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1.
《自然资源学报》1993,8(4):381-384
第1期红壤丘陵森林生态系统矿质元素循环的计算机模拟·············································……李飞(1)天山北坡中段天然草场牧草产量遥感动态监测模式·························一黄敬峰桑长青冯振武(10)浙江省草山草坡的特点及开发利用战略-以常山县为例····································……何绍箕(18)江苏东沙的资源及开发潜力··················一···一···················一·························……蒋炳兴(26)藏北  相似文献   

2.
刘纪阳  薛爽  张营  刘强 《环境科学学报》2021,41(5):1930-1939
以Suwannee River NOM(SRNOM)和Upper Mississippi River NOM(UMRNOM)两种水源溶解性有机质(DOM)为代表,利用500W高压氙灯作为光源模拟太阳光,进行室内光解实验.考察了冻融前后两种DOM在不同pH条件下的光谱特性参数及其与苊的结合常数(KDOC),同时通过苊的表观光解速率常数(KOBS)研究冰相与水相中不同pH条件下DOM对苊的光解影响,并进行了相关性分析.结果表明,无论在冰相还是水相中,苊都可以直接进行光降解,同时两种DOM均能促进苊的光解.在水相中,随着pH的升高,两种DOM的SUVA254E2/E3a254a350与苊的KOBS均有上升,而KDOC则呈现下降趋势.同时KOBSKDOCa350及SUVA254均具有显著相关性.而冰相中,KOBSKDOC随pH的变化趋势与水相一致,但SUVA254E2/E3a254a350没有明显变化趋势.KOBSKDOC相比于水相也有明显下降.此外.冰相中的KOBS仅与KDOC存在显著相关,而与其他参数均无相关性,这也说明冰中的光化学反应可能具有更加复杂的机制.  相似文献   

3.
《自然资源学报》1987,2(4):381-384
第1期关于海滦河平原的缺水和引水问题······················……:·········&;#183;····&;#183;·······················……黄让堂等(l)农业水资源配置效果的计算分析··········“···一·”·······‘…….”一,’’·.........······一··,·…刘昌明杜伟(9)广东省海岸带国土资原的开发和管理·········“················一·“····“····&;#183;,.·············……徐君亮刘军(2。)红树林及其土坡·····&;#183;·····”·”·············”···········  相似文献   

4.
《自然资源学报》1989,4(4):381-384
第1期依靠科学技术进步,努力把旱作农业区的生产提高到一个新水平··················……郑重(1)黄土高原旱地农业自然生产力潜势评价··························……;..·············……张沁文等(4)建立开放系统,发展西北半干旱地区农业·······································……‘··……刘霎浩(垃)西北黄土高原半干旱一半湿润地区旱作农田降水生产潜力及开发途径·········……王立祥等(19)以山西为中心的能源基地的资源开发·······································  相似文献   

5.
《自然资源学报》2003,18(6):773-780
第1期…………………………黄河下游影响带地下水资源评价及合理开发利用邵景力赵云章崔亚莉等(1)松……………………………………………………辽盆地北部的地热资源及其开发利用方向汪在君(8)典型流域土地利用/覆被……………………………变化及其景观生态效应于兴修杨桂山李恒鹏(13)黄土丘陵小流域土地利用的时空分布及其……………与地形因子的关系邱扬傅伯杰王军等(20)…………………………………黄土高原沟壑区小流域土壤干层的分布特征何福红黄明斌党廷辉(30)黄土高原沟壑区小流域土壤NO3--N的……………积累特征及其影响因素郭胜利郝明德党廷辉(37)……………………………………黄土丘陵区小流域生态经济系统  相似文献   

