Development and In Situ Application of Deformation Monitoring System for Concrete-Face Rockfill Dam Using Fiber Optic Gyroscope.

Deformation monitoring is of importance to ensure the operation status of concrete-face rockfill dams (CFRD). This paper reported a novel fiber optic gyroscope (FOG) monitoring system for continuously monitoring face slab deformation of CFRD, which consisted of a permanent monitoring pipeline and a sensing vehicle. The monitoring pipeline was made of steel pipes and polyvinyl chloride polymer connectors, which was embedded in a slot of the crushing-type sidewall beneath the concrete face slab of CFRD, forming a permanent monitoring channel. The sensing vehicle was equipped with a high-precision FOG sensor. A low-pass filter was designed to eliminate the vibration noise of the angular velocities of the sensing vehicle during the monitoring process. An in situ test was carried out on the Shuibuya dam, the highest CFRD in the world. The measurements of the FOG monitoring system agreed well with traditional instrument measurements, serving as validation of the system. The FOG monitoring system has the advantages of excellent repeatability, long service life, distributed monitoring, and automatic measurement.

The evolution of crop cultivation and paleoenvironment in the Longji Terraces, southern China: Organic geochemical evidence from paleosols.

The Longji ancient agricultural terraces in the Longji Mountain area (Guilin, southern China), which still remain in use, are famous for their magnificent terraced landscape with a mix of ecosystem and human inhabitation. Previous research has revealed the genesis and preliminary paleoenvironmental record of the agricultural terraces, but little is known about variations in crop cultivation over time. In this study, organic geochemical analyses and radiocarbon dating of an aggradational cultivated soil from a terrace profile were used to explore crop type variation and relevant paleoenvironmental change during the period of cultivation on the Longji Terraces. Hydroponic farming with rice (C3) planting has been the dominant cultivation mode since the initial construction of the terraces. Warm-dry climate contributed to the growth of drought-tolerant crop (C4) cultivation in the late 15th century. Temperature deterioration during the Little Ice Age had a negative impact on dry and hydroponic farming activities from the late 15th century to the late 19th century, while climate warming after the Little Ice Age promoted the redevelopment of hydroponic farming.

[Soil fertility characteristics under different land use patterns in depressions between karst hills].

Soil samples were collected from the depressions between karst hills by grid sampling method (5 m x 5 m), soil pH, soil organic carbon (SOC), total nitrogen (TN), total phosphorus (TP), total potassium (TK), available nitrogen (AN), available phosphorus (AP), and available potassium (AK) in surface layer (0-20 cm) under different land use patterns (burning, cutting, cutting plus root removal, enclosure, maize plantation, and pasture plantation) were measured, the main factors of influencing the soil fertility was identified by principal component analysis (PCA), and the relationships between soil nutrients and microorganisms were demonstrated by canonical correlation analysis (CCA). The results showed that the soil was slightly alkaline (pH 7.83-7.98), and the soil fertility differed under the different land use patterns, with 76.78-116.05 g x kg(-1) of SOC, 4.29-6.23 g x kg(-1) of TN, 1.15-1.47 g x kg(-1) of TP, 3.59-6.05 g x kg(-1) of TK, 331.49-505.49 mg x kg(-1) of AN), 3.92-10.91 mg x kg(-1) of AP, and 136.28-198.10 mg x kg(-1) of AK. These soil indexes except pH showed moderate or strong variation. Different land use patterns had various impacts on soil fertility: Soil nutrients such as SOC, TN, TP, and AN were most significantly influenced by land use patterns in the depressions between karst hills; Followed by soil microorganisms, especially soil actinomycetes, and the effect decreased with the increasing gradient of human disturbance from enclosure, burning, cutting, cutting plus root removal, pasture plantation, and maize plantation. CCA elucidated that considerable interactions existed in soil TP with MBP (microbial biomass phosphorus), TK with MBC (microbial biomass carbon), TN with actinomycetes in the burned area, while TN and MBC in the cutting treatment, AP and MBN (microbial biomass nitrogen) in the treatment of cutting plus root removal, pH with MBC and fungus in the enclosure treatment, TN and TK with MBP in the maize plantation, pH with fungi and actinomycetes in the pasture plantation. Land use patterns changed the soil fertility in the depressions between karst hills; therefore, in the ecological restoration and reconstruction of karst region with fragmented landforms and shallow soil, rational land use patterns should be adopted to improve the soil quality of degraded ecosystems.

[Choice of macroinvertebrate metrics for constructing a benthic-index of biotic integrity based on the disturbance gradients in the Qinjiang River Basin].

The selection of proper macroinvertebrate metrics was a key step in the successful construction of benthic-index of biotic integrity (B-IBI). In the context of lack of sufficient reference sites, the responses of biotic metrics to the stress gradients have been proved crucially important in metrics selection. We explored this using a data set (twenty-two sampling sites), where water environmental parameters, habitat quality index (HQI) and zoobenthos were measured and sampled using standardized methodology in the winter dry season (January, 2010) within the Qinjiang Rvier basin, Guangxi. Water quality stress gradients were synthesized using principle component analysis. Twelve out of the 38 candidate metrics were excluded because of high co-linearity ( [ r ] > 0.80, P < 0.05) with others. Multiple regression analysis of the rest twenty-six metrics, environmental gradients (PC I and PC II ) and habitat quality index showed that thirteen metrics significantly correlated (P < 0.05) with the environmental stressors (PCs and HQI). Eight of these metrics, family richness, Ephemeroptera richness, Coleoptera richness; Ephemeroptera, Plecoptera and Trichoptera (EPT) abundance, proportion of dominant species; proportion of predators; Shannon-Weaver diversity index for genus; and Biotic index (BI), satisfied the selection criteria (e. g., operational simplicity) and were thus candidates for developing a multimetric system to assess river health in our study region. We suggest that the response of metrics to environmental gradient is an ideal alternative for the construction of benthic-index of biotic integrity in the context of insufficient reference sites.

[Litter decomposition of dominant plantations in Guangxi and its effects on leachate quality].

To understand the decomposition characteristics of the litters in different forest plantations and the effects of released substances during litter decomposition on the leachate quality, litter samples (leaf, shoot, and cortices) were collected from five forest plantations (1 year-old Eucalyptus urophylla x E. grandis, EU1; 4 year-old Eucalyptus urophylla x E. grandis, EU4; 7 year-old Acacia mangium x A. auriculaef, AM; 13 year-old Pinus massoniana Lamb, PL; and mixed broad-leaved softwood, BL), and incubated at 28 degrees C, using water leached for 255 days. In the first 105 days, the litter leachates of EU1 and EU4 had significantly higher coloration and N and P contents and lower pH than those of AM, PL, and BL. On the 255th day, the cumulative chemical oxygen demand (COD) in the leaf litters leachates of EU1 and EU4 was 193.9 and 212.8 g x kg(-1), being 4.2, 4.0, and 4.3 times and 5.3, 4.4, and 4.7 times higher than that of AM, PL, and BL, respectively. The mass loss rate and the N and P leaching rate of the leaf litter of EU1 were significantly higher than those of AM, PL, and BL. The mass loss rate of cortices of EU1 was significantly higher than that of PL. No significant difference was observed for the leaching rate of the shoot litters between AM, PL, and BL. Among the litter samples, leaf litter was easiest to be decomposed, while shoot litter was most difficult to be decomposed. The pH value of the litter leachates of Eucalyptus plantations was significantly negatively correlated with leachate chroma and COD, and the COD had significant positive correlations with the concentrations of total N and P in the leachates.