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Acid rain phenomenon of the Pearl River Delta region is growing, and bring a range of ecological issues, especially the impact on surface water quality. Select Moso bamboo, lychee, broad-leaved forest three major water conservation forest in Guangzhou, an important water source Liuxihe National Forest Park, several water samples (precipitation, penetrating rain, stemflow, surface runoff, subsurface flow, collection, analysis and comprehensive evaluation of the water quality of runoff), purification function of chemical deposition of three different types of water conservation forests. 1. The Liuxihe the rainfall season changed greatly, pH values ??and rainfall negatively related to significantly lower pH in the rainy season and dry season peaceful water pH value is relatively high. The rainfall year weighted average pH of 4.52, 52% frequency of acid rain. Precipitation of major cations as Ca2 and NH4, the annual weighted average concentration of 48.47μeq / L and the 27.13μeq / L, of Zn2 (1.46μeq / L), Pb2 (0.08μeq / L) and the Cu2 (0.06μeq / L) heavy metal ions are present in small amounts. The major anions SO42-, weighted average 81.75μeq / L, accounted for 61.29% of the total amount of anions. The other anions Cl-, F-, NO3-weighted average, respectively 35.81μeq / L, 7.4μeq / L, and 7.73μeq / L. The Liuxihe the acid rain type as sulfate, SO42-pollution anion. 2. Chemical composition of rainwater from different sources, where most of the Mg (34.8%) and Cl (25.11%), a small part of the Ca (0.71%), K (1.51%) and SO42-(1.16%) comes from the ocean, marine source of precipitation, F-, NO3-, total P, Pb2, Al3, Cu2, Zn2 contribution is very small and can be ignored. Al and toxic heavy metal elements Cu, Zn and Pb from the surrounding area for the mining and refining of the ore, and N and P are mainly derived from the emissions generated in the production process of the fertilizer plant and dust, SO42-contaminants from the surrounding areas the near-distance transmission. 3. Ca2, Mg2, K through the forest canopy showed strong leaching concentration rise sharply; NH4, F, Cu2, Zn2?? Building ended swindle Su Ji ǘ fuel the Municipal? Forest canopy showed adsorption function; NO3-and SO42-exhibit different laws in the bamboo forest and broadleaf forest, broadleaf forest concentration decreases, while a slight increase in concentration after bamboo forest, Pb2 performed contrary to law, and species characteristics related. Leaved canopy layer of the NO3-and SO42-strong impoundment and storage filter function, penetrating the higher concentration of Pb2 perhaps more due to the broad-leaved canopy layer of Pb dry deposition precipitation scouring concentration rise. Water ion concentration of the soil surface and canopy water, most of the ions showed the trend of concentration, SO42-, NH4 and NO3-increase may be due to the soil surface litter decomposition, soil surface the acidification is important reasons; other ions, CA2, Mg2, Zn2, Cu2, Pb2 reduced by the concentration of the soil surface, soil surface leading to Al3 increase of these ions exhibit a strong purification and absorption function. Overall the water forest ecosystem soil layer and vegetation layer has strong purification and storage reservoir function, reducing the total runoff outside the F-ion concentration. Li Zhilin total runoff in the concentration of NO3-and Al3 higher than precipitation, the NO3-more due to anthropogenic disturbance larger, Al3 too much is due to Li Zhilin soil acidification is more serious. 5 different forest types the different purification ability of the ion. Anion SO42-, NO3-and cation NH4, Ca2, Mg2, Al3 heavy metal ions purification capacity, broad-leaved forest strongest, Li Zhilin worst. In heavy rain, especially under the conditions of typhoons and storms, the total runoff ions such as Pb2 concentration has remained stable change is due to its content of less forest has strong adsorption function; Some ions such as Al3, Cu2, Zn2 their concentration and NH4 flood peak after peak performance lag, poor mobility of the metal ions, and precipitation is not easy, easy to accumulate, and NH4 is not timely complete nitrification and led to the deposition of high concentration; Other ions such as NO3-, Ca2, Mg2, the concentration of K peak appeared in the flood peak before described the stronger its mobility. COD concentration of three water forest runoff peak rainfall conditions in the flood peak after and its major pollutants, the major pollutants of the broad-leaved forest of NH4, bamboo and Li Zhilin pollutants compared with Al3. 7 found through a comprehensive evaluation of the three water conservation forest runoff water quality, changes in water quality have significant seasonal fluctuations. Broadleaf forest and bamboo groves dry season (12 - next February), the water quality is relatively poor, single water quality above the standard, comprehensive water quality is generally Ⅱ and Ⅲ water quality. Broad-leaved forest runoff pollutants P is mainly produced by the decomposition of litter; the bamboo forest runoff pollutants for N and P, the bamboo forest fertilizer conservation relatively poor, leading to the weathering of rocks and litter decomposition N and P loss. By human disturbance larger Li Zhilin, the total runoff of pollutants is N, the summer season of frequent human farming the water quality is relatively poor. Overall, in addition to Li Zhilin, the Liuxihe water total forest runoff water quality better throughout the year belongs Ⅰ and Ⅱ Grade.
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