6.
为探索浙江省中部地区大气细颗粒物(PM2.5)中水溶性离子的组成特征及其季节变化,采集了兰溪市市区和近郊两个站点2016年4个季节的PM2.5样品,利用双通道离子色谱对水溶性无机离子(Cl-、NO3-、SO42-、Na+、NH4+、K+、Ca2+、Mg2+)进行了定量分析.结果表明,兰溪PM2.5中离子总浓度存在明显的冬季高、夏季低的季节变化趋势,年均值为21.19 μg·m-3,约占PM2.5质量的45%;SO42-、NO3-和NH4+是水溶性离子中最主要的组分,年均浓度分别为8.11、5.92、3.87 μg·m-3.Cl-和NO3-浓度的季节变化最为显著,冬/夏浓度比接近10,其半挥发特性是导致兰溪PM2.5中离子组成呈现季节变化的重要原因.兰溪PM2.5中NO3-/SO42-比值的冬季平均值为1.18,说明流动源对兰溪PM2.5有很大贡献;夏季(以及春、秋季)时NO3-/SO42-比值较低,且与PM2.5浓度呈负相关,与矿物尘结合的硝酸根离子的较大贡献可能是导致夏季PM2.5浓度较低时NO3-/SO42-比值较高的主要原因.阴阳离子平衡、相关性及主成分分析(PCA)结果表明,矿物尘对兰溪市PM2.5的酸度及离子赋存状态有较大影响;冬季及春、秋季兰溪的PM2.5具有一定的酸性;NO3-和SO42-主要与NH4+结合,但部分可能与钙等其他组分结合;Cl-和K+主要来源于生物质燃烧,但K+的年均浓度仅为0.31 μg·m-3,说明生物质燃烧对兰溪PM2.5的贡献不大.  相似文献   

7.
《自然资源学报》1990,5(4):385-388
第1期、尹护、、少‘、了、,、Jr、J产℃,声、户2中国干旱区径流的形成及转化·························,……我国淡水湖泊资源开发探讨—以东平湖为例·····……吉林省天然矿泉水资源基本特征与开发战略········……试论攀钢基地的矿产资源体系·、························……赣江流域山丘荒地的形成、危害和开发途径··········……黄土高原主要农作物水分盈亏与雨养农业问题·····……用筑后模型估算我国植物气候生产力···················,…系统决策与作物布局—徐州地区秋作物布局实例分析赣江流域丘陵山区资源经济结构梯度的数量  相似文献   

8.
不同植被类型及土壤对径流水化学特征的影响   总被引:2,自引:1,他引:1  
在不同植被类型覆盖条件下,对降雨形成地表径流和地下径流的化学成分变化及其与土壤剖面性质的关系进行分析,结果表明:地表径流和地下径流的化学特征与雨水基本相同,阳离子主要以Ca2+为主,离子排序为Ca2+>K+>Na+>Mg2+>NH4+,阴离子以SO42-为主,SO42->NO3->Cl-.降雨形成地表径流和地下径流后,各成分浓度发生了明显的变化,水体中主要的阴阳离子如Ca2+、Mg2+、K+、Na+、SO42-、Cl-等浓度增加,与雨水相比为内贮型化学成分,地下径流中Ca2+、Mg2+、SO42-和Cl-增加的幅度显著高于地表径流.相关分析结果显示,地下径流pH受到土壤pH的强烈影响,受土壤胶体吸附的影响,水体中Ca2+、Mg2+、K+、Na+等阳离子与土壤交换性阳离子之间一般呈负相关的关系,由于阴离子容易随水流失,水体中SO42-、NO3-和Cl-与土壤相关离子之间普遍呈正相关关系.  相似文献   

9.
任坤  潘晓东  梁嘉鹏  彭聪  曾洁 《环境科学》2021,42(5):2268-2275
利用多同位素(C、N和O)和水化学方法解析贵州八步地下河流域水体中硝酸盐(NO3-)来源与转化过程,利用SIAR模型定量计算NO3-不同输入端的贡献比例.结果表明,研究区地下水NO3-污染严重,近38%的地下水样品NO3-超过饮用水限值.地下水的δ15N-NO3值介于2.3‰~30.33‰,均值9.68‰,δ18O-NO3值介于2.65‰~13.73‰,均值6.64‰,δ18O-H2O值介于-8.83‰~-7.37‰,均值-8.18‰.同位素组成(δ15N-NO3δ18O-NO3δ18O-H2O)指示硝化作用主导着流域内氮素循环.硝化作用产生的硝酸加速了碳酸盐岩溶解,导致地下水中δ13CDICδ15N-NO3存在显著负相关性(P<0.001),说明δ13CDICδ15N-NO3相结合是判断岩溶水中NO3-转化的有效手段.地下水和地表水中NO3-主要来源于土壤氮、粪肥污水和铵态氮肥料,其对地下水中NO3-贡献率分别为36.19%、33.71%和30.1%,对地表水贡献率分别为39.15%、36.08%和24.77%.岩溶流域内污水处理应同时去除污水中的NO3-和NH4+,农业区应科学施肥,以有效降低地下水中NO3-的补给通量.  相似文献   

