Case study on nitrogen and phosphorus emissions from paddy field in Taihu region

The agricultural non-point source pollution by nitrogen (N) and phosphorus (P) loss from typical paddy soil (whitish soil, Bai Tu in Chinese) in the Taihu Lake region was investigated through a case study. Results shown that the net load of nutrients from white soil is 34.1 kg ha(-1) for total nitrogen (TN), distributed as 19.4 kg ha(-1), in the rice season and 14.7 kg ha(-1) in the wheat season, and for total phosphorus (TP) 1.75 kg ha(-1), distributed as 1.16 kg ha(-1) in the rice season and 0.58 kg ha(-1) in the wheat season. The major chemical species of N loss is different in the two seasons. NH4-N is main the form in the rice season (53% of TN). NO3-N is the main form in wheat season (46% of TN). Particle-P is the main form in both seasons, (about 56% of TP). The nutrient loss varied with time of the year. The main loss of nutrients happened in the 10 days after planting, 64% of TN and 42% of TP loss, respectively. Rainfall and fertilizer application are the key factors which influence nitrogen and phosphorus loss from arable land, especially rainfall events shortly after fertilizer application. So it is very important to improve the field management of the nutrients and water during the early days of planting.     

Occupational risks and the value and modelling of a measurement of severity

In studies of occupational risks, severity, which is a component of the estimation of every risk, appears as a multifaceted entity assessable according to numerous criteria. A method of measuring the degree of severity of the consequences of potentially dangerous events would be of undeniable value to organisations seeking to improve their understanding of the complexity of such events. The need to control severity is highlighted by scientifically acquired improvements in the understanding of occupational risks, by certain new regulatory obligations in Europe, and by some requirements in the financial management of organisations. We put forward a statistical way of integrating several constituent elements of severity and hence of determining a relevant, synthetic, one-dimensional index. This is achieved by means of principal component analysis (PCA), which is used here to calculate a resultant severity, as in some physical measurements. We also investigate how severity may be statistically modelled, with the aim of contributing to the quantitative assessment of occupational risks. The choice of parametric models is detailed and illustrated by the search for a suitable model for workplace accidents in an organisational setting. The practical value of modelling severity is two-fold. First, one is able to study the distribution of the numerical values of severity over a continuum (a theoretically infinite numerical set) rather than through a limited number of arbitrarily defined categories. Second, with a generally applicable parametric model, one can estimate the law of probability of a measurement of severity in a particular situation, notably recent or new. Lastly, the statistical concept of risk curve is defined and discussed. The goal is to incorporate the severity component into the risk assessment in the form of a probability law, thus circumventing the difficulties associated with an analysis of scenarios.     

COMPARISON OF DESIGN STORM CONCEPTS USING CONTINUOUS SIMULATION WITH SHORT DURATION STORMS1

ABSTRACT: The objectives of this paper were to test the ability of various design storm distributions to simulate the actual rainfall pattern and to compare the runoff rates used in the design of stormwater management devices in the State of Florida using continuous simulation approach. The analyses were performed for four gaged stations to evaluate the applicability of design storm distributions in different parts of the State of Florida. The approach used in this study compared the peak runoff rates from design storms based on the various distributions to those that would result from actual rainfall events. A series of continuous runoff rates were developed through the use of actual fifteen-minute recorded rainfall data, Horton type infiltration decay and recovery rate, and a continuous simulation model. The runoff rates were analyzed using frequency distributions to obtain peak runoff rates associated with different return periods based on the assumption that the continuous simulation approach closely predicts the actual runoff rates from the gaged stations. The results show that the behavior of the design storm distributions varies for different watershed characteristics in different parts of the state. The study also suggests that in general the Florida Department of Transportation and the Suwanne River Water Management (FDOT/ SRWMD) distributions appeared to agree with the continuous simulation results.     

Seasonal abundance and toxicity of the dinoflagellate Gambierdiscus spp. (Dinophyceae), the causative agent of ciguatera in Tahiti, French Polynesia

