Potential groundwater recharge zones within New Zealand

Water resources in New Zealand are not evenly distributed across the country which makes it difficult to adequately allocate the use of water resources in every basin. Groundwater is a fundamental water resource in New Zealand for agricultural, industrial and domestic use. Detailed knowledge regarding groundwater recharge potential is a pre-requisite for sustainable groundwater management, including the assessment of its vulnerability to contamination by pollutants. In this study, a comprehensive GIS approach was used to map the potential groundwater recharge zones across New Zealand. National data sets of lithology, slope, aspect, land use, soil drainage and drainage density were converted to raster data sets with a spatial resolution of 500 m x 500 m and superimposed to derive groundwater potential zones. The resultant maps demonstrate that the potential is low in urban and mountainous areas, such as the Southern Alps, whereas the highest potential can be found in regions with large lakes and in the lower elevation plains areas, where Quaternary sediments prevail. The resulting maps can be used to identify areas of high nutrient leaching in zones where high groundwater recharge potential exists.

An Adaptive Estimation of Forecast Error Covariance Parameters for Kalman Filtering Data Assimilation

An adaptive estimation of forecast error covariance matrices is proposed for Kalman filtering data assim- ilation. A forecast error covariance matrix is initially estimated using an ensemble of perturbation forecasts. This initially estimated matrix is then adjusted with scale parameters that are adaptively estimated by minimizing -2log-likelihood of observed-minus-forecast residuals. The proposed approach could be applied to Kalman filtering data assimilation with imperfect models when the model error statistics are not known. A simple nonlinear model （Burgers＇ equation model） is used to demonstrate the efficacy of the proposed approach.

Climate change in the Tianshan and northern Kunlun Mountains based on GCM simulation ensemble with Bayesian model averaging

Climate change in mountainous regions has significant impacts on hydrological and ecological systems. This research studied the future temperature, precipitation and snowfall in the 21^（st） century for the Tianshan and northern Kunlun Mountains（TKM） based on the general circulation model（GCM） simulation ensemble from the coupled model intercomparison project phase 5（CMIP5） under the representative concentration pathway（RCP） lower emission scenario RCP4.5 and higher emission scenario RCP8.5 using the Bayesian model averaging（BMA） technique. Results show that（1） BMA significantly outperformed the simple ensemble analysis and BMA mean matches all the three observed climate variables;（2） at the end of the 21^（st） century（2070–2099） under RCP8.5, compared to the control period（1976–2005）, annual mean temperature and mean annual precipitation will rise considerably by 4.8°C and 5.2%, respectively, while mean annual snowfall will dramatically decrease by 26.5%;（3） precipitation will increase in the northern Tianshan region while decrease in the Amu Darya Basin. Snowfall will significantly decrease in the western TKM. Mean annual snowfall fraction will also decrease from 0.56 of 1976–2005 to 0.42 of 2070–2099 under RCP8.5; and（4） snowfall shows a high sensitivity to temperature in autumn and spring while a low sensitivity in winter, with the highest sensitivity values occurring at the edge areas of TKM. The projections mean that flood risk will increase and solid water storage will decrease.

Nitrogen pollution and source identification of urban ecosystem surface water in Beijing

Nitrogen contamination of surface water is a worldwide environmental problem with intensive agricul- ture and high population densities. We assessed the spatial and seasonal variation in concentrations of total nitrogen and different nitrogen species present in surface-water in Beijing, China. Also, chemical （NO3-N/C1-） and isotopic （615Nnitrate） indicators were used to identify nitrate sources. The results showed that, during 2009 and 2010, nitrate nitrogen concentrations ranged from 0.7 to 7.6 mg· L^-1, ammonium nitrogen from 0. I to 3.4 mg· L^-1, and total nitrogen from 2.4 to 17.0mg· L^-1. Inorganic nitrogen accounted for between 60 and 100% of total nitrogen at the ten monitoring sites. Nitrate nitrogen, ammonium nitrogen, and total nitrogen concentrations at the 2 downstream monitoring sites in south-eastern Beijing were significantly higher than those at the other eight upstream monitoring sites （P 〈 0.01）. Examination of seasonal variation showed that there was a significant inverse relationship between nitrate nitrogen concentrations and precipitation, and that nitrate nitrogen concentrations peaked in the dry seasons. The information given by the 15Nnitrate values and nitrate nitrogen concentrations, combined with the NO3-N/C1- ratio distribution, showed that domestic sewage was the major source of nitrate in Beijing. Methods to control and reduce sewage pollution are urgently needed to help manage surface water quality in Beijing.

Nitrate in shallow groundwater in typical agricultural and forest ecosystems in China,2004-2010

The nitrate-nitrogen（NO 3-N） concentrations from shallow groundwater wells situated in 29 of the Chinese Ecosystem Research Network field stations,representing typical agroand forest ecosystems,were assessed using monitoring data collected between 2004 and 2010.Results from this assessment permit a national scale assessment of nitrate concentrations in shallow groundwater,and allow linkages between nitrate concentrations in groundwater and broad land use categories to be made.Results indicated that most of the NO 3--N concentrations in groundwater from the agroand forest ecosystems were below the Class 3 drinking water standard stated in the Chinese National Standard：Quality Standard for Ground Water（≤ 20 mg/L）.Over the study period,the average NO 3--N concentrations were significantly higher in agro-ecosystems（4.1 ± 0.33 mg/L） than in forest ecosystems（0.5 ± 0.04 mg/L）.NO 3-N concentrations were relatively higher（〉 10 mg N /L） in 10 of the 43 wells sampled in the agricultural ecosystems.These elevated concentrations occurred mainly in the Ansai,Yucheng,Linze,Fukang,Akesu,and Cele field sites,which were located in arid and semiarid areas where irrigation rates are high.We suggest that improvements in N fertilizer application and irrigation management practices in the arid and semi-arid agricultural ecosystems of China are the key to managing groundwater nitrate concentrations.