10.
邯郸市近年来O3污染状况越发严峻,2018年夏季(6~8月),邯郸市O3日最大8 h平均浓度为175μg·m-3,超标天数达54 d,超标率59%,最高浓度达257μg·m-3.本研究应用WRF-CMAQ模式系统和光化学指标法对邯郸市夏季O3生成敏感性特征进行分析.结果表明,用H2O2/HNO3表征O3生成敏感性较其他指标在理论和模拟效果方面均更合适.基于精细化的源清单和网格分辨率,CMAQ对H2O2和HNO3有较好的模拟效果.对H2O2/HNO3的模拟结果显示,邯郸市VOCs控制区范围逐月减少,6月协同控制区范围占比最大,7月和8月以NOx控制区为主.邯郸市各区县VOCs和NOx排放量比值显著的空间差异,是O3生成敏感性差别的主要原因.VOCs/NOx<1.7的区域,其O3生成趋向于受VOCs控制,邯郸南部VOCs/NOx>6.9的区域,NOx是O3生成的主控因子,1.7x<6.9的区域更易受到VOCs和NOx的协同控制.当HCHO/NO2、O3/HNO3和O3/NOx过渡范围分别为0.35~0.6、20~35和10~25时,可以得到与H2O2/HNO3较为一致的敏感性空间分布,H2O2/(O3+NO2)不能指示出与其他指标一致的结果,表明该指标可能不适用于邯郸市.  相似文献   

11.
In New Zealand, phosphate (P) fertilisers used in agriculture are the main sources of the potentially toxic elements cadmium (Cd) and uranium (U), which occur as unwanted contaminants. New Zealand is developing draft soil guideline values (SGV) for maximum concentrations of Cd. To assess when soils under pasture for sheep production might reach a particular SGV, we analysed archived soil samples from a 23 yr P fertiliser trial. The pasture sites were at Whatawhata, North Island, New Zealand, and had received P fertiliser at the rates of 0, 30, 50 and 100 kg P ha−1 yr−1. From 1983 to 1989, P was applied as single superphosphate, from 1989 to 2006, P was applied as triple superphosphate. Soils from replicate paddocks were sampled annually to a depth of 75 mm on easy (10-20°) and steep (30-40°) slope classes. Total P, Cd and U were analysed by ICP-MS after acid digestion. Data were analysed by fitting trend lines using linear mixed models for two slope classes and for two sampling periods 1983-1989 and 1989-2006 when the soil sampling method and fertiliser type had been changed.The changes in total P, Cd and U were directly related to the type and amount of P fertiliser applied, the control treatment showed no significant change in P, Cd or U. At 50 and 100 kg P ha−1 yr−1 there were generally linear increases in total P and total U, and the same trend line applied to both time periods, but the rate of increase in P was greater on the easy slope class. For Cd, a “broken stick” model was needed to explain the data. Pre-1989, Cd increased in the 50 and 100 kg P ha−1 yr−1 treatment (0.036-0.045 mg kg−1 yr−1, respectively): post 1988 the rate of increase declined markedly on those two treatments (0.005-0.015 mg kg−1 yr−1, respectively), and declined absolutely in the 30 kg P ha−1 yr−1 treatments. The maximum content of Cd was in the 100 kg P ha−1 yr−1 treatment which reached 0.931 mg Cd kg−1 on the easy slope. For U there were steady linear increases for the 30, 50 and 100 kg P ha−1 treatments, and no significant difference between the steep and easy slopes, nor the two sampling periods, the maximum concentration obtained was 2.80 mg U kg−1 on the 100 kg P ha−1 treatment. The results suggest that at rates of P fertiliser likely to be applied to hill farms (<50 kg P ha−1 yr−1), and using P fertiliser with low Cd content, then the Cd concentration in this soil will never reach a SGV of 1 mg kg−1.  相似文献   

