Coupling effects of hydrological characteristics and nutrient load in sediments on the trophic state of reservoirs

Currently,lakes and artificial reservoirs are increasingly threatened by eutrophication,which is the result of the combined action of many natural and anthropogenic factors.In the past,the effect of nutrient load on the trophic state of water bodies has attracted much attention,while few studies have addressed the effect of hydrological characteristics.Therefore,to reveal the coupling effects of hydrological characteristics and nutrient load in sediments on the trophic state of water bodies,this study collected relevant data from 36 lakes and reservoirs across China.Pearson correlation analysis showed that trophic level index was positively and significantly correlated with nutrient load in sediments and hydraulic retention time,while it was negatively correlated with mean depth and hydraulic load.The principal component analysis showed that the nutrient load was the first major component that influenced the trophic state of water bodies,followed by the mean depth and hydraulic retention time.Eutrophication was prone to occur in water bodies with mean depth less than 7 m and hydraulic retention time greater than 14 d,and the trophic level index regression equation with hydrological characteristics and nutrient load in sediments was derived by multiple regression analysis.This study revealed that the trophic state of water bodies influenced by both nutrient load and hydrological characteristics.It provides a new idea to reduce the occurrence of eutrophication in reservoirs by using the artificial hydrological regulation capacity of reservoirs.

Reliable sensors based on graphene textile with negative resistance variation in three dimensions

The weft-knitted reduced graphene oxide(r-GO)textile that is made up of many conductive r-GO coated fibers was successfully prepared dependent on the electrospray deposition technique.Interestingly,the r-GO textile presents negative resistance variation not only in axial direction as the pressure increases but also in transverse direction as the lateral stretch increases which makes it has the advantage to fabricate the reliable sensors based on strain-resistance effect.The transverse-strain and pressure sensors based on the r-GO textiles all show the excellent sensing characteristics such as high sensitivity,reliability,and good durability,etc.The maximum gauge factors(GF)of the transverse-sensor are 27.1 and 153.5 in the x-and/-direction,respectively.And the practical detection range can up to 40%in the x-direction and 35%in the y-direction,respectively.The r-GO textile pressure sensor also shows high sensitivity for a broad pressure range that with a GF up to 716.8 kPa-1 for less than 4.5 kPa region and still has more sensitive pressure sensing characteristics even the pressure goes up to 14 kPa.Based on those good performances of r-GO textile sensors,its potential applications in human body states monitoring have been studied.