MT1-MMP expression was compared between the cartilage fragment group and the cartilage chunks group. In part B, articular chondrocytes were harvested from juvenile rabbits, MT1-MMP was transfected into the cells, and cell migration was evaluated using the Transwell and wound healing tests. RESULTS: The histology and confocal microscopy results revealed that cell accumulation occurred at the edge of cartilage fragments, and outgrowth was better in the cartilage fragment group than those in the cartilage chunks group. Similar results were observed for MT1-MMP expression. After MT1-MMP inhibition, cells did not accumulate at the edge of the cartilage fragments, and chondrocyte outgrowth did not occur. Furthermore, overexpression of MT1-MMP enhanced the migration of articular chondrocytes. CONCLUSIONS: Juvenile articular cartilage fragmentation improved chondrocyte migration by upregulating MT1-MMP.

Atmospheric nitrogen pollution in urban agglomeration and its impact on alpine lake-case study of Tianchi Lake.

The atmospheric pollution caused by human activities has been recognized as an important factor affecting the water quality of freshwater bodies. The process of the human factors' impact on high-altitude lakes in inland regions is not clear up to now. In this research, regions around Tianchi Lake were taken as a case study to explore the relation between the urban air pollution and alpine lake water quality. Multi-scale station observed data were analyzed for the urban NO2 pollution by means of relevance analysis and trend analysis, the field measured data were analyzed for the lake total nitrogen (TN) pollution using multiple methods including the water quantity and quality balance, remote sensing retrieval and nutrient load assessment. The sources and occurrence conditions of atmospheric pollution and lake pollution were identified by a multi-method driving factor analysis. As a result, there is sufficient direct and indirect evidence to prove that the serious air pollution in surrounding cities is an important cause of the nitrogen pollution in Tianchi Lake.

[TREATMENT OF RECURRENT PATELLAR DISLOCATION ASSOCIATED WITH OLD OSTEOCHONDRAL FRACTURE].

OBJECTIVE: To explore the treatment methed of recurrent patellar dislocation associated with old osteochondral fracture and to evaluate its effectiveness. METHODS: Between August 2010 and August 2014, 12 cases of recurrent patellar dislocation with old osteochondral fracture were treated. There were 4 males and 8 females with an average age of 18.3 years (range, 15-24 years). The left knee was involved in 7 cases and the right knee in 5 cases. All the patients had a history of patellar dislocation, the average interval from injury to first hospitalization was 7.6 months (range, 6-13 months). At preoperation, the range of motion (ROM) of the injured knee was (89.17 ± 13.11)degrees; the Lysholm score was 56.67 ± 18.91; the Q-angle was (17.50 ± 5.28)degrees; and tibial tuberosity-trochlear groove (TT-TG) distance was (18.33 ± 4.03) mm. The Q-angle was more than 20 degrees and TT-TG distance was more than 20 mm in 6 of 12 cases. There were 6 cases of patellar osteochondral fracture, 5 cases of lateral femoral condylar osteochondral fracture, and 1 case of patellar osteochondral fracture combined with lateral femoral condylar osteochondral fracture. After osteochondral fracture fragments were removed under arthroscope, lateral patellar retinaculum releasing and medial patellar retinaculum reefing was performed in 2 cases, medial patellofemoral ligament (MPFL) reconstruction combined with both lateral patellar retinaculum releasing and medial patellar retinaculum reefing in 4 cases, and MPFL reconstruction, lateral patellar retinaculum releasing, medial patellar retinaculum reefing, and tibial tubercle transfer in 6 cases. Results All wounds healed by first intention with no complication of infection, haematoma, skin necrosis, or bone nonunion. All patients were followed up 12-60 months with an average of 24.2 months. At 3 months after operation, all patellar dislocations were corrected; the Q-angle was (13.33 ± 1.37)degrees and the TT-TG distance was (12.17 ± 1.17) mm in 6 patients undergoing tibial tubercle transfer, showing significant differences when compared with preoperative values [(22.50 ± 2.17)degrees and (21.33 ± 2.34 mm (t = 15.25, P = 0.00; t = 8.27, P = 0.00. All patients achieved relief of knee pain and knee locking; the knee ROM and the Lysholm score at last follow-up were (120.42 ± 11.57)degrees and 89.25 ± 9.71, showing significant differences when compared with preoperative ones (t = -11.61, P = 0.00; t = -8.66, P = 0.00). CONCLUSION: It gas satisfactory short-term effectiveness to remove old osteochondral fragments that can not be rest and to correct patellar dislocation for recurrent patellar dislocation with old osteochondral fracture.