12.
应用紫外-可见光吸收光谱研究白塔堡河丰水期沉积物孔隙水中水溶性有机物(DOM)的来源、结构及腐殖化程度.采集白塔堡河干流13个沉积物孔隙水样品,分析DOM紫外光谱特性,推演出9个紫外光谱指数(SUVA254、E2/E4、E4/E6、E2/E3、S275~295、S350~400、A2/A1、A3/A1和A3/A2),研究DOM的组成与结构特征,评价DOM的腐殖化水平.白塔堡河沉积物孔隙水中DOM组成、机构及腐殖化水平呈现沿农村河段向城镇与城市河段递变,农村河段DOM分子量大于城镇与城市河段的,农村河段的DOM分子的聚合度、芳化度、腐殖化水平高于城镇与城市河段的,而DOM中富里酸的含量沿农村河段向城镇与城市河段增加.A2/A1、A3/A1和A3/A2和其它6个指标呈负相关,表明DOM的腐殖化水平随着A2/A1、A3/A1和A3/A2的值增大而升高,而随着其它指标的增大而降低.A2/A1、A3/A1和A3/A2更加精确地评价DOM腐殖化水平,辨识不同采样点DOM腐殖化进程.  相似文献   

13.
大气NOx测量准确性问题分析   总被引:1,自引:1,他引:0  
采用美国热电公司的NO-N02-NOx分析仪(Model 42i TL)和NOy分析仪(Model 42i NOy),在2011年1月-10月期间,对北京城市大气中的NO、NOx和NOy进行了连续在线测量.两台仪器对NO的测量结果具有较高的一致性(r>0.998,p<0.01),说明两台仪器测量精度基本一致.将NOy分析仪(Model 42i NOy)采样口处安装和不安装颗粒物过滤膜两种条件下测量的NOy结果与NO-NO2-NOx分析仪所测的NOx结果分别进行了相关性分析([NOy] =0.989x[NOx],R2 =0.993;[NOy] =1.134 ×[NOx],R2=0.959),得出以下两个结论:①以颗粒态硝酸盐为代表的颗粒物是造成NOx与NOy偏差的主要原因,其所占比例在10%左右;②目前Model 42i-TL所测NOx的浓度水平较真实值偏高,其测量值更接近气态NOy的浓度水平.为估算NO2测值被高估的程度(以2011年8月6日-15日观测数据为例),用扣除部分气态NOz物种(HONO、HNO3、PAN、PPN)的修正方法,推论出在夏季N02被高估约7%(R2=0.968).  相似文献   

14.
Lowland rice fields constitute a semi aquatic environment, which is potentially suitable for fish production. Little is known about the effect of fish on greenhouse gas emissions from integrated rice–fish systems. An experiment was carried out at the Bangladesh Agricultural University to assess the effect of the stocking of fish on methane emissions from rice fields. Common carp, Cyprinus carpio L., and Nile Tilapia, Oreochromis niloticus (L.) were stocked in a mixed culture and subjected to three different input regimes: (1) urea fertilization according to the recommendation of the Bangladesh Rice Research Institute (BRRI), (2) supplementary feeding at 2 × maintenance level and (3) an elevated feeding schedule where 4 × maintenance level was fed initially and 2 × maintenance level towards the end of the growth period. Rice only with urea fertilization according to BRRI-recommendation was included as the control. The presence of fish increased methane emissions in all three rice–fish treatments. Average emission over the cropping season was 34, 37, and 32 mg m−2 h−1 in the rice–fish treatments, respectively, and 20 mg m−2 h−1 in rice only. Apart from an increase in methane emission, a significant drop (p < 0.05) in floodwater pH and dissolved oxygen concentration was observed in the rice–fish plots. Both parameters were the lowest in the treatment where a higher feeding rate was provided. Due to the fish activity, floodwater in the rice–fish treatments was more turbid, as reflected in higher particulate inorganic matter (PIOM). An elevated level of dissolved methane was observed in the floodwater of the feed supplemented rice–fish plots. Methane emissions showed negative correlation with morning and afternoon pH of the floodwater (r = −0.46; r = −0.56, p < 0.001) and morning and afternoon dissolved oxygen level (r = −0.53; r = −0.46, p < 0.001). Positive correlations were recorded between morning and afternoon floodwater temperature (r = 0.49; r = 0.44, p < 0.001) and with air temperature (r = 0.54, p < 0.001). The results suggest that the stocking of fish has an increasing effect on methane emissions from rice fields.  相似文献   

