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Rainfall makes impacts on the process of solidification/stabilization (S/S) and the long-term safety of solidified matrix. In this study, the effect of rainfall on solidification/stabilization process was investigated by the rainfall test. The unconfined compressive strength (UCS) and toxicity characteristic leaching procedure (TCLP) were adopted to characterize the properties of S/S sediments before and after the rainfall test. The samples cured for 28 days were selected for semi-dynamic leaching tests with a simulated acidic leachant prepared at pH of 2.0, 4.0 and 7.0. The effectiveness of S/S treatment was evaluated by diffusion coefficient ( D e ) and leachability index (LX). The results indicated that UCS decreased at maximum deterioration rate of 34.23% after 7 days of curing, along with the minimum rate of 7.98% after 28 days by rainfall, with greater than 14 days referred. The rainfall had little effect on the leaching characteristics of heavy metals during the curing process. However, the simulated acid rain made significant impacts on the leaching behaviours of the heavy metals in the S/S materials. All the values of cumulative fraction of leached heavy metals were less than 2.0%, exhibition of good stabilization of cement. Furthermore, the calculated diffusion coefficient ( D e ) for Cu was 1.28 × 10 1 cm 2 s –1 , indicating its low mobility of heavy metal ions in S/S sediments. Furthermore, the calculated diffusion coefficients ( D i ) for Cd, Cu and Pb were 7.44 × 10 −11 , 8.18 × 10 −12 and 7.85 × 10 −12 cm 2 s –1 , respectively, indicating their relatively low mobility of heavy metal in S/S sediments.

In this work, mesoporous aluminosilicate supports (Al-SBA-15) were prepared using in situ “pH-adjusting” method, and Ag nanoparticles were supported on Al-SBA-15 supports by using the simple impregnation method. The effect of the Si/Al ratios of mesoporous support on the structure of Ag catalysts and the catalytic performance for the preferential oxidation of CO (CO PROX) in H2-rich gases was investigated. The Ag/Al-SBA-15 catalyst with an appropriate Si/Al molar ratio of 200 has been found to show highly catalytic activity, selectivity and stability. A series of supports and corresponding supported Ag catalysts with different Si/Al ratios were characterized by ICP-AES, XRD, N2 adsorption–desorption, 27Al NMR, FT-IR of adsorbed pyridine, TEM, H2-TPR and XPS. The results indicated that the addition of a small amount of Al is beneficial to the formation of small sized highly dispersed metal Ag particles in the channel, consequently improving the catalytic activity. In addition, the Ag/Al-SBA-15 (200) catalyst also exhibited better catalytic activity under the presence of H2O and CO2 in the stream.

The Yangtze River estuary (YRE) and Hangzhou Bay (HZB) is of environmental significance because of the negative impact from industrial activities and rapid development of aquaculture on the south bank of HZB (SHZB) in recent years. This study investigated the distribution and risk assessments of trace metals (Cr, Cu, Zn, Hg, Pb, and Cd) accumulated in surface sediments by sampling in YRE, outer and south HZB. Copper and Zn concentration (avg. 35.4 and 98.7 mg kg-1, respectively) in surface sediments were generally higher than the background suggesting a widespread of Cu and Zn in the coastal area of Yangtze River Delta. High concentrations of Cu (~ 42 mg kg-1), Zn (~ 111 mg kg-1), Cd (~ 0.27 mg kg-1), and Hg (~ 0.047 mg kg-1) were found in inner estuary of YRE and decreased offshore as a result of terrestrial input and dilution effect of total metal contents by "cleaner" sediments from the adjacent sea. In outer HZB, accumulation of terrestrial derived metal has taken place near the Zhoushan Islands. Increase in sediment metal concentration from the west (inner) to the east (outer) of SHZB gave rise to the input of fine-grained sediments contaminated with metals from outer bay. According the results from geoaccumulation index, nearly 75% of samples from YRE were moderately polluted (1.0