The benthic dinoflagellate Gambierdiscus spp. is the primary causative agent of ciguatera fish poisoning in French Polynesia. However, the initiation of ciguatera outbreaks and the factors that control ciguatoxin production in this dinoflagellate are still poorly understood. In this paper, we present some original data concerning the seasonal abundance and toxicity of natural populations of Gambierdiscus spp. based on a long-term survey in a ciguateric site of the island of Tahiti. From February 1993 to December 1997, Gambierdiscus spp. population densities were monitored weekly in the Atimaono barrier reef of Papara in relation to temperature and salinity. Densities peaked at 4992 cells g⁻¹ in October 1994 and constituted ≥1000 cells g⁻¹ on several occasions. A total of 58 blooms were recorded in the area, of which 65% occurred in 1995 and 1996 alone. Our data confirmed the high endemicity of Gambierdiscus spp. in the Papara area. Refined analysis of our raw data by a principal-component analysis of processes (PCAP) revealed a seasonality in cell densities from February 1993 to May 1995. During this period, Gambierdiscus spp. populations tended to reach maximum abundance at the beginning and end of the hot season. In contrast, salinity did not appear to be a determining factor in the seasonal abundance of this dinoflagellate. The noticeable increase in both peak densities and frequency of blooms further noticed in 1995 and 1996 was preceded by unusually high water temperatures in January to April 1994, concomitant with a severe coral-bleaching episode. During the course of the study, a total of 303 × 10⁶ cells obtained from 48 successive blooms was harvested. Toxicity screening revealed that toxin production was maximum from October 1994 through December 1996. No correlation was found between toxicity of these blooms and their biomass nor the seasonal pattern of temperatures. It is suggested that the toxicity of naturally-occurring blooms of Gambierdiscus spp. and, consequently, the severity of ciguatera incidents in a given area, is mainly dependent on the clonal nature of cells which coexist within local populations of this dinoflagellate. Received: 12 October 1998 / Accepted: 15 June 1999     

Degradation pathways of PCBs upon UV irradiation in hexane.

The photodegradations of eight individual PCB congeners (5, 31, 52, 77, 87, 126, 138, 169) in hexane have been investigated employing a mercury lamp. All degradation reactions of the above mentioned PCB congeners are of the pseudo first order. The principal products of PCB decomposition are the less chlorinated biphenyls, and no PCB-solvent adducts are found. Symmetrical and coplanar PCB congeners show lower photoreactivities. The reactivities of the chlorine atoms at various positions of PCB rings are generally in the order: ortho > meta > para. Photodechlorinations occur mainly on the more substituted rings, when the numbers of chlorine atoms on the two phenyl rings are unequal. During photodegradation, some coplanar PCB congeners are formed, which make the TEQ of solutions to decrease slowly or even to increase.     

Storm-induced transfer of particulate trace metals to the deep-sea in the Gulf of Lion (NW Mediterranean Sea)

In order to calculate budgets of particulate matter and sediment-bound contaminants leaving the continental shelf of the Gulf of Lion (GoL), settling particles were collected in March 2011 during a major storm, using sediment traps. The collecting devices were deployed in the Cap de Creus submarine canyon, which represents the main export route. Particulate matter samples were analyzed to obtain mass fluxes and contents in organic carbon, Al, Cr, Co, Ni, Cu, Zn, Cd, Pb and La, Nd and Sm. The natural or anthropogenic origin of trace metals was assessed using enrichment factors (EFs). Results are that Zn, Cu and Pb appeared to be of anthropogenic origin, whereas Ni, Co and Cr appeared to be strictly natural. The anthropogenic contribution of all elements (except Cd) was refined by acid-leaching (HCl 1 N) techniques, confirming that Zn, Cu and Pb are the elements that are the most enriched. However, although those elements are highly labile (59–77 %), they do not reflect severe enrichment (EFs <4). Most particles originate from the Rhone River. This has been confirmed by two different tracing procedures using rare earth elements ratios and concentrations of acid-leaching residual trace metals. Our results hence indicate that even in this western extremity of the GoL, storm events mainly export Rhone-derived particles via the Cap de Creus submarine canyons to the deep-sea environments. This export of material is significant as it represents about a third of the annual PTM input from the Rhone River.     

Plume rise and spread in buoyant releases from elevated sources in the lower atmosphere

This study focuses on the influence of emission conditions—velocity and temperature—on the dynamics of a buoyant gas release in the atmosphere. The investigations are performed by means of wind tunnel experiments and numerical simulations. The aim is to evaluate the reliability of a Lagrangian code to simulate the dispersion of a plume produced by pollutant emissions influenced by thermal and inertial phenomena. This numerical code implements the coupling between a Lagrangian stochastic model and an integral plume rise model being able to estimate the centroid trajectory. We verified the accuracy of the plume rise model and we investigated the ability of two Lagrangian models to evaluate the plume spread by means of comparisons between experiments and numerical solutions. A quantitative study of the performances of the models through some suitable statistical indices is presented and critically discussed. This analysis shows that an additional spread has to be introduced in the Lagrangian trajectory equation in order to account the dynamical and thermal effects induced by the source conditions.     