15.
赖立  谢强  方文侃  邢明超  吴德意 《环境科学》2016,37(4):1444-1450
在磁铁矿纳米颗粒表面包被硅壳后再包被水合氧化铝,制备了具备核壳结构的磁性纳米颗粒除磷吸附剂(磁性氧化铝),通过XRD、TEM、VSM、BET比表面积测定进行了表征.XRD和TEM结果显示了核壳结构的存在,其饱和磁化强度达56.00 emu·g~(-1),比表面积达47.27 m~2·g~(-1).Langmuir模型计算的磷最大吸附量为12.90 mg·g~(-1),且在25℃和50℃下均保持稳定,反应快速,40min磷去除率达96%以上.磁性纳米吸附剂对磷的吸附与pH关系密切,在p H为5~9时磷去除率达90%以上.采用实际污水实验,最佳投量为1.25 kg·t~(-1).吸附-脱附-再生实验结果表明,磷吸附率随循环次数增加稍有下降,吸附的磷可以通过1 mol·L~(-1)的NaOH脱附,脱附率为90%左右,且吸附剂可以进行再生,具有反复利用和回收磷资源的潜力.  相似文献   

16.
This study focused on the adsorptive behaviors of humic acid onto freshly prepared hydrous MnO2(s) (δMnO2), and investigated the feasibility of employing δMnO2 for humic acid removal from drinking water. Effects of such parameters as molecular mass of humic acid, kinds of divalent cations on adsorptive behaviors and possible mechanisms involved were investigated. This study indicated that humic acid with higher molecular mass exhibited more tendency of adsorbing onto δMnO2 than that with lower molecular mass. Ca2+ facilitated more humic acid adsorption than Mg2+; UV-Vis spectra analysis indicated higher capabilities of Ca2+ coordinating with acidic functional groups of humic acid than that of Mg2+. Additionally, ζ potential characterization indicated that Ca2+ showed higher potential of increasing gz potential of δMnO2 than Mg2+. Ca2+ of 1.0 mmol/L increased ζ potential of δMnO2 from −37 mV (pH 7.9) to +7 mV (pH 7.2), while 1.0 mmol/L Mg2+ increased to lower value as −9 mV (pH 6.5), correspondingly. Fourier transform infrared (FTIR) spectra demonstrated the adsorption of humic acid onto δMnO2, showing the important roles of-COO functional groups and surface Mn-OH in the adsorption of humic acid onto δMnO2. Translated from Acta Scientiae Circumstantiae, 2005, 25(3): 351–355 [译自: 环境科学学报]  相似文献   

17.
纳米Fe3 O4-H2 O2 非均相Fenton反应催化氧化邻苯二酚   总被引:4,自引:3,他引:1  
何洁  杨晓芳  张伟军  王东升 《环境科学》2013,34(5):1773-1781
由四氧化三铁(Fe3O4)-过氧化氢(H2O2)构成的非均相Fenton体系主要利用H2O2分解产生的羟基自由基氧化去除难降解有机污染物.研究了邻苯二酚在纳米Fe3O4-H2O2构成的非均相Fenton体系中的催化氧化特征,同时对实验室制备的纳米级Fe3O4和商品微米级Fe3O4两种催化剂的催化活性进行比较,并考察了H2O2初始浓度对邻苯二酚的催化氧化的影响.结果表明,自制纳米Fe3O4-H2O2体系较商品Fe3O4-H2O2体系,能更快速地去除溶液中的邻苯二酚和总有机碳(TOC),邻苯二酚的去除率接近100%,同时能迅速催化H2O2分解.邻苯二酚的催化氧化反应遵循准一级反应动力学方程,H2O2的分解反应能用三级反应动力学方程较好拟合.此外,反应过程中铁释放低于0.3 mg.L-1,不足以启动均相Fenton反应,反应机制为由界面反应控制的非均相反应机制.  相似文献   