Quantifying the effects of forests on water and soil conservation helps further understanding of ecological functions and improving vegetation reconstruction in water-eroded areas. Studies on the effects of vegetation on water and soil conservation have generally focused on vegetation types or vegetation horizontal distribution densities. However, only a few studies have used indicators that consider the vegetation vertical distribution. This study used the leaf area index (LAI) to investigate the relationship between forests and water and soil conservation in experimental plots. From 2007 to 2010, rainfall characteristics, LAI, and water and soil loss in 144 natural erosive rainfall events were measured from five pure tree plots (Pinus massoniana). These tree plots were located in Hetian Town, Changting County, Fujian Province, which is a typical water-eroded area in Southern China. Quadratic polynomial regression models for LAI and water/soil conservation effects (RE/SE) were established for each plot. The RE and SE corresponded to the ratios of the runoff depth (RD) and the soil loss (SL) of each pure tree plot to those of the control plot under each rainfall event. The transformation LAIs of the LAI–RE and LAI–SE curves, as well as the rainfall characteristics for the different water/soil conservation effects, were computed. The increasing LAI resulted in descending, descending–ascending, ascending–descending, and ascending trends in the LAI–RE and LAI–SE curves. The rainfall frequencies corresponding to each trend of LAI–RE and LAI–SE were different, and the rainfall distributions were not uniform per year. The effects of soil conservation in the plots were superior to those of water conservation. Most of the RE and SE values presented a positive effect on water and soil conservation. The main factor that caused different effects was rainfall intensity. During heavy rains (e.g., rainfall erosivity R = 145 MJmm/hah and maximum 30 min intensity I30 = 13 mm/h), the main effects were positive, whereas light rains (e.g., R = 70 MJmm/hah and I30 = 8 mm/h) generally led to negative effects. When the rainfall erosivity was lower than that of the positive or the negative effects to a threshold and the tree LAI reached a transform- ation value, the relationships between LAI and RE or SE notably transformed. Results showed that the plot-transformation LAIs for water and soil conservation during rainfall events were both approximately 1.0 in our study. These results could be used to come up with a more efficient way to alleviate water and soil loss in water-eroded areas.

Quantitative analysis of time scale effects is conducive to further understanding of vegetation water and soil conservation mechanism. Based on the observation data of the grass covered and bare soil (control) experimental plots located in Hetian Town, Changting County of Fujian Province from 2007 to 2010, the characteristics of 4 parameters (precipitation, vegetation, RE and SE) were analyzed at precipitation event, month, season, and annual scales, and then the linear regression models were established to describe the relationships between RE(SE) and its influencing factors of precipitation and vegetation. RE (SE) means the ratio of runoff depth (soil loss) of grass covered plot to that of the control plot. Results show that these 4 parameters presented different magnitude and variation on different time scales. RE and SE were relatively stable either within or among different time scales due to their ratios reducing the influence of other factors. The coupling of precipitation and vegetation led to better water conservation effect at lower RE (< 0.3) at precipitation event scale as well as at season scale, while the water conservation effect was dominated by precipitation at slightly higher (0.3-0.4) and higher (>0.7) REs at precipitation event scale as well as at annual scale (R2 > 0.78). For the soil conservation effect, precipitation or/and vegetation was/were the dominated influence factor(s) at precipitation event and annual scales, and the grass LAI could basically describe the positive conservation effect (SE0.55), while the maximum 30 min intensity (I30) could describe the negative conservation effect more accurately (SE>1, R2>0.79). More uncertainties (R2≈0.4) exist in the models of both RE and SE at two moderate time scales (month and season). Consequently, factors influencing water and soil conservation effect of grass present different variation and coupling characteristics on different time scales, indicating the importance of time scale at the study on water and soil conservation.

Assessing the effects of vegetation on water and soil conversation is the key basis for research and management of ecological restoration on water-eroded areas. In this study, the runoff depth, soil loss and corresponding precipitation of five plots planted respectively with Pueraria lobata, Lespedeza bicolor Turcz, Manglietia yuyuanensis Law, Paspalum natatu Fliigge, Paspalum wettsteinii Hackel and one control plot were observed monthly from 2003 to 2010 in Hetian town of Changting County, Fujian Province, a typical water-eroded area in southern China. Then the effects of different vegetation on water/soil conversation (RE/SE) were determined using the ratios of runoff depth/soil loss between vegetated plots to the control plot. Meanwhile, the effect of rainfall on the water and soil loss was also analyzed. The results showed that, both the water and soil conservation effects of Pueraria lobata and Manglietia yuyuanensis Law are better than Lespedeza bicolor Turcz and Paspalum natatu, while Paspalum wettsteinii Hackel are the worst. The differences of effects of water conservation are more significantly than those of soil conversation between five kinds of vegetations. The runoff depth is mainly affected by rainfall, the determination coefficients (R2) of linear regression models between rainfall and runoff depth of all planted plots are all greater than 0.9, whereas the determination coefficients of the linear regression models between rainfall and soil loss vary form 0.3 to 0.8 for different vegetated plots. These results provide a reference for vegetation reconstruction in the current and similar areas.