Three-dimensional hydrodynamic modeling of the Chicago River, Illinois

We present and describe results from a three-dimensional model applied to the Chicago River under a wet weather condition. Chicago River is an integral part of Chicago, the third largest city in United States, for recreational, commercial and industrial purposes. Although the flow in the Chicago River is supposed to be from north to south, the flow acquires a three-dimensional nature at various points in the river. The reasons for the three dimensionality of the flow can be attributed to the dynamic boundary conditions generated by combined sewer overflow (CSO) events during wet weather conditions, as well as the presence of confluences of various branches of the river with creeks and slips. This work presents the hydrodynamic application and validation of a three dimensional numerical model, which was used to simulate the flow in the Chicago River for a period of 8?days in September of 2008, during which the torrential rains in the city of Chicago led to intense CSO events. The numerical model used for the aforementioned exercise is the Environmental Fluid Dynamics Code (EFDC) which solves the three dimensional vertically hydrostatic, free surface, turbulence averaged equations of motions for a variable density fluid. The results obtained by the numerical model were validated with the help of stage values obtained from the USGS gauging station [Station No. 05536123] present inside the domain of interest. It was estimated that during the storm September 2008, several billion gallons of water were discharged into Lake Michigan from the Chicago River Controlling Works to prevent city flooding. The 3D model also provides a tool for the management of the waterways, in particular for future analysis of different alternatives being considered to reverse the Chicago River once again with the goal of preventing the passage of invasive species (e.g. Asian carp) towards the Great Lakes.     

Time and space: genetic structure of the cohorts of the common sea urchin <Emphasis Type="Italic">Paracentrotus</Emphasis><Emphasis Type="Italic">lividus</Emphasis> in Western Mediterranean

Spatio-temporal variability in settlement and recruitment, high mortality during the first life-history stages, and selection may determine the genetic structure of cohorts of long-lived marine invertebrates at small scales. We conducted a spatial and temporal analysis of the common Mediterranean Sea urchin Paracentrotus lividus to determine the genetic structure of cohorts at different scales. In Tossa de Mar (NW Mediterranean), recruitment was followed over 5 consecutive springs (2006–2010). In spring 2008, recruits and two-year-old individuals were collected at 6 locations along East and South Iberian coasts separated from 200 to over 1,100 km. All cohorts presented a high genetic diversity based on a fragment of mtCOI. Our results showed a marked genetic homogeneity in the temporal monitoring and a low degree of spatial structure in 2006. In 2008, coupled with an abnormality in the usual circulation patterns in the area, the genetic structure of the southern populations studied changed markedly, with arrival of many private haplotypes. This fact highlights the importance of point events in renewing the genetic makeup of populations, which can only be detected through analysis of the cohort structure coupling temporal and spatial perspectives.     

Heterologous overexpression of Populus euphratica BAK1;1 gene enhanced resistance to Pst DC3000 in tobacco北大核心CSCD

BRI1-ASSOCIATED RECEPTORKINASE1(BAK1), a leucine-rich repeat (LRR) receptor protein kinase, plays a significant role in brassinosteroid (BR) signaling. Furthermore, it combines with other LRR-RLKs protein to initiate immune response in plants. The objective of this study was to (1) investigate the function of the Populus euphratica BAK1;1 gene in the resistance of transgenic tobacco to Pseudomonas syringae pv. tomato DC3000 (Pst DC3000) and (2) discuss the regulation pathway of PeBAK1;1 involved in the resistance to plant pathogen. We cloned the cDNA sequence of the P. euphratica PeBAK1;1 gene, constructed the pBI121-35S::PeBAK1;1 over-expression vector, and then transformed it into wild-type tobacco by Agrobacterium-mediated transformation to obtain PeBA K 1;1-overexpressing transgenic tobacco plants. The bioinformatic analysis showed that the PeBAK1;1 protein contained all the structural features of the plant SERK family. The phylogenetic tree showed that PeBAK1;1 has the highest sequence homology with PtBAK1. The gene expression profile results indicated that the expression of PeBAK1;1 in the root was higher than that in the leaf and stem. The wild-type tobacco plants showed an obvious susceptibility to Pst DC3000, whereas the transgenic plants exhibited enhanced resistance to Pst DC3000. Compared with that of the wild-type (WT), the real-time PCR and quantitative real-time PCR analysis revealed that the expression of pathogenesis-related genes (including PR1, PR3, PR4, and PR5), BAK1-interacting receptor kinase 1 gene, and BONZAI1 gene was upregulated in 35S::PeBAK1;1 transgenic tobacco plants. In conclusion, the PeBAK1;1 gene plays a positive regulatory role in 35S::PeBAK1;1 transgenic tobacco against Pst DC3000, which can enhance the resistance of plants to pathogen. © 2018 Science Press. All rights reserved.