18.
Knowing underlying practices for current greenhouse gas (GHG) emissions is a necessary precursor for developing best management practices aimed at reducing N2O emissions. The effect of no-till management on nitrous oxide (N2O), a potent greenhouse gas, remains largely unclear, especially in perennial agroecosystems. The objective of this study was to compare direct N2O emissions associated with management events in a cover-cropped Mediterranean vineyard under conventional tillage (CT) versus no-till (NT) practices. This study took place in a wine grape vineyard over one full growing season, with a focus on the seven to ten days following vineyard floor management and precipitation events. Cumulative N2O emissions in the NT system were greater under both the vine and the tractor row compared to CT, with 0.15 ± 0.026 kg N2O-N ha−1 growing season−1 emitted from the CT vine compared to 0.22 ± 0.032 kg N2O-N ha−1 growing season−1 emitted from the NT vine and 0.13 ± 0.048 kg N2O-N ha−1growing season−1 emitted from the CT row compared to 0.19 ± 0.019 kg N2O-N ha−1 growing season−1 from the NT row. Yet these variations were not significant, indicating no differences in seasonal N2O emissions following conversion from CT to NT compared to long-term CT management. Individual management events such as fertilization and cover cropping, however, had a major impact on seasonal emissions, indicating that management events play a critical role in N2O emission patterns.  相似文献   

19.
温度对汞抑制土壤脲酶动力学影响研究   总被引:10,自引:0,他引:10  
以不同施肥方式、不同有机质含量的草甸棕壤和黑土4个土样为对象,研究了不同温度条件下,汞(Hg)对土壤脲酶动力学特征的影响.结果表明,同一类型、有机质含量高的土壤脲酶活性、酶促最大反应速度(Vmax)和Vmax/Km均高于有机质含量低的土壤,表明有机质对脲酶的吸附能力较强;黑土VmaxVmax/Km值总体上大于草甸棕壤,但酶活性和米氏常数(Km)值在不同土壤类型之间规律性较差,反映出酶活性由总酶量和酶-底物亲和力等因素共同决定;黑土Km值大小与有机质含量相一致,而草甸棕壤则相反,表明有机质含量和施肥方式均会对Km值产生影响;在最适温度以下,随温度升高,土壤的脲酶活性、VmaxVmax/Km值均增加;Hg对土壤脲酶表现出典型的反竞争性抑制现象;Hg对脲酶活性的抑制作用及对KmVmaxVmax/Km的负效应均随温度升高而有增加的趋势,揭示出土壤对脲酶的保护能力随温度升高而有所下降.  相似文献   

20.
Evaluation of denitrification capacities is necessary to develop a sustainable manure management system in order to reduce NO3 leaching and N2O emissions from agricultural soils. Denitrification rates were measured using the acetylene inhibition technique on intact soil cores from eight Andosols under three different cropping systems in an intensive livestock catchment of central Japan. The N application rates ranged from 200 to 800 kg N ha−1 yr−1. The denitrification rates were highly variable across fields, and were influenced significantly by land uses and manure forms. Compared with upland fields, paddy rice fields had a greater denitrification rate up to 1380 and 85 mg N m−2 day−1 in the top 30-cm soil layer during flooding and non-flooding periods, respectively. In upland fields, the maximum value for the top 30-cm soils was 44 mg N m−2 day−1 and most of the rates were less than 10 mg N m−2 day−1. The greater denitrification rates were often associated with slurry application rather than composted dry manure. Overall, denitrification from Andosols in this study displayed a lower capacity than that of non-Andosols.  相似文献   

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