Surface and tropospheric ozone trends in the Southern Hemisphere since 1990: possible linkages to poleward expansion of the Hadley circulation

Increases in free tropospheric ozone over the past two decades are mainly in the Northern Hemisphere that have been widely documented,while ozone trends in the Southern Hemisphere(SH)remain largely unexplained.Here we first show that in-situ and satellite observations document increases of tropospheric ozone in the SH over 1990–2015.We then use a global chemical transport model to diagnose drivers of these trends.We find that increases of anthropogenic emissions(including methane)are not the most significant contributors.Instead,we explain the trend as due to changes in meteorology,and particularly in transport patterns.We propose a possible linkage of the ozone increases to meridional transport pattern shifts driven by poleward expansion of the SH Hadley circulation(SHHC).The SHHC poleward expansion allows more downward transport of ozone from the stratosphere to the troposphere at higher latitudes,and also enhances tropospheric ozone production through stronger lifting of tropical ozone precursors to the upper troposphere.These together may lead to increasing tropospheric ozone in the extratropical SH,particularly in the middle/upper troposphere and in austral autumn.Poleward expansion of the Hadley circulation is partly driven by greenhouse warming,and the associated increase in tropospheric ozone potentially provides a positive climate feedback amplifying the warming that merits further quantification.

PyLUR:Efficient software for land use regression modeling the spatial distribution of air pollutants using GDAL/OGR library in Python

Land use regression(LUR)models have been widely used in air pollution modeling.This regressionbased approach estimates the ambient pollutant concentrations at un-sampled points of interest by considering the relationship between ambient concentrations and several predictor variables selected from the surrounding environment.Although conceptually quite simple,its successful implementation requires detailed knowledge of the area,expertise in GIS,statistics,and programming skills,which makes this modeling approach relatively inaccessible to novice users.In this contribution,we present a LUR modeling and pollution-mapping software named PyLUR.It uses GDAL/OGR libraries based on the Python platform and can build a LUR model and generate pollutant concentration maps efficiently.This self-developed software comprises four modules:a potential predictor variable generation module,a regression modeling module,a model validation module,and a prediction and mapping module.The performance of the newly developed PyLUR is compared to an existing LUR modeling software called RLUR(with similar functions implemented on R language platform)in terms of model accuracy,processing efficiency and software stability.The results show that PyLUR out-performs RLUR for modeling in the Bradford and Auckland case studies examined.Furthermore,PyLUR is much more efficient in data processing and it has a capability to handle detailed GIS input data.

Numerical Simulation Study on the Scientific and Methodological Aspects of the Brazilian Proposal

In this paper, by using a simple climate model (SCM), a numerical simulationstudy has been conducted on the scientific and methodological aspects of Brazilian Proposal. Firstthe initial check of simple climate model has been done, then we do some sensitivity studies ontimeframes (attribution start and end dates, and evaluation date), and three attribution methods(marginal attribution method, proportional attribution method, and time-sliced attribution method),at last we get the main conclusions as follows: The simple climate model can represent the resultsof more complex climate model (e.g., HadCM3), and it is thus used to study the scientific andmethodological aspects of the Brazilian Proposal. Because of the limited knowledge of science anddata, although attributing a part of temperature increase to different GHG (greenhouse gas) emissionsource, there is considerable temperature increase unattributed to regional emissions. Therefore itis uncertain to make Brazilian Proposal as the method for the responsibility share of future GHGdecrease emission. The choices of different timeframes (attribution start and end dates, andevaluation date) and future emission SRES (Special Report on Emission Scenarios) make greatinfluence on the regional contributions to global climate changes, but different attribution methodshave only a little influence.

Integrated bioremediation techniques in a shrimp farming environment under controlled conditions

This study investigated the integrated bioremediation techniques for a shrimp culture system to reduce unconsumed feed and the contents of suspended solids（SS）, nutrients and organic pollutants using barracuda,clamworm, scallop, large algae and a biofilter. A multi-pool internal circulation system was designed to test the effectiveness of the techniques in the laboratory. The experimental result has shown that Argopecten irradians,Gracilaria lemaneiformis and the biofilter efficiently reduced the contents of SS, dissolved inorganic carbon（DIC）and dissolved organic carbon（DOC） in the breeding wastewater. The amount of unconsumed feed was significantly reduced by barracuda and clamworm, but there was an increase in the contents of SS, DIC and DOC in the water due to disturbance by the barracuda and clamworm. The capacity of macroalgae to extract inorganic nitrogen was insufficient. However, the balance of the nitrogen fixation rate of macroalgae and the biological exhaust nitrogen rate within the system should be fully considered. The use of the biofilter alone was not optimal for the remediation of organic matter in shrimp effluent so that auxiliary foam separation technology is needed to improve the ability of the system to remove macromolecules. This study provides a basis for the further development of remediation techniques to reduce the environmental impact of shrimp aquaculture.